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-rw-r--r--arch/Kconfig7
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--arch/x86/include/asm/Kbuild1
-rw-r--r--arch/x86/include/asm/a.out-core.h10
-rw-r--r--arch/x86/include/asm/debugreg.h33
-rw-r--r--arch/x86/include/asm/hw_breakpoint.h73
-rw-r--r--arch/x86/include/asm/processor.h14
-rw-r--r--arch/x86/kernel/Makefile2
-rw-r--r--arch/x86/kernel/hw_breakpoint.c545
-rw-r--r--arch/x86/kernel/kgdb.c6
-rw-r--r--arch/x86/kernel/kprobes.c9
-rw-r--r--arch/x86/kernel/machine_kexec_32.c2
-rw-r--r--arch/x86/kernel/machine_kexec_64.c2
-rw-r--r--arch/x86/kernel/process.c21
-rw-r--r--arch/x86/kernel/process_32.c6
-rw-r--r--arch/x86/kernel/process_64.c7
-rw-r--r--arch/x86/kernel/ptrace.c293
-rw-r--r--arch/x86/kernel/signal.c9
-rw-r--r--arch/x86/kernel/traps.c73
-rw-r--r--arch/x86/kvm/x86.c18
-rw-r--r--arch/x86/mm/kmmio.c8
-rw-r--r--arch/x86/power/cpu.c26
-rw-r--r--include/linux/hw_breakpoint.h137
-rw-r--r--include/linux/perf_event.h37
-rw-r--r--kernel/Makefile1
-rw-r--r--kernel/exit.c5
-rw-r--r--kernel/hw_breakpoint.c494
-rw-r--r--kernel/kallsyms.c1
-rw-r--r--kernel/perf_event.c136
-rw-r--r--kernel/trace/Kconfig21
-rw-r--r--kernel/trace/Makefile1
-rw-r--r--kernel/trace/trace.h7
-rw-r--r--kernel/trace/trace_entries.h16
-rw-r--r--kernel/trace/trace_ksym.c554
-rw-r--r--kernel/trace/trace_selftest.c55
-rw-r--r--samples/Kconfig6
-rw-r--r--samples/Makefile3
-rw-r--r--samples/hw_breakpoint/Makefile1
-rw-r--r--samples/hw_breakpoint/data_breakpoint.c88
39 files changed, 2512 insertions, 217 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 7f418bb..eef3bbb 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -126,4 +126,11 @@ config HAVE_DMA_API_DEBUG
config HAVE_DEFAULT_NO_SPIN_MUTEXES
bool
+config HAVE_HW_BREAKPOINT
+ bool
+ depends on HAVE_PERF_EVENTS
+ select ANON_INODES
+ select PERF_EVENTS
+
+
source "kernel/gcov/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 72ace95..178084b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -49,6 +49,7 @@ config X86
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_BZIP2
select HAVE_KERNEL_LZMA
+ select HAVE_HW_BREAKPOINT
select HAVE_ARCH_KMEMCHECK
config OUTPUT_FORMAT
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index 4a8e80c..9f828f8 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -10,6 +10,7 @@ header-y += ptrace-abi.h
header-y += sigcontext32.h
header-y += ucontext.h
header-y += processor-flags.h
+header-y += hw_breakpoint.h
unifdef-y += e820.h
unifdef-y += ist.h
diff --git a/arch/x86/include/asm/a.out-core.h b/arch/x86/include/asm/a.out-core.h
index bb70e39..7a15588 100644
--- a/arch/x86/include/asm/a.out-core.h
+++ b/arch/x86/include/asm/a.out-core.h
@@ -17,6 +17,7 @@
#include <linux/user.h>
#include <linux/elfcore.h>
+#include <asm/debugreg.h>
/*
* fill in the user structure for an a.out core dump
@@ -32,14 +33,7 @@ static inline void aout_dump_thread(struct pt_regs *regs, struct user *dump)
>> PAGE_SHIFT;
dump->u_dsize -= dump->u_tsize;
dump->u_ssize = 0;
- dump->u_debugreg[0] = current->thread.debugreg0;
- dump->u_debugreg[1] = current->thread.debugreg1;
- dump->u_debugreg[2] = current->thread.debugreg2;
- dump->u_debugreg[3] = current->thread.debugreg3;
- dump->u_debugreg[4] = 0;
- dump->u_debugreg[5] = 0;
- dump->u_debugreg[6] = current->thread.debugreg6;
- dump->u_debugreg[7] = current->thread.debugreg7;
+ aout_dump_debugregs(dump);
if (dump->start_stack < TASK_SIZE)
dump->u_ssize = ((unsigned long)(TASK_SIZE - dump->start_stack))
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 3ea6f37..fdabd84 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -18,6 +18,7 @@
#define DR_TRAP1 (0x2) /* db1 */
#define DR_TRAP2 (0x4) /* db2 */
#define DR_TRAP3 (0x8) /* db3 */
+#define DR_TRAP_BITS (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)
#define DR_STEP (0x4000) /* single-step */
#define DR_SWITCH (0x8000) /* task switch */
@@ -49,6 +50,8 @@
#define DR_LOCAL_ENABLE_SHIFT 0 /* Extra shift to the local enable bit */
#define DR_GLOBAL_ENABLE_SHIFT 1 /* Extra shift to the global enable bit */
+#define DR_LOCAL_ENABLE (0x1) /* Local enable for reg 0 */
+#define DR_GLOBAL_ENABLE (0x2) /* Global enable for reg 0 */
#define DR_ENABLE_SIZE 2 /* 2 enable bits per register */
#define DR_LOCAL_ENABLE_MASK (0x55) /* Set local bits for all 4 regs */
@@ -67,4 +70,34 @@
#define DR_LOCAL_SLOWDOWN (0x100) /* Local slow the pipeline */
#define DR_GLOBAL_SLOWDOWN (0x200) /* Global slow the pipeline */
+/*
+ * HW breakpoint additions
+ */
+#ifdef __KERNEL__
+
+DECLARE_PER_CPU(unsigned long, dr7);
+
+static inline void hw_breakpoint_disable(void)
+{
+ /* Zero the control register for HW Breakpoint */
+ set_debugreg(0UL, 7);
+
+ /* Zero-out the individual HW breakpoint address registers */
+ set_debugreg(0UL, 0);
+ set_debugreg(0UL, 1);
+ set_debugreg(0UL, 2);
+ set_debugreg(0UL, 3);
+}
+
+static inline int hw_breakpoint_active(void)
+{
+ return __get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK;
+}
+
+extern void aout_dump_debugregs(struct user *dump);
+
+extern void hw_breakpoint_restore(void);
+
+#endif /* __KERNEL__ */
+
#endif /* _ASM_X86_DEBUGREG_H */
diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h
new file mode 100644
index 0000000..0675a7c
--- /dev/null
+++ b/arch/x86/include/asm/hw_breakpoint.h
@@ -0,0 +1,73 @@
+#ifndef _I386_HW_BREAKPOINT_H
+#define _I386_HW_BREAKPOINT_H
+
+#ifdef __KERNEL__
+#define __ARCH_HW_BREAKPOINT_H
+
+/*
+ * The name should probably be something dealt in
+ * a higher level. While dealing with the user
+ * (display/resolving)
+ */
+struct arch_hw_breakpoint {
+ char *name; /* Contains name of the symbol to set bkpt */
+ unsigned long address;
+ u8 len;
+ u8 type;
+};
+
+#include <linux/kdebug.h>
+#include <linux/percpu.h>
+#include <linux/list.h>
+
+/* Available HW breakpoint length encodings */
+#define X86_BREAKPOINT_LEN_1 0x40
+#define X86_BREAKPOINT_LEN_2 0x44
+#define X86_BREAKPOINT_LEN_4 0x4c
+#define X86_BREAKPOINT_LEN_EXECUTE 0x40
+
+#ifdef CONFIG_X86_64
+#define X86_BREAKPOINT_LEN_8 0x48
+#endif
+
+/* Available HW breakpoint type encodings */
+
+/* trigger on instruction execute */
+#define X86_BREAKPOINT_EXECUTE 0x80
+/* trigger on memory write */
+#define X86_BREAKPOINT_WRITE 0x81
+/* trigger on memory read or write */
+#define X86_BREAKPOINT_RW 0x83
+
+/* Total number of available HW breakpoint registers */
+#define HBP_NUM 4
+
+struct perf_event;
+struct pmu;
+
+extern int arch_check_va_in_userspace(unsigned long va, u8 hbp_len);
+extern int arch_validate_hwbkpt_settings(struct perf_event *bp,
+ struct task_struct *tsk);
+extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+ unsigned long val, void *data);
+
+
+int arch_install_hw_breakpoint(struct perf_event *bp);
+void arch_uninstall_hw_breakpoint(struct perf_event *bp);
+void hw_breakpoint_pmu_read(struct perf_event *bp);
+void hw_breakpoint_pmu_unthrottle(struct perf_event *bp);
+
+extern void
+arch_fill_perf_breakpoint(struct perf_event *bp);
+
+unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type);
+int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type);
+
+extern int arch_bp_generic_fields(int x86_len, int x86_type,
+ int *gen_len, int *gen_type);
+
+extern struct pmu perf_ops_bp;
+
+#endif /* __KERNEL__ */
+#endif /* _I386_HW_BREAKPOINT_H */
+
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c978648..6f8ec1c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -30,6 +30,7 @@ struct mm_struct;
#include <linux/math64.h>
#include <linux/init.h>
+#define HBP_NUM 4
/*
* Default implementation of macro that returns current
* instruction pointer ("program counter").
@@ -422,6 +423,8 @@ extern unsigned int xstate_size;
extern void free_thread_xstate(struct task_struct *);
extern struct kmem_cache *task_xstate_cachep;
+struct perf_event;
+
struct thread_struct {
/* Cached TLS descriptors: */
struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
@@ -443,13 +446,10 @@ struct thread_struct {
unsigned long fs;
#endif
unsigned long gs;
- /* Hardware debugging registers: */
- unsigned long debugreg0;
- unsigned long debugreg1;
- unsigned long debugreg2;
- unsigned long debugreg3;
- unsigned long debugreg6;
- unsigned long debugreg7;
+ /* Save middle states of ptrace breakpoints */
+ struct perf_event *ptrace_bps[HBP_NUM];
+ /* Debug status used for traps, single steps, etc... */
+ unsigned long debugreg6;
/* Fault info: */
unsigned long cr2;
unsigned long trap_no;
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index d8e5d0cd..4f2e66e 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -40,7 +40,7 @@ obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o
obj-y += bootflag.o e820.o
obj-y += pci-dma.o quirks.o i8237.o topology.o kdebugfs.o
-obj-y += alternative.o i8253.o pci-nommu.o
+obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o
obj-y += tsc.o io_delay.o rtc.o
obj-$(CONFIG_X86_TRAMPOLINE) += trampoline.o
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
new file mode 100644
index 0000000..752daeb
--- /dev/null
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -0,0 +1,545 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) 2007 Alan Stern
+ * Copyright (C) 2009 IBM Corporation
+ * Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com>
+ */
+
+/*
+ * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
+ * using the CPU's debug registers.
+ */
+
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/irqflags.h>
+#include <linux/notifier.h>
+#include <linux/kallsyms.h>
+#include <linux/kprobes.h>
+#include <linux/percpu.h>
+#include <linux/kdebug.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+
+#include <asm/hw_breakpoint.h>
+#include <asm/processor.h>
+#include <asm/debugreg.h>
+
+/* Per cpu debug control register value */
+DEFINE_PER_CPU(unsigned long, dr7);
+EXPORT_PER_CPU_SYMBOL(dr7);
+
+/* Per cpu debug address registers values */
+static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]);
+
+/*
+ * Stores the breakpoints currently in use on each breakpoint address
+ * register for each cpus
+ */
+static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
+
+
+/*
+ * Encode the length, type, Exact, and Enable bits for a particular breakpoint
+ * as stored in debug register 7.
