1 files changed, 51 insertions, 10 deletions
diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c
index e950a2058a19..782ce3efa2c1 100644
--- a/arch/ppc64/kernel/kprobes.c
+++ b/arch/ppc64/kernel/kprobes.c
@@ -32,15 +32,14 @@
 #include <linux/ptrace.h>
 #include <linux/spinlock.h>
 #include <linux/preempt.h>
+#include <asm/cacheflush.h>
 #include <asm/kdebug.h>
 #include <asm/sstep.h>
-/* kprobe_status settings */
-#define KPROBE_HIT_ACTIVE       0x00000001
-#define KPROBE_HIT_SS           0x00000002
 static struct kprobe *current_kprobe;
 static unsigned long kprobe_status, kprobe_saved_msr;
+static struct kprobe *kprobe_prev;
+static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
 static struct pt_regs jprobe_saved_regs;
 int arch_prepare_kprobe(struct kprobe *p)
@@ -61,16 +60,25 @@ int arch_prepare_kprobe(struct kprobe *p)
 void arch_copy_kprobe(struct kprobe *p)
 {
        memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+        p->opcode = *p->addr;
 }
-void arch_remove_kprobe(struct kprobe *p)
+void arch_arm_kprobe(struct kprobe *p)
 {
+        *p->addr = BREAKPOINT_INSTRUCTION;
+        flush_icache_range((unsigned long) p->addr,
+                           (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }
-static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs)
+void arch_disarm_kprobe(struct kprobe *p)
 {
        *p->addr = p->opcode;
-        regs->nip = (unsigned long)p->addr;
+        flush_icache_range((unsigned long) p->addr,
+                           (unsigned long) p->addr + sizeof(kprobe_opcode_t));
+}
+void arch_remove_kprobe(struct kprobe *p)
+{
 }
 static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
@@ -83,6 +91,20 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
                regs->nip = (unsigned long)&p->ainsn.insn;
 }
+static inline void save_previous_kprobe(void)
+{
+        kprobe_prev = current_kprobe;
+        kprobe_status_prev = kprobe_status;
+        kprobe_saved_msr_prev = kprobe_saved_msr;
+}
+static inline void restore_previous_kprobe(void)
+{
+        current_kprobe = kprobe_prev;
+        kprobe_status = kprobe_status_prev;
+        kprobe_saved_msr = kprobe_saved_msr_prev;
+}
 static inline int kprobe_handler(struct pt_regs *regs)
 {
        struct kprobe *p;
@@ -101,8 +123,19 @@ static inline int kprobe_handler(struct pt_regs *regs)
                                unlock_kprobes();
                                goto no_kprobe;
                        }
-                        disarm_kprobe(p, regs);
+                        /* We have reentered the kprobe_handler(), since
-                        ret = 1;
+                         * another probe was hit while within the handler.
+                         * We here save the original kprobes variables and
+                         * just single step on the instruction of the new probe
+                         * without calling any user handlers.
+                         */
+                        save_previous_kprobe();
+                        current_kprobe = p;
+                        kprobe_saved_msr = regs->msr;
+                        p->nmissed++;
+                        prepare_singlestep(p, regs);
+                        kprobe_status = KPROBE_REENTER;
+                        return 1;
                } else {
                        p = current_kprobe;
                        if (p->break_handler && p->break_handler(p, regs)) {
@@ -184,13 +217,21 @@ static inline int post_kprobe_handler(struct pt_regs *regs)
        if (!kprobe_running())
                return 0;
-        if (current_kprobe->post_handler)
+        if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
+                kprobe_status = KPROBE_HIT_SSDONE;
                current_kprobe->post_handler(current_kprobe, regs, 0);
+        }
        resume_execution(current_kprobe, regs);
        regs->msr |= kprobe_saved_msr;
+        /*Restore back the original saved kprobes variables and continue. */
+        if (kprobe_status == KPROBE_REENTER) {
+                restore_previous_kprobe();
+                goto out;
+        }
        unlock_kprobes();
+out:
        preempt_enable_no_resched();
        /*