x86, dumpstack: Correct stack dump info when frame pointer is available

Current stack dump code scans entire stack and check each entry
contains a pointer to kernel code. If CONFIG_FRAME_POINTER=y it
could mark whether the pointer is valid or not based on value of
the frame pointer. Invalid entries could be preceded by '?' sign.

However this was not going to happen because scan start point
was always higher than the frame pointer so that they could not
meet.

Commit 9c0729dc8062 ("x86: Eliminate bp argument from the stack
tracing routines") delayed bp acquisition point, so the bp was
read in lower frame, thus all of the entries were marked
invalid.

This patch fixes this by reverting above commit while retaining
stack_frame() helper as suggested by Frederic Weisbecker.

End result looks like below:

before:

 [    3.508329] Call Trace:
 [    3.508551]  [<ffffffff814f35c9>] ? panic+0x91/0x199
 [    3.508662]  [<ffffffff814f3739>] ? printk+0x68/0x6a
 [    3.508770]  [<ffffffff81a981b2>] ? mount_block_root+0x257/0x26e
 [    3.508876]  [<ffffffff81a9821f>] ? mount_root+0x56/0x5a
 [    3.508975]  [<ffffffff81a98393>] ? prepare_namespace+0x170/0x1a9
 [    3.509216]  [<ffffffff81a9772b>] ? kernel_init+0x1d2/0x1e2
 [    3.509335]  [<ffffffff81003894>] ? kernel_thread_helper+0x4/0x10
 [    3.509442]  [<ffffffff814f6880>] ? restore_args+0x0/0x30
 [    3.509542]  [<ffffffff81a97559>] ? kernel_init+0x0/0x1e2
 [    3.509641]  [<ffffffff81003890>] ? kernel_thread_helper+0x0/0x10

after:

 [    3.522991] Call Trace:
 [    3.523351]  [<ffffffff814f35b9>] panic+0x91/0x199
 [    3.523468]  [<ffffffff814f3729>] ? printk+0x68/0x6a
 [    3.523576]  [<ffffffff81a981b2>] mount_block_root+0x257/0x26e
 [    3.523681]  [<ffffffff81a9821f>] mount_root+0x56/0x5a
 [    3.523780]  [<ffffffff81a98393>] prepare_namespace+0x170/0x1a9
 [    3.523885]  [<ffffffff81a9772b>] kernel_init+0x1d2/0x1e2
 [    3.523987]  [<ffffffff81003894>] kernel_thread_helper+0x4/0x10
 [    3.524228]  [<ffffffff814f6880>] ? restore_args+0x0/0x30
 [    3.524345]  [<ffffffff81a97559>] ? kernel_init+0x0/0x1e2
 [    3.524445]  [<ffffffff81003890>] ? kernel_thread_helper+0x0/0x10

 -v5:
   * fix build breakage with oprofile

 -v4:
   * use 0 instead of regs->bp
   * separate out printk changes

 -v3:
   * apply comment from Frederic
   * add a couple of printk fixes

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Soren Sandmann <ssp@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Robert Richter <robert.richter@amd.com>
LKML-Reference: <1300416006-3163-1-git-send-email-namhyung@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
index 518bbbb9ee59135bd6e3213dc3550803c9df2b47..fe2cc6e105fa97b907874fe52601e4fb08fd6334 100644 (file)
--- a/arch/x86/include/asm/kdebug.h
+++ b/arch/x86/include/asm/kdebug.h
@@ -26,7 +26,7 @@ extern void die(const char *, struct pt_regs *,long);
 extern int __must_check __die(const char *, struct pt_regs *, long);
 extern void show_registers(struct pt_regs *regs);
 extern void show_trace(struct task_struct *t, struct pt_regs *regs,
-                      unsigned long *sp);
+                      unsigned long *sp, unsigned long bp);
 extern void __show_regs(struct pt_regs *regs, int all);
 extern void show_regs(struct pt_regs *regs);
 extern unsigned long oops_begin(void);

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 52b5c7ed3608d9fc439c5ca69bf58ca1b8ebef88..d7e89c83645d275c3cc7b3677c05f28528cc771d 100644 (file)
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -47,7 +47,7 @@ struct stacktrace_ops {
 };
 
 void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
-               unsigned long *stack,
+               unsigned long *stack, unsigned long bp,
                const struct stacktrace_ops *ops, void *data);
 
