1 files changed, 52 insertions, 43 deletions

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 7819022a8db5..b54ccc07f379 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -30,9 +30,10 @@
 #include <linux/kprobes.h>
 #include <linux/kexec.h>
 #include <linux/unwind.h>
+#include <linux/uaccess.h>
+#include <linux/bug.h>
 
 #include <asm/system.h>
-#include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/atomic.h>
 #include <asm/debugreg.h>
@@ -108,7 +109,7 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
         preempt_enable_no_resched();
 }
 
-static int kstack_depth_to_print = 12;
+int kstack_depth_to_print = 12;
 #ifdef CONFIG_STACK_UNWIND
 static int call_trace = 1;
 #else
@@ -225,16 +226,25 @@ 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)
+
 /*
  * x86-64 can have upto three kernel stacks: 
  * process stack
@@ -242,12 +252,20 @@ static int dump_trace_unwind(struct unwind_frame_info *info, void *context)
  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
  */
 
-void dump_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * stack,
+static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
+{
+        void *t = (void *)tinfo;
+        return p > t && p < t + THREAD_SIZE - 3;
+}
+
+void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
+                unsigned long *stack,
                 struct stacktrace_ops *ops, void *data)
 {
-        const unsigned cpu = smp_processor_id();
-        unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
+        const unsigned cpu = get_cpu();
+        unsigned long *irqstack_end = (unsigned long*)cpu_pda(cpu)->irqstackptr;
         unsigned used = 0;
+        struct thread_info *tinfo;
 
         if (!tsk)
                 tsk = current;
@@ -261,28 +279,30 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
                         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);
+                        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\n",
+                                ops->warning_symbol(data,
+                                             "DWARF2 unwinder stuck at %s",
                                              UNW_PC(&info));
                                 if ((long)UNW_SP(&info) < 0) {
-                                        ops->warning(data, "Leftover inexact backtrace:\n");
+                                        MSG("Leftover inexact backtrace:");
                                         stack = (unsigned long *)UNW_SP(&info);
                                         if (!stack)
-                                                return;
+                                                goto out;
                                 } else
-                                        ops->warning(data, "Full inexact backtrace again:\n");
+                                        MSG("Full inexact backtrace again:");
                         } else if (call_trace >= 1)
-                                return;
+                                goto out;
                         else
-                                ops->warning(data, "Full inexact backtrace again:\n");
+                                MSG("Full inexact backtrace again:");
                 } else
-                        ops->warning(data, "Inexact backtrace:\n");
+                        MSG("Inexact backtrace:");
         }
         if (!stack) {
                 unsigned long dummy;
@@ -299,9 +319,9 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
 #define HANDLE_STACK(cond) \
         do while (cond) { \
                 unsigned long addr = *stack++; \
-                if (oops_in_progress ?          \
-                        __kernel_text_address(addr) : \
-                        kernel_text_address(addr)) { \
+                /* Use unlocked access here because except for NMIs     \
+                   we should be already protected against module unloads */ \
+                if (__kernel_text_address(addr)) { \
                         /* \
                          * If the address is either in the text segment of the \
                          * kernel, or in the region which contains vmalloc'ed \
@@ -364,8 +384,11 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
         /*
          * This handles the process stack:
          */
-        HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0);
+        tinfo = current_thread_info();
+        HANDLE_STACK (valid_stack_ptr(tinfo, stack));
 #undef HANDLE_STACK
+out:
+        put_cpu();
 }
 EXPORT_SYMBOL(dump_trace);
 
@@ -502,30 +525,15 @@ bad:
         printk("\n");
 }       
 
-void handle_BUG(struct pt_regs *regs)
-{ 
-        struct bug_frame f;
-        long len;
-        const char *prefix = "";
+int is_valid_bugaddr(unsigned long rip)
+{
+        unsigned short ud2;
 
-        if (user_mode(regs))
-                return; 
-        if (__copy_from_user(&f, (const void __user *) regs->rip,
-                             sizeof(struct bug_frame)))
-                return; 
-        if (f.filename >= 0 ||
-            f.ud2[0] != 0x0f || f.ud2[1] != 0x0b) 
-                return;
-        len = __strnlen_user((char *)(long)f.filename, PATH_MAX) - 1;
-        if (len < 0 || len >= PATH_MAX)
-                f.filename = (int)(long)"unmapped filename";
-        else if (len > 50) {
-                f.filename += len - 50;
-                prefix = "...";
-        }
-        printk("----------- [cut here ] --------- [please bite here ] ---------\n");
-        printk(KERN_ALERT "Kernel BUG at %s%.50s:%d\n", prefix, (char *)(long)f.filename, f.line);
-} 
+        if (__copy_from_user(&ud2, (const void __user *) rip, sizeof(ud2)))
+                return 0;
+
+        return ud2 == 0x0b0f;
+}
 
 #ifdef CONFIG_BUG
 void out_of_line_bug(void)
@@ -605,7 +613,9 @@ void die(const char * str, struct pt_regs * regs, long err)
 {
         unsigned long flags = oops_begin();
 
-        handle_BUG(regs);
+        if (!user_mode(regs))
+                report_bug(regs->rip);
+
         __die(str, regs, err);
         oops_end(flags);
         do_exit(SIGSEGV); 
@@ -772,8 +782,7 @@ mem_parity_error(unsigned char reason, struct pt_regs * regs)
 {
         printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n",
                 reason);
-        printk(KERN_EMERG "You probably have a hardware problem with your "
-                "RAM chips\n");
+        printk(KERN_EMERG "You have some hardware problem, likely on the PCI bus.\n");
 
         if (panic_on_unrecovered_nmi)
                 panic("NMI: Not continuing");