Commit 0ccde0a2 authored Apr 28, 2006 by Ananth N Mavinakayanahalli Committed by Paul Mackerras May 03, 2006

[PATCH] powerpc/kprobes: fix singlestep out-of-line



We currently single-step inline if the instruction on which a kprobe is
inserted is a trap variant.

- variants (such as tdnei, used by BUG()) typically evaluate a condition
  and cause a trap only if the condition is satisfied.
- kprobes uses the unconditional "trap" (0x7fe00008) and single-stepping
  again on this instruction, resulting in another trap without
  evaluating the condition is obviously incorrect.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

parent 054d8ff3

arch/powerpc/kernel/kprobes.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -90,14 +90,14 @@ void __kprobes arch_remove_kprobe(struct kprobe *p)

		static void __kprobes prepare_singlestep(struct kprobe p, struct pt_regs regs)
		{
		kprobe_opcode_t insn = *p->ainsn.insn;

		regs->msr \|= MSR_SE;

		/* single step inline if it is a trap variant */
		if (is_trap(insn))
		regs->nip = (unsigned long)p->addr;
		else
		/*
		* On powerpc we should single step on the original
		* instruction even if the probed insn is a trap
		* variant as values in regs could play a part in
		* if the trap is taken or not
		*/
		regs->nip = (unsigned long)p->ainsn.insn;
		}