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authorAnanth N Mavinakayanahalli <ananth@in.ibm.com>2007-04-18 15:57:51 +1000
committerPaul Mackerras <paulus@samba.org>2007-04-24 21:31:58 +1000
commite6349a958b3577da6e5c5eacda85c07f9a364cb5 (patch)
tree2d013d593c49ce13d9ce068dab70a876c3730de5 /arch/powerpc/kernel/kprobes.c
parent6888199f7fe5ea496f48bb6de67b9b7f05b8071b (diff)
[POWERPC] kprobes: Eliminate sstep exception if instruction can be emulated
For cases when probes are placed on instructions that can be emulated, don't take the single-step exception. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/kprobes.c')
-rw-r--r--arch/powerpc/kernel/kprobes.c36
1 files changed, 35 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index dd2886f97e9..ef647e7a9dc 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -59,12 +59,14 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
}
if (!ret) {
- memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+ memcpy(p->ainsn.insn, p->addr,
+ MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
p->opcode = *p->addr;
flush_icache_range((unsigned long)p->ainsn.insn,
(unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
}
+ p->ainsn.boostable = 0;
return ret;
}
@@ -232,6 +234,38 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
return 1;
ss_probe:
+ if (p->ainsn.boostable >= 0) {
+ unsigned int insn = *p->ainsn.insn;
+
+ /* regs->nip is also adjusted if emulate_step returns 1 */
+ ret = emulate_step(regs, insn);
+ if (ret > 0) {
+ /*
+ * Once this instruction has been boosted
+ * successfully, set the boostable flag
+ */
+ if (unlikely(p->ainsn.boostable == 0))
+ p->ainsn.boostable = 1;
+
+ if (p->post_handler)
+ p->post_handler(p, regs, 0);
+
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ reset_current_kprobe();
+ preempt_enable_no_resched();
+ return 1;
+ } else if (ret < 0) {
+ /*
+ * We don't allow kprobes on mtmsr(d)/rfi(d), etc.
+ * So, we should never get here... but, its still
+ * good to catch them, just in case...
+ */
+ printk("Can't step on instruction %x\n", insn);
+ BUG();
+ } else if (ret == 0)
+ /* This instruction can't be boosted */
+ p->ainsn.boostable = -1;
+ }
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;