diff options
author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-21 17:20:41 (GMT) |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-21 17:20:41 (GMT) |
commit | a95b0644b38c16c40b753224671b919b9af0b73c (patch) | |
tree | 62f4b54f35dd3a99d6a3c2337bddcf1c72c32c8c /arch | |
parent | e75118a7b581b19b08282c7819c1ec6f68b91b79 (diff) | |
parent | f7e35c5ba4322838ce84b23a2f1a6d6b7f0b57ec (diff) | |
download | linux-a95b0644b38c16c40b753224671b919b9af0b73c.tar.xz |
Merge branch 'for-next/kprobes' into for-next/core
* kprobes:
arm64: kprobes: Add KASAN instrumentation around stack accesses
arm64: kprobes: Cleanup jprobe_return
arm64: kprobes: Fix overflow when saving stack
arm64: kprobes: WARN if attempting to step with PSTATE.D=1
kprobes: Add arm64 case in kprobe example module
arm64: Add kernel return probes support (kretprobes)
arm64: Add trampoline code for kretprobes
arm64: kprobes instruction simulation support
arm64: Treat all entry code as non-kprobe-able
arm64: Blacklist non-kprobe-able symbol
arm64: Kprobes with single stepping support
arm64: add conditional instruction simulation support
arm64: Add more test functions to insn.c
arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature
Diffstat (limited to 'arch')
26 files changed, 1772 insertions, 10 deletions
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 51622ba..d3c0c23 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -121,7 +121,6 @@ extern unsigned long profile_pc(struct pt_regs *regs); #define MAX_REG_OFFSET (offsetof(struct pt_regs, ARM_ORIG_r0)) extern int regs_query_register_offset(const char *name); -extern const char *regs_query_register_name(unsigned int offset); extern bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr); extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n); diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1b196bf..ac4746f 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -86,8 +86,11 @@ config ARM64 select HAVE_PERF_EVENTS select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP + select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RCU_TABLE_FREE select HAVE_SYSCALL_TRACEPOINTS + select HAVE_KPROBES + select HAVE_KRETPROBES if HAVE_KPROBES select IOMMU_DMA if IOMMU_SUPPORT select IRQ_DOMAIN select IRQ_FORCED_THREADING diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h index 2fcb9b7..4b6b3f7 100644 --- a/arch/arm64/include/asm/debug-monitors.h +++ b/arch/arm64/include/asm/debug-monitors.h @@ -66,6 +66,11 @@ #define CACHE_FLUSH_IS_SAFE 1 +/* kprobes BRK opcodes with ESR encoding */ +#define BRK64_ESR_MASK 0xFFFF +#define BRK64_ESR_KPROBES 0x0004 +#define BRK64_OPCODE_KPROBES (AARCH64_BREAK_MON | (BRK64_ESR_KPROBES << 5)) + /* AArch32 */ #define DBG_ESR_EVT_BKPT 0x4 #define DBG_ESR_EVT_VECC 0x5 diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h index 30e50eb..1dbaa90 100644 --- a/arch/arm64/include/asm/insn.h +++ b/arch/arm64/include/asm/insn.h @@ -120,6 +120,29 @@ enum aarch64_insn_register { AARCH64_INSN_REG_SP = 31 /* Stack pointer: as load/store base reg */ }; +enum aarch64_insn_special_register { + AARCH64_INSN_SPCLREG_SPSR_EL1 = 0xC200, + AARCH64_INSN_SPCLREG_ELR_EL1 = 0xC201, + AARCH64_INSN_SPCLREG_SP_EL0 = 0xC208, + AARCH64_INSN_SPCLREG_SPSEL = 0xC210, + AARCH64_INSN_SPCLREG_CURRENTEL = 0xC212, + AARCH64_INSN_SPCLREG_DAIF = 0xDA11, + AARCH64_INSN_SPCLREG_NZCV = 0xDA10, + AARCH64_INSN_SPCLREG_FPCR = 0xDA20, + AARCH64_INSN_SPCLREG_DSPSR_EL0 = 0xDA28, + AARCH64_INSN_SPCLREG_DLR_EL0 = 0xDA29, + AARCH64_INSN_SPCLREG_SPSR_EL2 = 0xE200, + AARCH64_INSN_SPCLREG_ELR_EL2 = 0xE201, + AARCH64_INSN_SPCLREG_SP_EL1 = 0xE208, + AARCH64_INSN_SPCLREG_SPSR_INQ = 0xE218, + AARCH64_INSN_SPCLREG_SPSR_ABT = 0xE219, + AARCH64_INSN_SPCLREG_SPSR_UND = 0xE21A, + AARCH64_INSN_SPCLREG_SPSR_FIQ = 0xE21B, + AARCH64_INSN_SPCLREG_SPSR_EL3 = 0xF200, + AARCH64_INSN_SPCLREG_ELR_EL3 = 0xF201, + AARCH64_INSN_SPCLREG_SP_EL2 = 0xF210 +}; + enum aarch64_insn_variant { AARCH64_INSN_VARIANT_32BIT, AARCH64_INSN_VARIANT_64BIT @@ -223,8 +246,15 @@ static __always_inline bool aarch64_insn_is_##abbr(u32 code) \ static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \ { return (val); } +__AARCH64_INSN_FUNCS(adr_adrp, 0x1F000000, 0x10000000) +__AARCH64_INSN_FUNCS(prfm_lit, 0xFF000000, 0xD8000000) __AARCH64_INSN_FUNCS(str_reg, 0x3FE0EC00, 0x38206800) __AARCH64_INSN_FUNCS(ldr_reg, 0x3FE0EC00, 0x38606800) +__AARCH64_INSN_FUNCS(ldr_lit, 0xBF000000, 0x18000000) +__AARCH64_INSN_FUNCS(ldrsw_lit, 0xFF000000, 0x98000000) +__AARCH64_INSN_FUNCS(exclusive, 0x3F800000, 0x08000000) +__AARCH64_INSN_FUNCS(load_ex, 0x3F400000, 0x08400000) +__AARCH64_INSN_FUNCS(store_ex, 0x3F400000, 0x08000000) __AARCH64_INSN_FUNCS(stp_post, 0x7FC00000, 0x28800000) __AARCH64_INSN_FUNCS(ldp_post, 0x7FC00000, 0x28C00000) __AARCH64_INSN_FUNCS(stp_pre, 0x7FC00000, 0x29800000) @@ -273,10 +303,15 @@ __AARCH64_INSN_FUNCS(svc, 0xFFE0001F, 0xD4000001) __AARCH64_INSN_FUNCS(hvc, 0xFFE0001F, 0xD4000002) __AARCH64_INSN_FUNCS(smc, 0xFFE0001F, 0xD4000003) __AARCH64_INSN_FUNCS(brk, 0xFFE0001F, 0xD4200000) +__AARCH64_INSN_FUNCS(exception, 0xFF000000, 0xD4000000) __AARCH64_INSN_FUNCS(hint, 0xFFFFF01F, 0xD503201F) __AARCH64_INSN_FUNCS(br, 0xFFFFFC1F, 0xD61F0000) __AARCH64_INSN_FUNCS(blr, 0xFFFFFC1F, 0xD63F0000) __AARCH64_INSN_FUNCS(ret, 0xFFFFFC1F, 0xD65F0000) +__AARCH64_INSN_FUNCS(eret, 0xFFFFFFFF, 0xD69F03E0) +__AARCH64_INSN_FUNCS(mrs, 0xFFF00000, 0xD5300000) +__AARCH64_INSN_FUNCS(msr_imm, 0xFFF8F01F, 0xD500401F) +__AARCH64_INSN_FUNCS(msr_reg, 0xFFF00000, 0xD5100000) #undef __AARCH64_INSN_FUNCS @@ -286,6 +321,8 @@ bool aarch64_insn_is_branch_imm(u32 insn); int aarch64_insn_read(void *addr, u32 *insnp); int aarch64_insn_write(void *addr, u32 insn); enum aarch64_insn_encoding_class aarch64_get_insn_class(u32 insn); +bool aarch64_insn_uses_literal(u32 insn); +bool aarch64_insn_is_branch(u32 insn); u64 aarch64_insn_decode_immediate(enum aarch64_insn_imm_type type, u32 insn); u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, u32 insn, u64 imm); @@ -367,9 +404,13 @@ bool aarch32_insn_is_wide(u32 insn); #define A32_RT_OFFSET 12 #define A32_RT2_OFFSET 0 +u32 aarch64_insn_extract_system_reg(u32 insn); u32 aarch32_insn_extract_reg_num(u32 insn, int offset); u32 aarch32_insn_mcr_extract_opc2(u32 insn); u32 aarch32_insn_mcr_extract_crm(u32 insn); + +typedef bool (pstate_check_t)(unsigned long); +extern pstate_check_t * const aarch32_opcode_cond_checks[16]; #endif /* __ASSEMBLY__ */ #endif /* __ASM_INSN_H */ diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h new file mode 100644 index 0000000..61b4915 --- /dev/null +++ b/arch/arm64/include/asm/kprobes.h @@ -0,0 +1,62 @@ +/* + * arch/arm64/include/asm/kprobes.h + * + * Copyright (C) 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#ifndef _ARM_KPROBES_H +#define _ARM_KPROBES_H + +#include <linux/types.h> +#include <linux/ptrace.h> +#include <linux/percpu.h> + +#define __ARCH_WANT_KPROBES_INSN_SLOT +#define MAX_INSN_SIZE 1 +#define MAX_STACK_SIZE 128 + +#define flush_insn_slot(p) do { } while (0) +#define kretprobe_blacklist_size 0 + +#include <asm/probes.h> + +struct prev_kprobe { + struct kprobe *kp; + unsigned int status; +}; + +/* Single step context for kprobe */ +struct kprobe_step_ctx { + unsigned long ss_pending; + unsigned long match_addr; +}; + +/* per-cpu kprobe control block */ +struct kprobe_ctlblk { + unsigned int kprobe_status; + unsigned long saved_irqflag; + struct prev_kprobe prev_kprobe; + struct kprobe_step_ctx ss_ctx; + struct pt_regs jprobe_saved_regs; + char jprobes_stack[MAX_STACK_SIZE]; +}; + +void arch_remove_kprobe(struct kprobe *); +int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr); +int