+ */
+unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
+{
+ unsigned long bp_info;
+
+ bp_info = (len | type) & 0xf;
+ bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE);
+ bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)) |
+ DR_GLOBAL_SLOWDOWN;
+ return bp_info;
+}
+
+/*
+ * Decode the length and type bits for a particular breakpoint as
+ * stored in debug register 7. Return the "enabled" status.
+ */
+int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type)
+{
+ int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);
+
+ *len = (bp_info & 0xc) | 0x40;
+ *type = (bp_info & 0x3) | 0x80;
+
+ return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
+}
+
+/*
+ * Install a perf counter breakpoint.
+ *
+ * We seek a free debug address register and use it for this
+ * breakpoint. Eventually we enable it in the debug control register.
+ *
+ * Atomic: we hold the counter->ctx->lock and we only handle variables
+ * and registers local to this cpu.
+ */
+int arch_install_hw_breakpoint(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned long *dr7;
+ int i;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+
+ if (!*slot) {
+ *slot = bp;
+ break;
+ }
+ }
+
+ if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
+ return -EBUSY;
+
+ set_debugreg(info->address, i);
+ __get_cpu_var(cpu_debugreg[i]) = info->address;
+
+ dr7 = &__get_cpu_var(dr7);
+ *dr7 |= encode_dr7(i, info->len, info->type);
+
+ set_debugreg(*dr7, 7);
+
+ return 0;
+}
+
+/*
+ * Uninstall the breakpoint contained in the given counter.
+ *
+ * First we search the debug address register it uses and then we disable
+ * it.
+ *
+ * Atomic: we hold the counter->ctx->lock and we only handle variables
+ * and registers local to this cpu.
+ */
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned long *dr7;
+ int i;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+
+ if (*slot == bp) {
+ *slot = NULL;
+ break;
+ }
+ }
+
+ if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
+ return;
+
+ dr7 = &__get_cpu_var(dr7);
+ *dr7 &= ~encode_dr7(i, info->len, info->type);
+
+ set_debugreg(*dr7, 7);
+}
+
+static int get_hbp_len(u8 hbp_len)
+{
+ unsigned int len_in_bytes = 0;
+
+ switch (hbp_len) {
+ case X86_BREAKPOINT_LEN_1:
+ len_in_bytes = 1;
+ break;
+ case X86_BREAKPOINT_LEN_2:
+ len_in_bytes = 2;
+ break;
+ case X86_BREAKPOINT_LEN_4:
+ len_in_bytes = 4;
+ break;
+#ifdef CONFIG_X86_64
+ case X86_BREAKPOINT_LEN_8:
+ len_in_bytes = 8;
+ break;
+#endif
+ }
+ return len_in_bytes;
+}
+
+/*
+ * Check for virtual address in user space.
+ */
+int arch_check_va_in_userspace(unsigned long va, u8 hbp_len)
+{
+ unsigned int len;
+
+ len = get_hbp_len(hbp_len);
+
+ return (va <= TASK_SIZE - len);
+}
+
+/*
+ * Check for virtual address in kernel space.
+ */
+static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
+{
+ unsigned int len;
+
+ len = get_hbp_len(hbp_len);
+
+ return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+}
+
+/*
+ * Store a breakpoint's encoded address, length, and type.
+ */
+static int arch_store_info(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ /*
+ * For kernel-addresses, either the address or symbol name can be
+ * specified.
+ */
+ if (info->name)
+ info->address = (unsigned long)
+ kallsyms_lookup_name(info->name);
+ if (info->address)
+ return 0;
+
+ return -EINVAL;
+}
+
+int arch_bp_generic_fields(int x86_len, int x86_type,
+ int *gen_len, int *gen_type)
+{
+ /* Len */
+ switch (x86_len) {
+ case X86_BREAKPOINT_LEN_1:
+ *gen_len = HW_BREAKPOINT_LEN_1;
+ break;
+ case X86_BREAKPOINT_LEN_2:
+ *gen_len = HW_BREAKPOINT_LEN_2;
+ break;
+ case X86_BREAKPOINT_LEN_4:
+ *gen_len = HW_BREAKPOINT_LEN_4;
+ break;
+#ifdef CONFIG_X86_64
+ case X86_BREAKPOINT_LEN_8:
+ *gen_len = HW_BREAKPOINT_LEN_8;
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }
+
+ /* Type */
+ switch (x86_type) {
+ case X86_BREAKPOINT_EXECUTE:
+ *gen_type = HW_BREAKPOINT_X;
+ break;
+ case X86_BREAKPOINT_WRITE:
+ *gen_type = HW_BREAKPOINT_W;
+ break;
+ case X86_BREAKPOINT_RW:
+ *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+
+static int arch_build_bp_info(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+ info->address = bp->attr.bp_addr;
+
+ /* Len */
+ switch (bp->attr.bp_len) {
+ case HW_BREAKPOINT_LEN_1:
+ info->len = X86_BREAKPOINT_LEN_1;
+ break;
+ case HW_BREAKPOINT_LEN_2:
+ info->len = X86_BREAKPOINT_LEN_2;
+ break;
+ case HW_BREAKPOINT_LEN_4:
+ info->len = X86_BREAKPOINT_LEN_4;
+ break;
+#ifdef CONFIG_X86_64
+ case HW_BREAKPOINT_LEN_8:
+ info->len = X86_BREAKPOINT_LEN_8;
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }
+
+ /* Type */
+ switch (bp->attr.bp_type) {
+ case HW_BREAKPOINT_W:
+ info->type = X86_BREAKPOINT_WRITE;
+ break;
+ case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+ info->type = X86_BREAKPOINT_RW;
+ break;
+ case HW_BREAKPOINT_X:
+ info->type = X86_BREAKPOINT_EXECUTE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+/*
+ * Validate the arch-specific HW Breakpoint register settings
+ */
+int arch_validate_hwbkpt_settings(struct perf_event *bp,
+ struct task_struct *tsk)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned int align;
+ int ret;
+
+
+ ret = arch_build_bp_info(bp);
+ if (ret)
+ return ret;
+
+ ret = -EINVAL;
+
+ if (info->type == X86_BREAKPOINT_EXECUTE)
+ /*
+ * Ptrace-refactoring code
+ * For now, we'll allow instruction breakpoint only for user-space
+ * addresses
+ */
+ if ((!arch_check_va_in_userspace(info->address, info->len)) &&
+ info->len != X86_BREAKPOINT_EXECUTE)
+ return ret;
+
+ switch (info->len) {
+ case X86_BREAKPOINT_LEN_1:
+ align = 0;
+ break;
+ case X86_BREAKPOINT_LEN_2:
+ align = 1;
+ break;
+ case X86_BREAKPOINT_LEN_4:
+ align = 3;
+ break;
+#ifdef CONFIG_X86_64
+ case X86_BREAKPOINT_LEN_8:
+ align = 7;
+ break;
+#endif
+ default:
+ return ret;
+ }
+
+ if (bp->callback)
+ ret = arch_store_info(bp);
+
+ if (ret < 0)
+ return ret;
+ /*
+ * Check that the low-order bits of the address are appropriate
+ * for the alignment implied by len.
+ */
+ if (info->address & align)
+ return -EINVAL;
+
+ /* Check that the virtual address is in the proper range */
+ if (tsk) {
+ if (!arch_check_va_in_userspace(info->address, info->len))
+ return -EFAULT;
+ } else {
+ if (!arch_check_va_in_kernelspace(info->address, info->len))
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+/*
+ * Dump the debug register contents to the user.
+ * We can't dump our per cpu values because it
+ * may contain cpu wide breakpoint, something that
+ * doesn't belong to the current task.
+ *
+ * TODO: include non-ptrace user breakpoints (perf)
+ */
+void aout_dump_debugregs(struct user *dump)
+{
+ int i;
+ int dr7 = 0;
+ struct perf_event *bp;
+ struct arch_hw_breakpoint *info;
+ struct thread_struct *thread = &current->thread;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ bp = thread->ptrace_bps[i];
+
+ if (bp && !bp->attr.disabled) {
+ dump->u_debugreg[i] = bp->attr.bp_addr;
+ info = counter_arch_bp(bp);
+ dr7 |= encode_dr7(i, info->len, info->type);
+ } else {
+ dump->u_debugreg[i] = 0;
+ }
+ }
+
+ dump->u_debugreg[4] = 0;
+ dump->u_debugreg[5] = 0;
+ dump->u_debugreg[6] = current->thread.debugreg6;
+
+ dump->u_debugreg[7] = dr7;
+}
+EXPORT_SYMBOL_GPL(aout_dump_debugregs);
+
+/*
+ * Release the user breakpoints used by ptrace
+ */
+void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
+{
+ int i;
+ struct thread_struct *t = &tsk->thread;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ unregister_hw_breakpoint(t->ptrace_bps[i]);
+ t->ptrace_bps[i] = NULL;
+ }
+}
+
+void hw_breakpoint_restore(void)
+{
+ set_debugreg(__get_cpu_var(cpu_debugreg[0]), 0);
+ set_debugreg(__get_cpu_var(cpu_debugreg[1]), 1);
+ set_debugreg(__get_cpu_var(cpu_debugreg[2]), 2);
+ set_debugreg(__get_cpu_var(cpu_debugreg[3]), 3);
+ set_debugreg(current->thread.debugreg6, 6);
+ set_debugreg(__get_cpu_var(dr7), 7);
+}
+EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
+
+/*
+ * Handle debug exception notifications.
+ *
+ * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below.
+ *
+ * NOTIFY_DONE returned if one of the following conditions is true.
+ * i) When the causative address is from user-space and the exception
+ * is a valid one, i.e. not triggered as a result of lazy debug register
+ * switching
+ * ii) When there are more bits than trap<n> set in DR6 register (such
+ * as BD, BS or BT) indicating that more than one debug condition is
+ * met and requires some more action in do_debug().
+ *
+ * NOTIFY_STOP returned for all other cases
+ *
+ */
+static int __kprobes hw_breakpoint_handler(struct die_args *args)
+{
+ int i, cpu, rc = NOTIFY_STOP;
+ struct perf_event *bp;
+ unsigned long dr7, dr6;
+ unsigned long *dr6_p;
+
+ /* The DR6 value is pointed by args->err */
+ dr6_p = (unsigned long *)ERR_PTR(args->err);
+ dr6 = *dr6_p;
+
+ /* Do an early return if no trap bits are set in DR6 */
+ if ((dr6 & DR_TRAP_BITS) == 0)
+ return NOTIFY_DONE;
+
+ get_debugreg(dr7, 7);
+ /* Disable breakpoints during exception handling */
+ set_debugreg(0UL, 7);
+ /*
+ * Assert that local interrupts are disabled
+ * Reset the DRn bits in the virtualized register value.
+ * The ptrace trigger routine will add in whatever is needed.
+ */
+ current->thread.debugreg6 &= ~DR_TRAP_BITS;
+ cpu = get_cpu();
+
+ /* Handle all the breakpoints that were triggered */
+ for (i = 0; i < HBP_NUM; ++i) {
+ if (likely(!(dr6 & (DR_TRAP0 << i))))
+ continue;
+
+ /*
+ * The counter may be concurrently released but that can only
+ * occur from a call_rcu() path. We can then safely fetch
+ * the breakpoint, use its callback, touch its counter
+ * while we are in an rcu_read_lock() path.
+ */
+ rcu_read_lock();
+
+ bp = per_cpu(bp_per_reg[i], cpu);
+ if (bp)
+ rc = NOTIFY_DONE;
+ /*
+ * Reset the 'i'th TRAP bit in dr6 to denote completion of
+ * exception handling
+ */
+ (*dr6_p) &= ~(DR_TRAP0 << i);
+ /*
+ * bp can be NULL due to lazy debug register switching
+ * or due to concurrent perf counter removing.
+ */
+ if (!bp) {
+ rcu_read_unlock();
+ break;
+ }
+
+ (bp->callback)(bp, args->regs);
+
+ rcu_read_unlock();
+ }
+ if (dr6 & (~DR_TRAP_BITS))
+ rc = NOTIFY_DONE;
+
+ set_debugreg(dr7, 7);
+ put_cpu();
+
+ return rc;
+}
+
+/*
+ * Handle debug exception notifications.
