diff options
author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2015-03-02 14:45:49 (GMT) |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2015-03-02 14:45:49 (GMT) |
commit | 33be4ef116511f1079c4c3bf4b5547faf7439301 (patch) | |
tree | ce074111ea317b6c9f0274c2aecd513ce78353a3 /arch | |
parent | 788b94ba6c223d4ce955218d59075cd1edb92692 (diff) | |
parent | 021f5f12f2ab44874193c68fb19eea154493f83a (diff) | |
download | linux-33be4ef116511f1079c4c3bf4b5547faf7439301.tar.xz |
Merge 'tip/perf/urgent' into perf/core to pick fixes
Needed to build perf/core buildable in some cases.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/kprobes/core.c | 54 | ||||
-rw-r--r-- | arch/x86/kernel/kprobes/opt.c | 2 |
2 files changed, 42 insertions, 14 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 6a1146e..4e3d5a96 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -223,27 +223,48 @@ static unsigned long __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) { struct kprobe *kp; + unsigned long faddr; kp = get_kprobe((void *)addr); - /* There is no probe, return original address */ - if (!kp) + faddr = ftrace_location(addr); + /* + * Addresses inside the ftrace location are refused by + * arch_check_ftrace_location(). Something went terribly wrong + * if such an address is checked here. + */ + if (WARN_ON(faddr && faddr != addr)) + return 0UL; + /* + * Use the current code if it is not modified by Kprobe + * and it cannot be modified by ftrace. + */ + if (!kp && !faddr) return addr; /* - * Basically, kp->ainsn.insn has an original instruction. - * However, RIP-relative instruction can not do single-stepping - * at different place, __copy_instruction() tweaks the displacement of - * that instruction. In that case, we can't recover the instruction - * from the kp->ainsn.insn. + * Basically, kp->ainsn.insn has an original instruction. + * However, RIP-relative instruction can not do single-stepping + * at different place, __copy_instruction() tweaks the displacement of + * that instruction. In that case, we can't recover the instruction + * from the kp->ainsn.insn. * - * On the other hand, kp->opcode has a copy of the first byte of - * the probed instruction, which is overwritten by int3. And - * the instruction at kp->addr is not modified by kprobes except - * for the first byte, we can recover the original instruction - * from it and kp->opcode. + * On the other hand, in case on normal Kprobe, kp->opcode has a copy + * of the first byte of the probed instruction, which is overwritten + * by int3. And the instruction at kp->addr is not modified by kprobes + * except for the first byte, we can recover the original instruction + * from it and kp->opcode. + * + * In case of Kprobes using ftrace, we do not have a copy of + * the original instruction. In fact, the ftrace location might + * be modified at anytime and even could be in an inconsistent state. + * Fortunately, we know that the original code is the ideal 5-byte + * long NOP. */ - memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); - buf[0] = kp->opcode; + memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + if (faddr) + memcpy(buf, ideal_nops[NOP_ATOMIC5], 5); + else + buf[0] = kp->opcode; return (unsigned long)buf; } @@ -251,6 +272,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) * Recover the probed instruction at addr for further analysis. * Caller must lock kprobes by kprobe_mutex, or disable preemption * for preventing to release referencing kprobes. + * Returns zero if the instruction can not get recovered. */ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) { @@ -285,6 +307,8 @@ static int can_probe(unsigned long paddr) * normally used, we just go through if there is no kprobe. */ __addr = recover_probed_instruction(buf, addr); + if (!__addr) + return 0; kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE); insn_get_length(&insn); @@ -333,6 +357,8 @@ int __copy_instruction(u8 *dest, u8 *src) unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src); + if (!recovered_insn) + return 0; kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); insn_get_length(&insn); /* Another subsystem puts a breakpoint, failed to recover */ diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 0dd8d08..7b3b9d1 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -259,6 +259,8 @@ static int can_optimize(unsigned long paddr) */ return 0; recovered_insn = recover_probed_instruction(buf, addr); + if (!recovered_insn) + return 0; kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); insn_get_length(&insn); /* Another subsystem puts a breakpoint */ |