[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes

I386 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>

diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index fd35039..99565a6 100644 (file)
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -37,16 +37,11 @@
 #include <asm/kdebug.h>
 #include <asm/desc.h>
 
-static struct kprobe *current_kprobe;
-static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags;
-static struct kprobe *kprobe_prev;
-static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev;
-static struct pt_regs jprobe_saved_regs;
-static long *jprobe_saved_esp;
-/* copy of the kernel stack at the probe fire time */
-static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
 void jprobe_return_end(void);
 
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
 /*
  * returns non-zero if opcode modifies the interrupt flag.
  */
@@ -91,29 +86,30 @@ void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
 }
 
-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;
-       kprobe_old_eflags_prev = kprobe_old_eflags;
-       kprobe_saved_eflags_prev = kprobe_saved_eflags;
+       kcb->prev_kprobe.kp = kprobe_running();
+       kcb->prev_kprobe.status = kcb->kprobe_status;
+       kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
+       kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
 }
 
-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;
-       kprobe_old_eflags = kprobe_old_eflags_prev;
-       kprobe_saved_eflags = kprobe_saved_eflags_prev;
+       __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+       kcb->kprobe_status = kcb->prev_kprobe.status;
+       kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
+       kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
 }
 
-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 = p;
-       kprobe_saved_eflags = kprobe_old_eflags
+       __get_cpu_var(current_kprobe) = p;
+       kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
                = (regs->eflags & (TF_MASK | IF_MASK));
        if (is_IF_modifier(p->opcode))
-               kprobe_saved_eflags &= ~IF_MASK;
+               kcb->kprobe_saved_eflags &= ~IF_MASK;
 }
 
 static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
@@ -157,6 +153,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
        int ret = 0;
        kprobe_opcode_t *addr = NULL;
        unsigned long *lp;
+       struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
        /* Check if the application is using LDT entry for its code segment and
         * calculate the address by reading the base address from the LDT entry.
@@ -175,10 +172,10 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
                   Disarm the probe we just hit, and ignore it. */
                p = get_kprobe(addr);
                if (p) {
-                       if (kprobe_status == KPROBE_HIT_SS &&
+                       if (kcb->kprobe_status == KPROBE_HIT_SS &&
                                *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
                                regs->eflags &= ~TF_MASK;
-                               regs->eflags |= kprobe_saved_eflags;
+                               regs->eflags |= kcb->kprobe_saved_eflags;
                                unlock_kprobes();
                                goto no_kprobe;
                        }
@@ -188,14 +185,14 @@ 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++;
                        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;
                        }
@@ -235,8 +232,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
         * in post_kprobe_handler()
         */
        preempt_disable();
-       kprobe_status = KPROBE_HIT_ACTIVE;
-       set_current_kprobe(p, regs);
+       set_current_kprobe(p, regs, kcb);
+       kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 
        if (p->pre_handler && p->pre_handler(p, regs))
                /* handler has already set things up, so skip ss setup */
@@ -244,7 +241,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 
 ss_probe:
        prepare_singlestep(p, regs);
-       kprobe_status = KPROBE_HIT_SS;
+       kcb->kprobe_status = KPROBE_HIT_SS;
        return 1;
 
 no_kprobe:
@@ -312,6 +309,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
        BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
        regs->eip = orig_ret_address;
 
+       reset_current_kprobe();
        unlock_kprobes();
        preempt_enable_no_resched();
 
@@ -345,7 +343,8 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
  * that is atop the stack is the address following the copied instruction.
  * We need to make it the address following the original instruction.
  */
-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)
 {
        unsigned long *tos = (unsigned long *)&regs->esp;
        unsigned long next_eip = 0;
@@ -355,7 +354,7 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
        switch (p->ainsn.insn[0]) {
        case 0x9c:              /* pushfl */
                *tos &= ~(TF_MASK | IF_MASK);
-               *tos |= kprobe_old_eflags;
+               *tos |= kcb->kprobe_old_eflags;
                break;
        case 0xc3:              /* ret/lret */
        case 0xcb:
@@ -400,22 +399,26 @@ 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->eflags |= kprobe_saved_eflags;
+       resume_execution(cur, regs, kcb);
+       regs->eflags |= kcb->kprobe_saved_eflags;
 
