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-rw-r--r--arch/arm64/kernel/stacktrace.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ad20981dfda4..2a1a7a281d34 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -32,6 +32,30 @@
* add sp, sp, #0x10
*/
+
+void start_backtrace(struct stackframe *frame, unsigned long fp,
+ unsigned long pc)
+{
+ frame->fp = fp;
+ frame->pc = pc;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ frame->graph = 0;
+#endif
+
+ /*
+ * Prime the first unwind.
+ *
+ * In unwind_frame() we'll check that the FP points to a valid stack,
+ * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
+ * treated as a transition to whichever stack that happens to be. The
+ * prev_fp value won't be used, but we set it to 0 such that it is
+ * definitely not an accessible stack address.
+ */
+ bitmap_zero(frame->stacks_done, __NR_STACK_TYPES);
+ frame->prev_fp = 0;
+ frame->prev_type = STACK_TYPE_UNKNOWN;
+}
+
/*
* Unwind from one frame record (A) to the next frame record (B).
*