diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2017-03-29 14:00:25 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-04-12 09:23:45 +0200 |
| commit | 804dec5bda9b4fcdab5f67fe61db4a0498af5221 (patch) | |
| tree | 21c03ef2a8d261208348be56333abfb9b9d036ab | |
| parent | 17880e4d5777df4770081ecf0750471cda57f86b (diff) | |
kprobes/x86: Do not modify singlestep buffer while resuming
Do not modify singlestep execution buffer (kprobe.ainsn.insn)
while resuming from single-stepping, instead, modifies
the buffer to add a jump back instruction at preparing
buffer.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/149076361560.22469.1610155860343077495.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 42 |
1 files changed, 20 insertions, 22 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 6327f95832a0..a654054eae7e 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -399,23 +399,36 @@ int __copy_instruction(u8 *dest, u8 *src) return length; } +/* Prepare reljump right after instruction to boost */ +static void prepare_boost(struct kprobe *p, int length) +{ + if (can_boost(p->ainsn.insn, p->addr) && + MAX_INSN_SIZE - length >= RELATIVEJUMP_SIZE) { + /* + * These instructions can be executed directly if it + * jumps back to correct address. + */ + synthesize_reljump(p->ainsn.insn + length, p->addr + length); + p->ainsn.boostable = 1; + } else { + p->ainsn.boostable = -1; + } +} + static int arch_copy_kprobe(struct kprobe *p) { - int ret; + int len; /* Copy an instruction with recovering if other optprobe modifies it.*/ - ret = __copy_instruction(p->ainsn.insn, p->addr); - if (!ret) + len = __copy_instruction(p->ainsn.insn, p->addr); + if (!len) return -EINVAL; /* * __copy_instruction can modify the displacement of the instruction, * but it doesn't affect boostable check. */ - if (can_boost(p->ainsn.insn, p->addr)) - p->ainsn.boostable = 0; - else - p->ainsn.boostable = -1; + prepare_boost(p, len); /* Check whether the instruction modifies Interrupt Flag or not */ p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); @@ -878,21 +891,6 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs, break; } - if (p->ainsn.boostable == 0) { - if ((regs->ip > copy_ip) && - (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { - /* - * These instructions can be executed directly if it - * jumps back to correct address. - */ - synthesize_reljump((void *)regs->ip, - (void *)orig_ip + (regs->ip - copy_ip)); - p->ainsn.boostable = 1; - } else { - p->ainsn.boostable = -1; - } - } - regs->ip += orig_ip - copy_ip; no_change: |