+ */
+int __kprobes hw_breakpoint_exceptions_notify(
+ struct notifier_block *unused, unsigned long val, void *data)
+{
+ if (val != DIE_DEBUG)
+ return NOTIFY_DONE;
+
+ return hw_breakpoint_handler(data);
+}
+
+void hw_breakpoint_pmu_read(struct perf_event *bp)
+{
+ /* TODO */
+}
+
+void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
+{
+ /* TODO */
+}
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8d82a77..34e86b6 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -43,6 +43,7 @@
#include <linux/smp.h>
#include <linux/nmi.h>
+#include <asm/debugreg.h>
#include <asm/apicdef.h>
#include <asm/system.h>
@@ -434,6 +435,11 @@ single_step_cont(struct pt_regs *regs, struct die_args *args)
"resuming...\n");
kgdb_arch_handle_exception(args->trapnr, args->signr,
args->err, "c", "", regs);
+ /*
+ * Reset the BS bit in dr6 (pointed by args->err) to
+ * denote completion of processing
+ */
+ (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
return NOTIFY_STOP;
}
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index c5f1f11..3fe86d7 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -56,6 +56,7 @@
#include <asm/uaccess.h>
#include <asm/alternative.h>
#include <asm/insn.h>
+#include <asm/debugreg.h>
void jprobe_return_end(void);
@@ -945,8 +946,14 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
ret = NOTIFY_STOP;
break;
case DIE_DEBUG:
- if (post_kprobe_handler(args->regs))
+ if (post_kprobe_handler(args->regs)) {
+ /*
+ * Reset the BS bit in dr6 (pointed by args->err) to
+ * denote completion of processing
+ */
+ (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
ret = NOTIFY_STOP;
+ }
break;
case DIE_GPF:
/*
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index c1c429d..c843f84 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -25,6 +25,7 @@
#include <asm/desc.h>
#include <asm/system.h>
#include <asm/cacheflush.h>
+#include <asm/debugreg.h>
static void set_idt(void *newidt, __u16 limit)
{
@@ -202,6 +203,7 @@ void machine_kexec(struct kimage *image)
/* Interrupts aren't acceptable while we reboot */
local_irq_disable();
+ hw_breakpoint_disable();
if (image->preserve_context) {
#ifdef CONFIG_X86_IO_APIC
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 84c3bf2..4a8bb82 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -18,6 +18,7 @@
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
+#include <asm/debugreg.h>
static int init_one_level2_page(struct kimage *image, pgd_t *pgd,
unsigned long addr)
@@ -282,6 +283,7 @@ void machine_kexec(struct kimage *image)
/* Interrupts aren't acceptable while we reboot */
local_irq_disable();
+ hw_breakpoint_disable();
if (image->preserve_context) {
#ifdef CONFIG_X86_IO_APIC
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 5284cd2..744508e 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -10,6 +10,7 @@
#include <linux/clockchips.h>
#include <linux/random.h>
#include <trace/events/power.h>
+#include <linux/hw_breakpoint.h>
#include <asm/system.h>
#include <asm/apic.h>
#include <asm/syscalls.h>
@@ -17,6 +18,7 @@
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/ds.h>
+#include <asm/debugreg.h>
unsigned long idle_halt;
EXPORT_SYMBOL(idle_halt);
@@ -103,14 +105,7 @@ void flush_thread(void)
}
#endif
- clear_tsk_thread_flag(tsk, TIF_DEBUG);
-
- tsk->thread.debugreg0 = 0;
- tsk->thread.debugreg1 = 0;
- tsk->thread.debugreg2 = 0;
- tsk->thread.debugreg3 = 0;
- tsk->thread.debugreg6 = 0;
- tsk->thread.debugreg7 = 0;
+ flush_ptrace_hw_breakpoint(tsk);
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
/*
* Forget coprocessor state..
@@ -192,16 +187,6 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
else if (next->debugctlmsr != prev->debugctlmsr)
update_debugctlmsr(next->debugctlmsr);
- if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
- set_debugreg(next->debugreg0, 0);
- set_debugreg(next->debugreg1, 1);
- set_debugreg(next->debugreg2, 2);
- set_debugreg(next->debugreg3, 3);
- /* no 4 and 5 */
- set_debugreg(next->debugreg6, 6);
- set_debugreg(next->debugreg7, 7);
- }
-
if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
test_tsk_thread_flag(next_p, TIF_NOTSC)) {
/* prev and next are different */
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 4cf7956..d5bd313 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -58,6 +58,7 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/ds.h>
+#include <asm/debugreg.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
@@ -259,7 +260,12 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
task_user_gs(p) = get_user_gs(regs);
+ p->thread.io_bitmap_ptr = NULL;
tsk = current;
+ err = -ENOMEM;
+
+ memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index eb62cbc..70cf158 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -52,6 +52,7 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/ds.h>
+#include <asm/debugreg.h>
asmlinkage extern void ret_from_fork(void);
@@ -297,12 +298,16 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.fs = me->thread.fs;
p->thread.gs = me->thread.gs;
+ p->thread.io_bitmap_ptr = NULL;
savesegment(gs, p->thread.gsindex);
savesegment(fs, p->thread.fsindex);
savesegment(es, p->thread.es);
savesegment(ds, p->thread.ds);
+ err = -ENOMEM;
+ memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+
if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
if (!p->thread.io_bitmap_ptr) {
@@ -341,6 +346,7 @@ out:
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
+
return err;
}
@@ -495,6 +501,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
*/
if (preload_fpu)
__math_state_restore();
+
return prev_p;
}
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index c4f76d2..b25f894 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -22,6 +22,8 @@
#include <linux/seccomp.h>
#include <linux/signal.h>
#include <linux/workqueue.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -34,6 +36,7 @@
#include <asm/prctl.h>
#include <asm/proto.h>
#include <asm/ds.h>
+#include <asm/hw_breakpoint.h>
#include "tls.h"
@@ -249,11 +252,6 @@ static int set_segment_reg(struct task_struct *task,
return 0;
}
-static unsigned long debugreg_addr_limit(struct task_struct *task)
-{
- return TASK_SIZE - 3;
-}
-
#else /* CONFIG_X86_64 */
#define FLAG_MASK (FLAG_MASK_32 | X86_EFLAGS_NT)
@@ -378,15 +376,6 @@ static int set_segment_reg(struct task_struct *task,
return 0;
}
-static unsigned long debugreg_addr_limit(struct task_struct *task)
-{
-#ifdef CONFIG_IA32_EMULATION
- if (test_tsk_thread_flag(task, TIF_IA32))
- return IA32_PAGE_OFFSET - 3;
-#endif
- return TASK_SIZE_MAX - 7;
-}
-
#endif /* CONFIG_X86_32 */
static unsigned long get_flags(struct task_struct *task)
@@ -566,99 +555,229 @@ static int genregs_set(struct task_struct *target,
return ret;
}
+static void ptrace_triggered(struct perf_event *bp, void *data)
+{
+ int i;
+ struct thread_struct *thread = &(current->thread);
+
+ /*
+ * Store in the virtual DR6 register the fact that the breakpoint
+ * was hit so the thread's debugger will see it.
+ */
+ for (i = 0; i < HBP_NUM; i++) {
+ if (thread->ptrace_bps[i] == bp)
+ break;
+ }
+
+ thread->debugreg6 |= (DR_TRAP0 << i);
+}
+
/*
- * This function is trivial and will be inlined by the compiler.
- * Having it separates the implementation details of debug
- * registers from the interface details of ptrace.
+ * Walk through every ptrace breakpoints for this thread and
+ * build the dr7 value on top of their attributes.
+ *
*/
-static unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
+static unsigned long ptrace_get_dr7(struct perf_event *bp[])
{
- switch (n) {
- case 0: return child->thread.debugreg0;
- case 1: return child->thread.debugreg1;
- case 2: return child->thread.debugreg2;
- case 3: return child->thread.debugreg3;
- case 6: return child->thread.debugreg6;
- case 7: return child->thread.debugreg7;
+ int i;
+ int dr7 = 0;
+ struct arch_hw_breakpoint *info;
+
+ for (i = 0; i < HBP_NUM; i++) {
+ if (bp[i] && !bp[i]->attr.disabled) {
+ info = counter_arch_bp(bp[i]);
+ dr7 |= encode_dr7(i, info->len, info->type);
+ }
}
- return 0;
+
+ return dr7;
}
-static int ptrace_set_debugreg(struct task_struct *child,
- int n, unsigned long data)
+/*
+ * Handle ptrace writes to debug register 7.
+ */
+static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
{
- int i;
+ struct thread_struct *thread = &(tsk->thread);
+ unsigned long old_dr7;
+ int i, orig_ret = 0, rc = 0;
+ int enabled, second_pass = 0;
+ unsigned len, type;
+ int gen_len, gen_type;
+ struct perf_event *bp;
+
+ data &= ~DR_CONTROL_RESERVED;
+ old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
+restore:
+ /*
+ * Loop through all the hardware breakpoints, making the
+ * appropriate changes to each.
+ */
+ for (i = 0; i < HBP_NUM; i++) {
+ enabled = decode_dr7(data, i, &len, &type);
+ bp = thread->ptrace_bps[i];
+
+ if (!enabled) {
+ if (bp) {
+ /*
+ * Don't unregister the breakpoints right-away,
+ * unless all register_user_hw_breakpoint()
+ * requests have succeeded. This prevents
+ * any window of opportunity for debug
+ * register grabbing by other users.
+ */
+ if (!second_pass)
+ continue;
+ thread->ptrace_bps[i] = NULL;
+ unregister_hw_breakpoint(bp);
+ }
+ continue;
+ }
- if (unlikely(n == 4 || n == 5))
- return -EIO;
+ /*
+ * We shoud have at least an inactive breakpoint at this
+ * slot. It means the user is writing dr7 without having
+ * written the address register first
+ */
+ if (!bp) {
+ rc = -EINVAL;
+ break;
+ }
- if (n < 4 && unlikely(data >= debugreg_addr_limit(child)))
- return -EIO;
+ rc = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
+ if (rc)
+ break;
- switch (n) {
- case 0: child->thread.debugreg0 = data; break;
- case 1: child->thread.debugreg1 = data; break;
- case 2: child->thread.debugreg2 = data; break;
- case 3: child->thread.debugreg3 = data; break;
+ /*
+ * This is a temporary thing as bp is unregistered/registered
+ * to simulate modification
+ */
+ bp = modify_user_hw_breakpoint(bp, bp->attr.bp_addr, gen_len,
+ gen_type, bp->callback,
+ tsk, true);
+ thread->ptrace_bps[i] = NULL;
- case 6:
- if ((data & ~0xffffffffUL) != 0)
- return -EIO;
- child->thread.debugreg6 = data;
- break;
+ if (!bp) { /* incorrect bp, or we have a bug in bp API */
+ rc = -EINVAL;
+ break;
+ }
+ if (IS_ERR(bp)) {
+ rc = PTR_ERR(bp);
+ bp = NULL;
+ break;
+ }
+ thread->ptrace_bps[i] = bp;
+ }
+ /*
+ * Make a second pass to free the remaining unused breakpoints
+ * or to restore the original breakpoints if an error occurred.
+ */
+ if (!second_pass) {
+ second_pass = 1;
+ if (rc < 0) {
+ orig_ret = rc;
+ data = old_dr7;
+ }
+ goto restore;
+ }
+ return ((orig_ret < 0) ? orig_ret : rc);
+}
- case 7:
+/*
+ * Handle PTRACE_PEEKUSR calls for the debug register area.
