1 files changed, 140 insertions, 28 deletions

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index ae31deb2d06..f065eb05d25 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -1,41 +1,69 @@
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
 
-#include "stacktrace.h"
+#include <asm/stacktrace.h>
+#include <asm/traps.h>
 
-int walk_stackframe(unsigned long fp, unsigned long low, unsigned long high,
-		    int (*fn)(struct stackframe *, void *), void *data)
+#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
+/*
+ * Unwind the current stack frame and store the new register values in the
+ * structure passed as argument. Unwinding is equivalent to a function return,
+ * hence the new PC value rather than LR should be used for backtrace.
+ *
+ * With framepointer enabled, a simple function prologue looks like this:
+ *	mov	ip, sp
+ *	stmdb	sp!, {fp, ip, lr, pc}
+ *	sub	fp, ip, #4
+ *
+ * A simple function epilogue looks like this:
+ *	ldm	sp, {fp, sp, pc}
+ *
+ * Note that with framepointer enabled, even the leaf functions have the same
+ * prologue and epilogue, therefore we can ignore the LR value in this case.
+ */
+int notrace unwind_frame(struct stackframe *frame)
 {
-	struct stackframe *frame;
+	unsigned long high, low;
+	unsigned long fp = frame->fp;
 
-	do {
-		/*
-		 * Check current frame pointer is within bounds
-		 */
-		if (fp < (low + 12) || fp + 4 >= high)
-			break;
+	/* only go to a higher address on the stack */
+	low = frame->sp;
+	high = ALIGN(low, THREAD_SIZE);
 
-		frame = (struct stackframe *)(fp - 12);
-
-		if (fn(frame, data))
-			break;
+	/* check current frame pointer is within bounds */
+	if (fp < low + 12 || fp > high - 4)
+		return -EINVAL;
 
-		/*
-		 * Update the low bound - the next frame must always
-		 * be at a higher address than the current frame.
-		 */
-		low = fp + 4;
-		fp = frame->fp;
-	} while (fp);
+	/* restore the registers from the stack frame */
+	frame->fp = *(unsigned long *)(fp - 12);
+	frame->sp = *(unsigned long *)(fp - 8);
+	frame->pc = *(unsigned long *)(fp - 4);
 
 	return 0;
 }
+#endif
+
+void notrace walk_stackframe(struct stackframe *frame,
+		     int (*fn)(struct stackframe *, void *), void *data)
+{
+	while (1) {
+		int ret;
+
+		if (fn(frame, data))
+			break;
+		ret = unwind_frame(frame);
+		if (ret < 0)
+			break;
+	}
+}
 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;
 };
 
@@ -43,27 +71,111 @@ 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))
+		return 0;
 	if (data->skip) {
 		data->skip--;
 		return 0;
 	}
 
-	trace->entries[trace->nr_entries++] = frame->lr;
+	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(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;
-	unsigned long fp, base;
+	struct stackframe frame;
 
 	data.trace = trace;
+	data.last_pc = ULONG_MAX;
 	data.skip = trace->skip;
-	base = (unsigned long)task_stack_page(current);
-	asm("mov %0, fp" : "=r" (fp));
+	data.no_sched_functions = nosched;
+
+	if (tsk != current) {
+#ifdef CONFIG_SMP
+		/*
+		 * What guarantees do we have here that 'tsk' is not
+		 * running on another CPU?  For now, ignore it as we
+		 * can't guarantee we won't explode.
+		 */
+		if (trace->nr_entries < trace->max_entries)
+			trace->entries[trace->nr_entries++] = ULONG_MAX;
+		return;
+#else
+		frame.fp = thread_saved_fp(tsk);
+		frame.sp = thread_saved_sp(tsk);
+		frame.lr = 0;		/* recovered from the stack */
+		frame.pc = thread_saved_pc(tsk);
+#endif
+	} else {
+		register unsigned long current_sp asm ("sp");
+
+		/* 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;
+	}
+
+	walk_stackframe(&frame, save_trace, &data);
+	if (trace->nr_entries < trace->max_entries)
+		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;
 
-	walk_stackframe(fp, base, base + THREAD_SIZE, save_trace, &data);
+	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(current, trace, 0);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 #endif