11 files changed, 77 insertions, 18 deletions

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 90e0c35ae60d..fc650f64df43 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -92,4 +92,5 @@ void save_stack_trace(struct stack_trace *trace)
 {
         save_stack_trace_tsk(current, trace);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 #endif
diff --git a/arch/avr32/kernel/stacktrace.c b/arch/avr32/kernel/stacktrace.c
index 9a68190bbffd..f4bdb448049c 100644
--- a/arch/avr32/kernel/stacktrace.c
+++ b/arch/avr32/kernel/stacktrace.c
@@ -51,3 +51,4 @@ void save_stack_trace(struct stack_trace *trace)
                 fp = frame->fp;
         }
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c
index ebd9db8d1ece..5eb4681a73d2 100644
--- a/arch/mips/kernel/stacktrace.c
+++ b/arch/mips/kernel/stacktrace.c
@@ -73,3 +73,4 @@ void save_stack_trace(struct stack_trace *trace)
         prepare_frametrace(regs);
         save_context_stack(trace, regs);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index 962944038430..3cf0d94ba340 100644
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -12,6 +12,7 @@
 
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
+#include <linux/module.h>
 #include <asm/ptrace.h>
 
 /*
@@ -44,3 +45,4 @@ void save_stack_trace(struct stack_trace *trace)
                 sp = newsp;
         }
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 85e46a5d0e08..57571f10270c 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -81,6 +81,7 @@ void save_stack_trace(struct stack_trace *trace)
                            S390_lowcore.thread_info,
                            S390_lowcore.thread_info + THREAD_SIZE, 1);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
@@ -93,3 +94,4 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
         if (trace->nr_entries < trace->max_entries)
                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
diff --git a/arch/sh/kernel/stacktrace.c b/arch/sh/kernel/stacktrace.c
index d41e561be20e..1b2ae35c4a76 100644
--- a/arch/sh/kernel/stacktrace.c
+++ b/arch/sh/kernel/stacktrace.c
@@ -34,3 +34,4 @@ void save_stack_trace(struct stack_trace *trace)
                 }
         }
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
diff --git a/arch/sparc64/kernel/stacktrace.c b/arch/sparc64/kernel/stacktrace.c
index c73ce3f4197e..b3e3737750d8 100644
--- a/arch/sparc64/kernel/stacktrace.c
+++ b/arch/sparc64/kernel/stacktrace.c
@@ -1,6 +1,7 @@
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
 #include <linux/thread_info.h>
+#include <linux/module.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
@@ -47,3 +48,4 @@ void save_stack_trace(struct stack_trace *trace)
                         trace->entries[trace->nr_entries++] = pc;
         } while (trace->nr_entries < trace->max_entries);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index c28c342c162f..a03e7f6d90c3 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -74,6 +74,7 @@ void save_stack_trace(struct stack_trace *trace)
         if (trace->nr_entries < trace->max_entries)
                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
@@ -81,3 +82,4 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
         if (trace->nr_entries < trace->max_entries)
                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
diff --git a/kernel/backtracetest.c b/kernel/backtracetest.c
index d1a7605c5b8f..a5e026bc45c4 100644
--- a/kernel/backtracetest.c
+++ b/kernel/backtracetest.c
@@ -10,30 +10,73 @@
  * of the License.
  */
 
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/sched.h>
-#include <linux/delay.h>
+#include <linux/stacktrace.h>
+
+static void backtrace_test_normal(void)
+{
+        printk("Testing a backtrace from process context.\n");
+        printk("The following trace is a kernel self test and not a bug!\n");
 
-static struct timer_list backtrace_timer;
+        dump_stack();
+}
 
-static void backtrace_test_timer(unsigned long data)
+static DECLARE_COMPLETION(backtrace_work);
+
+static void backtrace_test_irq_callback(unsigned long data)
+{
+        dump_stack();
+        complete(&backtrace_work);
+}
+
+static DECLARE_TASKLET(backtrace_tasklet, &backtrace_test_irq_callback, 0);
+
+static void backtrace_test_irq(void)
 {
         printk("Testing a backtrace from irq context.\n");
         printk("The following trace is a kernel self test and not a bug!\n");
-        dump_stack();
+
+        init_completion(&backtrace_work);
+        tasklet_schedule(&backtrace_tasklet);
+        wait_for_completion(&backtrace_work);
+}
+
+#ifdef CONFIG_STACKTRACE
+static void backtrace_test_saved(void)
+{
+        struct stack_trace trace;
+        unsigned long entries[8];
+
+        printk("Testing a saved backtrace.\n");
+        printk("The following trace is a kernel self test and not a bug!\n");
+
+        trace.nr_entries = 0;
+        trace.max_entries = ARRAY_SIZE(entries);
+        trace.entries = entries;
+        trace.skip = 0;
+
+        save_stack_trace(&trace);
+        print_stack_trace(&trace, 0);
+}
+#else
+static void backtrace_test_saved(void)
+{
+        printk("Saved backtrace test skipped.\n");
 }
+#endif
+
 static int backtrace_regression_test(void)
 {
         printk("====[ backtrace testing ]===========\n");
-        printk("Testing a backtrace from process context.\n");
-        printk("The following trace is a kernel self test and not a bug!\n");
-        dump_stack();
 
-        init_timer(&backtrace_timer);
-        backtrace_timer.function = backtrace_test_timer;
-        mod_timer(&backtrace_timer, jiffies + 10);
+        backtrace_test_normal();
+        backtrace_test_irq();
+        backtrace_test_saved();
 
-        msleep(10);
         printk("====[ end of backtrace testing ]====\n");
         return 0;
 }
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index b71816e47a30..94b527ef1d1e 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -6,19 +6,21 @@
  *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  */
 #include <linux/sched.h>
+#include <linux/module.h>
 #include <linux/kallsyms.h>
 #include <linux/stacktrace.h>
 
 void print_stack_trace(struct stack_trace *trace, int spaces)
 {
-        int i, j;
+        int i;
 
-        for (i = 0; i < trace->nr_entries; i++) {
-                unsigned long ip = trace->entries[i];
+        if (WARN_ON(!trace->entries))
+                return;
 
-                for (j = 0; j < spaces + 1; j++)
-                        printk(" ");
-                print_ip_sym(ip);
+        for (i = 0; i < trace->nr_entries; i++) {
+                printk("%*c", 1 + spaces, ' ');
+                print_ip_sym(trace->entries[i]);
         }
 }
+EXPORT_SYMBOL_GPL(print_stack_trace);
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d8b6279a9b42..c459e8547bd8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -419,7 +419,6 @@ config DEBUG_LOCKING_API_SELFTESTS
 
 config STACKTRACE
         bool
-        depends on DEBUG_KERNEL
         depends on STACKTRACE_SUPPORT
 
 config DEBUG_KOBJECT
@@ -563,6 +562,9 @@ config BACKTRACE_SELF_TEST
           for distributions or general kernels, but only for kernel
           developers working on architecture code.
 
+          Note that if you want to also test saved backtraces, you will
+          have to enable STACKTRACE as well.
+
           Say N if you are unsure.
 
 config LKDTM