kprobe_exceptions_notify(struct notifier_block *self, + unsigned long val, void *data); +int kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr); +int kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr); +void kretprobe_trampoline(void); +void __kprobes *trampoline_probe_handler(struct pt_regs *regs); + +#endif /* _ARM_KPROBES_H */ diff --git a/arch/arm64/include/asm/probes.h b/arch/arm64/include/asm/probes.h new file mode 100644 index 0000000..5af574d --- /dev/null +++ b/arch/arm64/include/asm/probes.h @@ -0,0 +1,35 @@ +/* + * arch/arm64/include/asm/probes.h + * + * Copyright (C) 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ +#ifndef _ARM_PROBES_H +#define _ARM_PROBES_H + +#include <asm/opcodes.h> + +struct kprobe; +struct arch_specific_insn; + +typedef u32 kprobe_opcode_t; +typedef void (kprobes_handler_t) (u32 opcode, long addr, struct pt_regs *); + +/* architecture specific copy of original instruction */ +struct arch_specific_insn { + kprobe_opcode_t *insn; + pstate_check_t *pstate_cc; + kprobes_handler_t *handler; + /* restore address after step xol */ + unsigned long restore; +}; + +#endif diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index 10e6f1d..3fd15fdf4 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -73,6 +73,7 @@ #define COMPAT_PT_DATA_ADDR 0x10004 #define COMPAT_PT_TEXT_END_ADDR 0x10008 #ifndef __ASSEMBLY__ +#include <linux/bug.h> /* sizeof(struct user) for AArch32 */ #define COMPAT_USER_SZ 296 @@ -118,6 +119,8 @@ struct pt_regs { u64 syscallno; }; +#define MAX_REG_OFFSET offsetof(struct pt_regs, pstate) + #define arch_has_single_step() (1) #ifdef CONFIG_COMPAT @@ -143,9 +146,59 @@ struct pt_regs { #define fast_interrupts_enabled(regs) \ (!((regs)->pstate & PSR_F_BIT)) -#define user_stack_pointer(regs) \ +#define GET_USP(regs) \ (!compat_user_mode(regs) ? (regs)->sp : (regs)->compat_sp) +#define SET_USP(ptregs, value) \ + (!compat_user_mode(regs) ? ((regs)->sp = value) : ((regs)->compat_sp = value)) + +extern int regs_query_register_offset(const char *name); +extern const char *regs_query_register_name(unsigned int offset); +extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, + unsigned int n); + +/** + * regs_get_register() - get register value from its offset + * @regs: pt_regs from which register value is gotten + * @offset: offset of the register. + * + * regs_get_register returns the value of a register whose offset from @regs. + * The @offset is the offset of the register in struct pt_regs. + * If @offset is bigger than MAX_REG_OFFSET, this returns 0. + */ +static inline u64 regs_get_register(struct pt_regs *regs, unsigned int offset) +{ + u64 val = 0; + + WARN_ON(offset & 7); + + offset >>= 3; + switch (offset) { + case 0 ... 30: + val = regs->regs[offset]; + break; + case offsetof(struct pt_regs, sp) >> 3: + val = regs->sp; + break; + case offsetof(struct pt_regs, pc) >> 3: + val = regs->pc; + break; + case offsetof(struct pt_regs, pstate) >> 3: + val = regs->pstate; + break; + default: + val = 0; + } + + return val; +} + +/* Valid only for Kernel mode traps. */ +static inline unsigned long kernel_stack_pointer(struct pt_regs *regs) +{ + return regs->sp; +} + static inline unsigned long regs_return_value(struct pt_regs *regs) { return regs->regs[0]; @@ -155,8 +208,15 @@ static inline unsigned long regs_return_value(struct pt_regs *regs) struct task_struct; int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task); -#define instruction_pointer(regs) ((unsigned long)(regs)->pc) +#define GET_IP(regs) ((unsigned long)(regs)->pc) +#define SET_IP(regs, value) ((regs)->pc = ((u64) (value))) + +#define GET_FP(ptregs) ((unsigned long)(ptregs)->regs[29]) +#define SET_FP(ptregs, value) ((ptregs)->regs[29] = ((u64) (value))) + +#include <asm-generic/ptrace.h> +#undef profile_pc extern unsigned long profile_pc(struct pt_regs *regs); #endif /* __ASSEMBLY__ */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 9ef8ec6..0b9e49a 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -26,8 +26,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE $(call if_changed,objcopy) arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \ - sys_compat.o entry32.o \ - ../../arm/kernel/opcodes.o + sys_compat.o entry32.o arm64-obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o arm64-obj-$(CONFIG_ARM64_MODULE_PLTS) += module-plts.o @@ -49,7 +48,7 @@ arm64-obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o arm64-obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o \ cpu-reset.o -obj-y += $(arm64-obj-y) vdso/ +obj-y += $(arm64-obj-y) vdso/ probes/ obj-m += $(arm64-obj-m) head-y := head.o extra-y += $(head-y) vmlinux.lds diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c index 2dc4440..78f3680 100644 --- a/arch/arm64/kernel/arm64ksyms.c +++ b/arch/arm64/kernel/arm64ksyms.c @@ -27,6 +27,7 @@ #include <linux/uaccess.h> #include <linux/io.h> #include <linux/arm-smccc.h> +#include <linux/kprobes.h> #include <asm/checksum.h> @@ -68,6 +69,7 @@ EXPORT_SYMBOL(test_and_change_bit); #ifdef CONFIG_FUNCTION_TRACER EXPORT_SYMBOL(_mcount); +NOKPROBE_SYMBOL(_mcount); #endif /* arm-smccc */ diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index fab5603..5f72475 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -344,6 +344,21 @@ static int emulate_swpX(unsigned int address, unsigned int *data, return res; } +#define ARM_OPCODE_CONDITION_UNCOND 0xf + +static unsigned int __kprobes aarch32_check_condition(u32 opcode, u32 psr) +{ + u32 cc_bits = opcode >> 28; + + if (cc_bits != ARM_OPCODE_CONDITION_UNCOND) { + if ((*aarch32_opcode_cond_checks[cc_bits])(psr)) + return ARM_OPCODE_CONDTEST_PASS; + else + return ARM_OPCODE_CONDTEST_FAIL; + } + return ARM_OPCODE_CONDTEST_UNCOND; +} + /* * swp_handler logs the id of calling process, dissects the instruction, sanity * checks the memory location, calls emulate_swpX for the actual operation and @@ -358,7 +373,7 @@ static int swp_handler(struct pt_regs *regs, u32 instr) type = instr & TYPE_SWPB; - switch (arm_check_condition(instr, regs->pstate)) { + switch (aarch32_check_condition(instr, regs->pstate)) { case ARM_OPCODE_CONDTEST_PASS: break; case ARM_OPCODE_CONDTEST_FAIL: @@ -440,7 +455,7 @@ static int cp15barrier_handler(struct pt_regs *regs, u32 instr) { perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc); - switch (arm_check_condition(instr, regs->pstate)) { + switch (aarch32_check_condition(instr, regs->pstate)) { case ARM_OPCODE_CONDTEST_PASS: break; case ARM_OPCODE_CONDTEST_FAIL: diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 334a1cd..93ff592 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -51,6 +51,17 @@ int main(void) DEFINE(S_X5, offsetof(struct pt_regs, regs[5])); DEFINE(S_X6, offsetof(struct pt_regs, regs[6])); DEFINE(S_X7, offsetof(struct pt_regs, regs[7])); + DEFINE(S_X8, offsetof(struct pt_regs, regs[8])); + DEFINE(S_X10, offsetof(struct pt_regs, regs[10])); + DEFINE(S_X12, offsetof(struct pt_regs, regs[12])); + DEFINE(S_X14, offsetof(struct pt_regs, regs[14])); + DEFINE(S_X16, offsetof(struct pt_regs, regs[16])); + DEFINE(S_X18, offsetof(struct pt_regs, regs[18])); + DEFINE(S_X20, offsetof(struct pt_regs, regs[20])); + DEFINE(S_X22, offsetof(struct pt_regs, regs[22])); + DEFINE(S_X24, offsetof(struct pt_regs, regs[24])); + DEFINE(S_X26, offsetof(struct pt_regs, regs[26])); + DEFINE(S_X28, offsetof(struct pt_regs, regs[28])); DEFINE(S_LR, offsetof(struct pt_regs, regs[30])); DEFINE(S_SP, offsetof(struct pt_regs, sp)); #ifdef CONFIG_COMPAT diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index f17134d..91fff48 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -23,6 +23,7 @@ #include <linux/hardirq.h> #include <linux/init.h> #include <linux/ptrace.h> +#include <linux/kprobes.h> #include <linux/stat.h> #include <linux/uaccess.h> @@ -48,6 +49,7 @@ static void mdscr_write(u32 mdscr) asm volatile("msr mdscr_el1, %0" :: "r" (mdscr)); local_dbg_restore(flags); } +NOKPROBE_SYMBOL(mdscr_write); static u32 mdscr_read(void) { @@ -55,6 +57,7 @@ static u32 mdscr_read(void) asm volatile("mrs %0, mdscr_el1" : "=r" (mdscr)); return mdscr; } +NOKPROBE_SYMBOL(mdscr_read); /* * Allow root to disable self-hosted debug from userspace. @@ -103,6 +106,7 @@ void enable_debug_monitors(enum dbg_active_el el) mdscr_write(mdscr); } } +NOKPROBE_SYMBOL(enable_debug_monitors); void disable_debug_monitors(enum dbg_active_el el) { @@ -123,6 +127,7 @@ void disable_debug_monitors(enum dbg_active_el el) mdscr_write(mdscr); } } +NOKPROBE_SYMBOL(disable_debug_monitors); /* * OS lock clearing. @@ -167,11 +172,13 @@ static void set_regs_spsr_ss(struct pt_regs *regs) { regs->pstate |= DBG_SPSR_SS; } +NOKPROBE_SYMBOL(set_regs_spsr_ss); static void clear_regs_spsr_ss(struct pt_regs *regs) { regs->pstate &= ~DBG_SPSR_SS; } +NOKPROBE_SYMBOL(clear_regs_spsr_ss); /* EL1 Single Step Handler hooks */ static LIST_HEAD(step_hook); @@ -215,6 +222,7 @@ static int call_step_hook(struct pt_regs *regs, unsigned int esr) return retval; } +NOKPROBE_SYMBOL(call_step_hook); static void send_user_sigtrap(int si_code) { @@ -256,6 +264,10 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ user_rewind_single_step(current); } else { +#ifdef CONFIG_KPROBES + if (kprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED) + return 0; +#endif if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) return 0; @@ -269,6 +281,7 @@ static int single_step_handler(unsigned long addr, unsigned int esr, return 0; } +NOKPROBE_SYMBOL(single_step_handler); /* * Breakpoint handler is re-entrant as another breakpoint can @@ -306,19 +319,28 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr) return fn ? fn(regs, esr) : DBG_HOOK_ERROR; } +NOKPROBE_SYMBOL(call_break_hook); static int brk_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { if (user_mode(regs)) { send_user_sigtrap(TRAP_BRKPT); - } else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) { - pr_warning("Unexpected kernel BRK exception at EL1\n"); + } +#ifdef CONFIG_KPROBES + else if ((esr & BRK64_ESR_MASK) == BRK64_ESR_KPROBES) { + if (kprobe_breakpoint_handler(regs, esr) != DBG_HOOK_HANDLED) + return -EFAULT; + } +#endif + else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) { + pr_warn("Unexpected kernel BRK exception at EL1\n"); return -EFAULT; } return 0; } +NOKPROBE_SYMBOL(brk_handler); int aarch32_break_handler(struct pt_regs *regs) { @@ -355,6 +377,7 @@ int aarch32_break_handler(struct pt_regs *regs) send_user_sigtrap(TRAP_BRKPT); return 0; } +NOKPROBE_SYMBOL(aarch32_break_handler); static int __init debug_traps_init(void) { @@ -376,6 +399,7 @@ void user_rewind_single_step(struct task_struct *task) if (test_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP)) set_regs_spsr_ss(task_pt_regs(task)); } +NOKPROBE_SYMBOL(user_rewind_single_step); void user_fastforward_single_step(struct task_struct *task) { @@ -391,6 +415,7 @@ void kernel_enable_single_step(struct pt_regs *regs) mdscr_write(mdscr_read() | DBG_MDSCR_SS); enable_debug_monitors(DBG_ACTIVE_EL1); } +NOKPROBE_SYMBOL(kernel_enable_single_step); void kernel_disable_single_step(void) { @@ -398,12 +423,14 @@ void kernel_disable_single_step(void) mdscr_write(mdscr_read() & ~DBG_MDSCR_SS); disable_debug_monitors(DBG_ACTIVE_EL1); } +NOKPROBE_SYMBOL(kernel_disable_single_step); int kernel_active_single_step(void) { WARN_ON(!irqs_disabled()); return mdscr_read() & DBG_MDSCR_SS; } +NOKPROBE_SYMBOL(kernel_active_single_step); /* ptrace API */ void user_enable_single_step(struct task_struct *task) @@ -411,8 +438,10 @@ void user_enable_single_step(struct task_struct *task) set_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP); set_regs_spsr_ss(task_pt_regs(task)); } +NOKPROBE_SYMBOL(user_enable_single_step); void user_disable_single_step(struct task_struct *task) { clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP); } +NOKPROBE_SYMBOL(user_disable_single_step); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 3eca5d3..a03eb49 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -242,6 +242,7 @@ tsk .req x28 // current thread_info /* * Exception vectors. */ + .pushsection ".entry.text", "ax" .align 11 ENTRY(vectors) @@ -784,6 +785,8 @@ __ni_sys_trace: bl do_ni_syscall b __sys_trace_return + .popsection // .entry.text + /* * Special system call wrappers. */ diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index ce21aa8..26a6bf7 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -24,6 +24,7 @@ #include <linux/cpu_pm.h> #include <linux/errno.h> #include <linux/hw_breakpoint.h> +#include <linux/kprobes.h> #include <linux/perf_event.h> #include <linux/ptrace.h> #include <linux/smp.h> @@ -127,6 +128,7 @@ static u64 read_wb_reg(int reg, int n) return val; } +NOKPROBE_SYMBOL(read_wb_reg); static void write_wb_reg(int reg, int n, u64 val) { @@ -140,6 +142,7 @@ static void write_wb_reg(int reg, int n, u64 val) } isb(); } +NOKPROBE_SYMBOL(write_wb_reg); /* * Convert a breakpoint privilege level to the corresponding exception @@ -157,6 +160,7 @@ static enum dbg_active_el debug_exception_level(int privilege) return -EINVAL; } } +NOKPROBE_SYMBOL(debug_exception_level); enum hw_breakpoint_ops { HW_BREAKPOINT_INSTALL, @@ -575,6 +579,7 @@ static void toggle_bp_registers(int reg, enum dbg_active_el el, int enable) write_wb_reg(reg, i, ctrl); } } +NOKPROBE_SYMBOL(toggle_bp_registers); /* * Debug exception handlers. @@ -654,6 +659,7 @@ unlock: return 0; } +NOKPROBE_SYMBOL(breakpoint_handler); static int watchpoint_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) @@ -756,6 +762,7 @@ unlock: return 0; } +NOKPROBE_SYMBOL(watchpoint_handler); /* * Handle single-step exception. @@ -813,6 +820,7 @@ int reinstall_suspended_bps(struct pt_regs *regs) return !handled_exception; } +NOKPROBE_SYMBOL(reinstall_suspended_bps); /* * Context-switcher for restoring suspended breakpoints. diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c index 368c082..63f9432 100644 --- a/arch/arm64/kernel/insn.c +++ b/arch/arm64/kernel/insn.c @@ -30,6 +30,7 @@ #include <asm/cacheflush.h> #include <asm/debug-monitors.h> #include <asm/fixmap.h> +#include <asm/opcodes.h> #include <asm/insn.h> #define AARCH64_INSN_SF_BIT BIT(31) @@ -162,6 +163,32 @@ static bool __kprobes __aarch64_insn_hotpatch_safe(u32 insn) aarch64_insn_is_nop(insn); } +bool __kprobes aarch64_insn_uses_literal(u32 insn) +{ + /* ldr/ldrsw (literal), prfm */ + + return aarch64_insn_is_ldr_lit(insn) || + aarch64_insn_is_ldrsw_lit(insn) || + aarch64_insn_is_adr_adrp(insn) || + aarch64_insn_is_prfm_lit(insn); +} + +bool __kprobes aarch64_insn_is_branch(u32 insn) +{ + /* b, bl, cb*, tb*, b.cond, br, blr */ + + return aarch64_insn_is_b(insn) || + aarch64_insn_is_bl(insn) || + aarch64_insn_is_cbz(insn) || + aarch64_insn_is_cbnz(insn) || + aarch64_insn_is_tbz(insn) || + aarch64_insn_is_tbnz(insn) || + aarch64_insn_is_ret(insn) || + aarch64_insn_is_br(insn) || + aarch64_insn_is_blr(insn) || + aarch64_insn_is_bcond(insn); +} + /* * ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a * Section B2.6.5 "Concurrent modification and execution of instructions": @@ -1175,6 +1202,14 @@ u32 aarch64_set_branch_offset(u32 insn, s32 offset) BUG(); } +/* + * Extract the Op/CR data from a msr/mrs instruction. + */ +u32 aarch64_insn_extract_system_reg(u32 insn) +{ + return (insn & 0x1FFFE0) >> 5; +} + bool