1 files changed, 91 insertions, 92 deletions

diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index 76a28b0..dddeb67 100644
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -34,7 +34,6 @@
 #include <linux/config.h>
 #include <linux/kprobes.h>
 #include <linux/ptrace.h>
-#include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/preempt.h>
@@ -44,17 +43,10 @@
 #include <asm/kdebug.h>
 
 static DECLARE_MUTEX(kprobe_mutex);
-
-static struct kprobe *current_kprobe;
-static unsigned long kprobe_status, kprobe_old_rflags, kprobe_saved_rflags;
-static struct kprobe *kprobe_prev;
-static unsigned long kprobe_status_prev, kprobe_old_rflags_prev, kprobe_saved_rflags_prev;
-static struct pt_regs jprobe_saved_regs;
-static long *jprobe_saved_rsp;
 void jprobe_return_end(void);
 
-/* copy of the kernel stack at the probe fire time */
-static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
+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.
@@ -236,29 +228,30 @@ void __kprobes arch_remove_kprobe(struct kprobe *p)
 	up(&kprobe_mutex);
 }
 
-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_rflags_prev = kprobe_old_rflags;
-	kprobe_saved_rflags_prev = kprobe_saved_rflags;
+	kcb->prev_kprobe.kp = kprobe_running();
+	kcb->prev_kprobe.status = kcb->kprobe_status;
+	kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags;
+	kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags;
 }
 
-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_rflags = kprobe_old_rflags_prev;
-	kprobe_saved_rflags = kprobe_saved_rflags_prev;
+	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+	kcb->kprobe_status = kcb->prev_kprobe.status;
+	kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags;
+	kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags;
 }
 
-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_rflags = kprobe_old_rflags
+	__get_cpu_var(current_kprobe) = p;
+	kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags
 		= (regs->eflags & (TF_MASK | IF_MASK));
 	if (is_IF_modifier(p->ainsn.insn))
-		kprobe_saved_rflags &= ~IF_MASK;
+		kcb->kprobe_saved_rflags &= ~IF_MASK;
 }
 
 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
@@ -272,6 +265,7 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 		regs->rip = (unsigned long)p->ainsn.insn;
 }
 
+/* Called with kretprobe_lock held */
 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 				      struct pt_regs *regs)
 {
@@ -292,32 +286,30 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
         }
 }
 
-/*
- * Interrupts are disabled on entry as trap3 is an interrupt gate and they
- * remain disabled thorough out this function.
- */
 int __kprobes kprobe_handler(struct pt_regs *regs)
 {
 	struct kprobe *p;
 	int ret = 0;
 	kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t));
+	struct kprobe_ctlblk *kcb;
 
-	/* We're in an interrupt, but this is clear and BUG()-safe. */
+	/*
+	 * We don't want to be preempted for the entire
+	 * duration of kprobe processing
+	 */
 	preempt_disable();
+	kcb = get_kprobe_ctlblk();
 
 	/* Check we're not actually recursing */
 	if (kprobe_running()) {
-		/* We *are* holding lock here, so this is safe.
-		   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_rflags;
-				unlock_kprobes();
+				regs->eflags |= kcb->kprobe_saved_rflags;
 				goto no_kprobe;
-			} else if (kprobe_status == KPROBE_HIT_SSDONE) {
+			} else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) {
 				/* TODO: Provide re-entrancy from
 				 * post_kprobes_handler() and avoid exception
 				 * stack corruption while single-stepping on
@@ -325,6 +317,7 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 				 */
 				arch_disarm_kprobe(p);
 				regs->rip = (unsigned long)p->addr;
+				reset_current_kprobe();
 				ret = 1;
 			} else {
 				/* We have reentered the kprobe_handler(), since
@@ -334,27 +327,24 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 				 * 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;
 			}
 		}
-		/* If it's not ours, can't be delete race, (we hold lock). */
 		goto no_kprobe;
 	}
 
-	lock_kprobes();
 	p = get_kprobe(addr);
 	if (!p) {
-		unlock_kprobes();
 		if (*addr != BREAKPOINT_INSTRUCTION) {
 			/*
 			 * The breakpoint instruction was removed right
@@ -372,8 +362,8 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 		goto no_kprobe;
 	}
 
-	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 */
@@ -381,7 +371,7 @@ 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:
@@ -409,9 +399,10 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
         struct kretprobe_instance *ri = NULL;
         struct hlist_head *head;
         struct hlist_node *node, *tmp;
-	unsigned long orig_ret_address = 0;
+	unsigned long flags, orig_ret_address = 0;
 	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
 
+	spin_lock_irqsave(&kretprobe_lock, flags);
         head = kretprobe_inst_table_head(current);
 
 	/*
@@ -450,13 +441,14 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 	BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 	regs->rip = orig_ret_address;
 
-	unlock_kprobes();
+	reset_current_kprobe();
+	spin_unlock_irqrestore(&kretprobe_lock, flags);
 	preempt_enable_no_resched();
 
