[PATCH] Kprobes: Track kprobe on a per_cpu basis - ia64 changes

IA64 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, 58 insertions, 38 deletions

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 1e80ec80dd21..17e70b1b8d79 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -38,13 +38,8 @@
 
 extern void jprobe_inst_return(void);
 
-/* kprobe_status settings */
-#define KPROBE_HIT_ACTIVE       0x00000001
-#define KPROBE_HIT_SS           0x00000002
-
-static struct kprobe *current_kprobe, *kprobe_prev;
-static unsigned long kprobe_status, kprobe_status_prev;
-static struct pt_regs jprobe_saved_regs;
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 enum instruction_type {A, I, M, F, B, L, X, u};
 static enum instruction_type bundle_encoding[32][3] = {
@@ -313,21 +308,22 @@ static int __kprobes valid_kprobe_addr(int template, int slot,
         return 0;
 }
 
-static inline void save_previous_kprobe(void)
+static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-        kprobe_prev = current_kprobe;
-        kprobe_status_prev = kprobe_status;
+        kcb->prev_kprobe.kp = kprobe_running();
+        kcb->prev_kprobe.status = kcb->kprobe_status;
 }
 
-static inline void restore_previous_kprobe(void)
+static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-        current_kprobe = kprobe_prev;
-        kprobe_status = kprobe_status_prev;
+        __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+        kcb->kprobe_status = kcb->prev_kprobe.status;
 }
 
-static inline void set_current_kprobe(struct kprobe *p)
+static inline void set_current_kprobe(struct kprobe *p,
+                        struct kprobe_ctlblk *kcb)
 {
-        current_kprobe = p;
+        __get_cpu_var(current_kprobe) = p;
 }
 
 static void kretprobe_trampoline(void)
@@ -389,6 +385,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
         regs->cr_iip = orig_ret_address;
 
+        reset_current_kprobe();
         unlock_kprobes();
         preempt_enable_no_resched();
 
@@ -606,12 +603,13 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
         int ret = 0;
         struct pt_regs *regs = args->regs;
         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
         /* Handle recursion cases */
         if (kprobe_running()) {
                 p = get_kprobe(addr);
                 if (p) {
-                        if ( (kprobe_status == KPROBE_HIT_SS) &&
+                        if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
                                 ia64_psr(regs)->ss = 0;
                                 unlock_kprobes();
@@ -623,17 +621,17 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
                          * just single step on the instruction of the new probe
                          * without calling any user handlers.
                          */
-                        save_previous_kprobe();
-                        set_current_kprobe(p);
+                        save_previous_kprobe(kcb);
+                        set_current_kprobe(p, kcb);
                         p->nmissed++;
                         prepare_ss(p, regs);
-                        kprobe_status = KPROBE_REENTER;
+                        kcb->kprobe_status = KPROBE_REENTER;
                         return 1;
                 } else if (args->err == __IA64_BREAK_JPROBE) {
                         /*
                          * jprobe instrumented function just completed
                          */
-                        p = current_kprobe;
+                        p = __get_cpu_var(current_kprobe);
                         if (p->break_handler && p->break_handler(p, regs)) {
                                 goto ss_probe;
                         }
@@ -668,8 +666,8 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
          * in post_kprobes_handler()
          */
         preempt_disable();
-        kprobe_status = KPROBE_HIT_ACTIVE;
-        set_current_kprobe(p);
+        set_current_kprobe(p, kcb);
+        kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 
         if (p->pre_handler && p->pre_handler(p, regs))
                 /*
@@ -681,7 +679,7 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
 
 ss_probe:
         prepare_ss(p, regs);
-        kprobe_status = KPROBE_HIT_SS;
+        kcb->kprobe_status = KPROBE_HIT_SS;
         return 1;
 
 no_kprobe:
@@ -690,22 +688,25 @@ no_kprobe:
 
 static int __kprobes post_kprobes_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);
+        resume_execution(cur, regs);
 
         /*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:
@@ -715,15 +716,18 @@ out:
 
 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 {
-        if (!kprobe_running())
+        struct kprobe *cur = kprobe_running();
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+        if (!cur)
                 return 0;
 
-        if (current_kprobe->fault_handler &&
-            current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+        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);
+                reset_current_kprobe();
                 unlock_kprobes();
                 preempt_enable_no_resched();
         }
@@ -761,9 +765,10 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct jprobe *jp = container_of(p, struct jprobe, kp);
         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
         /* save architectural state */
-        jprobe_saved_regs = *regs;
+        kcb->jprobe_saved_regs = *regs;
 
         /* after rfi, execute the jprobe instrumented function */
         regs->cr_iip = addr & ~0xFULL;
@@ -781,7 +786,9 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
-        *regs = jprobe_saved_regs;
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+        *regs = kcb->jprobe_saved_regs;
         return 1;
 }
 
diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h
index 573a3574a24f..592abb000e29 100644
--- a/include/asm-ia64/kprobes.h
+++ b/include/asm-ia64/kprobes.h
@@ -26,6 +26,7 @@
  */
 #include <linux/types.h>
 #include <linux/ptrace.h>
+#include <linux/percpu.h>
 #include <asm/break.h>
 
 #define MAX_INSN_SIZE   16
@@ -62,6 +63,18 @@ typedef struct _bundle {
         } quad1;
 } __attribute__((__aligned__(16)))  bundle_t;
 
+struct prev_kprobe {
+        struct kprobe *kp;
+        unsigned long status;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+        unsigned long kprobe_status;
+        struct pt_regs jprobe_saved_regs;
+        struct prev_kprobe prev_kprobe;
+};
+
 #define JPROBE_ENTRY(pentry)    (kprobe_opcode_t *)pentry
 
 #define ARCH_SUPPORTS_KRETPROBES