[PATCH] Kprobes: Track kprobe on a per_cpu basis - sparc64 changes

Sparc64 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>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 87 insertions, 64 deletions

diff --git a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c
index 755a0d7d887f..b95984154dba 100644
--- a/arch/sparc64/kernel/kprobes.c
+++ b/arch/sparc64/kernel/kprobes.c
@@ -38,6 +38,9 @@
  * - Mark that we are no longer actively in a kprobe.
  */
 
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
         return 0;
@@ -66,46 +69,39 @@ void __kprobes 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 save_previous_kprobe(void)
+static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-        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;
+        kcb->prev_kprobe.kp = kprobe_running();
+        kcb->prev_kprobe.status = kcb->kprobe_status;
+        kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
+        kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
 }
 
-static inline void restore_previous_kprobe(void)
+static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-        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;
+        __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+        kcb->kprobe_status = kcb->prev_kprobe.status;
+        kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
+        kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
 }
 
-static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+                                struct kprobe_ctlblk *kcb)
 {
-        current_kprobe_orig_tnpc = regs->tnpc;
-        current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
-        current_kprobe = p;
+        __get_cpu_var(current_kprobe) = p;
+        kcb->kprobe_orig_tnpc = regs->tnpc;
+        kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
 }
 
-static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
+                        struct kprobe_ctlblk *kcb)
 {
         regs->tstate |= TSTATE_PIL;
 
         /*single step inline, if it a breakpoint instruction*/
         if (p->opcode == BREAKPOINT_INSTRUCTION) {
                 regs->tpc = (unsigned long) p->addr;
-                regs->tnpc = current_kprobe_orig_tnpc;
+                regs->tnpc = kcb->kprobe_orig_tnpc;
         } else {
                 regs->tpc = (unsigned long) &p->ainsn.insn[0];
                 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
@@ -117,6 +113,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
         struct kprobe *p;
         void *addr = (void *) regs->tpc;
         int ret = 0;
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
         if (kprobe_running()) {
                 /* We *are* holding lock here, so this is safe.
@@ -124,9 +121,9 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
                  */
                 p = get_kprobe(addr);
                 if (p) {
-                        if (kprobe_status == KPROBE_HIT_SS) {
+                        if (kcb->kprobe_status == KPROBE_HIT_SS) {
                                 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
-                                        current_kprobe_orig_tstate_pil);
+                                        kcb->kprobe_orig_tstate_pil);
                                 unlock_kprobes();
                                 goto no_kprobe;
                         }
@@ -136,14 +133,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
                          * just single step on the instruction of the new probe
                          * without calling any user handlers.
                          */
-                        save_previous_kprobe();
-                        set_current_kprobe(p, regs);
+                        save_previous_kprobe(kcb);
+                        set_current_kprobe(p, regs, kcb);
                         p->nmissed++;
-                        kprobe_status = KPROBE_REENTER;
-                        prepare_singlestep(p, regs);
+                        kcb->kprobe_status = KPROBE_REENTER;
+                        prepare_singlestep(p, regs, kcb);
                         return 1;
                 } else {
-                        p = current_kprobe;
+                        p = __get_cpu_var(current_kprobe);
                         if (p->break_handler && p->break_handler(p, regs))
                                 goto ss_probe;
                 }
@@ -174,14 +171,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
          * in post_kprobes_handler()
          */
         preempt_disable();
-        set_current_kprobe(p, regs);
-        kprobe_status = KPROBE_HIT_ACTIVE;
+        set_current_kprobe(p, regs, kcb);
+        kcb->kprobe_status = KPROBE_HIT_ACTIVE;
         if (p->pre_handler && p->pre_handler(p, regs))
                 return 1;
 
 ss_probe:
-        prepare_singlestep(p, regs);
-        kprobe_status = KPROBE_HIT_SS;
+        prepare_singlestep(p, regs, kcb);
+        kcb->kprobe_status = KPROBE_HIT_SS;
         return 1;
 
 no_kprobe:
@@ -262,11 +259,12 @@ static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
  * This function prepares to return from the post-single-step
  * breakpoint trap.
  */
-static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes resume_execution(struct kprobe *p,
+                struct pt_regs *regs, struct kprobe_ctlblk *kcb)
 {
         u32 insn = p->ainsn.insn[0];
 