+ */
+static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
+{
+ struct thread_struct *thread = &(tsk->thread);
+ unsigned long val = 0;
+
+ if (n < HBP_NUM) {
+ struct perf_event *bp;
+ bp = thread->ptrace_bps[n];
+ if (!bp)
+ return 0;
+ val = bp->hw.info.address;
+ } else if (n == 6) {
+ val = thread->debugreg6;
+ } else if (n == 7) {
+ val = ptrace_get_dr7(thread->ptrace_bps);
+ }
+ return val;
+}
+
+static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
+ unsigned long addr)
+{
+ struct perf_event *bp;
+ struct thread_struct *t = &tsk->thread;
+
+ if (!t->ptrace_bps[nr]) {
/*
- * Sanity-check data. Take one half-byte at once with
- * check = (val >> (16 + 4*i)) & 0xf. It contains the
- * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
- * 2 and 3 are LENi. Given a list of invalid values,
- * we do mask |= 1 << invalid_value, so that
- * (mask >> check) & 1 is a correct test for invalid
- * values.
- *
- * R/Wi contains the type of the breakpoint /
- * watchpoint, LENi contains the length of the watched
- * data in the watchpoint case.
- *
- * The invalid values are:
- * - LENi == 0x10 (undefined), so mask |= 0x0f00. [32-bit]
- * - R/Wi == 0x10 (break on I/O reads or writes), so
- * mask |= 0x4444.
- * - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
- * 0x1110.
- *
- * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
- *
- * See the Intel Manual "System Programming Guide",
- * 15.2.4
- *
- * Note that LENi == 0x10 is defined on x86_64 in long
- * mode (i.e. even for 32-bit userspace software, but
- * 64-bit kernel), so the x86_64 mask value is 0x5454.
- * See the AMD manual no. 24593 (AMD64 System Programming)
+ * Put stub len and type to register (reserve) an inactive but
+ * correct bp
*/
-#ifdef CONFIG_X86_32
-#define DR7_MASK 0x5f54
-#else
-#define DR7_MASK 0x5554
-#endif
- data &= ~DR_CONTROL_RESERVED;
- for (i = 0; i < 4; i++)
- if ((DR7_MASK >> ((data >> (16 + 4*i)) & 0xf)) & 1)
- return -EIO;
- child->thread.debugreg7 = data;
- if (data)
- set_tsk_thread_flag(child, TIF_DEBUG);
- else
- clear_tsk_thread_flag(child, TIF_DEBUG);
- break;
+ bp = register_user_hw_breakpoint(addr, HW_BREAKPOINT_LEN_1,
+ HW_BREAKPOINT_W,
+ ptrace_triggered, tsk,
+ false);
+ } else {
+ bp = t->ptrace_bps[nr];
+ t->ptrace_bps[nr] = NULL;
+ bp = modify_user_hw_breakpoint(bp, addr, bp->attr.bp_len,
+ bp->attr.bp_type,
+ bp->callback,
+ tsk,
+ bp->attr.disabled);
}
+ if (!bp)
+ return -EIO;
+ /*
+ * CHECKME: the previous code returned -EIO if the addr wasn't a
+ * valid task virtual addr. The new one will return -EINVAL in this
+ * case.
+ * -EINVAL may be what we want for in-kernel breakpoints users, but
+ * -EIO looks better for ptrace, since we refuse a register writing
+ * for the user. And anyway this is the previous behaviour.
+ */
+ if (IS_ERR(bp))
+ return PTR_ERR(bp);
+
+ t->ptrace_bps[nr] = bp;
+
return 0;
}
/*
+ * Handle PTRACE_POKEUSR calls for the debug register area.
+ */
+int ptrace_set_debugreg(struct task_struct *tsk, int n, unsigned long val)
+{
+ struct thread_struct *thread = &(tsk->thread);
+ int rc = 0;
+
+ /* There are no DR4 or DR5 registers */
+ if (n == 4 || n == 5)
+ return -EIO;
+
+ if (n == 6) {
+ thread->debugreg6 = val;
+ goto ret_path;
+ }
+ if (n < HBP_NUM) {
+ rc = ptrace_set_breakpoint_addr(tsk, n, val);
+ if (rc)
+ return rc;
+ }
+ /* All that's left is DR7 */
+ if (n == 7)
+ rc = ptrace_write_dr7(tsk, val);
+
+ret_path:
+ return rc;
+}
+
+/*
* These access the current or another (stopped) task's io permission
* bitmap for debugging or core dump.
*/
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 6a44a76..fbf3b07c 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -799,15 +799,6 @@ static void do_signal(struct pt_regs *regs)
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
- /*
- * Re-enable any watchpoints before delivering the
- * signal to user space. The processor register will
- * have been cleared if the watchpoint triggered
- * inside the kernel.
- */
- if (current->thread.debugreg7)
- set_debugreg(current->thread.debugreg7, 7);
-
/* Whee! Actually deliver the signal. */
if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
/*
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 7e37dce..3339917 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -529,77 +529,56 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk = current;
- unsigned long condition;
+ unsigned long dr6;
int si_code;
- get_debugreg(condition, 6);
+ get_debugreg(dr6, 6);
/* Catch kmemcheck conditions first of all! */
- if (condition & DR_STEP && kmemcheck_trap(regs))
+ if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
return;
+ /* DR6 may or may not be cleared by the CPU */
+ set_debugreg(0, 6);
/*
* The processor cleared BTF, so don't mark that we need it set.
*/
clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR);
tsk->thread.debugctlmsr = 0;
- if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
- SIGTRAP) == NOTIFY_STOP)
+ /* Store the virtualized DR6 value */
+ tsk->thread.debugreg6 = dr6;
+
+ if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
+ SIGTRAP) == NOTIFY_STOP)
return;
/* It's safe to allow irq's after DR6 has been saved */
preempt_conditional_sti(regs);
- /* Mask out spurious debug traps due to lazy DR7 setting */
- if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
- if (!tsk->thread.debugreg7)
- goto clear_dr7;
+ if (regs->flags & X86_VM_MASK) {
+ handle_vm86_trap((struct kernel_vm86_regs *) regs,
+ error_code, 1);
+ return;
}
-#ifdef CONFIG_X86_32
- if (regs->flags & X86_VM_MASK)
- goto debug_vm86;
-#endif
-
- /* Save debug status register where ptrace can see it */
- tsk->thread.debugreg6 = condition;
-
/*
- * Single-stepping through TF: make sure we ignore any events in
- * kernel space (but re-enable TF when returning to user mode).
+ * Single-stepping through system calls: ignore any exceptions in
+ * kernel space, but re-enable TF when returning to user mode.
+ *
+ * We already checked v86 mode above, so we can check for kernel mode
+ * by just checking the CPL of CS.
*/
- if (condition & DR_STEP) {
- if (!user_mode(regs))
- goto clear_TF_reenable;
+ if ((dr6 & DR_STEP) && !user_mode(regs)) {
+ tsk->thread.debugreg6 &= ~DR_STEP;
+ set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
+ regs->flags &= ~X86_EFLAGS_TF;
}
-
- si_code = get_si_code(condition);
- /* Ok, finally something we can handle */
- send_sigtrap(tsk, regs, error_code, si_code);
-
- /*
- * Disable additional traps. They'll be re-enabled when
- * the signal is delivered.
- */
-clear_dr7:
- set_debugreg(0, 7);
+ si_code = get_si_code(tsk->thread.debugreg6);
+ if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS))
+ send_sigtrap(tsk, regs, error_code, si_code);
preempt_conditional_cli(regs);
- return;
-#ifdef CONFIG_X86_32
-debug_vm86:
- /* reenable preemption: handle_vm86_trap() might sleep */
- dec_preempt_count();
- handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
- conditional_cli(regs);
- return;
-#endif
-
-clear_TF_reenable:
- set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
- regs->flags &= ~X86_EFLAGS_TF;
- preempt_conditional_cli(regs);
return;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ae07d26..4fc8017 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -42,6 +42,7 @@
#define CREATE_TRACE_POINTS
#include "trace.h"
+#include <asm/debugreg.h>
#include <asm/uaccess.h>
#include <asm/msr.h>
#include <asm/desc.h>
@@ -3643,14 +3644,15 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
trace_kvm_entry(vcpu->vcpu_id);
kvm_x86_ops->run(vcpu, kvm_run);
- if (unlikely(vcpu->arch.switch_db_regs || test_thread_flag(TIF_DEBUG))) {
- set_debugreg(current->thread.debugreg0, 0);
- set_debugreg(current->thread.debugreg1, 1);
- set_debugreg(current->thread.debugreg2, 2);
- set_debugreg(current->thread.debugreg3, 3);
- set_debugreg(current->thread.debugreg6, 6);
- set_debugreg(current->thread.debugreg7, 7);
- }
+ /*
+ * If the guest has used debug registers, at least dr7
+ * will be disabled while returning to the host.
+ * If we don't have active breakpoints in the host, we don't
+ * care about the messed up debug address registers. But if
+ * we have some of them active, restore the old state.
+ */
+ if (hw_breakpoint_active())
+ hw_breakpoint_restore();
set_bit(KVM_REQ_KICK, &vcpu->requests);
local_irq_enable();
diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 16ccbd7..11a4ad4 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -540,8 +540,14 @@ kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args)
struct die_args *arg = args;
if (val == DIE_DEBUG && (arg->err & DR_STEP))
- if (post_kmmio_handler(arg->err, arg->regs) == 1)
+ if (post_kmmio_handler(arg->err, arg->regs) == 1) {
+ /*
+ * Reset the BS bit in dr6 (pointed by args->err) to
+ * denote completion of processing
+ */
+ (*(unsigned long *)ERR_PTR(arg->err)) &= ~DR_STEP;
return NOTIFY_STOP;
+ }
return NOTIFY_DONE;
}
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 8aa85f1..0a979f3 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -18,6 +18,7 @@
#include <asm/mce.h>
#include <asm/xcr.h>
#include <asm/suspend.h>
+#include <asm/debugreg.h>
#ifdef CONFIG_X86_32
static struct saved_context saved_context;
@@ -142,31 +143,6 @@ static void fix_processor_context(void)
#endif
load_TR_desc(); /* This does ltr */
load_LDT(&current->active_mm->context); /* This does lldt */
-
- /*
- * Now maybe reload the debug registers
- */
- if (current->thread.debugreg7) {
-#ifdef CONFIG_X86_32
- set_debugreg(current->thread.debugreg0, 0);
- set_debugreg(current->thread.debugreg1, 1);
- set_debugreg(current->thread.debugreg2, 2);
- set_debugreg(current->thread.debugreg3, 3);
- /* no 4 and 5 */
- set_debugreg(current->thread.debugreg6, 6);
- set_debugreg(current->thread.debugreg7, 7);
-#else
- /* CONFIG_X86_64 */
- loaddebug(&current->thread, 0);
- loaddebug(&current->thread, 1);
- loaddebug(&current->thread, 2);
- loaddebug(&current->thread, 3);
- /* no 4 and 5 */
- loaddebug(&current->thread, 6);
- loaddebug(&current->thread, 7);
-#endif
- }
-
}
/**
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
new file mode 100644
index 0000000..0b98cbf
--- /dev/null
+++ b/include/linux/hw_breakpoint.h
@@ -0,0 +1,137 @@
+#ifndef _LINUX_HW_BREAKPOINT_H
+#define _LINUX_HW_BREAKPOINT_H
+
+#include <linux/perf_event.h>
+
+enum {
+ HW_BREAKPOINT_LEN_1 = 1,
+ HW_BREAKPOINT_LEN_2 = 2,
+ HW_BREAKPOINT_LEN_4 = 4,
+ HW_BREAKPOINT_LEN_8 = 8,
+};
+
+enum {
+ HW_BREAKPOINT_R = 1,
+ HW_BREAKPOINT_W = 2,
+ HW_BREAKPOINT_X = 4,
+};
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+
+static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
+{
+ return bp->attr.bp_addr;
+}
+
+static inline int hw_breakpoint_type(struct perf_event *bp)
+{
+ return bp->attr.bp_type;
+}
+
+static inline int hw_breakpoint_len(struct perf_event *bp)
+{
+ return bp->attr.bp_len;
+}
+
+extern struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active);
+
+/* FIXME: only change from the attr, and don't unregister */
+extern struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active);
+
+/*
+ * Kernel breakpoints are not associated with any particular thread.
