Remove stack unwinder for now

It has caused more problems than it ever really solved, and is
apparently not getting cleaned up and fixed.  We can put it back when
it's stable and isn't likely to make warning or bug events worse.

In the meantime, enable frame pointers for more readable stack traces.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 84 deletions

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index b54ccc07f37..1d9eb6db732 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -110,11 +110,6 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
 }
 
 int kstack_depth_to_print = 12;
-#ifdef CONFIG_STACK_UNWIND
-static int call_trace = 1;
-#else
-#define call_trace (-1)
-#endif
 
 #ifdef CONFIG_KALLSYMS
 void printk_address(unsigned long address)
@@ -217,32 +212,6 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
 	return NULL;
 }
 
-struct ops_and_data {
-	struct stacktrace_ops *ops;
-	void *data;
-};
-
-static int dump_trace_unwind(struct unwind_frame_info *info, void *context)
-{
-	struct ops_and_data *oad = (struct ops_and_data *)context;
-	int n = 0;
-	unsigned long sp = UNW_SP(info);
-
-	if (arch_unw_user_mode(info))
-		return -1;
-	while (unwind(info) == 0 && UNW_PC(info)) {
-		n++;
-		oad->ops->address(oad->data, UNW_PC(info));
-		if (arch_unw_user_mode(info))
-			break;
-		if ((sp & ~(PAGE_SIZE - 1)) == (UNW_SP(info) & ~(PAGE_SIZE - 1))
-		    && sp > UNW_SP(info))
-			break;
-		sp = UNW_SP(info);
-	}
-	return n;
-}
-
 #define MSG(txt) ops->warning(data, txt)
 
 /*
@@ -270,40 +239,6 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
 	if (!tsk)
 		tsk = current;
 
-	if (call_trace >= 0) {
-		int unw_ret = 0;
-		struct unwind_frame_info info;
-		struct ops_and_data oad = { .ops = ops, .data = data };
-
-		if (regs) {
-			if (unwind_init_frame_info(&info, tsk, regs) == 0)
-				unw_ret = dump_trace_unwind(&info, &oad);
-		} else if (tsk == current)
-			unw_ret = unwind_init_running(&info, dump_trace_unwind,
-						      &oad);
-		else {
-			if (unwind_init_blocked(&info, tsk) == 0)
-				unw_ret = dump_trace_unwind(&info, &oad);
-		}
-		if (unw_ret > 0) {
-			if (call_trace == 1 && !arch_unw_user_mode(&info)) {
-				ops->warning_symbol(data,
-					     "DWARF2 unwinder stuck at %s",
-					     UNW_PC(&info));
-				if ((long)UNW_SP(&info) < 0) {
-					MSG("Leftover inexact backtrace:");
-					stack = (unsigned long *)UNW_SP(&info);
-					if (!stack)
-						goto out;
-				} else
-					MSG("Full inexact backtrace again:");
-			} else if (call_trace >= 1)
-				goto out;
-			else
-				MSG("Full inexact backtrace again:");
-		} else
-			MSG("Inexact backtrace:");
-	}
 	if (!stack) {
 		unsigned long dummy;
 		stack = &dummy;
@@ -387,7 +322,6 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
 	tinfo = current_thread_info();
 	HANDLE_STACK (valid_stack_ptr(tinfo, stack));
 #undef HANDLE_STACK
-out:
 	put_cpu();
 }
 EXPORT_SYMBOL(dump_trace);
@@ -1188,21 +1122,3 @@ static int __init kstack_setup(char *s)
 	return 0;
 }
 early_param("kstack", kstack_setup);
-
-#ifdef CONFIG_STACK_UNWIND
-static int __init call_trace_setup(char *s)
-{
-	if (!s)
-		return -EINVAL;
-	if (strcmp(s, "old") == 0)
-		call_trace = -1;
-	else if (strcmp(s, "both") == 0)
-		call_trace = 0;
-	else if (strcmp(s, "newfallback") == 0)
-		call_trace = 1;
-	else if (strcmp(s, "new") == 0)
-		call_trace = 2;
-	return 0;
-}
-early_param("call_trace", call_trace_setup);
-#endif