aarch32_insn_is_wide(u32 insn) { return insn >= 0xe800; @@ -1200,3 +1235,101 @@ u32 aarch32_insn_mcr_extract_crm(u32 insn) { return insn & CRM_MASK; } + +static bool __kprobes __check_eq(unsigned long pstate) +{ + return (pstate & PSR_Z_BIT) != 0; +} + +static bool __kprobes __check_ne(unsigned long pstate) +{ + return (pstate & PSR_Z_BIT) == 0; +} + +static bool __kprobes __check_cs(unsigned long pstate) +{ + return (pstate & PSR_C_BIT) != 0; +} + +static bool __kprobes __check_cc(unsigned long pstate) +{ + return (pstate & PSR_C_BIT) == 0; +} + +static bool __kprobes __check_mi(unsigned long pstate) +{ + return (pstate & PSR_N_BIT) != 0; +} + +static bool __kprobes __check_pl(unsigned long pstate) +{ + return (pstate & PSR_N_BIT) == 0; +} + +static bool __kprobes __check_vs(unsigned long pstate) +{ + return (pstate & PSR_V_BIT) != 0; +} + +static bool __kprobes __check_vc(unsigned long pstate) +{ + return (pstate & PSR_V_BIT) == 0; +} + +static bool __kprobes __check_hi(unsigned long pstate) +{ + pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ + return (pstate & PSR_C_BIT) != 0; +} + +static bool __kprobes __check_ls(unsigned long pstate) +{ + pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ + return (pstate & PSR_C_BIT) == 0; +} + +static bool __kprobes __check_ge(unsigned long pstate) +{ + pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + return (pstate & PSR_N_BIT) == 0; +} + +static bool __kprobes __check_lt(unsigned long pstate) +{ + pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + return (pstate & PSR_N_BIT) != 0; +} + +static bool __kprobes __check_gt(unsigned long pstate) +{ + /*PSR_N_BIT ^= PSR_V_BIT */ + unsigned long temp = pstate ^ (pstate << 3); + + temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ + return (temp & PSR_N_BIT) == 0; +} + +static bool __kprobes __check_le(unsigned long pstate) +{ + /*PSR_N_BIT ^= PSR_V_BIT */ + unsigned long temp = pstate ^ (pstate << 3); + + temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ + return (temp & PSR_N_BIT) != 0; +} + +static bool __kprobes __check_al(unsigned long pstate) +{ + return true; +} + +/* + * Note that the ARMv8 ARM calls condition code 0b1111 "nv", but states that + * it behaves identically to 0b1110 ("al"). + */ +pstate_check_t * const aarch32_opcode_cond_checks[16] = { + __check_eq, __check_ne, __check_cs, __check_cc, + __check_mi, __check_pl, __check_vs, __check_vc, + __check_hi, __check_ls, __check_ge, __check_lt, + __check_gt, __check_le, __check_al, __check_al +}; diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index b5f063e..8c57f64 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -22,6 +22,7 @@ #include <linux/irq.h> #include <linux/kdebug.h> #include <linux/kgdb.h> +#include <linux/kprobes.h> #include <asm/traps.h> struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { @@ -230,6 +231,7 @@ static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) kgdb_handle_exception(1, SIGTRAP, 0, regs); return 0; } +NOKPROBE_SYMBOL(kgdb_brk_fn) static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) { @@ -238,12 +240,14 @@ static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) return 0; } +NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) { kgdb_handle_exception(1, SIGTRAP, 0, regs); return 0; } +NOKPROBE_SYMBOL(kgdb_step_brk_fn); static struct break_hook kgdb_brkpt_hook = { .esr_mask = 0xffffffff, diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile new file mode 100644 index 0000000..ce06312 --- /dev/null +++ b/arch/arm64/kernel/probes/Makefile @@ -0,0 +1,3 @@ +obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \ + kprobes_trampoline.o \ + simulate-insn.o diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c new file mode 100644 index 0000000..37e47a9 --- /dev/null +++ b/arch/arm64/kernel/probes/decode-insn.c @@ -0,0 +1,174 @@ +/* + * arch/arm64/kernel/probes/decode-insn.c + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/module.h> +#include <asm/kprobes.h> +#include <asm/insn.h> +#include <asm/sections.h> + +#include "decode-insn.h" +#include "simulate-insn.h" + +static bool __kprobes aarch64_insn_is_steppable(u32 insn) +{ + /* + * Branch instructions will write a new value into the PC which is + * likely to be relative to the XOL address and therefore invalid. + * Deliberate generation of an exception during stepping is also not + * currently safe. Lastly, MSR instructions can do any number of nasty + * things we can't handle during single-stepping. + */ + if (aarch64_get_insn_class(insn) == AARCH64_INSN_CLS_BR_SYS) { + if (aarch64_insn_is_branch(insn) || + aarch64_insn_is_msr_imm(insn) || + aarch64_insn_is_msr_reg(insn) || + aarch64_insn_is_exception(insn) || + aarch64_insn_is_eret(insn)) + return false; + + /* + * The MRS instruction may not return a correct value when + * executing in the single-stepping environment. We do make one + * exception, for reading the DAIF bits. + */ + if (aarch64_insn_is_mrs(insn)) + return aarch64_insn_extract_system_reg(insn) + != AARCH64_INSN_SPCLREG_DAIF; + + /* + * The HINT instruction is is problematic when single-stepping, + * except for the NOP case. + */ + if (aarch64_insn_is_hint(insn)) + return aarch64_insn_is_nop(insn); + + return true; + } + + /* + * Instructions which load PC relative literals are not going to work + * when executed from an XOL slot. Instructions doing an exclusive + * load/store are not going to complete successfully when single-step + * exception handling happens in the middle of the sequence. + */ + if (aarch64_insn_uses_literal(insn) || + aarch64_insn_is_exclusive(insn)) + return false; + + return true; +} + +/* Return: + * INSN_REJECTED If instruction is one not allowed to kprobe, + * INSN_GOOD If instruction is supported and uses instruction slot, + * INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot. + */ +static enum kprobe_insn __kprobes +arm_probe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) +{ + /* + * Instructions reading or modifying the PC won't work from the XOL + * slot. + */ + if (aarch64_insn_is_steppable(insn)) + return INSN_GOOD; + + if (aarch64_insn_is_bcond(insn)) { + asi->handler = simulate_b_cond; + } else if (aarch64_insn_is_cbz(insn) || + aarch64_insn_is_cbnz(insn)) { + asi->handler = simulate_cbz_cbnz; + } else if (aarch64_insn_is_tbz(insn) || + aarch64_insn_is_tbnz(insn)) { + asi->handler = simulate_tbz_tbnz; + } else if (aarch64_insn_is_adr_adrp(insn)) { + asi->handler = simulate_adr_adrp; + } else if (aarch64_insn_is_b(insn) || + aarch64_insn_is_bl(insn)) { + asi->handler = simulate_b_bl; + } else if (aarch64_insn_is_br(insn) || + aarch64_insn_is_blr(insn) || + aarch64_insn_is_ret(insn)) { + asi->handler = simulate_br_blr_ret; + } else if (aarch64_insn_is_ldr_lit(insn)) { + asi->handler = simulate_ldr_literal; + } else if (aarch64_insn_is_ldrsw_lit(insn)) { + asi->handler = simulate_ldrsw_literal; + } else { + /* + * Instruction cannot be stepped out-of-line and we don't + * (yet) simulate it. + */ + return INSN_REJECTED; + } + + return INSN_GOOD_NO_SLOT; +} + +static bool __kprobes +is_probed_address_atomic(kprobe_opcode_t *scan_start, kprobe_opcode_t *scan_end) +{ + while (scan_start > scan_end) { + /* + * atomic region starts from exclusive load and ends with + * exclusive store. + */ + if (aarch64_insn_is_store_ex(le32_to_cpu(*scan_start))) + return false; + else if (aarch64_insn_is_load_ex(le32_to_cpu(*scan_start))) + return true; + scan_start--; + } + + return false; +} + +enum kprobe_insn __kprobes +arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi) +{ + enum kprobe_insn decoded; + kprobe_opcode_t insn = le32_to_cpu(*addr); + kprobe_opcode_t *scan_start = addr - 1; + kprobe_opcode_t *scan_end = addr - MAX_ATOMIC_CONTEXT_SIZE; +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR) + struct module *mod; +#endif + + if (addr >= (kprobe_opcode_t *)_text && + scan_end < (kprobe_opcode_t *)_text) + scan_end = (kprobe_opcode_t *)_text; +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR) + else { + preempt_disable(); + mod = __module_address((unsigned long)addr); + if (mod && within_module_init((unsigned long)addr, mod) && + !within_module_init((unsigned long)scan_end, mod)) + scan_end = (kprobe_opcode_t *)mod->init_layout.base; + else if (mod && within_module_core((unsigned long)addr, mod) && + !within_module_core((unsigned long)scan_end, mod)) + scan_end = (kprobe_opcode_t *)mod->core_layout.base; + preempt_enable(); + } +#endif + decoded = arm_probe_decode_insn(insn, asi); + + if (decoded == INSN_REJECTED || + is_probed_address_atomic(scan_start, scan_end)) + return INSN_REJECTED; + + return decoded; +} diff --git a/arch/arm64/kernel/probes/decode-insn.h b/arch/arm64/kernel/probes/decode-insn.h new file mode 100644 index 0000000..d438289 --- /dev/null +++ b/arch/arm64/kernel/probes/decode-insn.h @@ -0,0 +1,35 @@ +/* + * arch/arm64/kernel/probes/decode-insn.h + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#ifndef _ARM_KERNEL_KPROBES_ARM64_H +#define _ARM_KERNEL_KPROBES_ARM64_H + +/* + * ARM strongly recommends a limit of 128 bytes between LoadExcl and + * StoreExcl instructions in a single thread of execution. So keep the + * max atomic context size as 32. + */ +#define MAX_ATOMIC_CONTEXT_SIZE (128 / sizeof(kprobe_opcode_t)) + +enum kprobe_insn { + INSN_REJECTED, + INSN_GOOD_NO_SLOT, + INSN_GOOD, +}; + +enum kprobe_insn __kprobes +arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi); + +#endif /* _ARM_KERNEL_KPROBES_ARM64_H */ diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c new file mode 100644 index 0000000..bf97685 --- /dev/null +++ b/arch/arm64/kernel/probes/kprobes.c @@ -0,0 +1,686 @@ +/* + * arch/arm64/kernel/probes/kprobes.c + * + * Kprobes support for ARM64 + * + * Copyright (C) 2013 Linaro Limited. + * Author: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + * + */ +#include <linux/kasan.h> +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/stop_machine.h> +#include <linux/stringify.h> +#include <asm/traps.h> +#include <asm/ptrace.h> +#include <asm/cacheflush.h> +#include <asm/debug-monitors.h> +#include <asm/system_misc.h> +#include <asm/insn.h> +#include <asm/uaccess.h> +#include <asm/irq.h> +#include <asm-generic/sections.h> + +#include "decode-insn.h" + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static void __kprobes +post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); + +static inline unsigned long min_stack_size(unsigned long addr) +{ + unsigned long size; + + if (on_irq_stack(addr, raw_smp_processor_id())) + size = IRQ_STACK_PTR(raw_smp_processor_id()) - addr; + else + size = (unsigned long)current_thread_info() + THREAD_START_SP - addr; + + return min(size, FIELD_SIZEOF(struct kprobe_ctlblk, jprobes_stack)); +} + +static void __kprobes arch_prepare_ss_slot(struct kprobe *p) +{ + /* prepare insn slot */ + p->ainsn.insn[0] = cpu_to_le32(p->opcode); + + flush_icache_range((uintptr_t) (p->ainsn.insn), + (uintptr_t) (p->ainsn.insn) + + MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + + /* + * Needs restoring of return address after stepping xol. + */ + p->ainsn.restore = (unsigned long) p->addr + + sizeof(kprobe_opcode_t); +} + +static void __kprobes arch_prepare_simulate(struct kprobe *p) +{ + /* This instructions is not executed xol. No need to adjust the PC */ + p->ainsn.restore = 0; +} + +static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (p->ainsn.handler) + p->ainsn.handler((u32)p->opcode, (long)p->addr, regs); + + /* single step simulated, now go for post processing */ + post_kprobe_handler(kcb, regs); +} + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + unsigned long probe_addr = (unsigned long)p->addr; + extern char __start_rodata[]; + extern char __end_rodata[]; + + if (probe_addr & 0x3) + return -EINVAL; + + /* copy instruction */ + p->opcode = le32_to_cpu(*p->addr); + + if (in_exception_text(probe_addr)) + return -EINVAL; + if (probe_addr >= (unsigned long) __start_rodata && + probe_addr <= (unsigned long) __end_rodata) + return -EINVAL; + + /* decode instruction */ + switch (arm_kprobe_decode_insn(p->addr, &p->ainsn)) { + case INSN_REJECTED: /* insn not supported */ + return -EINVAL; + + case INSN_GOOD_NO_SLOT: /* insn need simulation */ + p->ainsn.insn = NULL; + break; + + case INSN_GOOD: /* instruction uses slot */ + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + break; + }; + + /* prepare the instruction */ + if (p->ainsn.insn) + arch_prepare_ss_slot(p); + else + arch_prepare_simulate(p); + + return 0; +} + +static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) +{ + void *addrs[1]; + u32 insns[1]; + + addrs[0] = (void *)addr; + insns[0] = (u32)opcode; + + return aarch64_insn_patch_text(addrs, insns, 1); +} + +/* arm kprobe: install breakpoint in text */ +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, BRK64_OPCODE_KPROBES); +} + +/* disarm kprobe: remove breakpoint from text */ +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, p->opcode); +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (p->ainsn.insn) { + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; + } +} + +static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp = kprobe_running(); + kcb->prev_kprobe.status = kcb->kprobe_status; +} + +static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); + kcb->kprobe_status = kcb->prev_kprobe.status; +} + +static void __kprobes set_current_kprobe(struct kprobe *p) +{ + __this_cpu_write(current_kprobe, p); +} + +/* + * The D-flag (Debug mask) is set (masked) upon debug exception entry. + * Kprobes needs to clear (unmask) D-flag -ONLY- in case of recursive + * probe i.e. when probe hit from kprobe handler context upon + * executing the pre/post handlers. In this case we return with + * D-flag clear so that single-stepping can be carried-out. + * + * Leave D-flag set in all other cases. + */ +static void __kprobes +spsr_set_debug_flag(struct pt_regs *regs, int mask) +{ + unsigned long spsr = regs->pstate; + + if (mask) + spsr |= PSR_D_BIT; + else + spsr &= ~PSR_D_BIT; + + regs->pstate = spsr; +} + +/* + * Interrupts need to be disabled before single-step mode is set, and not + * reenabled until after single-step mode ends. + * Without disabling interrupt on local CPU, there is a chance of + * interrupt occurrence in the period of exception return and start of + * out-of-line single-step, that result in wrongly single stepping + * into the interrupt handler. + */ +static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb, + struct pt_regs *regs) +{ + kcb->saved_irqflag = regs->pstate; + regs->pstate |= PSR_I_BIT; +} + +static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, + struct pt_regs *regs) +{ + if (kcb->saved_irqflag & PSR_I_BIT) + regs->pstate |= PSR_I_BIT; + else + regs->pstate &= ~PSR_I_BIT; +} + +static void __kprobes +set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr) +{ + kcb->ss_ctx.ss_pending = true; + kcb->ss_ctx.match_addr = addr + sizeof(kprobe_opcode_t); +} + +static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) +{ + kcb->ss_ctx.ss_pending = false; + kcb->ss_ctx.match_addr = 0; +} + +static void __kprobes setup_singlestep(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb, int reenter) +{ + unsigned long slot; + + if (reenter) { + save_previous_kprobe(kcb); + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_REENTER; + } else { + kcb->kprobe_status = KPROBE_HIT_SS; + } + + + if (p->ainsn.insn) { + /* prepare for single stepping */ + slot = (unsigned long)p->ainsn.insn; + + set_ss_context(kcb, slot); /* mark pending ss */ + + if (kcb->kprobe_status == KPROBE_REENTER) + spsr_set_debug_flag(regs, 0); + else + WARN_ON(regs->pstate & PSR_D_BIT); + + /* IRQs and single stepping do not mix well. */ + kprobes_save_local_irqflag(kcb, regs); + kernel_enable_single_step(regs); + instruction_pointer_set(regs, slot); + } else { + /* insn simulation */ + arch_simulate_insn(p, regs); + } +} + +static int __kprobes reenter_kprobe(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: + case KPROBE_HIT_ACTIVE: + kprobes_inc_nmissed_count(p); + setup_singlestep(p, regs, kcb, 1); + break; + case KPROBE_HIT_SS: + case KPROBE_REENTER: + pr_warn("Unrecoverable kprobe detected at %p.