[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>
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 856ef1a..f788663 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -90,15 +90,15 @@
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
- regs->nip = (unsigned long)p->ainsn.insn;
+ /*
+ * 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;
}
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)