1 files changed, 55 insertions, 5 deletions

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index af4e8c8a5422..f065eb05d254 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -3,6 +3,7 @@
 #include <linux/stacktrace.h>
 
 #include <asm/stacktrace.h>
+#include <asm/traps.h>
 
 #if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
 /*
@@ -61,6 +62,7 @@ EXPORT_SYMBOL(walk_stackframe);
 #ifdef CONFIG_STACKTRACE
 struct stack_trace_data {
         struct stack_trace *trace;
+        unsigned long last_pc;
         unsigned int no_sched_functions;
         unsigned int skip;
 };
@@ -69,6 +71,7 @@ static int save_trace(struct stackframe *frame, void *d)
 {
         struct stack_trace_data *data = d;
         struct stack_trace *trace = data->trace;
+        struct pt_regs *regs;
         unsigned long addr = frame->pc;
 
         if (data->no_sched_functions && in_sched_functions(addr))
@@ -80,16 +83,39 @@ static int save_trace(struct stackframe *frame, void *d)
 
         trace->entries[trace->nr_entries++] = addr;
 
+        if (trace->nr_entries >= trace->max_entries)
+                return 1;
+
+        /*
+         * in_exception_text() is designed to test if the PC is one of
+         * the functions which has an exception stack above it, but
+         * unfortunately what is in frame->pc is the return LR value,
+         * not the saved PC value.  So, we need to track the previous
+         * frame PC value when doing this.
+         */
+        addr = data->last_pc;
+        data->last_pc = frame->pc;
+        if (!in_exception_text(addr))
+                return 0;
+
+        regs = (struct pt_regs *)frame->sp;
+
+        trace->entries[trace->nr_entries++] = regs->ARM_pc;
+
         return trace->nr_entries >= trace->max_entries;
 }
 
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+/* This must be noinline to so that our skip calculation works correctly */
+static noinline void __save_stack_trace(struct task_struct *tsk,
+        struct stack_trace *trace, unsigned int nosched)
 {
         struct stack_trace_data data;
         struct stackframe frame;
 
         data.trace = trace;
+        data.last_pc = ULONG_MAX;
         data.skip = trace->skip;
+        data.no_sched_functions = nosched;
 
         if (tsk != current) {
 #ifdef CONFIG_SMP
@@ -102,7 +128,6 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
                         trace->entries[trace->nr_entries++] = ULONG_MAX;
                 return;
 #else
-                data.no_sched_functions = 1;
                 frame.fp = thread_saved_fp(tsk);
                 frame.sp = thread_saved_sp(tsk);
                 frame.lr = 0;           /* recovered from the stack */
@@ -111,11 +136,12 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
         } else {
                 register unsigned long current_sp asm ("sp");
 
-                data.no_sched_functions = 0;
+                /* We don't want this function nor the caller */
+                data.skip += 2;
                 frame.fp = (unsigned long)__builtin_frame_address(0);
                 frame.sp = current_sp;
                 frame.lr = (unsigned long)__builtin_return_address(0);
-                frame.pc = (unsigned long)save_stack_trace_tsk;
+                frame.pc = (unsigned long)__save_stack_trace;
         }
 
         walk_stackframe(&frame, save_trace, &data);
@@ -123,9 +149,33 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 
+void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+        struct stack_trace_data data;
+        struct stackframe frame;
+
+        data.trace = trace;
+        data.skip = trace->skip;
+        data.no_sched_functions = 0;
+
+        frame.fp = regs->ARM_fp;
+        frame.sp = regs->ARM_sp;
+        frame.lr = regs->ARM_lr;
+        frame.pc = regs->ARM_pc;
+
+        walk_stackframe(&frame, save_trace, &data);
+        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)
+{
+        __save_stack_trace(tsk, trace, 1);
+}
+
 void save_stack_trace(struct stack_trace *trace)
 {
-        save_stack_trace_tsk(current, trace);
+        __save_stack_trace(current, trace, 0);
 }
 EXPORT_SYMBOL_GPL(save_stack_trace);
 #endif