[PATCH] Kprobes: Track kprobe on a per_cpu basis - ppc64 changes

PPC64 changes to track kprobe execution on a per-cpu basis.  We now track the
kprobe state machine independently on each cpu using an arch specific kprobe
control block.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 69 insertions, 40 deletions

diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c
index 6071ee99f5cb..3f89f3e5584a 100644
--- a/arch/ppc64/kernel/kprobes.c
+++ b/arch/ppc64/kernel/kprobes.c
@@ -37,12 +37,8 @@
 #include <asm/sstep.h>
 
 static DECLARE_MUTEX(kprobe_mutex);
-
-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;
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
@@ -108,18 +104,25 @@ 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)
+static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+        kcb->prev_kprobe.kp = kprobe_running();
+        kcb->prev_kprobe.status = kcb->kprobe_status;
+        kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;
+}
+
+static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-        kprobe_prev = current_kprobe;
-        kprobe_status_prev = kprobe_status;
-        kprobe_saved_msr_prev = kprobe_saved_msr;
+        __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+        kcb->kprobe_status = kcb->prev_kprobe.status;
+        kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
 }
 
-static inline void restore_previous_kprobe(void)
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+                                struct kprobe_ctlblk *kcb)
 {
-        current_kprobe = kprobe_prev;
-        kprobe_status = kprobe_status_prev;
-        kprobe_saved_msr = kprobe_saved_msr_prev;
+        __get_cpu_var(current_kprobe) = p;
+        kcb->kprobe_saved_msr = regs->msr;
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
@@ -145,6 +148,7 @@ static inline int kprobe_handler(struct pt_regs *regs)
         struct kprobe *p;
         int ret = 0;
         unsigned int *addr = (unsigned int *)regs->nip;
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
         /* Check we're not actually recursing */
         if (kprobe_running()) {
@@ -153,10 +157,10 @@ static inline int kprobe_handler(struct pt_regs *regs)
                 p = get_kprobe(addr);
                 if (p) {
                         kprobe_opcode_t insn = *p->ainsn.insn;
-                        if (kprobe_status == KPROBE_HIT_SS &&
+                        if (kcb->kprobe_status == KPROBE_HIT_SS &&
                                         is_trap(insn)) {
                                 regs->msr &= ~MSR_SE;
-                                regs->msr |= kprobe_saved_msr;
+                                regs->msr |= kcb->kprobe_saved_msr;
                                 unlock_kprobes();
                                 goto no_kprobe;
                         }
@@ -166,15 +170,15 @@ static inline int kprobe_handler(struct pt_regs *regs)
                          * 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;
+                        save_previous_kprobe(kcb);
+                        set_current_kprobe(p, regs, kcb);
+                        kcb->kprobe_saved_msr = regs->msr;
                         p->nmissed++;
                         prepare_singlestep(p, regs);
-                        kprobe_status = KPROBE_REENTER;
+                        kcb->kprobe_status = KPROBE_REENTER;
                         return 1;
                 } else {
-                        p = current_kprobe;
+                        p = __get_cpu_var(current_kprobe);
                         if (p->break_handler && p->break_handler(p, regs)) {
                                 goto ss_probe;
                         }
@@ -214,16 +218,15 @@ static inline int kprobe_handler(struct pt_regs *regs)
          * in post_kprobe_handler().
          */
         preempt_disable();
-        kprobe_status = KPROBE_HIT_ACTIVE;
-        current_kprobe = p;
-        kprobe_saved_msr = regs->msr;
+        kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+        set_current_kprobe(p, regs, kcb);
         if (p->pre_handler && p->pre_handler(p, regs))
                 /* handler has already set things up, so skip ss setup */
                 return 1;
 
 ss_probe:
         prepare_singlestep(p, regs);
-        kprobe_status = KPROBE_HIT_SS;
+        kcb->kprobe_status = KPROBE_HIT_SS;
         return 1;
 
 no_kprobe:
@@ -292,6 +295,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
         regs->nip = orig_ret_address;
 
+        reset_current_kprobe();
         unlock_kprobes();
         preempt_enable_no_resched();
 
@@ -324,22 +328,26 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 
 static inline int post_kprobe_handler(struct pt_regs *regs)
 {
-        if (!kprobe_running())
+        struct kprobe *cur = kprobe_running();
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+        if (!cur)
                 return 0;
 
-        if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
-                kprobe_status = KPROBE_HIT_SSDONE;
-                current_kprobe->post_handler(current_kprobe, regs, 0);
+        if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+                kcb->kprobe_status = KPROBE_HIT_SSDONE;
+                cur->post_handler(cur, regs, 0);
         }
 
-        resume_execution(current_kprobe, regs);
-        regs->msr |= kprobe_saved_msr;
+        resume_execution(cur, regs);
+        regs->msr |= kcb->kprobe_saved_msr;
 
         /*Restore back the original saved kprobes variables and continue. */
-        if (kprobe_status == KPROBE_REENTER) {
-                restore_previous_kprobe();
+        if (kcb->kprobe_status == KPROBE_REENTER) {
+                restore_previous_kprobe(kcb);
                 goto out;
         }
+        reset_current_kprobe();
         unlock_kprobes();
 out:
         preempt_enable_no_resched();
@@ -358,15 +366,18 @@ out:
 /* Interrupts disabled, kprobe_lock held. */
 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
-        if (current_kprobe->fault_handler
-            && current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+        struct kprobe *cur = kprobe_running();
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+        if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
                 return 1;
 
-        if (kprobe_status & KPROBE_HIT_SS) {
-                resume_execution(current_kprobe, regs);
+        if (kcb->kprobe_status & KPROBE_HIT_SS) {
+                resume_execution(cur, regs);
                 regs->msr &= ~MSR_SE;
-                regs->msr |= kprobe_saved_msr;
+                regs->msr |= kcb->kprobe_saved_msr;
 
+                reset_current_kprobe();
                 unlock_kprobes();
                 preempt_enable_no_resched();
         }
@@ -411,8 +422,9 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct jprobe *jp = container_of(p, struct jprobe, kp);
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
-        memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
+        memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
 
         /* setup return addr to the jprobe handler routine */
         regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
@@ -432,12 +444,14 @@ void __kprobes jprobe_return_end(void)
 
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
         /*
          * FIXME - we should ideally be validating that we got here 'cos
          * of the "trap" in jprobe_return() above, before restoring the
          * saved regs...
          */
-        memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
+        memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
         return 1;
 }
 
diff --git a/include/asm-powerpc/kprobes.h b/include/asm-powerpc/kprobes.h
index b2f09f17fbe0..6cd0a3bfa280 100644
--- a/include/asm-powerpc/kprobes.h
+++ b/include/asm-powerpc/kprobes.h
@@ -27,6 +27,7 @@
  */
 #include <linux/types.h>
 #include <linux/ptrace.h>
+#include <linux/percpu.h>
 
 struct pt_regs;
 
@@ -53,6 +54,20 @@ struct arch_specific_insn {
         kprobe_opcode_t *insn;
 };
 
+struct prev_kprobe {
+        struct kprobe *kp;
+        unsigned long status;
+        unsigned long saved_msr;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+        unsigned long kprobe_status;
+        unsigned long kprobe_saved_msr;
+        struct pt_regs jprobe_saved_regs;
+        struct prev_kprobe prev_kprobe;
+};
+
 #ifdef CONFIG_KPROBES
 extern int kprobe_exceptions_notify(struct notifier_block *self,
                                     unsigned long val, void *data);