         /*
          * By returning a non-zero value, we are telling
-         * kprobe_handler() that we have handled unlocking
-         * and re-enabling preemption.
+         * kprobe_handler() that we don't want the post_handler
+	 * to run (and have re-enabled preemption)
          */
         return 1;
 }
@@ -483,7 +475,8 @@ 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->rsp;
 	unsigned long next_rip = 0;
@@ -498,7 +491,7 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 	switch (*insn) {
 	case 0x9c:		/* pushfl */
 		*tos &= ~(TF_MASK | IF_MASK);
-		*tos |= kprobe_old_rflags;
+		*tos |= kcb->kprobe_old_rflags;
 		break;
 	case 0xc3:		/* ret/lret */
 	case 0xcb:
@@ -537,30 +530,28 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 	}
 }
 
-/*
- * Interrupts are disabled on entry as trap1 is an interrupt gate and they
- * remain disabled thoroughout this function.  And we hold kprobe lock.
- */
 int __kprobes 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_rflags;
+	resume_execution(cur, regs, kcb);
+	regs->eflags |= kcb->kprobe_saved_rflags;
 
 	/* Restore 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;
-	} else {
-		unlock_kprobes();
 	}
+	reset_current_kprobe();
 out:
 	preempt_enable_no_resched();
 
@@ -575,18 +566,19 @@ out:
 	return 1;
 }
 
-/* Interrupts disabled, kprobe_lock held. */
 int __kprobes 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_rflags;
+	if (kcb->kprobe_status & KPROBE_HIT_SS) {
+		resume_execution(cur, regs, kcb);
+		regs->eflags |= kcb->kprobe_old_rflags;
 
-		unlock_kprobes();
+		reset_current_kprobe();
 		preempt_enable_no_resched();
 	}
 	return 0;
@@ -599,39 +591,41 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 				       unsigned long val, void *data)
 {
 	struct die_args *args = (struct die_args *)data;
+	int ret = NOTIFY_DONE;
+
 	switch (val) {
 	case DIE_INT3:
 		if (kprobe_handler(args->regs))
-			return NOTIFY_STOP;
+			ret = NOTIFY_STOP;
 		break;
 	case DIE_DEBUG:
 		if (post_kprobe_handler(args->regs))
-			return NOTIFY_STOP;
+			ret = NOTIFY_STOP;
 		break;
 	case DIE_GPF:
-		if (kprobe_running() &&
-		    kprobe_fault_handler(args->regs, args->trapnr))
-			return NOTIFY_STOP;
-		break;
 	case DIE_PAGE_FAULT:
+		/* kprobe_running() needs smp_processor_id() */
+		preempt_disable();
 		if (kprobe_running() &&
 		    kprobe_fault_handler(args->regs, args->trapnr))
-			return NOTIFY_STOP;
+			ret = NOTIFY_STOP;
+		preempt_enable();
 		break;
 	default:
 		break;
 	}
-	return NOTIFY_DONE;
+	return ret;
 }
 
 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_rsp = (long *) regs->rsp;
-	addr = (unsigned long)jprobe_saved_rsp;
+	kcb->jprobe_saved_regs = *regs;
+	kcb->jprobe_saved_rsp = (long *) regs->rsp;
+	addr = (unsigned long)(kcb->jprobe_saved_rsp);
 	/*
 	 * As Linus pointed out, gcc assumes that the callee
 	 * owns the argument space and could overwrite it, e.g.
@@ -639,7 +633,8 @@ 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->rip = (unsigned long)(jp->entry);
 	return 1;
@@ -647,36 +642,40 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
 void __kprobes jprobe_return(void)
 {
-	preempt_enable_no_resched();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
 	asm volatile ("       xchg   %%rbx,%%rsp     \n"
 		      "       int3			\n"
 		      "       .globl jprobe_return_end	\n"
 		      "       jprobe_return_end:	\n"
 		      "       nop			\n"::"b"
-		      (jprobe_saved_rsp):"memory");
+		      (kcb->jprobe_saved_rsp):"memory");
 }
 
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 	u8 *addr = (u8 *) (regs->rip - 1);
-	unsigned long stack_addr = (unsigned long)jprobe_saved_rsp;
+	unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp);
 	struct jprobe *jp = container_of(p, struct jprobe, kp);
 
 	if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
-		if ((long *)regs->rsp != jprobe_saved_rsp) {
+		if ((long *)regs->rsp != kcb->jprobe_saved_rsp) {
 			struct pt_regs *saved_regs =
-			    container_of(jprobe_saved_rsp, struct pt_regs, rsp);
+			    container_of(kcb->jprobe_saved_rsp,
+					    struct pt_regs, rsp);
 			printk("current rsp %p does not match saved rsp %p\n",
-			       (long *)regs->rsp, jprobe_saved_rsp);
+			       (long *)regs->rsp, kcb->jprobe_saved_rsp);
 			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));
+		preempt_enable_no_resched();
 		return 1;
 	}
 	return 0;