Crude heuristic stack scanning on x86-64.

Sun Nov 18 18:12:09 2007  Søren Sandmann  <sandmann@redhat.com>

       * module/sysprof-module.c (heuristic_trace): Crude heuristic stack
       scanning on x86-64.

       * module/sysprof-module.c (copy_kernel_stack): New function



svn path=/trunk/; revision=392

ChangeLog

@@ -1,3 +1,10 @@
+Sun Nov 18 18:12:09 2007  Søren Sandmann  <sandmann@redhat.com>
+
+	* module/sysprof-module.c (heuristic_trace): Crude heuristic stack
+	scanning on x86-64.
+	
+	* module/sysprof-module.c (copy_kernel_stack): New function
+
 Sun Nov 18 13:23:39 2007  Søren Sandmann  <sandmann@redhat.com>
 
 	* module/sysprof-module.c (sysprof_read): Return ssize_t instead

module/sysprof-module.c

@@ -112,80 +112,9 @@ minimum (int a, int b)
 	return a > b ? b : a;
 }
 
-static void
+static struct pt_regs *
-framepointer_trace (struct pt_regs *regs, SysprofStackTrace *trace)
+copy_kernel_stack (struct pt_regs *regs,
-{
-	void *framepointer;
-	int i;
-	StackFrame frame;
-
-	i = 0;
-	
-	trace->addresses[i++] = (void *)regs->REG_INS_PTR;
-
-	framepointer = (void *)regs->REG_FRAME_PTR;
-	
-	while (read_frame (framepointer, &frame) == 0			&&
-	       i < SYSPROF_MAX_ADDRESSES				&&
-	       (unsigned long)framepointer >= regs->REG_STACK_PTR)
-	{
-		trace->addresses[i++] = (void *)frame.return_address;
-		framepointer = (StackFrame *)frame.next;
-	}
-	
-	trace->n_addresses = i;
-}
-
-static void
-heuristic_trace (struct pt_regs *regs,
 		   SysprofStackTrace *trace)
-{
-	return framepointer_trace (regs, trace);
-}
-
-#ifdef OLD_PROFILE
-static int timer_notify(struct notifier_block * self, unsigned long val, void * data)
-#else
-static int
-timer_notify (struct pt_regs *regs)
-#endif
-{
-#ifdef OLD_PROFILE
-	struct pt_regs * regs = (struct pt_regs *)data;
-#endif
-	SysprofStackTrace *trace = &(area->traces[area->head]);
-	int i;
-	int is_user;
-	static atomic_t in_timer_notify = ATOMIC_INIT(1);
-	int n;
-
-	n = ++get_cpu_var(n_samples);
-	put_cpu_var(n_samples);
-
-	if (n % INTERVAL != 0)
-		return 0;
-	
-	/* 0: locked, 1: unlocked */
-	if (!atomic_dec_and_test(&in_timer_notify))
-		goto out;
-
-	is_user = user_mode(regs);
-
-	if (!current || current->pid == 0 || !current->mm)
-		goto out;
-	
-	if (is_user && current->state != TASK_RUNNING)
-		goto out;
-
-	memset(trace, 0, sizeof (SysprofStackTrace));
-	
-	trace->pid = current->pid;
-
-	trace->n_kernel_words = 0;
-	trace->n_addresses = 0;
-
-	i = 0;
-	if (!is_user)
 {
 	int n_bytes;
 	char *esp;
@@ -214,14 +143,113 @@ timer_notify (struct pt_regs *regs)
 	}
 	
 	/* Now trace the user stack */
-		regs = (struct pt_regs *)eos;
+	return (struct pt_regs *)eos;
 }
 
+static void
+framepointer_trace (struct pt_regs *regs, SysprofStackTrace *trace)
+{
+	void *framepointer;
+	int i;
+	StackFrame frame;
+
+	i = 1;
+	
+	framepointer = (void *)regs->REG_FRAME_PTR;
+	
+	while (read_frame (framepointer, &frame) == 0			&&
+	       i < SYSPROF_MAX_ADDRESSES				&&
+	       (unsigned long)framepointer >= regs->REG_STACK_PTR)
+	{
+		trace->addresses[i++] = (void *)frame.return_address;
+		framepointer = (StackFrame *)frame.next;
+	}
+	
+	trace->n_addresses = i;
+}
+
+static void
+heuristic_trace (struct pt_regs *regs,
+		 SysprofStackTrace *trace)
+{
+	unsigned long esp = regs->REG_STACK_PTR;
+	unsigned long eos = current->mm->start_stack;
+
+	if (esp < eos - (current->mm->stack_vm << PAGE_SHIFT)) {
+		/* Stack pointer is not in stack map */
+
+		return;
+	}
+	
+	if (eos > esp) {
+		unsigned long i;
+		int j;
+
+		j = 1;
+		for (i = esp; i < eos && j < SYSPROF_MAX_ADDRESSES; i += sizeof (void *)) {
+			void *x;
+			if (__copy_from_user_inatomic (
+				    &x, (char *)i, sizeof (x)) == 0)
+				trace->addresses[j++] = x;
+		}
+		
+		trace->n_addresses = j;
+	}
+}
+
+#ifdef OLD_PROFILE
+static int timer_notify(struct notifier_block * self, unsigned long val, void * data)
+#else
+static int
+timer_notify (struct pt_regs *regs)
+#endif
+{
+#ifdef OLD_PROFILE
+	struct pt_regs * regs = (struct pt_regs *)data;
+#endif
+	SysprofStackTrace *trace = &(area->traces[area->head]);
+	int is_user;
+	static atomic_t in_timer_notify = ATOMIC_INIT(1);
+	int n;
+
+	n = ++get_cpu_var(n_samples);
+	put_cpu_var(n_samples);
+
+	if (n % INTERVAL != 0)
+		return 0;
+	
+	/* 0: locked, 1: unlocked */
+	if (!atomic_dec_and_test(&in_timer_notify))
+		goto out;
+
+	is_user = user_mode(regs);
+
+	if (!current || current->pid == 0)
+		goto out;
+	
+	if (is_user && current->state != TASK_RUNNING)
+		goto out;
+
+	memset(trace, 0, sizeof (SysprofStackTrace));
+	
+	trace->pid = current->pid;
+
+	trace->n_kernel_words = 0;
+	trace->n_addresses = 0;
+
+	if (!is_user)
+		regs = copy_kernel_stack (regs, trace);
+
+	trace->addresses[0] = (void *)regs->REG_INS_PTR;
+	trace->n_addresses = 1;
+
+	if (current->mm) {
 #ifdef CONFIG_X86_64
 		heuristic_trace (regs, trace);
 #elif CONFIG_X86
 		framepointer_trace (regs, trace);
 #endif
+	}
 	
 	if (trace->n_addresses == SYSPROF_MAX_ADDRESSES)
 		trace->truncated = 1;