+ */
+extern struct perf_event *
+register_wide_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active);
+
+extern struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active);
+
+extern int register_perf_hw_breakpoint(struct perf_event *bp);
+extern int __register_perf_hw_breakpoint(struct perf_event *bp);
+extern void unregister_hw_breakpoint(struct perf_event *bp);
+extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);
+
+extern int reserve_bp_slot(struct perf_event *bp);
+extern void release_bp_slot(struct perf_event *bp);
+
+extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
+
+static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
+{
+ return &bp->hw.info;
+}
+
+#else /* !CONFIG_HAVE_HW_BREAKPOINT */
+
+static inline struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active) { return NULL; }
+static inline struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active) { return NULL; }
+static inline struct perf_event *
+register_wide_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active) { return NULL; }
+static inline struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active) { return NULL; }
+static inline int
+register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
+static inline int
+__register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
+static inline void unregister_hw_breakpoint(struct perf_event *bp) { }
+static inline void
+unregister_wide_hw_breakpoint(struct perf_event **cpu_events) { }
+static inline int
+reserve_bp_slot(struct perf_event *bp) {return -ENOSYS; }
+static inline void release_bp_slot(struct perf_event *bp) { }
+
+static inline void flush_ptrace_hw_breakpoint(struct task_struct *tsk) { }
+
+static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
+{
+ return NULL;
+}
+
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
+#endif /* _LINUX_HW_BREAKPOINT_H */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7f87563..b5cdac0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -18,6 +18,10 @@
#include <linux/ioctl.h>
#include <asm/byteorder.h>
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+#include <asm/hw_breakpoint.h>
+#endif
+
/*
* User-space ABI bits:
*/
@@ -31,6 +35,7 @@ enum perf_type_id {
PERF_TYPE_TRACEPOINT = 2,
PERF_TYPE_HW_CACHE = 3,
PERF_TYPE_RAW = 4,
+ PERF_TYPE_BREAKPOINT = 5,
PERF_TYPE_MAX, /* non-ABI */
};
@@ -209,6 +214,15 @@ struct perf_event_attr {
__u32 wakeup_events; /* wakeup every n events */
__u32 wakeup_watermark; /* bytes before wakeup */
};
+
+ union {
+ struct { /* Hardware breakpoint info */
+ __u64 bp_addr;
+ __u32 bp_type;
+ __u32 bp_len;
+ };
+ };
+
__u32 __reserved_2;
__u64 __reserved_3;
@@ -478,6 +492,11 @@ struct hw_perf_event {
s64 remaining;
struct hrtimer hrtimer;
};
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ union { /* breakpoint */
+ struct arch_hw_breakpoint info;
+ };
+#endif
};
atomic64_t prev_count;
u64 sample_period;
@@ -546,6 +565,8 @@ struct perf_pending_entry {
void (*func)(struct perf_pending_entry *);
};
+typedef void (*perf_callback_t)(struct perf_event *, void *);
+
/**
* struct perf_event - performance event kernel representation:
*/
@@ -588,7 +609,7 @@ struct perf_event {
u64 tstamp_running;
u64 tstamp_stopped;
- struct perf_event_attr attr;
+ struct perf_event_attr attr;
struct hw_perf_event hw;
struct perf_event_context *ctx;
@@ -641,6 +662,10 @@ struct perf_event {
struct event_filter *filter;
#endif
+ perf_callback_t callback;
+
+ perf_callback_t event_callback;
+
#endif /* CONFIG_PERF_EVENTS */
};
@@ -745,6 +770,13 @@ extern int hw_perf_group_sched_in(struct perf_event *group_leader,
struct perf_cpu_context *cpuctx,
struct perf_event_context *ctx, int cpu);
extern void perf_event_update_userpage(struct perf_event *event);
+extern int perf_event_release_kernel(struct perf_event *event);
+extern struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr,
+ int cpu,
+ pid_t pid,
+ perf_callback_t callback);
+extern u64 perf_event_read_value(struct perf_event *event);
struct perf_sample_data {
u64 type;
@@ -821,6 +853,7 @@ extern int sysctl_perf_event_sample_rate;
extern void perf_event_init(void);
extern void perf_tp_event(int event_id, u64 addr, u64 count,
void *record, int entry_size);
+extern void perf_bp_event(struct perf_event *event, void *data);
#ifndef perf_misc_flags
#define perf_misc_flags(regs) (user_mode(regs) ? PERF_RECORD_MISC_USER : \
@@ -855,6 +888,8 @@ static inline int perf_event_task_enable(void) { return -EINVAL; }
static inline void
perf_sw_event(u32 event_id, u64 nr, int nmi,
struct pt_regs *regs, u64 addr) { }
+static inline void
+perf_bp_event(struct perf_event *event, void *data) { }
static inline void perf_event_mmap(struct vm_area_struct *vma) { }
static inline void perf_event_comm(struct task_struct *tsk) { }
diff --git a/kernel/Makefile b/kernel/Makefile
index b8d4cd8..17b575e 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -95,6 +95,7 @@ obj-$(CONFIG_RING_BUFFER) += trace/
obj-$(CONFIG_SMP) += sched_cpupri.o
obj-$(CONFIG_SLOW_WORK) += slow-work.o
obj-$(CONFIG_PERF_EVENTS) += perf_event.o
+obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/exit.c b/kernel/exit.c
index f7864ac..3f45e3c 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -49,6 +49,7 @@
#include <linux/init_task.h>
#include <linux/perf_event.h>
#include <trace/events/sched.h>
+#include <linux/hw_breakpoint.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -978,6 +979,10 @@ NORET_TYPE void do_exit(long code)
proc_exit_connector(tsk);
/*
+ * FIXME: do that only when needed, using sched_exit tracepoint
+ */
+ flush_ptrace_hw_breakpoint(tsk);
+ /*
* Flush inherited counters to the parent - before the parent
* gets woken up by child-exit notifications.
*/
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
new file mode 100644
index 0000000..9ea9414
--- /dev/null
+++ b/kernel/hw_breakpoint.c
@@ -0,0 +1,494 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) 2007 Alan Stern
+ * Copyright (C) IBM Corporation, 2009
+ * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
+ *
+ * Thanks to Ingo Molnar for his many suggestions.
+ */
+
+/*
+ * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
+ * using the CPU's debug registers.
+ * This file contains the arch-independent routines.
+ */
+
+#include <linux/irqflags.h>
+#include <linux/kallsyms.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+
+#include <linux/hw_breakpoint.h>
+
+#include <asm/processor.h>
+
+#ifdef CONFIG_X86
+#include <asm/debugreg.h>
+#endif
+
+/*
+ * Constraints data
+ */
+
+/* Number of pinned cpu breakpoints in a cpu */
+static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned);
+
+/* Number of pinned task breakpoints in a cpu */
+static DEFINE_PER_CPU(unsigned int, task_bp_pinned[HBP_NUM]);
+
+/* Number of non-pinned cpu/task breakpoints in a cpu */
+static DEFINE_PER_CPU(unsigned int, nr_bp_flexible);
+
+/* Gather the number of total pinned and un-pinned bp in a cpuset */
+struct bp_busy_slots {
+ unsigned int pinned;
+ unsigned int flexible;
+};
+
+/* Serialize accesses to the above constraints */
+static DEFINE_MUTEX(nr_bp_mutex);
+
+/*
+ * Report the maximum number of pinned breakpoints a task
+ * have in this cpu
+ */
+static unsigned int max_task_bp_pinned(int cpu)
+{
+ int i;
+ unsigned int *tsk_pinned = per_cpu(task_bp_pinned, cpu);
+
+ for (i = HBP_NUM -1; i >= 0; i--) {
+ if (tsk_pinned[i] > 0)
+ return i + 1;
+ }
+
+ return 0;
+}
+
+/*
+ * Report the number of pinned/un-pinned breakpoints we have in
+ * a given cpu (cpu > -1) or in all of them (cpu = -1).
+ */
+static void fetch_bp_busy_slots(struct bp_busy_slots *slots, int cpu)
+{
+ if (cpu >= 0) {
+ slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu);
+ slots->pinned += max_task_bp_pinned(cpu);
+ slots->flexible = per_cpu(nr_bp_flexible, cpu);
+
+ return;
+ }
+
+ for_each_online_cpu(cpu) {
+ unsigned int nr;
+
+ nr = per_cpu(nr_cpu_bp_pinned, cpu);
+ nr += max_task_bp_pinned(cpu);
+
+ if (nr > slots->pinned)
+ slots->pinned = nr;
+
+ nr = per_cpu(nr_bp_flexible, cpu);
+
+ if (nr > slots->flexible)
+ slots->flexible = nr;
+ }
+}
+
+/*
+ * Add a pinned breakpoint for the given task in our constraint table
+ */
+static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)
+{
+ int count = 0;
+ struct perf_event *bp;
+ struct perf_event_context *ctx = tsk->perf_event_ctxp;
+ unsigned int *task_bp_pinned;
+ struct list_head *list;
+ unsigned long flags;
+
+ if (WARN_ONCE(!ctx, "No perf context for this task"))
+ return;
+
+ list = &ctx->event_list;
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ /*
+ * The current breakpoint counter is not included in the list
+ * at the open() callback time
+ */
+ list_for_each_entry(bp, list, event_entry) {
+ if (bp->attr.type == PERF_TYPE_BREAKPOINT)
+ count++;
+ }
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (WARN_ONCE(count < 0, "No breakpoint counter found in the counter list"))
+ return;
+
+ task_bp_pinned = per_cpu(task_bp_pinned, cpu);
+ if (enable) {
+ task_bp_pinned[count]++;
+ if (count > 0)
+ task_bp_pinned[count-1]--;
+ } else {
+ task_bp_pinned[count]--;
+ if (count > 0)
+ task_bp_pinned[count-1]++;
+ }
+}
+
+/*
+ * Add/remove the given breakpoint in our constraint table
+ */
+static void toggle_bp_slot(struct perf_event *bp, bool enable)
+{
+ int cpu = bp->cpu;
+ struct task_struct *tsk = bp->ctx->task;
+
+ /* Pinned counter task profiling */
+ if (tsk) {
+ if (cpu >= 0) {
+ toggle_bp_task_slot(tsk, cpu, enable);
+ return;
+ }
+
+ for_each_online_cpu(cpu)
+ toggle_bp_task_slot(tsk, cpu, enable);
+ return;
+ }
+
+ /* Pinned counter cpu profiling */
+ if (enable)
+ per_cpu(nr_cpu_bp_pinned, bp->cpu)++;
+ else
+ per_cpu(nr_cpu_bp_pinned, bp->cpu)--;
+}
+
+/*
+ * Contraints to check before allowing this new breakpoint counter:
+ *
+ * == Non-pinned counter == (Considered as pinned for now)
+ *
+ * - If attached to a single cpu, check:
+ *
+ * (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu)
+ * + max(per_cpu(task_bp_pinned, cpu)))) < HBP_NUM
+ *
+ * -> If there are already non-pinned counters in this cpu, it means
+ * there is already a free slot for them.
+ * Otherwise, we check that the maximum number of per task
+ * breakpoints (for this cpu) plus the number of per cpu breakpoint
+ * (for this cpu) doesn't cover every registers.
+ *
+ * - If attached to every cpus, check:
+ *
+ * (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *))
+ * + max(per_cpu(task_bp_pinned, *)))) < HBP_NUM
+ *
+ * -> This is roughly the same, except we check the number of per cpu
+ * bp for every cpu and we keep the max one. Same for the per tasks
+ * breakpoints.
+ *
+ *
+ * == Pinned counter ==
+ *
+ * - If attached to a single cpu, check:
+ *
+ * ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu)
+ * + max(per_cpu(task_bp_pinned, cpu))) < HBP_NUM
+ *
+ * -> Same checks as before. But now the nr_bp_flexible, if any, must keep
+ * one register at least (or they will never be fed).