-        regs->tpc = current_kprobe_orig_tnpc;
+        regs->tpc = kcb->kprobe_orig_tnpc;
         regs->tnpc = relbranch_fixup(insn,
                                      (unsigned long) p->addr,
                                      (unsigned long) &p->ainsn.insn[0],
@@ -274,26 +272,30 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
         retpc_fixup(regs, insn, (unsigned long) p->addr);
 
         regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
-                        current_kprobe_orig_tstate_pil);
+                        kcb->kprobe_orig_tstate_pil);
 }
 
 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);
+        resume_execution(cur, regs, kcb);
 
         /*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();
@@ -304,13 +306,16 @@ 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, kcb);
 
+                reset_current_kprobe();
                 unlock_kprobes();
                 preempt_enable_no_resched();
         }
@@ -370,24 +375,21 @@ asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
 }
 
 /* Jprobes support.  */
-static struct pt_regs jprobe_saved_regs;
-static struct pt_regs *jprobe_saved_regs_location;
-static struct sparc_stackf jprobe_saved_stack;
-
 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();
 
-        jprobe_saved_regs_location = regs;
-        memcpy(&jprobe_saved_regs, regs, sizeof(*regs));
+        kcb->jprobe_saved_regs_location = regs;
+        memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
 
         /* Save a whole stack frame, this gets arguments
          * pushed onto the stack after using up all the
          * arg registers.
          */
-        memcpy(&jprobe_saved_stack,
+        memcpy(&(kcb->jprobe_saved_stack),
                (char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
-               sizeof(jprobe_saved_stack));
+               sizeof(kcb->jprobe_saved_stack));
 
         regs->tpc  = (unsigned long) jp->entry;
         regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
@@ -411,14 +413,15 @@ extern void __show_regs(struct pt_regs * regs);
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
         u32 *addr = (u32 *) regs->tpc;
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
         if (addr == (u32 *) jprobe_return_trap_instruction) {
-                if (jprobe_saved_regs_location != regs) {
+                if (kcb->jprobe_saved_regs_location != regs) {
                         printk("JPROBE: Current regs (%p) does not match "
                                "saved regs (%p).\n",
-                               regs, jprobe_saved_regs_location);
+                               regs, kcb->jprobe_saved_regs_location);
                         printk("JPROBE: Saved registers\n");
-                        __show_regs(jprobe_saved_regs_location);
+                        __show_regs(kcb->jprobe_saved_regs_location);
                         printk("JPROBE: Current registers\n");
                         __show_regs(regs);
                         BUG();
@@ -427,11 +430,11 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
                  * first so that UREG_FP is the original one for
                  * the stack frame restore.
                  */
-                memcpy(regs, &jprobe_saved_regs, sizeof(*regs));
+                memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
 
                 memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
-                       &jprobe_saved_stack,
-                       sizeof(jprobe_saved_stack));
+                       &(kcb->jprobe_saved_stack),
+                       sizeof(kcb->jprobe_saved_stack));
 
                 return 1;
         }
diff --git a/include/asm-sparc64/kprobes.h b/include/asm-sparc64/kprobes.h
index a8d326a598f0..7ba845320f5c 100644
--- a/include/asm-sparc64/kprobes.h
+++ b/include/asm-sparc64/kprobes.h
@@ -3,6 +3,7 @@
 
 #include <linux/config.h>
 #include <linux/types.h>
+#include <linux/percpu.h>
 
 typedef u32 kprobe_opcode_t;
 
@@ -18,6 +19,25 @@ struct arch_specific_insn {
         kprobe_opcode_t insn[MAX_INSN_SIZE];
 };
 
+struct prev_kprobe {
+        struct kprobe *kp;
+        unsigned int status;
+        unsigned long orig_tnpc;
+        unsigned long orig_tstate_pil;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+        unsigned long kprobe_status;
+        unsigned long kprobe_orig_tnpc;
+        unsigned long kprobe_orig_tstate_pil;
+        long *jprobe_saved_esp;
+        struct pt_regs jprobe_saved_regs;
+        struct pt_regs *jprobe_saved_regs_location;
+        struct sparc_stackf jprobe_saved_stack;
+        struct prev_kprobe prev_kprobe;
+};
+
 #ifdef CONFIG_KPROBES
 extern int kprobe_exceptions_notify(struct notifier_block *self,
                                     unsigned long val, void *data);