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>

3 files changed, 0 insertions, 117 deletions

diff --git a/arch/i386/defconfig b/arch/i386/defconfig
index 3265208e5899..e075ff05c46d 100644
--- a/arch/i386/defconfig
+++ b/arch/i386/defconfig
@@ -1493,8 +1493,6 @@ CONFIG_DEBUG_BUGVERBOSE=y
 # CONFIG_DEBUG_VM is not set
 # CONFIG_DEBUG_LIST is not set
 # CONFIG_FRAME_POINTER is not set
-CONFIG_UNWIND_INFO=y
-CONFIG_STACK_UNWIND=y
 # CONFIG_FORCED_INLINING is not set
 # CONFIG_HEADERS_CHECK is not set
 # CONFIG_RCU_TORTURE_TEST is not set
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index de34b7fed3c1..06461b8b715d 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -979,38 +979,6 @@ ENTRY(spurious_interrupt_bug)
 	jmp error_code
 	CFI_ENDPROC
 
-#ifdef CONFIG_STACK_UNWIND
-ENTRY(arch_unwind_init_running)
-	CFI_STARTPROC
-	movl	4(%esp), %edx
-	movl	(%esp), %ecx
-	leal	4(%esp), %eax
-	movl	%ebx, PT_EBX(%edx)
-	xorl	%ebx, %ebx
-	movl	%ebx, PT_ECX(%edx)
-	movl	%ebx, PT_EDX(%edx)
-	movl	%esi, PT_ESI(%edx)
-	movl	%edi, PT_EDI(%edx)
-	movl	%ebp, PT_EBP(%edx)
-	movl	%ebx, PT_EAX(%edx)
-	movl	$__USER_DS, PT_DS(%edx)
-	movl	$__USER_DS, PT_ES(%edx)
-	movl	$0, PT_GS(%edx)
-	movl	%ebx, PT_ORIG_EAX(%edx)
-	movl	%ecx, PT_EIP(%edx)
-	movl	12(%esp), %ecx
-	movl	$__KERNEL_CS, PT_CS(%edx)
-	movl	%ebx, PT_EFLAGS(%edx)
-	movl	%eax, PT_OLDESP(%edx)
-	movl	8(%esp), %eax
-	movl	%ecx, 8(%esp)
-	movl	PT_EBX(%edx), %ebx
-	movl	$__KERNEL_DS, PT_OLDSS(%edx)
-	jmpl	*%eax
-	CFI_ENDPROC
-ENDPROC(arch_unwind_init_running)
-#endif
-
 ENTRY(kernel_thread_helper)
 	pushl $0		# fake return address for unwinder
 	CFI_STARTPROC
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 2b30dbf8d117..0efad8aeb41a 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -94,11 +94,6 @@ asmlinkage void spurious_interrupt_bug(void);
 asmlinkage void machine_check(void);
 
 int kstack_depth_to_print = 24;
-#ifdef CONFIG_STACK_UNWIND
-static int call_trace = 1;
-#else
-#define call_trace (-1)
-#endif
 ATOMIC_NOTIFIER_HEAD(i386die_chain);
 
 int register_die_notifier(struct notifier_block *nb)
@@ -152,33 +147,6 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo,
 	return ebp;
 }
 
-struct ops_and_data {
-	struct stacktrace_ops *ops;
-	void *data;
-};
-
-static asmlinkage int
-dump_trace_unwind(struct unwind_frame_info *info, void *data)
-{
-	struct ops_and_data *oad = (struct ops_and_data *)data;
-	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(msg) ops->warning(data, msg)
 
 void dump_trace(struct task_struct *task, struct pt_regs *regs,
@@ -190,41 +158,6 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
 	if (!task)
 		task = 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, task, regs) == 0)
-				unw_ret = dump_trace_unwind(&info, &oad);
-		} else if (task == current)
-			unw_ret = unwind_init_running(&info, dump_trace_unwind,
-						      &oad);
-		else {
-			if (unwind_init_blocked(&info, task) == 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 (UNW_SP(&info) >= PAGE_OFFSET) {
-					MSG("Leftover inexact backtrace:");
-					stack = (void *)UNW_SP(&info);
-					if (!stack)
-						return;
-					ebp = UNW_FP(&info);
-				} else
-					MSG("Full inexact backtrace again:");
-			} else if (call_trace >= 1)
-				return;
-			else
-				MSG("Full inexact backtrace again:");
-		} else
-			MSG("Inexact backtrace:");
-	}
 	if (!stack) {
 		unsigned long dummy;
 		stack = &dummy;
@@ -1258,19 +1191,3 @@ static int __init kstack_setup(char *s)
 	return 1;
 }
 __setup("kstack=", kstack_setup);
-
-#ifdef CONFIG_STACK_UNWIND
-static int __init call_trace_setup(char *s)
-{
-	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") == 2)
-		call_trace = 2;
-	return 1;
-}
-__setup("call_trace=", call_trace_setup);
-#endif