diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2021-03-03 00:25:46 +0900 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-03-23 16:07:56 +0100 |
| commit | 6256e668b7af9d81472e03c6a171630c08f8858a (patch) | |
| tree | 1d687fd9f6b8f49949034a72272924a28f488ee2 /arch/x86/kernel/traps.c | |
| parent | a194acd316f93f3435a64de3b37dca2b5a77b338 (diff) | |
x86/kprobes: Use int3 instead of debug trap for single-step
Use int3 instead of debug trap exception for single-stepping the
probed instructions. Some instructions which change the ip
registers or modify IF flags are emulated because those are not
able to be single-stepped by int3 or may allow the interrupt
while single-stepping.
This actually changes the kprobes behavior.
- kprobes can not probe following instructions; int3, iret,
far jmp/call which get absolute address as immediate,
indirect far jmp/call, indirect near jmp/call with addressing
by memory (register-based indirect jmp/call are OK), and
vmcall/vmlaunch/vmresume/vmxoff.
- If the kprobe post_handler doesn't set before registering,
it may not be called in some case even if you set it afterwards.
(IOW, kprobe booster is enabled at registration, user can not
change it)
But both are rare issue, unsupported instructions will not be
used in the kernel (or rarely used), and post_handlers are
rarely used (I don't see it except for the test code).
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/161469874601.49483.11985325887166921076.stgit@devnote2
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 0da8d2a889cb..a5d254057b88 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -890,9 +890,6 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, if ((dr6 & DR_STEP) && is_sysenter_singlestep(regs)) dr6 &= ~DR_STEP; - if (kprobe_debug_handler(regs)) - goto out; - /* * The kernel doesn't use INT1 */ |