+ *
+ * - If attached to every cpus, check:
+ *
+ * ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
+ * + max(per_cpu(task_bp_pinned, *))) < HBP_NUM
+ */
+int reserve_bp_slot(struct perf_event *bp)
+{
+ struct bp_busy_slots slots = {0};
+ int ret = 0;
+
+ mutex_lock(&nr_bp_mutex);
+
+ fetch_bp_busy_slots(&slots, bp->cpu);
+
+ /* Flexible counters need to keep at least one slot */
+ if (slots.pinned + (!!slots.flexible) == HBP_NUM) {
+ ret = -ENOSPC;
+ goto end;
+ }
+
+ toggle_bp_slot(bp, true);
+
+end:
+ mutex_unlock(&nr_bp_mutex);
+
+ return ret;
+}
+
+void release_bp_slot(struct perf_event *bp)
+{
+ mutex_lock(&nr_bp_mutex);
+
+ toggle_bp_slot(bp, false);
+
+ mutex_unlock(&nr_bp_mutex);
+}
+
+
+int __register_perf_hw_breakpoint(struct perf_event *bp)
+{
+ int ret;
+
+ ret = reserve_bp_slot(bp);
+ if (ret)
+ return ret;
+
+ if (!bp->attr.disabled)
+ ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
+
+ return ret;
+}
+
+int register_perf_hw_breakpoint(struct perf_event *bp)
+{
+ bp->callback = perf_bp_event;
+
+ return __register_perf_hw_breakpoint(bp);
+}
+
+/*
+ * Register a breakpoint bound to a task and a given cpu.
+ * If cpu is -1, the breakpoint is active for the task in every cpu
+ * If the task is -1, the breakpoint is active for every tasks in the given
+ * cpu.
+ */
+static struct perf_event *
+register_user_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ pid_t pid,
+ int cpu,
+ bool active)
+{
+ struct perf_event_attr *attr;
+ struct perf_event *bp;
+
+ attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+ if (!attr)
+ return ERR_PTR(-ENOMEM);
+
+ attr->type = PERF_TYPE_BREAKPOINT;
+ attr->size = sizeof(*attr);
+ attr->bp_addr = addr;
+ attr->bp_len = len;
+ attr->bp_type = type;
+ /*
+ * Such breakpoints are used by debuggers to trigger signals when
+ * we hit the excepted memory op. We can't miss such events, they
+ * must be pinned.
+ */
+ attr->pinned = 1;
+
+ if (!active)
+ attr->disabled = 1;
+
+ bp = perf_event_create_kernel_counter(attr, cpu, pid, triggered);
+ kfree(attr);
+
+ return bp;
+}
+
+/**
+ * register_user_hw_breakpoint - register a hardware breakpoint for user space
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @tsk: pointer to 'task_struct' of the process to which the address belongs
+ * @active: should we activate it while registering it
+ *
+ */
+struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active)
+{
+ return register_user_hw_breakpoint_cpu(addr, len, type, triggered,
+ tsk->pid, -1, active);
+}
+EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
+
+/**
+ * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
+ * @bp: the breakpoint structure to modify
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @tsk: pointer to 'task_struct' of the process to which the address belongs
+ * @active: should we activate it while registering it
+ */
+struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active)
+{
+ /*
+ * FIXME: do it without unregistering
+ * - We don't want to lose our slot
+ * - If the new bp is incorrect, don't lose the older one
+ */
+ unregister_hw_breakpoint(bp);
+
+ return register_user_hw_breakpoint(addr, len, type, triggered,
+ tsk, active);
+}
+EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
+
+/**
+ * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
+ * @bp: the breakpoint structure to unregister
+ */
+void unregister_hw_breakpoint(struct perf_event *bp)
+{
+ if (!bp)
+ return;
+ perf_event_release_kernel(bp);
+}
+EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
+
+static struct perf_event *
+register_kernel_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active)
+{
+ return register_user_hw_breakpoint_cpu(addr, len, type, triggered,
+ -1, cpu, active);
+}
+
+/**
+ * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @active: should we activate it while registering it
+ *
+ * @return a set of per_cpu pointers to perf events
+ */
+struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active)
+{
+ struct perf_event **cpu_events, **pevent, *bp;
+ long err;
+ int cpu;
+
+ cpu_events = alloc_percpu(typeof(*cpu_events));
+ if (!cpu_events)
+ return ERR_PTR(-ENOMEM);
+
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ bp = register_kernel_hw_breakpoint_cpu(addr, len, type,
+ triggered, cpu, active);
+
+ *pevent = bp;
+
+ if (IS_ERR(bp) || !bp) {
+ err = PTR_ERR(bp);
+ goto fail;
+ }
+ }
+
+ return cpu_events;
+
+fail:
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ if (IS_ERR(*pevent) || !*pevent)
+ break;
+ unregister_hw_breakpoint(*pevent);
+ }
+ free_percpu(cpu_events);
+ /* return the error if any */
+ return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
+
+/**
+ * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
+ * @cpu_events: the per cpu set of events to unregister
+ */
+void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)
+{
+ int cpu;
+ struct perf_event **pevent;
+
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ unregister_hw_breakpoint(*pevent);
+ }
+ free_percpu(cpu_events);
+}
+EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
+
+static struct notifier_block hw_breakpoint_exceptions_nb = {
+ .notifier_call = hw_breakpoint_exceptions_notify,
+ /* we need to be notified first */
+ .priority = 0x7fffffff
+};
+
+static int __init init_hw_breakpoint(void)
+{
+ return register_die_notifier(&hw_breakpoint_exceptions_nb);
+}
+core_initcall(init_hw_breakpoint);
+
+
+struct pmu perf_ops_bp = {
+ .enable = arch_install_hw_breakpoint,
+ .disable = arch_uninstall_hw_breakpoint,
+ .read = hw_breakpoint_pmu_read,
+ .unthrottle = hw_breakpoint_pmu_unthrottle
+};
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 8b6b8b6..8e5288a 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -181,6 +181,7 @@ unsigned long kallsyms_lookup_name(const char *name)
}
return module_kallsyms_lookup_name(name);
}
+EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
unsigned long),
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3256e36..3852e26 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -29,6 +29,7 @@
#include <linux/kernel_stat.h>
#include <linux/perf_event.h>
#include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>
#include <asm/irq_regs.h>
@@ -1725,6 +1726,26 @@ static int perf_release(struct inode *inode, struct file *file)
return 0;
}
+int perf_event_release_kernel(struct perf_event *event)
+{
+ struct perf_event_context *ctx = event->ctx;
+
+ WARN_ON_ONCE(ctx->parent_ctx);
+ mutex_lock(&ctx->mutex);
+ perf_event_remove_from_context(event);
+ mutex_unlock(&ctx->mutex);
+
+ mutex_lock(&event->owner->perf_event_mutex);
+ list_del_init(&event->owner_entry);
+ mutex_unlock(&event->owner->perf_event_mutex);
+ put_task_struct(event->owner);
+
+ free_event(event);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_release_kernel);
+
static int perf_event_read_size(struct perf_event *event)
{
int entry = sizeof(u64); /* value */
@@ -1750,7 +1771,7 @@ static int perf_event_read_size(struct perf_event *event)
return size;
}
-static u64 perf_event_read_value(struct perf_event *event)
+u64 perf_event_read_value(struct perf_event *event)
{
struct perf_event *child;
u64 total = 0;
@@ -1761,6 +1782,7 @@ static u64 perf_event_read_value(struct perf_event *event)
return total;
}
+EXPORT_SYMBOL_GPL(perf_event_read_value);
static int perf_event_read_entry(struct perf_event *event,
u64 read_format, char __user *buf)
@@ -4231,6 +4253,51 @@ static void perf_event_free_filter(struct perf_event *event)
#endif /* CONFIG_EVENT_PROFILE */
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+static void bp_perf_event_destroy(struct perf_event *event)
+{
+ release_bp_slot(event);
+}
+
+static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+{
+ int err;
+ /*
+ * The breakpoint is already filled if we haven't created the counter
+ * through perf syscall
+ * FIXME: manage to get trigerred to NULL if it comes from syscalls
+ */
+ if (!bp->callback)
+ err = register_perf_hw_breakpoint(bp);
+ else
+ err = __register_perf_hw_breakpoint(bp);
+ if (err)
+ return ERR_PTR(err);
+
+ bp->destroy = bp_perf_event_destroy;
+
+ return &perf_ops_bp;
+}
+
+void perf_bp_event(struct perf_event *bp, void *regs)
+{
+ /* TODO */
+}
+#else
+static void bp_perf_event_destroy(struct perf_event *event)
+{
+}
+
+static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+{
+ return NULL;
+}
+
+void perf_bp_event(struct perf_event *bp, void *regs)
+{
+}
+#endif
+
atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
static void sw_perf_event_destroy(struct perf_event *event)
@@ -4297,6 +4364,7 @@ perf_event_alloc(struct perf_event_attr *attr,
struct perf_event_context *ctx,
struct perf_event *group_leader,
struct perf_event *parent_event,
+ perf_callback_t callback,
gfp_t gfpflags)
{
const struct pmu *pmu;
@@ -4339,6 +4407,11 @@ perf_event_alloc(struct perf_event_attr *attr,
event->state = PERF_EVENT_STATE_INACTIVE;
+ if (!callback && parent_event)
+ callback = parent_event->callback;
+
+ event->callback = callback;
+
if (attr->disabled)
event->state = PERF_EVENT_STATE_OFF;
@@ -4373,6 +4446,11 @@ perf_event_alloc(struct perf_event_attr *attr,
pmu = tp_perf_event_init(event);
break;
+ case PERF_TYPE_BREAKPOINT:
+ pmu = bp_perf_event_init(event);
+ break;
+
+
default:
break;
}
@@ -4615,7 +4693,7 @@ SYSCALL_DEFINE5(perf_event_open,
}
event = perf_event_alloc(&attr, cpu, ctx, group_leader,
- NULL, GFP_KERNEL);
+ NULL, NULL, GFP_KERNEL);
err = PTR_ERR(event);
if (IS_ERR(event))
goto err_put_context;
@@ -4663,6 +4741,58 @@ err_put_context:
return err;
}
+/**
+ * perf_event_create_kernel_counter
+ *
+ * @attr: attributes of the counter to create
+ * @cpu: cpu in which the counter is bound
+ * @pid: task to profile
+ */
+struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
+ pid_t pid, perf_callback_t callback)
+{
+ struct perf_event *event;
+ struct perf_event_context *ctx;
+ int err;
+
+ /*
+ * Get the target context (task or percpu):
+ */
+
+ ctx = find_get_context(pid, cpu);
+ if (IS_ERR(ctx))
+ return NULL;
+
+ event = perf_event_alloc(attr, cpu, ctx, NULL,
+ NULL, callback, GFP_KERNEL);
+ err = PTR_ERR(event);
+ if (IS_ERR(event))
+ goto err_put_context;
+
+ event->filp = NULL;
+ WARN_ON_ONCE(ctx->parent_ctx);
+ mutex_lock(&ctx->mutex);
+ perf_install_in_context(ctx, event, cpu);
+ ++ctx->generation;
+ mutex_unlock(&ctx->mutex);
+
+ event->owner = current;
+ get_task_struct(current);
+ mutex_lock(&current->perf_event_mutex);
+ list_add_tail(&event->owner_entry, &current->perf_event_list);
+ mutex_unlock(&current->perf_event_mutex);
+
+ return event;
+
+err_put_context:
+ if (err < 0)
+ put_ctx(ctx);
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+
/*
* inherit a event from parent task to child task:
*/
@@ -4688,7 +4818,7 @@ inherit_event(struct perf_event *parent_event,
child_event = perf_event_alloc(&parent_event->attr,
parent_event->cpu, child_ctx,
group_leader, parent_event,
- GFP_KERNEL);
+ NULL, GFP_KERNEL);
if (IS_ERR(child_event))
return child_event;
get_ctx(child_ctx);
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index f056716..d006554 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -339,6 +339,27 @@ config POWER_TRACER
power management decisions, specifically the C-state and P-state
behavior.
