commit 5bc27dc2f55fd3043597b5a8de6536183f28a449
author Arjan van de Ven <arjan@linux.intel.com> Wed Jan 30 13:33:07 2008 +0100
committer Ingo Molnar <mingo@elte.hu> Wed Jan 30 13:33:07 2008 +0100
tree dca83b12fb2f01f85a9e31bf1fb3802bd2cfef2a
parent e9d4efddbec3d852d435b370b9c40ff7ac24afe6

x86: pull bp calculation earlier into the backtrace path

Right now, we take the stack pointer early during the backtrace path, but
only calculate bp several functions deep later, making it hard to reconcile
the stack and bp backtraces (as well as showing several internal backtrace
functions on the stack with bp based backtracing).

This patch moves the bp taking to the same place we take the stack pointer;
sadly this ripples through several layers of the back tracing stack,
but it's not all that bad in the end I hope.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/traps_32.c

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 959d40e..6f3bb28 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -120,15 +120,6 @@
 {
 	struct stack_frame *frame = (struct stack_frame *)bp;
 
-	/*
-	 * if EBP is "deeper" into the stack than the actual stack pointer,
-	 * we need to rewind the stack pointer a little to start at the
-	 * first stack frame, but only if EBP is in this stack frame.
-	 */
-	if (stack > (unsigned long *) bp
-			&& valid_stack_ptr(tinfo, frame, sizeof(*frame)))
-		stack = (unsigned long *) bp;
-
 	while (valid_stack_ptr(tinfo, stack, sizeof(*stack))) {
 		unsigned long addr;
 
@@ -139,7 +130,7 @@
 				frame = frame->next_frame;
 				bp = (unsigned long) frame;
 			} else {
-				ops->address(data, addr, 0);
+				ops->address(data, addr, bp == 0);
 			}
 		}
 		stack++;
@@ -150,11 +141,9 @@
 #define MSG(msg) ops->warning(data, msg)
 
 void dump_trace(struct task_struct *task, struct pt_regs *regs,
-	        unsigned long *stack,
+		unsigned long *stack, unsigned long bp,
 		const struct stacktrace_ops *ops, void *data)
 {
-	unsigned long bp = 0;
-
 	if (!task)
 		task = current;
 
@@ -234,20 +223,20 @@
 
 static void
 show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
-		   unsigned long * stack, char *log_lvl)
+		unsigned long *stack, unsigned long bp, char *log_lvl)
 {
-	dump_trace(task, regs, stack, &print_trace_ops, log_lvl);
+	dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
 	printk("%s =======================\n", log_lvl);
 }
 
 void show_trace(struct task_struct *task, struct pt_regs *regs,
-		unsigned long * stack)
+		unsigned long *stack, unsigned long bp)
 {
-	show_trace_log_lvl(task, regs, stack, "");
+	show_trace_log_lvl(task, regs, stack, bp, "");
 }
 
 static void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-			       unsigned long *sp, char *log_lvl)
+		       unsigned long *sp, unsigned long bp, char *log_lvl)
 {
 	unsigned long *stack;
 	int i;
@@ -268,13 +257,13 @@
 		printk("%08lx ", *stack++);
 	}
 	printk("\n%sCall Trace:\n", log_lvl);
-	show_trace_log_lvl(task, regs, sp, log_lvl);
+	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp)
 {
 	printk("       ");
-	show_stack_log_lvl(task, NULL, sp, "");
+	show_stack_log_lvl(task, NULL, sp, 0, "");
 }
 
 /*
@@ -283,13 +272,19 @@
 void dump_stack(void)
 {
 	unsigned long stack;
+	unsigned long bp = 0;
+
+#ifdef CONFIG_FRAME_POINTER
+	if (!bp)
+		asm("movl %%ebp, %0" : "=r" (bp):);
+#endif
 
 	printk("Pid: %d, comm: %.20s %s %s %.*s\n",
 		current->pid, current->comm, print_tainted(),
 		init_utsname()->release,
 		(int)strcspn(init_utsname()->version, " "),
 		init_utsname()->version);
-	show_trace(current, NULL, &stack);
+	show_trace(current, NULL, &stack, bp);
 }
 
 EXPORT_SYMBOL(dump_stack);
@@ -314,7 +309,7 @@
 		unsigned char c;
 
 		printk("\n" KERN_EMERG "Stack: ");
-		show_stack_log_lvl(NULL, regs, &regs->sp, KERN_EMERG);
+		show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
 
 		printk(KERN_EMERG "Code: ");