diff options
| author | Anju T <anju@linux.vnet.ibm.com> | 2017-02-08 15:20:52 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-02-10 13:28:05 +1100 |
| commit | 762df10bad6954b353ee649c387a8ffacf6dc347 (patch) | |
| tree | 5dfc2db1b445fcd4e7124f08b45329f157e49456 | |
| parent | 51c9c0843993528bffc920c54c2121d9e6f8b090 (diff) | |
powerpc/kprobes: Optimize kprobe in kretprobe_trampoline()
Kprobe placed on the kretprobe_trampoline() during boot time can be
optimized, since the instruction at probe point is a 'nop'.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| -rw-r--r-- | arch/powerpc/kernel/kprobes.c | 8 | ||||
| -rw-r--r-- | arch/powerpc/kernel/optprobes.c | 7 |
2 files changed, 11 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 735ff3d3f77d..45e4f82b230d 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -285,6 +285,7 @@ asm(".global kretprobe_trampoline\n" ".type kretprobe_trampoline, @function\n" "kretprobe_trampoline:\n" "nop\n" + "blr\n" ".size kretprobe_trampoline, .-kretprobe_trampoline\n"); /* @@ -337,6 +338,13 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p, kretprobe_assert(ri, orig_ret_address, trampoline_address); regs->nip = orig_ret_address; + /* + * Make LR point to the orig_ret_address. + * When the 'nop' inside the kretprobe_trampoline + * is optimized, we can do a 'blr' after executing the + * detour buffer code. + */ + regs->link = orig_ret_address; reset_current_kprobe(); kretprobe_hash_unlock(current, &flags); diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index 17f4c94142d3..2282bf4e63cd 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c @@ -72,12 +72,11 @@ static unsigned long can_optimize(struct kprobe *p) /* * kprobe placed for kretprobe during boot time - * is not optimizing now. - * - * TODO: Optimize kprobe in kretprobe_trampoline + * has a 'nop' instruction, which can be emulated. + * So further checks can be skipped. */ if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) - return 0; + return (unsigned long)p->addr + sizeof(kprobe_opcode_t); /* * We only support optimizing kernel addresses, but not |