1 files changed, 62 insertions, 21 deletions

diff --git a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c
index 7066d7ba667a..bdac631cf011 100644
--- a/arch/sparc64/kernel/kprobes.c
+++ b/arch/sparc64/kernel/kprobes.c
@@ -6,7 +6,6 @@
 #include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
-
 #include <asm/kdebug.h>
 #include <asm/signal.h>
 
@@ -47,25 +46,59 @@ void arch_copy_kprobe(struct kprobe *p)
 {
         p->ainsn.insn[0] = *p->addr;
         p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
+        p->opcode = *p->addr;
 }
 
-void arch_remove_kprobe(struct kprobe *p)
+void arch_arm_kprobe(struct kprobe *p)
 {
+        *p->addr = BREAKPOINT_INSTRUCTION;
+        flushi(p->addr);
 }
 
-/* kprobe_status settings */
-#define KPROBE_HIT_ACTIVE       0x00000001
-#define KPROBE_HIT_SS           0x00000002
+void arch_disarm_kprobe(struct kprobe *p)
+{
+        *p->addr = p->opcode;
+        flushi(p->addr);
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+}
 
 static struct kprobe *current_kprobe;
 static unsigned long current_kprobe_orig_tnpc;
 static unsigned long current_kprobe_orig_tstate_pil;
 static unsigned int kprobe_status;
+static struct kprobe *kprobe_prev;
+static unsigned long kprobe_orig_tnpc_prev;
+static unsigned long kprobe_orig_tstate_pil_prev;
+static unsigned int kprobe_status_prev;
 
-static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+static inline void save_previous_kprobe(void)
+{
+        kprobe_status_prev = kprobe_status;
+        kprobe_orig_tnpc_prev = current_kprobe_orig_tnpc;
+        kprobe_orig_tstate_pil_prev = current_kprobe_orig_tstate_pil;
+        kprobe_prev = current_kprobe;
+}
+
+static inline void restore_previous_kprobe(void)
+{
+        kprobe_status = kprobe_status_prev;
+        current_kprobe_orig_tnpc = kprobe_orig_tnpc_prev;
+        current_kprobe_orig_tstate_pil = kprobe_orig_tstate_pil_prev;
+        current_kprobe = kprobe_prev;
+}
+
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
 {
         current_kprobe_orig_tnpc = regs->tnpc;
         current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
+        current_kprobe = p;
+}
+
+static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
         regs->tstate |= TSTATE_PIL;
 
         /*single step inline, if it a breakpoint instruction*/
@@ -78,17 +111,6 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
         }
 }
 
-static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs)
-{
-        *p->addr = p->opcode;
-        flushi(p->addr);
-
-        regs->tpc = (unsigned long) p->addr;
-        regs->tnpc = current_kprobe_orig_tnpc;
-        regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
-                        current_kprobe_orig_tstate_pil);
-}
-
 static int kprobe_handler(struct pt_regs *regs)
 {
         struct kprobe *p;
@@ -109,8 +131,18 @@ static int kprobe_handler(struct pt_regs *regs)
                                 unlock_kprobes();
                                 goto no_kprobe;
                         }
-                        disarm_kprobe(p, regs);
-                        ret = 1;
+                        /* We have reentered the kprobe_handler(), since
+                         * 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();
+                        set_current_kprobe(p, regs);
+                        p->nmissed++;
+                        kprobe_status = KPROBE_REENTER;
+                        prepare_singlestep(p, regs);
+                        return 1;
                 } else {
                         p = current_kprobe;
                         if (p->break_handler && p->break_handler(p, regs))
@@ -138,8 +170,8 @@ static int kprobe_handler(struct pt_regs *regs)
                 goto no_kprobe;
         }
 
+        set_current_kprobe(p, regs);
         kprobe_status = KPROBE_HIT_ACTIVE;
-        current_kprobe = p;
         if (p->pre_handler && p->pre_handler(p, regs))
                 return 1;
 
@@ -245,12 +277,20 @@ 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);
 
+        /*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();
 
         return 1;
@@ -392,3 +432,4 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
         }
         return 0;
 }
+