1 files changed, 23 insertions, 55 deletions

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 09d37d66b630..76809ccd309c 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -42,33 +42,17 @@
  */
 int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 {
-	unsigned long high, low;
 	unsigned long fp = frame->fp;
-	unsigned long irq_stack_ptr;
+
+	if (fp & 0xf)
+		return -EINVAL;
 
 	if (!tsk)
 		tsk = current;
 
-	/*
-	 * Switching between stacks is valid when tracing current and in
-	 * non-preemptible context.
-	 */
-	if (tsk == current && !preemptible())
-		irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
-	else
-		irq_stack_ptr = 0;
-
-	low  = frame->sp;
-	/* irq stacks are not THREAD_SIZE aligned */
-	if (on_irq_stack(frame->sp, raw_smp_processor_id()))
-		high = irq_stack_ptr;
-	else
-		high = ALIGN(low, THREAD_SIZE) - 0x20;
-
-	if (fp < low || fp > high || fp & 0xf)
+	if (!on_accessible_stack(tsk, fp))
 		return -EINVAL;
 
-	frame->sp = fp + 0x10;
 	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
 	frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
 
@@ -86,34 +70,13 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
 	/*
-	 * Check whether we are going to walk through from interrupt stack
-	 * to task stack.
-	 * If we reach the end of the stack - and its an interrupt stack,
-	 * unpack the dummy frame to find the original elr.
-	 *
-	 * Check the frame->fp we read from the bottom of the irq_stack,
-	 * and the original task stack pointer are both in current->stack.
+	 * Frames created upon entry from EL0 have NULL FP and PC values, so
+	 * don't bother reporting these. Frames created by __noreturn functions
+	 * might have a valid FP even if PC is bogus, so only terminate where
+	 * both are NULL.
 	 */
-	if (frame->sp == irq_stack_ptr) {
-		struct pt_regs *irq_args;
-		unsigned long orig_sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
-
-		if (object_is_on_stack((void *)orig_sp) &&
-		   object_is_on_stack((void *)frame->fp)) {
-			frame->sp = orig_sp;
-
-			/* orig_sp is the saved pt_regs, find the elr */
-			irq_args = (struct pt_regs *)orig_sp;
-			frame->pc = irq_args->pc;
-		} else {
-			/*
-			 * This frame has a non-standard format, and we
-			 * didn't fix it, because the data looked wrong.
-			 * Refuse to output this frame.
-			 */
-			return -EINVAL;
-		}
-	}
+	if (!frame->fp && !frame->pc)
+		return -EINVAL;
 
 	return 0;
 }
@@ -167,7 +130,6 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 	data.no_sched_functions = 0;
 
 	frame.fp = regs->regs[29];
-	frame.sp = regs->sp;
 	frame.pc = regs->pc;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	frame.graph = current->curr_ret_stack;
@@ -178,7 +140,8 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+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;
@@ -188,17 +151,16 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 
 	data.trace = trace;
 	data.skip = trace->skip;
+	data.no_sched_functions = nosched;
 
 	if (tsk != current) {
-		data.no_sched_functions = 1;
 		frame.fp = thread_saved_fp(tsk);
-		frame.sp = thread_saved_sp(tsk);
 		frame.pc = thread_saved_pc(tsk);
 	} else {
-		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_stack_pointer;
-		frame.pc = (unsigned long)save_stack_trace_tsk;
+		frame.pc = (unsigned long)__save_stack_trace;
 	}
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	frame.graph = tsk->curr_ret_stack;
@@ -212,9 +174,15 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 }
 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 
+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