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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>
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51c9c08439
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2 changed files with 11 additions and 4 deletions
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@ -285,6 +285,7 @@ asm(".global kretprobe_trampoline\n"
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".type kretprobe_trampoline, @function\n"
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"kretprobe_trampoline:\n"
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"nop\n"
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"blr\n"
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".size kretprobe_trampoline, .-kretprobe_trampoline\n");
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/*
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@ -337,6 +338,13 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
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kretprobe_assert(ri, orig_ret_address, trampoline_address);
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regs->nip = orig_ret_address;
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/*
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* Make LR point to the orig_ret_address.
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* When the 'nop' inside the kretprobe_trampoline
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* is optimized, we can do a 'blr' after executing the
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* detour buffer code.
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*/
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regs->link = orig_ret_address;
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reset_current_kprobe();
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kretprobe_hash_unlock(current, &flags);
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@ -72,12 +72,11 @@ static unsigned long can_optimize(struct kprobe *p)
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/*
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* kprobe placed for kretprobe during boot time
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* is not optimizing now.
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*
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* TODO: Optimize kprobe in kretprobe_trampoline
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* has a 'nop' instruction, which can be emulated.
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* So further checks can be skipped.
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*/
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if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
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return 0;
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return (unsigned long)p->addr + sizeof(kprobe_opcode_t);
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/*
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* We only support optimizing kernel addresses, but not
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