 #ifdef CONFIG_X86_32
@@ -86,11 +86,11 @@ stack_frame(struct task_struct *task, struct pt_regs *regs)
 
 extern void
 show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                  unsigned long *stack, char *log_lvl);
+                  unsigned long *stack, unsigned long bp, char *log_lvl);
 
 extern void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                  unsigned long *sp, char *log_lvl);
+                  unsigned long *sp, unsigned long bp, char *log_lvl);
 
 extern unsigned int code_bytes;
 

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 279bc9de1cc7285c99fe414be3bf97ba9e8ed22e..30612764cd3bafdb63e10a4ebac2b8748a0c0928 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1792,7 +1792,7 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 
        perf_callchain_store(entry, regs->ip);
 
-       dump_trace(NULL, regs, NULL, &backtrace_ops, entry);
+       dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
 }
 
 #ifdef CONFIG_COMPAT

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 220a1c11cfde4280e22ccf6b691e1c2b4c8ea64c..999e2793590b2275fe36d1c81d3bb74e69143a9d 100644 (file)
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -175,21 +175,21 @@ static const struct stacktrace_ops print_trace_ops = {
 
 void
 show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack, char *log_lvl)
+               unsigned long *stack, unsigned long bp, char *log_lvl)
 {
        printk("%sCall Trace:\n", log_lvl);
-       dump_trace(task, regs, stack, &print_trace_ops, log_lvl);
+       dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
 }
 
 void show_trace(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack)
+               unsigned long *stack, unsigned long bp)
 {
-       show_trace_log_lvl(task, regs, stack, "");
+       show_trace_log_lvl(task, regs, stack, bp, "");
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp)
 {
-       show_stack_log_lvl(task, NULL, sp, "");
+       show_stack_log_lvl(task, NULL, sp, 0, "");
 }
 
 /*
@@ -197,14 +197,16 @@ void show_stack(struct task_struct *task, unsigned long *sp)
  */
 void dump_stack(void)
 {
+       unsigned long bp;
        unsigned long stack;
 
+       bp = stack_frame(current, NULL);
        printk("Pid: %d, comm: %.20s %s %s %.*s\n",
                current->pid, current->comm, print_tainted(),
                init_utsname()->release,
                (int)strcspn(init_utsname()->version, " "),
                init_utsname()->version);
-       show_trace(NULL, NULL, &stack);
+       show_trace(NULL, NULL, &stack, bp);
 }
 EXPORT_SYMBOL(dump_stack);
 

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 74cc1eda384b8d26437a10fa55e3f64cfcf4545a..3b97a80ce32948ffa995f7b310024f901811703b 100644 (file)
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -17,12 +17,11 @@
 #include <asm/stacktrace.h>
 
 
-void dump_trace(struct task_struct *task,
-               struct pt_regs *regs, unsigned long *stack,
+void dump_trace(struct task_struct *task, struct pt_regs *regs,
+               unsigned long *stack, unsigned long bp,
                const struct stacktrace_ops *ops, void *data)
 {
        int graph = 0;
-       unsigned long bp;
 
        if (!task)
                task = current;
@@ -35,7 +34,9 @@ void dump_trace(struct task_struct *task,
                        stack = (unsigned long *)task->thread.sp;
        }
 
-       bp = stack_frame(task, regs);
+       if (!bp)
+               bp = stack_frame(task, regs);
+
        for (;;) {
                struct thread_info *context;
 
@@ -55,7 +56,7 @@ EXPORT_SYMBOL(dump_trace);
 
 void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                  unsigned long *sp, char *log_lvl)
+                  unsigned long *sp, unsigned long bp, char *log_lvl)
 {
        unsigned long *stack;
        int i;
@@ -77,7 +78,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
                touch_nmi_watchdog();
        }
        printk(KERN_CONT "\n");
-       show_trace_log_lvl(task, regs, sp, log_lvl);
+       show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 }
 
