powerpc/kprobes: Pause function_graph tracing during jprobes handling

[pandora-kernel.git] / arch / powerpc / kernel / kprobes.c

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index c533525..fe3f4ef 100644 (file)
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -32,6 +32,7 @@
 #include <linux/module.h>
 #include <linux/kdebug.h>
 #include <linux/slab.h>
+#include <linux/ftrace.h>
 #include <asm/cacheflush.h>
 #include <asm/sstep.h>
 #include <asm/uaccess.h>
@@ -378,17 +379,6 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
  * single-stepped a copy of the instruction.  The address of this
  * copy is p->ainsn.insn.
  */
-static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
-{
-       int ret;
-       unsigned int insn = *p->ainsn.insn;
-
-       regs->nip = (unsigned long)p->addr;
-       ret = emulate_step(regs, insn);
-       if (ret == 0)
-               regs->nip = (unsigned long)p->addr + 4;
-}
-
 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
 {
        struct kprobe *cur = kprobe_running();
@@ -406,7 +396,8 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
                cur->post_handler(cur, regs, 0);
        }
 
-       resume_execution(cur, regs);
+       /* Adjust nip to after the single-stepped instruction */
+       regs->nip = (unsigned long)cur->addr + 4;
        regs->msr |= kcb->kprobe_saved_msr;
 
        /*Restore back the original saved kprobes variables and continue. */
@@ -540,6 +531,15 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
        regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
 #endif
 
+       /*
+        * jprobes use jprobe_return() which skips the normal return
+        * path of the function, and this messes up the accounting of the
+        * function graph tracer.
+        *
+        * Pause function graph tracing while performing the jprobe function.
+        */
+       pause_graph_tracing();
+
        return 1;
 }
 
@@ -562,6 +562,8 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
         * saved regs...
         */
        memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
+       /* It's OK to start function graph tracing again */
+       unpause_graph_tracing();
        preempt_enable_no_resched();
        return 1;
 }