+config KSYM_TRACER
+ bool "Trace read and write access on kernel memory locations"
+ depends on HAVE_HW_BREAKPOINT
+ select TRACING
+ help
+ This tracer helps find read and write operations on any given kernel
+ symbol i.e. /proc/kallsyms.
+
+config PROFILE_KSYM_TRACER
+ bool "Profile all kernel memory accesses on 'watched' variables"
+ depends on KSYM_TRACER
+ help
+ This tracer profiles kernel accesses on variables watched through the
+ ksym tracer ftrace plugin. Depending upon the hardware, all read
+ and write operations on kernel variables can be monitored for
+ accesses.
+
+ The results will be displayed in:
+ /debugfs/tracing/profile_ksym
+
+ Say N if unsure.
config STACK_TRACER
bool "Trace max stack"
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index edc3a3c..cd9ecd8 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -54,6 +54,7 @@ obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o
obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o
obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
+obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
obj-$(CONFIG_EVENT_TRACING) += power-traces.o
libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b4e4212..4da6ede 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -11,6 +11,7 @@
#include <linux/ftrace.h>
#include <trace/boot.h>
#include <linux/kmemtrace.h>
+#include <linux/hw_breakpoint.h>
#include <linux/trace_seq.h>
#include <linux/ftrace_event.h>
@@ -37,6 +38,7 @@ enum trace_type {
TRACE_KMEM_ALLOC,
TRACE_KMEM_FREE,
TRACE_BLK,
+ TRACE_KSYM,
__TRACE_LAST_TYPE,
};
@@ -232,6 +234,7 @@ extern void __ftrace_bad_type(void);
TRACE_KMEM_ALLOC); \
IF_ASSIGN(var, ent, struct kmemtrace_free_entry, \
TRACE_KMEM_FREE); \
+ IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\
__ftrace_bad_type(); \
} while (0)
@@ -387,6 +390,8 @@ int register_tracer(struct tracer *type);
void unregister_tracer(struct tracer *type);
int is_tracing_stopped(void);
+extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
+
extern unsigned long nsecs_to_usecs(unsigned long nsecs);
#ifdef CONFIG_TRACER_MAX_TRACE
@@ -461,6 +466,8 @@ extern int trace_selftest_startup_branch(struct tracer *trace,
struct trace_array *tr);
extern int trace_selftest_startup_hw_branches(struct tracer *trace,
struct trace_array *tr);
+extern int trace_selftest_startup_ksym(struct tracer *trace,
+ struct trace_array *tr);
#endif /* CONFIG_FTRACE_STARTUP_TEST */
extern void *head_page(struct trace_array_cpu *data);
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index ead3d72..c16a08f 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -364,3 +364,19 @@ FTRACE_ENTRY(kmem_free, kmemtrace_free_entry,
F_printk("type:%u call_site:%lx ptr:%p",
__entry->type_id, __entry->call_site, __entry->ptr)
);
+
+FTRACE_ENTRY(ksym_trace, ksym_trace_entry,
+
+ TRACE_KSYM,
+
+ F_STRUCT(
+ __field( unsigned long, ip )
+ __field( unsigned char, type )
+ __array( char , cmd, TASK_COMM_LEN )
+ __field( unsigned long, addr )
+ ),
+
+ F_printk("ip: %pF type: %d ksym_name: %pS cmd: %s",
+ (void *)__entry->ip, (unsigned int)__entry->type,
+ (void *)__entry->addr, __entry->cmd)
+);
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
new file mode 100644
index 0000000..11935b5
--- /dev/null
+++ b/kernel/trace/trace_ksym.c
@@ -0,0 +1,554 @@
+/*
+ * trace_ksym.c - Kernel Symbol Tracer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2009
+ */
+
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/debugfs.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+
+#include "trace_output.h"
+#include "trace_stat.h"
+#include "trace.h"
+
+#include <linux/hw_breakpoint.h>
+#include <asm/hw_breakpoint.h>
+
+/*
+ * For now, let us restrict the no. of symbols traced simultaneously to number
+ * of available hardware breakpoint registers.
+ */
+#define KSYM_TRACER_MAX HBP_NUM
+
+#define KSYM_TRACER_OP_LEN 3 /* rw- */
+
+struct trace_ksym {
+ struct perf_event **ksym_hbp;
+ unsigned long ksym_addr;
+ int type;
+ int len;
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+ unsigned long counter;
+#endif
+ struct hlist_node ksym_hlist;
+};
+
+static struct trace_array *ksym_trace_array;
+
+static unsigned int ksym_filter_entry_count;
+static unsigned int ksym_tracing_enabled;
+
+static HLIST_HEAD(ksym_filter_head);
+
+static DEFINE_MUTEX(ksym_tracer_mutex);
+
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+
+#define MAX_UL_INT 0xffffffff
+
+void ksym_collect_stats(unsigned long hbp_hit_addr)
+{
+ struct hlist_node *node;
+ struct trace_ksym *entry;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) {
+ if ((entry->ksym_addr == hbp_hit_addr) &&
+ (entry->counter <= MAX_UL_INT)) {
+ entry->counter++;
+ break;
+ }
+ }
+ rcu_read_unlock();
+}
+#endif /* CONFIG_PROFILE_KSYM_TRACER */
+
+void ksym_hbp_handler(struct perf_event *hbp, void *data)
+{
+ struct ring_buffer_event *event;
+ struct ksym_trace_entry *entry;
+ struct pt_regs *regs = data;
+ struct ring_buffer *buffer;
+ int pc;
+
+ if (!ksym_tracing_enabled)
+ return;
+
+ buffer = ksym_trace_array->buffer;
+
+ pc = preempt_count();
+
+ event = trace_buffer_lock_reserve(buffer, TRACE_KSYM,
+ sizeof(*entry), 0, pc);
+ if (!event)
+ return;
+
+ entry = ring_buffer_event_data(event);
+ entry->ip = instruction_pointer(regs);
+ entry->type = hw_breakpoint_type(hbp);
+ entry->addr = hw_breakpoint_addr(hbp);
+ strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);
+
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+ ksym_collect_stats(hw_breakpoint_addr(hbp));
+#endif /* CONFIG_PROFILE_KSYM_TRACER */
+
+ trace_buffer_unlock_commit(buffer, event, 0, pc);
+}
+
+/* Valid access types are represented as
+ *
+ * rw- : Set Read/Write Access Breakpoint
+ * -w- : Set Write Access Breakpoint
+ * --- : Clear Breakpoints
+ * --x : Set Execution Break points (Not available yet)
+ *
+ */
+static int ksym_trace_get_access_type(char *str)
+{
+ int access = 0;
+
+ if (str[0] == 'r')
+ access |= HW_BREAKPOINT_R;
+
+ if (str[1] == 'w')
+ access |= HW_BREAKPOINT_W;
+
+ if (str[2] == 'x')
+ access |= HW_BREAKPOINT_X;
+
+ switch (access) {
+ case HW_BREAKPOINT_R:
+ case HW_BREAKPOINT_W:
+ case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+ return access;
+ default:
+ return -EINVAL;
+ }
+}
+
+/*
+ * There can be several possible malformed requests and we attempt to capture
+ * all of them. We enumerate some of the rules
+ * 1. We will not allow kernel symbols with ':' since it is used as a delimiter.
+ * i.e. multiple ':' symbols disallowed. Possible uses are of the form
+ * <module>:<ksym_name>:<op>.
+ * 2. No delimiter symbol ':' in the input string
+ * 3. Spurious operator symbols or symbols not in their respective positions
+ * 4. <ksym_name>:--- i.e. clear breakpoint request when ksym_name not in file
+ * 5. Kernel symbol not a part of /proc/kallsyms
+ * 6. Duplicate requests
+ */
+static int parse_ksym_trace_str(char *input_string, char **ksymname,
+ unsigned long *addr)
+{
+ int ret;
+
+ *ksymname = strsep(&input_string, ":");
+ *addr = kallsyms_lookup_name(*ksymname);
+
+ /* Check for malformed request: (2), (1) and (5) */
+ if ((!input_string) ||
+ (strlen(input_string) != KSYM_TRACER_OP_LEN) ||
+ (*addr == 0))
+ return -EINVAL;;
+
+ ret = ksym_trace_get_access_type(input_string);
+
+ return ret;
+}
+
+int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
+{
+ struct trace_ksym *entry;
+ int ret = -ENOMEM;
+
+ if (ksym_filter_entry_count >= KSYM_TRACER_MAX) {
+ printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No"
+ " new requests for tracing can be accepted now.\n",
+ KSYM_TRACER_MAX);
+ return -ENOSPC;
+ }
+
+ entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ entry->type = op;
+ entry->ksym_addr = addr;
+ entry->len = HW_BREAKPOINT_LEN_4;
+
+ ret = -EAGAIN;
+ entry->ksym_hbp = register_wide_hw_breakpoint(entry->ksym_addr,
+ entry->len, entry->type,
+ ksym_hbp_handler, true);
+ if (IS_ERR(entry->ksym_hbp)) {
+ entry->ksym_hbp = NULL;
+ ret = PTR_ERR(entry->ksym_hbp);
+ }
+
+ if (!entry->ksym_hbp) {
+ printk(KERN_INFO "ksym_tracer request failed. Try again"
+ " later!!\n");
+ goto err;
+ }
+
+ hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head);
+ ksym_filter_entry_count++;
+
+ return 0;
+
+err:
+ kfree(entry);
+
+ return ret;
+}
+
+static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ struct trace_ksym *entry;
+ struct hlist_node *node;
+ struct trace_seq *s;
+ ssize_t cnt = 0;
+ int ret;
+
+ s = kmalloc(sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+ trace_seq_init(s);
+
+ mutex_lock(&ksym_tracer_mutex);
+
+ hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
+ ret = trace_seq_printf(s, "%pS:", (void *)entry->ksym_addr);
+ if (entry->type == HW_BREAKPOINT_R)
+ ret = trace_seq_puts(s, "r--\n");
+ else if (entry->type == HW_BREAKPOINT_W)
+ ret = trace_seq_puts(s, "-w-\n");
+ else if (entry->type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R))
+ ret = trace_seq_puts(s, "rw-\n");
+ WARN_ON_ONCE(!ret);
+ }
+
+ cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
+
+ mutex_unlock(&ksym_tracer_mutex);
+
+ kfree(s);
+
+ return cnt;
+}
+
+static void __ksym_trace_reset(void)
+{
+ struct trace_ksym *entry;
+ struct hlist_node *node, *node1;
+
+ mutex_lock(&ksym_tracer_mutex);
+ hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,
+ ksym_hlist) {
+ unregister_wide_hw_breakpoint(entry->ksym_hbp);
+ ksym_filter_entry_count--;
+ hlist_del_rcu(&(entry->ksym_hlist));
+ synchronize_rcu();
+ kfree(entry);
+ }
+ mutex_unlock(&ksym_tracer_mutex);
+}
+
+static ssize_t ksym_trace_filter_write(struct file *file,
+ const char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ struct trace_ksym *entry;
+ struct hlist_node *node;
+ char *input_string, *ksymname = NULL;
+ unsigned long ksym_addr = 0;
+ int ret, op, changed = 0;
+
+ input_string = kzalloc(count + 1, GFP_KERNEL);
+ if (!input_string)
+ return -ENOMEM;
+
+ if (copy_from_user(input_string, buffer, count)) {
+ kfree(input_string);
+ return -EFAULT;
+ }
+ input_string[count] = '\0';
+
+ strstrip(input_string);
+
+ /*
+ * Clear all breakpoints if:
+ * 1: echo > ksym_trace_filter
+ * 2: echo 0 > ksym_trace_filter
+ * 3: echo "*:---" > ksym_trace_filter
+ */
+ if (!input_string[0] || !strcmp(input_string, "0") ||