        /*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();
@@ -434,14 +437,17 @@ 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);
-               regs->eflags |= kprobe_old_eflags;
+       if (kcb->kprobe_status & KPROBE_HIT_SS) {
+               resume_execution(cur, regs, kcb);
+               regs->eflags |= kcb->kprobe_old_eflags;
 
+               reset_current_kprobe();
                unlock_kprobes();
                preempt_enable_no_resched();
        }
@@ -484,10 +490,11 @@ 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 kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
-       jprobe_saved_regs = *regs;
-       jprobe_saved_esp = &regs->esp;
-       addr = (unsigned long)jprobe_saved_esp;
+       kcb->jprobe_saved_regs = *regs;
+       kcb->jprobe_saved_esp = &regs->esp;
+       addr = (unsigned long)(kcb->jprobe_saved_esp);
 
        /*
         * TBD: As Linus pointed out, gcc assumes that the callee
@@ -496,7 +503,8 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
         * we also save and restore enough stack bytes to cover
         * the argument area.
         */
-       memcpy(jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr));
+       memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
+                       MIN_STACK_SIZE(addr));
        regs->eflags &= ~IF_MASK;
        regs->eip = (unsigned long)(jp->entry);
        return 1;
@@ -504,34 +512,38 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
 void __kprobes jprobe_return(void)
 {
+       struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
        asm volatile ("       xchgl   %%ebx,%%esp     \n"
                      "       int3                      \n"
                      "       .globl jprobe_return_end  \n"
                      "       jprobe_return_end:        \n"
                      "       nop                       \n"::"b"
-                     (jprobe_saved_esp):"memory");
+                     (kcb->jprobe_saved_esp):"memory");
 }
 
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
+       struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
        u8 *addr = (u8 *) (regs->eip - 1);
-       unsigned long stack_addr = (unsigned long)jprobe_saved_esp;
+       unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp);
        struct jprobe *jp = container_of(p, struct jprobe, kp);
 
        if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
-               if (&regs->esp != jprobe_saved_esp) {
+               if (&regs->esp != kcb->jprobe_saved_esp) {
                        struct pt_regs *saved_regs =
-                           container_of(jprobe_saved_esp, struct pt_regs, esp);
+                           container_of(kcb->jprobe_saved_esp,
+                                           struct pt_regs, esp);
                        printk("current esp %p does not match saved esp %p\n",
-                              &regs->esp, jprobe_saved_esp);
+                              &regs->esp, kcb->jprobe_saved_esp);
                        printk("Saved registers for jprobe %p\n", jp);
                        show_registers(saved_regs);
                        printk("Current registers\n");
                        show_registers(regs);
                        BUG();
                }
-               *regs = jprobe_saved_regs;
-               memcpy((kprobe_opcode_t *) stack_addr, jprobes_stack,
+               *regs = kcb->jprobe_saved_regs;
+               memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
                       MIN_STACK_SIZE(stack_addr));
                return 1;
        }

diff --git a/include/asm-i386/kprobes.h b/include/asm-i386/kprobes.h
index 8b6d3a9..ca916a8 100644 (file)
--- a/include/asm-i386/kprobes.h
+++ b/include/asm-i386/kprobes.h
@@ -49,6 +49,23 @@ struct arch_specific_insn {
        kprobe_opcode_t insn[MAX_INSN_SIZE];
 };
 
+struct prev_kprobe {
+       struct kprobe *kp;
+       unsigned long status;
+       unsigned long old_eflags;
+       unsigned long saved_eflags;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+       unsigned long kprobe_status;
+       unsigned long kprobe_old_eflags;
+       unsigned long kprobe_saved_eflags;
+       long *jprobe_saved_esp;
+       struct pt_regs jprobe_saved_regs;
+       kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
+       struct prev_kprobe prev_kprobe;
+};
 
 /* trap3/1 are intr gates for kprobes.  So, restore the status of IF,
  * if necessary, before executing the original int3/1 (trap) handler.