\n", p->addr); + dump_kprobe(p); + BUG(); + break; + default: + WARN_ON(1); + return 0; + } + + return 1; +} + +static void __kprobes +post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) +{ + struct kprobe *cur = kprobe_running(); + + if (!cur) + return; + + /* return addr restore if non-branching insn */ + if (cur->ainsn.restore != 0) + instruction_pointer_set(regs, cur->ainsn.restore); + + /* restore back original saved kprobe variables and continue */ + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); + return; + } + /* call post handler */ + kcb->kprobe_status = KPROBE_HIT_SSDONE; + if (cur->post_handler) { + /* post_handler can hit breakpoint and single step + * again, so we enable D-flag for recursive exception. + */ + cur->post_handler(cur, regs, 0); + } + + reset_current_kprobe(); +} + +int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) +{ + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + switch (kcb->kprobe_status) { + case KPROBE_HIT_SS: + case KPROBE_REENTER: + /* + * We are here because the instruction being single + * stepped caused a page fault. We reset the current + * kprobe and the ip points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + instruction_pointer_set(regs, (unsigned long) cur->addr); + if (!instruction_pointer(regs)) + BUG(); + + kernel_disable_single_step(); + if (kcb->kprobe_status == KPROBE_REENTER) + spsr_set_debug_flag(regs, 1); + + if (kcb->kprobe_status == KPROBE_REENTER) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); + + break; + case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SSDONE: + /* + * We increment the nmissed count for accounting, + * we can also use npre/npostfault count for accounting + * these specific fault cases. + */ + kprobes_inc_nmissed_count(cur); + + /* + * We come here because instructions in the pre/post + * handler caused the page_fault, this could happen + * if handler tries to access user space by + * copy_from_user(), get_user() etc. Let the + * user-specified handler try to fix it first. + */ + if (cur->fault_handler && cur->fault_handler(cur, regs, fsr)) + return 1; + + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + if (fixup_exception(regs)) + return 1; + } + return 0; +} + +int __kprobes kprobe_exceptions_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + return NOTIFY_DONE; +} + +static void __kprobes kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p, *cur_kprobe; + struct kprobe_ctlblk *kcb; + unsigned long addr = instruction_pointer(regs); + + kcb = get_kprobe_ctlblk(); + cur_kprobe = kprobe_running(); + + p = get_kprobe((kprobe_opcode_t *) addr); + + if (p) { + if (cur_kprobe) { + if (reenter_kprobe(p, regs, kcb)) + return; + } else { + /* Probe hit */ + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it prepped + * for calling the break_handler below on re-entry, + * so get out doing nothing more here. + * + * pre_handler can hit a breakpoint and can step thru + * before return, keep PSTATE D-flag enabled until + * pre_handler return back. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) { + setup_singlestep(p, regs, kcb, 0); + return; + } + } + } else if ((le32_to_cpu(*(kprobe_opcode_t *) addr) == + BRK64_OPCODE_KPROBES) && cur_kprobe) { + /* We probably hit a jprobe. Call its break handler. */ + if (cur_kprobe->break_handler && + cur_kprobe->break_handler(cur_kprobe, regs)) { + setup_singlestep(cur_kprobe, regs, kcb, 0); + return; + } + } + /* + * The breakpoint instruction was removed right + * after we hit it. Another cpu has removed + * either a probepoint or a debugger breakpoint + * at this address. In either case, no further + * handling of this interrupt is appropriate. + * Return back to original instruction, and continue. + */ +} + +static int __kprobes +kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr) +{ + if ((kcb->ss_ctx.ss_pending) + && (kcb->ss_ctx.match_addr == addr)) { + clear_ss_context(kcb); /* clear pending ss */ + return DBG_HOOK_HANDLED; + } + /* not ours, kprobes should ignore it */ + return DBG_HOOK_ERROR; +} + +int __kprobes +kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + int retval; + + /* return error if this is not our step */ + retval = kprobe_ss_hit(kcb, instruction_pointer(regs)); + + if (retval == DBG_HOOK_HANDLED) { + kprobes_restore_local_irqflag(kcb, regs); + kernel_disable_single_step(); + + if (kcb->kprobe_status == KPROBE_REENTER) + spsr_set_debug_flag(regs, 1); + + post_kprobe_handler(kcb, regs); + } + + return retval; +} + +int __kprobes +kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) +{ + kprobe_handler(regs); + return DBG_HOOK_HANDLED; +} + +int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct jprobe *jp = container_of(p, struct jprobe, kp); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + long stack_ptr = kernel_stack_pointer(regs); + + kcb->jprobe_saved_regs = *regs; + /* + * As Linus pointed out, gcc assumes that the callee + * owns the argument space and could overwrite it, e.g. + * tailcall optimization. So, to be absolutely safe + * we also save and restore enough stack bytes to cover + * the argument area. + */ + kasan_disable_current(); + memcpy(kcb->jprobes_stack, (void *)stack_ptr, + min_stack_size(stack_ptr)); + kasan_enable_current(); + + instruction_pointer_set(regs, (unsigned long) jp->entry); + preempt_disable(); + pause_graph_tracing(); + return 1; +} + +void __kprobes jprobe_return(void) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + /* + * Jprobe handler return by entering break exception, + * encoded same as kprobe, but with following conditions + * -a special PC to identify it from the other kprobes. + * -restore stack addr to original saved pt_regs + */ + asm volatile(" mov sp, %0 \n" + "jprobe_return_break: brk %1 \n" + : + : "r" (kcb->jprobe_saved_regs.sp), + "I" (BRK64_ESR_KPROBES) + : "memory"); + + unreachable(); +} + +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + long stack_addr = kcb->jprobe_saved_regs.sp; + long orig_sp = kernel_stack_pointer(regs); + struct jprobe *jp = container_of(p, struct jprobe, kp); + extern const char jprobe_return_break[]; + + if (instruction_pointer(regs) != (u64) jprobe_return_break) + return 0; + + if (orig_sp != stack_addr) { + struct pt_regs *saved_regs = + (struct pt_regs *)kcb->jprobe_saved_regs.sp; + pr_err("current sp %lx does not match saved sp %lx\n", + orig_sp, stack_addr); + pr_err("Saved registers for jprobe %p\n", jp); + show_regs(saved_regs); + pr_err("Current registers\n"); + show_regs(regs); + BUG(); + } + unpause_graph_tracing(); + *regs = kcb->jprobe_saved_regs; + kasan_disable_current(); + memcpy((void *)stack_addr, kcb->jprobes_stack, + min_stack_size(stack_addr)); + kasan_enable_current(); + preempt_enable_no_resched(); + return 