 
@@ -102,7 +103,7 @@ void show_registers(struct pt_regs *regs)
                u8 *ip;
 
                printk(KERN_EMERG "Stack:\n");
-               show_stack_log_lvl(NULL, regs, &regs->sp, KERN_EMERG);
+               show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
 
                printk(KERN_EMERG "Code: ");
 

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index a6b6fcf7f0aee9665e00fc2ed8d8d9290fc0423a..e71c98d3c0d2d7ff4fc2085d646d31b56bc6a476 100644 (file)
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -139,8 +139,8 @@ fixup_bp_irq_link(unsigned long bp, unsigned long *stack,
  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
  */
 
-void dump_trace(struct task_struct *task,
-               struct pt_regs *regs, unsigned long *stack,
+void dump_trace(struct task_struct *task, struct pt_regs *regs,
+               unsigned long *stack, unsigned long bp,
                const struct stacktrace_ops *ops, void *data)
 {
        const unsigned cpu = get_cpu();
@@ -150,7 +150,6 @@ void dump_trace(struct task_struct *task,
        struct thread_info *tinfo;
        int graph = 0;
        unsigned long dummy;
-       unsigned long bp;
 
        if (!task)
                task = current;
@@ -161,7 +160,8 @@ void dump_trace(struct task_struct *task,
                        stack = (unsigned long *)task->thread.sp;
        }
 
-       bp = stack_frame(task, regs);
+       if (!bp)
+               bp = stack_frame(task, regs);
        /*
         * Print function call entries in all stacks, starting at the
         * current stack address. If the stacks consist of nested
@@ -225,7 +225,7 @@ EXPORT_SYMBOL(dump_trace);
 
 void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                  unsigned long *sp, char *log_lvl)
+                  unsigned long *sp, unsigned long bp, char *log_lvl)
 {
        unsigned long *irq_stack_end;
        unsigned long *irq_stack;
@@ -269,7 +269,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
        preempt_enable();
 
        printk(KERN_CONT "\n");
-       show_trace_log_lvl(task, regs, sp, log_lvl);
+       show_trace_log_lvl(task, regs, sp, bp, log_lvl);
 }
 
 void show_registers(struct pt_regs *regs)
@@ -298,7 +298,7 @@ void show_registers(struct pt_regs *regs)
 
                printk(KERN_EMERG "Stack:\n");
                show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
-                                  KERN_EMERG);
+                                  0, KERN_EMERG);
 
                printk(KERN_EMERG "Code: ");
 

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 99fa3adf014190d166c9c8d7b2250febf27cec42..d46cbe46b7aba845ab1a2261a569f0178ec954b0 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -87,7 +87,7 @@ void exit_thread(void)
 void show_regs(struct pt_regs *regs)
 {
        show_registers(regs);
-       show_trace(NULL, regs, (unsigned long *)kernel_stack_pointer(regs));
+       show_trace(NULL, regs, (unsigned long *)kernel_stack_pointer(regs), 0);
 }
 
 void show_regs_common(void)

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 938c8e10a19abeae0e2c814e182a0920ff0328f9..6515733a289d858fde792d8db8f35bca3cad503d 100644 (file)
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -73,7 +73,7 @@ static const struct stacktrace_ops save_stack_ops_nosched = {
  */
 void save_stack_trace(struct stack_trace *trace)
 {
-       dump_trace(current, NULL, NULL, &save_stack_ops, trace);
+       dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
@@ -81,14 +81,14 @@ EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_regs(struct stack_trace *trace, struct pt_regs *regs)
 {
-       dump_trace(current, regs, NULL, &save_stack_ops, trace);
+       dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
-       dump_trace(tsk, NULL, NULL, &save_stack_ops_nosched, trace);
+       dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index 72cbec14d783867cb5f5fa8547eb6fcee2fe28b9..2d49d4e19a3619c0be2c7d17a892b8aea582048f 100644 (file)
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -126,7 +126,7 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
        if (!user_mode_vm(regs)) {
                unsigned long stack = kernel_stack_pointer(regs);
                if (depth)
-                       dump_trace(NULL, regs, (unsigned long *)stack,
+                       dump_trace(NULL, regs, (unsigned long *)stack, 0,
                                   &backtrace_ops, &depth);
                return;
        }