3 files changed, 37 insertions, 15 deletions

diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index 6877e7187113..a79633d702bf 100644
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -172,6 +172,7 @@ architectures:
 - ia64 (Does not support probes on instruction slot1.)
 - sparc64 (Return probes not yet implemented.)
 - arm
+- ppc
 
 3. Configuring Kprobes
 
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 74693d91731f..4ba2af125450 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -34,6 +34,13 @@
 #include <asm/cacheflush.h>
 #include <asm/sstep.h>
 #include <asm/uaccess.h>
+#include <asm/system.h>
+
+#ifdef CONFIG_BOOKE
+#define MSR_SINGLESTEP  (MSR_DE)
+#else
+#define MSR_SINGLESTEP  (MSR_SE)
+#endif
 
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -53,7 +60,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
                 ret = -EINVAL;
         }
 
-        /* insn must be on a special executable page on ppc64 */
+        /* insn must be on a special executable page on ppc64.  This is
+         * not explicitly required on ppc32 (right now), but it doesn't hurt */
         if (!ret) {
                 p->ainsn.insn = get_insn_slot();
                 if (!p->ainsn.insn)
@@ -100,7 +108,11 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
          * possible we'd get the single step reported for an exception handler
          * like Decrementer or External Interrupt */
         regs->msr &= ~MSR_EE;
-        regs->msr |= MSR_SE;
+        regs->msr |= MSR_SINGLESTEP;
+#ifdef CONFIG_BOOKE
+        regs->msr &= ~MSR_CE;
+        mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
+#endif
 
         /*
          * On powerpc we should single step on the original
@@ -163,7 +175,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
                         kprobe_opcode_t insn = *p->ainsn.insn;
                         if (kcb->kprobe_status == KPROBE_HIT_SS &&
                                         is_trap(insn)) {
-                                regs->msr &= ~MSR_SE;
+                                /* Turn off 'trace' bits */
+                                regs->msr &= ~MSR_SINGLESTEP;
                                 regs->msr |= kcb->kprobe_saved_msr;
                                 goto no_kprobe;
                         }
@@ -404,10 +417,10 @@ out:
 
         /*
          * if somebody else is singlestepping across a probe point, msr
-         * will have SE set, in which case, continue the remaining processing
+         * will have DE/SE set, in which case, continue the remaining processing
          * of do_debug, as if this is not a probe hit.
          */
-        if (regs->msr & MSR_SE)
+        if (regs->msr & MSR_SINGLESTEP)
                 return 0;
 
         return 1;
@@ -430,7 +443,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
                  * normal page fault.
                  */
                 regs->nip = (unsigned long)cur->addr;
-                regs->msr &= ~MSR_SE;
+                regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */
                 regs->msr |= kcb->kprobe_saved_msr;
                 if (kcb->kprobe_status == KPROBE_REENTER)
                         restore_previous_kprobe(kcb);
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 4b5b7ff4f78b..b463d48145a4 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1030,21 +1030,29 @@ void SoftwareEmulation(struct pt_regs *regs)
 
 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
 
-void DebugException(struct pt_regs *regs, unsigned long debug_status)
+void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)
 {
         if (debug_status & DBSR_IC) {   /* instruction completion */
                 regs->msr &= ~MSR_DE;
+
+                /* Disable instruction completion */
+                mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_IC);
+                /* Clear the instruction completion event */
+                mtspr(SPRN_DBSR, DBSR_IC);
+
+                if (notify_die(DIE_SSTEP, "single_step", regs, 5,
+                               5, SIGTRAP) == NOTIFY_STOP) {
+                        return;
+                }
+
+                if (debugger_sstep(regs))
+                        return;
+
                 if (user_mode(regs)) {
                         current->thread.dbcr0 &= ~DBCR0_IC;
-                } else {
-                        /* Disable instruction completion */
-                        mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_IC);
-                        /* Clear the instruction completion event */
-                        mtspr(SPRN_DBSR, DBSR_IC);
-                        if (debugger_sstep(regs))
-                                return;
                 }
-                _exception(SIGTRAP, regs, TRAP_TRACE, 0);
+
+                _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
         }
 }
 #endif /* CONFIG_4xx || CONFIG_BOOKE */