1; +} + +bool arch_within_kprobe_blacklist(unsigned long addr) +{ + extern char __idmap_text_start[], __idmap_text_end[]; + extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[]; + + if ((addr >= (unsigned long)__kprobes_text_start && + addr < (unsigned long)__kprobes_text_end) || + (addr >= (unsigned long)__entry_text_start && + addr < (unsigned long)__entry_text_end) || + (addr >= (unsigned long)__idmap_text_start && + addr < (unsigned long)__idmap_text_end) || + !!search_exception_tables(addr)) + return true; + + if (!is_kernel_in_hyp_mode()) { + if ((addr >= (unsigned long)__hyp_text_start && + addr < (unsigned long)__hyp_text_end) || + (addr >= (unsigned long)__hyp_idmap_text_start && + addr < (unsigned long)__hyp_idmap_text_end)) + return true; + } + + return false; +} + +void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) +{ + struct kretprobe_instance *ri = NULL; + struct hlist_head *head, empty_rp; + struct hlist_node *tmp; + unsigned long flags, orig_ret_address = 0; + unsigned long trampoline_address = + (unsigned long)&kretprobe_trampoline; + kprobe_opcode_t *correct_ret_addr = NULL; + + INIT_HLIST_HEAD(&empty_rp); + kretprobe_hash_lock(current, &head, &flags); + + /* + * It is possible to have multiple instances associated with a given + * task either because multiple functions in the call path have + * return probes installed on them, and/or more than one + * return probe was registered for a target function. + * + * We can handle this because: + * - instances are always pushed into the head of the list + * - when multiple return probes are registered for the same + * function, the (chronologically) first instance's ret_addr + * will be the real return address, and all the rest will + * point to kretprobe_trampoline. + */ + hlist_for_each_entry_safe(ri, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + orig_ret_address = (unsigned long)ri->ret_addr; + + if (orig_ret_address != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; + } + + kretprobe_assert(ri, orig_ret_address, trampoline_address); + + correct_ret_addr = ri->ret_addr; + hlist_for_each_entry_safe(ri, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + orig_ret_address = (unsigned long)ri->ret_addr; + if (ri->rp && ri->rp->handler) { + __this_cpu_write(current_kprobe, &ri->rp->kp); + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; + ri->ret_addr = correct_ret_addr; + ri->rp->handler(ri, regs); + __this_cpu_write(current_kprobe, NULL); + } + + recycle_rp_inst(ri, &empty_rp); + + if (orig_ret_address != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; + } + + kretprobe_hash_unlock(current, &flags); + + hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { + hlist_del(&ri->hlist); + kfree(ri); + } + return (void *)orig_ret_address; +} + +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)regs->regs[30]; + + /* replace return addr (x30) with trampoline */ + regs->regs[30] = (long)&kretprobe_trampoline; +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + return 0; +} + +int __init arch_init_kprobes(void) +{ + return 0; +} diff --git a/arch/arm64/kernel/probes/kprobes_trampoline.S b/arch/arm64/kernel/probes/kprobes_trampoline.S new file mode 100644 index 0000000..5d6e7f1 --- /dev/null +++ b/arch/arm64/kernel/probes/kprobes_trampoline.S @@ -0,0 +1,81 @@ +/* + * trampoline entry and return code for kretprobes. + */ + +#include <linux/linkage.h> +#include <asm/asm-offsets.h> +#include <asm/assembler.h> + + .text + + .macro save_all_base_regs + stp x0, x1, [sp, #S_X0] + stp x2, x3, [sp, #S_X2] + stp x4, x5, [sp, #S_X4] + stp x6, x7, [sp, #S_X6] + stp x8, x9, [sp, #S_X8] + stp x10, x11, [sp, #S_X10] + stp x12, x13, [sp, #S_X12] + stp x14, x15, [sp, #S_X14] + stp x16, x17, [sp, #S_X16] + stp x18, x19, [sp, #S_X18] + stp x20, x21, [sp, #S_X20] + stp x22, x23, [sp, #S_X22] + stp x24, x25, [sp, #S_X24] + stp x26, x27, [sp, #S_X26] + stp x28, x29, [sp, #S_X28] + add x0, sp, #S_FRAME_SIZE + stp lr, x0, [sp, #S_LR] + /* + * Construct a useful saved PSTATE + */ + mrs x0, nzcv + mrs x1, daif + orr x0, x0, x1 + mrs x1, CurrentEL + orr x0, x0, x1 + mrs x1, SPSel + orr x0, x0, x1 + stp xzr, x0, [sp, #S_PC] + .endm + + .macro restore_all_base_regs + ldr x0, [sp, #S_PSTATE] + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) + msr nzcv, x0 + ldp x0, x1, [sp, #S_X0] + ldp x2, x3, [sp, #S_X2] + ldp x4, x5, [sp, #S_X4] + ldp x6, x7, [sp, #S_X6] + ldp x8, x9, [sp, #S_X8] + ldp x10, x11, [sp, #S_X10] + ldp x12, x13, [sp, #S_X12] + ldp x14, x15, [sp, #S_X14] + ldp x16, x17, [sp, #S_X16] + ldp x18, x19, [sp, #S_X18] + ldp x20, x21, [sp, #S_X20] + ldp x22, x23, [sp, #S_X22] + ldp x24, x25, [sp, #S_X24] + ldp x26, x27, [sp, #S_X26] + ldp x28, x29, [sp, #S_X28] + .endm + +ENTRY(kretprobe_trampoline) + sub sp, sp, #S_FRAME_SIZE + + save_all_base_regs + + mov x0, sp + bl trampoline_probe_handler + /* + * Replace trampoline address in lr with actual orig_ret_addr return + * address. + */ + mov lr, x0 + + restore_all_base_regs + + add sp, sp, #S_FRAME_SIZE + ret + +ENDPROC(kretprobe_trampoline) diff --git a/arch/arm64/kernel/probes/simulate-insn.c b/arch/arm64/kernel/probes/simulate-insn.c new file mode 100644 index 0000000..8977ce9 --- /dev/null +++ b/arch/arm64/kernel/probes/simulate-insn.c @@ -0,0 +1,217 @@ +/* + * arch/arm64/kernel/probes/simulate-insn.c + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#include <linux/kernel.h> +#include <linux/kprobes.h> + +#include "simulate-insn.h" + +#define sign_extend(x, signbit) \ + ((x) | (0 - ((x) & (1 << (signbit))))) + +#define bbl_displacement(insn) \ + sign_extend(((insn) & 0x3ffffff) << 2, 27) + +#define bcond_displacement(insn) \ + sign_extend(((insn >> 5) & 0x7ffff) << 2, 20) + +#define cbz_displacement(insn) \ + sign_extend(((insn >> 5) & 0x7ffff) << 2, 20) + +#define tbz_displacement(insn) \ + sign_extend(((insn >> 5) & 0x3fff) << 2, 15) + +#define ldr_displacement(insn) \ + sign_extend(((insn >> 5) & 0x7ffff) << 2, 20) + +static inline void set_x_reg(struct pt_regs *regs, int reg, u64 val) +{ + if (reg < 31) + regs->regs[reg] = val; +} + +static inline void set_w_reg(struct pt_regs *regs, int reg, u64 val) +{ + if (reg < 31) + regs->regs[reg] = lower_32_bits(val); +} + +static inline u64 get_x_reg(struct pt_regs *regs, int reg) +{ + if (reg < 31) + return regs->regs[reg]; + else + return 0; +} + +static inline u32 get_w_reg(struct pt_regs *regs, int reg) +{ + if (reg < 31) + return lower_32_bits(regs->regs[reg]); + else + return 0; +} + +static bool __kprobes check_cbz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + + return (opcode & (1 << 31)) ? + (get_x_reg(regs, xn) == 0) : (get_w_reg(regs, xn) == 0); +} + +static bool __kprobes check_cbnz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + + return (opcode & (1 << 31)) ? + (get_x_reg(regs, xn) != 0) : (get_w_reg(regs, xn) != 0); +} + +static bool __kprobes check_tbz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f); + + return ((get_x_reg(regs, xn) >> bit_pos) & 0x1) == 0; +} + +static bool __kprobes check_tbnz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f); + + return ((get_x_reg(regs, xn) >> bit_pos) & 0x1) != 0; +} + +/* + * instruction simulation functions + */ +void __kprobes +simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs) +{ + long imm, xn, val; + + xn = opcode & 0x1f; + imm = ((opcode >> 3) & 0x1ffffc) | ((opcode >> 29) & 0x3); + imm = sign_extend(imm, 20); + if (opcode & 0x80000000) + val = (imm<<12) + (addr & 0xfffffffffffff000); + else + val = imm + addr; + + set_x_reg(regs, xn, val); + + instruction_pointer_set(regs, instruction_pointer(regs) + 4); +} + +void __kprobes +simulate_b_bl(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = bbl_displacement(opcode); + + /* Link register is x30 */ + if (opcode & (1 << 31)) + set_x_reg(regs, 30, addr + 4); + + instruction_pointer_set(regs, addr + disp); +} + +void __kprobes +simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = 4; + + if (aarch32_opcode_cond_checks[opcode & 0xf](regs->pstate & 0xffffffff)) + disp = bcond_displacement(opcode); + + instruction_pointer_set(regs, addr + disp); +} + +void __kprobes +simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs) +{ + int xn = (opcode >> 5) & 0x1f; + + /* update pc first in case we're doing a "blr lr" */ + instruction_pointer_set(regs, get_x_reg(regs, xn)); + + /* Link register is x30 */ + if (((opcode >> 21) & 0x3) == 1) + set_x_reg(regs, 30, addr + 4); +} + +void __kprobes +simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = 4; + + if (opcode & (1 << 24)) { + if (check_cbnz(opcode, regs)) + disp = cbz_displacement(opcode); + } else { + if (check_cbz(opcode, regs)) + disp = cbz_displacement(opcode); + } + instruction_pointer_set(regs, addr + disp); +} + +void __kprobes +simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = 4; + + if (opcode & (1 << 24)) { + if (check_tbnz(opcode, regs)) + disp = tbz_displacement(opcode); + } else { + if (check_tbz(opcode, regs)) + disp = tbz_displacement(opcode); + } + instruction_pointer_set(regs, addr + disp); +} + +void __kprobes +simulate_ldr_literal(u32 opcode, long addr, struct pt_regs *regs) +{ + u64 *load_addr; + int xn = opcode & 0x1f; + int disp; + + disp = ldr_displacement(opcode); + load_addr = (u64 *) (addr + disp); + + if (opcode & (1 << 30)) /* x0-x30 */ + set_x_reg(regs, xn, *load_addr); + else /* w0-w30 */ + set_w_reg(regs, xn, *load_addr); + + instruction_pointer_set(regs, instruction_pointer(regs) + 4); +} + +void __kprobes +simulate_ldrsw_literal(u32 opcode, long addr, struct pt_regs *regs) +{ + s32 *load_addr; + int xn = opcode & 0x1f; + int disp; + + disp = ldr_displacement(opcode); + load_addr = (s32 *) (addr + disp); + + set_x_reg(regs, xn, *load_addr); + + instruction_pointer_set(regs, instruction_pointer(regs) + 4); +} diff --git a/arch/arm64/kernel/probes/simulate-insn.h b/arch/arm64/kernel/probes/simulate-insn.h new file mode 100644 index 0000000..050bde6 --- /dev/null +++ b/arch/arm64/kernel/probes/simulate-insn.h @@ -0,0 +1,28 @@ +/* + * arch/arm64/kernel/probes/simulate-insn.h + * + * Copyright (C) 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#ifndef _ARM_KERNEL_KPROBES_SIMULATE_INSN_H +#define _ARM_KERNEL_KPROBES_SIMULATE_INSN_H + +void simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs); +void simulate_b_bl(u32 opcode, long addr, struct pt_regs *regs); +void simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs); +void simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs); +void simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs); +void simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs); +void simulate_ldr_literal(u32 opcode, long addr, struct pt_regs *regs); +void simulate_ldrsw_literal(u32 opcode, long addr, struct pt_regs *regs); + +#endif /* _ARM_KERNEL_KPROBES_SIMULATE_INSN_H */ diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 3f6cd5c..030c1d5 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -48,6 +48,107 @@ #define CREATE_TRACE_POINTS #include <trace/events/syscalls.h> +struct pt_regs_offset { + const char *name; + int offset; +}; + +#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)} +#define REG_OFFSET_END {.name = NULL, .offset = 0} +#define GPR_OFFSET_NAME(r) \ + {.name = "x" #r, .offset = offsetof(struct pt_regs, regs[r])} + +static const struct pt_regs_offset regoffset_table[] = { + GPR_OFFSET_NAME(0), + GPR_OFFSET_NAME(1), + GPR_OFFSET_NAME(2), + GPR_OFFSET_NAME(3), + GPR_OFFSET_NAME(4), + GPR_OFFSET_NAME(5), + GPR_OFFSET_NAME(6), + GPR_OFFSET_NAME(7), + GPR_OFFSET_NAME(8), + GPR_OFFSET_NAME(9), + GPR_OFFSET_NAME(10), + GPR_OFFSET_NAME(11), + GPR_OFFSET_NAME(12), + GPR_OFFSET_NAME(13), + GPR_OFFSET_NAME(14), + GPR_OFFSET_NAME(15), + GPR_OFFSET_NAME(16), + GPR_OFFSET_NAME(17), + GPR_OFFSET_NAME(18), + GPR_OFFSET_NAME(19), + GPR_OFFSET_NAME(20), + GPR_OFFSET_NAME(21), + GPR_OFFSET_NAME(22), + GPR_OFFSET_NAME(23), + GPR_OFFSET_NAME(24), + GPR_OFFSET_NAME(25), + GPR_OFFSET_NAME(26), + GPR_OFFSET_NAME(27), + GPR_OFFSET_NAME(28), + GPR_OFFSET_NAME(29), + GPR_OFFSET_NAME(30), + {.name = "lr", .offset = offsetof(struct pt_regs, regs[30])}, + REG_OFFSET_NAME(sp), + REG_OFFSET_NAME(pc), + REG_OFFSET_NAME(pstate), + REG_OFFSET_END, +}; + +/** + * regs_query_register_offset() - query register offset from its name + * @name: the name of a register + * + * regs_query_register_offset() returns the offset of a register in struct + * pt_regs from its name. If the name is invalid, this returns -EINVAL; + */ +int regs_query_register_offset(const char *name) +{ + const struct pt_regs_offset *roff; + + for (roff = regoffset_table; roff->name != NULL; roff++) + if (!strcmp(roff->name, name)) + return roff->offset; + return -EINVAL; +} + +/** + * regs_within_kernel_stack() - check the address in the stack + * @regs: pt_regs which contains kernel stack pointer. + * @addr: address which is checked. + * + * regs_within_kernel_stack() checks @addr is within the kernel stack page(s). + * If @addr is within the kernel stack, it returns true. If not, returns false. + */ +static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) +{ + return ((addr & ~(THREAD_SIZE - 1)) == + (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) || + on_irq_stack(addr, raw_smp_processor_id()); +} + +/** + * regs_get_kernel_stack_nth() - get Nth entry of the stack + * @regs: pt_regs which contains kernel stack pointer. + * @n: stack entry number. + * + * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which + * is specified by @regs. If the @n th entry is NOT in the kernel stack, + * this returns 0. + */ +unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n) +{ + unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs); + + addr += n; + if (regs_within_kernel_stack(regs, (unsigned long)addr)) + return *addr; + else + return 0; +} + /* * TODO: does not yet catch signals sent when the child dies. * in exit.c or in signal.c. diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 0de7be4..89d6e17 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -118,9 +118,11 @@ SECTIONS __exception_text_end = .; IRQENTRY_TEXT SOFTIRQENTRY_TEXT + ENTRY_TEXT TEXT_TEXT SCHED_TEXT LOCK_TEXT + KPROBES_TEXT HYPERVISOR_TEXT IDMAP_TEXT HIBERNATE_TEXT diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index fc5a34a..4ebda51 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -41,6 +41,28 @@ static const char *fault_name(unsigned int esr); +#ifdef CONFIG_KPROBES +static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) +{ + int ret = 0; + + /* kprobe_running() needs smp_processor_id() */ + if (!user_mode(regs)) { + preempt_disable(); + if (kprobe_running() && kprobe_fault_handler(regs, esr)) + ret = 1; + preempt_enable(); + } + + return ret; +} +#else +static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) +{ + return 0; +} +#endif + /* * Dump out the page tables associated with 'addr' in mm 'mm'. */ @@ -262,6 +284,9 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC; unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + if (notify_page_fault(regs, esr)) + return 0; + tsk = current; mm = tsk->mm; @@ -632,6 +657,7 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, return rv; } +NOKPROBE_SYMBOL(do_debug_exception); #ifdef CONFIG_ARM64_PAN void cpu_enable_pan(void *__unused) |