+ !strcmp(input_string, "*:---")) {
+ __ksym_trace_reset();
+ kfree(input_string);
+ return count;
+ }
+
+ ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr);
+ if (ret < 0) {
+ kfree(input_string);
+ return ret;
+ }
+
+ mutex_lock(&ksym_tracer_mutex);
+
+ ret = -EINVAL;
+ hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
+ if (entry->ksym_addr == ksym_addr) {
+ /* Check for malformed request: (6) */
+ if (entry->type != op)
+ changed = 1;
+ else
+ goto out;
+ break;
+ }
+ }
+ if (changed) {
+ unregister_wide_hw_breakpoint(entry->ksym_hbp);
+ entry->type = op;
+ if (op > 0) {
+ entry->ksym_hbp =
+ register_wide_hw_breakpoint(entry->ksym_addr,
+ entry->len, entry->type,
+ ksym_hbp_handler, true);
+ if (IS_ERR(entry->ksym_hbp))
+ entry->ksym_hbp = NULL;
+ if (!entry->ksym_hbp)
+ goto out;
+ }
+ ksym_filter_entry_count--;
+ hlist_del_rcu(&(entry->ksym_hlist));
+ synchronize_rcu();
+ kfree(entry);
+ ret = 0;
+ goto out;
+ } else {
+ /* Check for malformed request: (4) */
+ if (op == 0)
+ goto out;
+ ret = process_new_ksym_entry(ksymname, op, ksym_addr);
+ }
+out:
+ mutex_unlock(&ksym_tracer_mutex);
+
+ kfree(input_string);
+
+ if (!ret)
+ ret = count;
+ return ret;
+}
+
+static const struct file_operations ksym_tracing_fops = {
+ .open = tracing_open_generic,
+ .read = ksym_trace_filter_read,
+ .write = ksym_trace_filter_write,
+};
+
+static void ksym_trace_reset(struct trace_array *tr)
+{
+ ksym_tracing_enabled = 0;
+ __ksym_trace_reset();
+}
+
+static int ksym_trace_init(struct trace_array *tr)
+{
+ int cpu, ret = 0;
+
+ for_each_online_cpu(cpu)
+ tracing_reset(tr, cpu);
+ ksym_tracing_enabled = 1;
+ ksym_trace_array = tr;
+
+ return ret;
+}
+
+static void ksym_trace_print_header(struct seq_file *m)
+{
+ seq_puts(m,
+ "# TASK-PID CPU# Symbol "
+ "Type Function\n");
+ seq_puts(m,
+ "# | | | "
+ " | |\n");
+}
+
+static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
+{
+ struct trace_entry *entry = iter->ent;
+ struct trace_seq *s = &iter->seq;
+ struct ksym_trace_entry *field;
+ char str[KSYM_SYMBOL_LEN];
+ int ret;
+
+ if (entry->type != TRACE_KSYM)
+ return TRACE_TYPE_UNHANDLED;
+
+ trace_assign_type(field, entry);
+
+ ret = trace_seq_printf(s, "%11s-%-5d [%03d] %pS", field->cmd,
+ entry->pid, iter->cpu, (char *)field->addr);
+ if (!ret)
+ return TRACE_TYPE_PARTIAL_LINE;
+
+ switch (field->type) {
+ case HW_BREAKPOINT_R:
+ ret = trace_seq_printf(s, " R ");
+ break;
+ case HW_BREAKPOINT_W:
+ ret = trace_seq_printf(s, " W ");
+ break;
+ case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
+ ret = trace_seq_printf(s, " RW ");
+ break;
+ default:
+ return TRACE_TYPE_PARTIAL_LINE;
+ }
+
+ if (!ret)
+ return TRACE_TYPE_PARTIAL_LINE;
+
+ sprint_symbol(str, field->ip);
+ ret = trace_seq_printf(s, "%s\n", str);
+ if (!ret)
+ return TRACE_TYPE_PARTIAL_LINE;
+
+ return TRACE_TYPE_HANDLED;
+}
+
+struct tracer ksym_tracer __read_mostly =
+{
+ .name = "ksym_tracer",
+ .init = ksym_trace_init,
+ .reset = ksym_trace_reset,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_ksym,
+#endif
+ .print_header = ksym_trace_print_header,
+ .print_line = ksym_trace_output
+};
+
+__init static int init_ksym_trace(void)
+{
+ struct dentry *d_tracer;
+ struct dentry *entry;
+
+ d_tracer = tracing_init_dentry();
+ ksym_filter_entry_count = 0;
+
+ entry = debugfs_create_file("ksym_trace_filter", 0644, d_tracer,
+ NULL, &ksym_tracing_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs "
+ "'ksym_trace_filter' file\n");
+
+ return register_tracer(&ksym_tracer);
+}
+device_initcall(init_ksym_trace);
+
+
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+static int ksym_tracer_stat_headers(struct seq_file *m)
+{
+ seq_puts(m, " Access Type ");
+ seq_puts(m, " Symbol Counter\n");
+ seq_puts(m, " ----------- ");
+ seq_puts(m, " ------ -------\n");
+ return 0;
+}
+
+static int ksym_tracer_stat_show(struct seq_file *m, void *v)
+{
+ struct hlist_node *stat = v;
+ struct trace_ksym *entry;
+ int access_type = 0;
+ char fn_name[KSYM_NAME_LEN];
+
+ entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);
+
+ access_type = entry->type;
+
+ switch (access_type) {
+ case HW_BREAKPOINT_R:
+ seq_puts(m, " R ");
+ break;
+ case HW_BREAKPOINT_W:
+ seq_puts(m, " W ");
+ break;
+ case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
+ seq_puts(m, " RW ");
+ break;
+ default:
+ seq_puts(m, " NA ");
+ }
+
+ if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0)
+ seq_printf(m, " %-36s", fn_name);
+ else
+ seq_printf(m, " %-36s", "<NA>");
+ seq_printf(m, " %15lu\n", entry->counter);
+
+ return 0;
+}
+
+static void *ksym_tracer_stat_start(struct tracer_stat *trace)
+{
+ return ksym_filter_head.first;
+}
+
+static void *
+ksym_tracer_stat_next(void *v, int idx)
+{
+ struct hlist_node *stat = v;
+
+ return stat->next;
+}
+
+static struct tracer_stat ksym_tracer_stats = {
+ .name = "ksym_tracer",
+ .stat_start = ksym_tracer_stat_start,
+ .stat_next = ksym_tracer_stat_next,
+ .stat_headers = ksym_tracer_stat_headers,
+ .stat_show = ksym_tracer_stat_show
+};
+
+__init static int ksym_tracer_stat_init(void)
+{
+ int ret;
+
+ ret = register_stat_tracer(&ksym_tracer_stats);
+ if (ret) {
+ printk(KERN_WARNING "Warning: could not register "
+ "ksym tracer stats\n");
+ return 1;
+ }
+
+ return 0;
+}
+fs_initcall(ksym_tracer_stat_init);
+#endif /* CONFIG_PROFILE_KSYM_TRACER */
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index d2cdbab..dc98309 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -17,6 +17,7 @@ static inline int trace_valid_entry(struct trace_entry *entry)
case TRACE_GRAPH_ENT:
case TRACE_GRAPH_RET:
case TRACE_HW_BRANCHES:
+ case TRACE_KSYM:
return 1;
}
return 0;
@@ -808,3 +809,57 @@ trace_selftest_startup_hw_branches(struct tracer *trace,
return ret;
}
#endif /* CONFIG_HW_BRANCH_TRACER */
+
+#ifdef CONFIG_KSYM_TRACER
+static int ksym_selftest_dummy;
+
+int
+trace_selftest_startup_ksym(struct tracer *trace, struct trace_array *tr)
+{
+ unsigned long count;
+ int ret;
+
+ /* start the tracing */
+ ret = tracer_init(trace, tr);
+ if (ret) {
+ warn_failed_init_tracer(trace, ret);
+ return ret;
+ }
+
+ ksym_selftest_dummy = 0;
+ /* Register the read-write tracing request */
+
+ ret = process_new_ksym_entry("ksym_selftest_dummy",
+ HW_BREAKPOINT_R | HW_BREAKPOINT_W,
+ (unsigned long)(&ksym_selftest_dummy));
+
+ if (ret < 0) {
+ printk(KERN_CONT "ksym_trace read-write startup test failed\n");
+ goto ret_path;
+ }
+ /* Perform a read and a write operation over the dummy variable to
+ * trigger the tracer
+ */
+ if (ksym_selftest_dummy == 0)
+ ksym_selftest_dummy++;
+
+ /* stop the tracing. */
+ tracing_stop();
+ /* check the trace buffer */
+ ret = trace_test_buffer(tr, &count);
+ trace->reset(tr);
+ tracing_start();
+
+ /* read & write operations - one each is performed on the dummy variable
+ * triggering two entries in the trace buffer
+ */
+ if (!ret && count != 2) {
+ printk(KERN_CONT "Ksym tracer startup test failed");
+ ret = -1;
+ }
+
+ret_path:
+ return ret;
+}
+#endif /* CONFIG_KSYM_TRACER */
+
diff --git a/samples/Kconfig b/samples/Kconfig
index b92bde3..e4be84a 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -40,5 +40,11 @@ config SAMPLE_KRETPROBES
default m
depends on SAMPLE_KPROBES && KRETPROBES
+config SAMPLE_HW_BREAKPOINT
+ tristate "Build kernel hardware breakpoint examples -- loadable module only"
+ depends on HAVE_HW_BREAKPOINT && m
+ help
+ This builds kernel hardware breakpoint example modules.
+
endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 43343a0..0f15e6d 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,3 +1,4 @@
# Makefile for Linux samples code
-obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ tracepoints/ trace_events/
+obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ tracepoints/ trace_events/ \
+ hw_breakpoint/
diff --git a/samples/hw_breakpoint/Makefile b/samples/hw_breakpoint/Makefile
new file mode 100644
index 0000000..0f5c31c
--- /dev/null
+++ b/samples/hw_breakpoint/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_HW_BREAKPOINT) += data_breakpoint.o
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
new file mode 100644
index 0000000..5bc9819
--- /dev/null
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -0,0 +1,88 @@
+/*
+ * data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * usage: insmod data_breakpoint.ko ksym=<ksym_name>
+ *
+ * This file is a kernel module that places a breakpoint over ksym_name kernel
+ * variable using Hardware Breakpoint register. The corresponding handler which
+ * prints a backtrace is invoked everytime a write operation is performed on
+ * that variable.
+ *
+ * Copyright (C) IBM Corporation, 2009
+ */
+#include <linux/module.h> /* Needed by all modules */
+#include <linux/kernel.h> /* Needed for KERN_INFO */
+#include <linux/init.h> /* Needed for the macros */
+#include <linux/kallsyms.h>
+
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+
+struct perf_event **sample_hbp;
+
+static char ksym_name[KSYM_NAME_LEN] = "pid_max";
+module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
+MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
+ " write operations on the kernel symbol");
+
+static void sample_hbp_handler(struct perf_event *temp, void *data)
+{
+ printk(KERN_INFO "%s value is changed\n", ksym_name);
+ dump_stack();
+ printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
+}
+
+static int __init hw_break_module_init(void)
+{
+ int ret;
+ unsigned long addr;
+
+ addr = kallsyms_lookup_name(ksym_name);
+
+ sample_hbp = register_wide_hw_breakpoint(addr, HW_BREAKPOINT_LEN_4,
+ HW_BREAKPOINT_W | HW_BREAKPOINT_R,
+ sample_hbp_handler, true);
+ if (IS_ERR(sample_hbp)) {
+ ret = PTR_ERR(sample_hbp);
+ goto fail;
+ } else if (!sample_hbp) {
+ ret = -EINVAL;
+ goto fail;
+ }
+
+ printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);
+
+ return 0;
+
+fail:
+ printk(KERN_INFO "Breakpoint registration failed\n");
+
+ return ret;
+}
+
+static void __exit hw_break_module_exit(void)
+{
+ unregister_wide_hw_breakpoint(sample_hbp);
+ printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
+}
+
+module_init(hw_break_module_init);
+module_exit(hw_break_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("K.Prasad");
+MODULE_DESCRIPTION("ksym breakpoint");