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>

2 files changed, 0 insertions, 115 deletions

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