[PATCH] i386: reliable stack trace support (i386)

These are the i386-specific pieces to enable reliable stack traces. This is
going to be even more useful once CFI annotations get added to he assembly
code, namely to entry.S.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 40 insertions, 10 deletions

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index dcc14477af1..28658466786 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -28,6 +28,7 @@
 #include <linux/utsname.h>
 #include <linux/kprobes.h>
 #include <linux/kexec.h>
+#include <linux/unwind.h>
 
 #ifdef CONFIG_EISA
 #include <linux/ioport.h>
@@ -47,7 +48,7 @@
 #include <asm/desc.h>
 #include <asm/i387.h>
 #include <asm/nmi.h>
-
+#include <asm/unwind.h>
 #include <asm/smp.h>
 #include <asm/arch_hooks.h>
 #include <asm/kdebug.h>
@@ -170,14 +171,43 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo,
         return ebp;
 }
 
-static void show_trace_log_lvl(struct task_struct *task,
+static asmlinkage void show_trace_unwind(struct unwind_frame_info *info, void *log_lvl)
+{
+        int printed = 0; /* nr of entries already printed on current line */
+
+        while (unwind(info) == 0 && UNW_PC(info)) {
+                printed = print_addr_and_symbol(UNW_PC(info), log_lvl, printed);
+                if (arch_unw_user_mode(info))
+                        break;
+        }
+        if (printed)
+                printk("\n");
+}
+
+static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
                                unsigned long *stack, char *log_lvl)
 {
         unsigned long ebp;
+        struct unwind_frame_info info;
 
         if (!task)
                 task = current;
 
+        if (regs) {
+                if (unwind_init_frame_info(&info, task, regs) == 0) {
+                        show_trace_unwind(&info, log_lvl);
+                        return;
+                }
+        } else if (task == current) {
+                if (unwind_init_running(&info, show_trace_unwind, log_lvl) == 0)
+                        return;
+        } else {
+                if (unwind_init_blocked(&info, task) == 0) {
+                        show_trace_unwind(&info, log_lvl);
+                        return;
+                }
+        }
+
         if (task == current) {
                 /* Grab ebp right from our regs */
                 asm ("movl %%ebp, %0" : "=r" (ebp) : );
@@ -198,13 +228,13 @@ static void show_trace_log_lvl(struct task_struct *task,
         }
 }
 
-void show_trace(struct task_struct *task, unsigned long * stack)
+void show_trace(struct task_struct *task, struct pt_regs *regs, unsigned long * stack)
 {
-        show_trace_log_lvl(task, stack, "");
+        show_trace_log_lvl(task, regs, stack, "");
 }
 
-static void show_stack_log_lvl(struct task_struct *task, unsigned long *esp,
-                               char *log_lvl)
+static void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
+                               unsigned long *esp, char *log_lvl)
 {
         unsigned long *stack;
         int i;
@@ -225,13 +255,13 @@ static void show_stack_log_lvl(struct task_struct *task, unsigned long *esp,
                 printk("%08lx ", *stack++);
         }
         printk("\n%sCall Trace:\n", log_lvl);
-        show_trace_log_lvl(task, esp, log_lvl);
+        show_trace_log_lvl(task, regs, esp, log_lvl);
 }
 
 void show_stack(struct task_struct *task, unsigned long *esp)
 {
         printk("       ");
-        show_stack_log_lvl(task, esp, "");
+        show_stack_log_lvl(task, NULL, esp, "");
 }
 
 /*
@@ -241,7 +271,7 @@ void dump_stack(void)
 {
         unsigned long stack;
 
-        show_trace(current, &stack);
+        show_trace(current, NULL, &stack);
 }
 
 EXPORT_SYMBOL(dump_stack);
@@ -285,7 +315,7 @@ void show_registers(struct pt_regs *regs)
                 u8 __user *eip;
 
                 printk("\n" KERN_EMERG "Stack: ");
-                show_stack_log_lvl(NULL, (unsigned long *)esp, KERN_EMERG);
+                show_stack_log_lvl(NULL, regs, (unsigned long *)esp, KERN_EMERG);
 
                 printk(KERN_EMERG "Code: ");