arm64: stacktrace: Move start_backtrace() out of the header

Currently start_backtrace() is a static inline function in the header.
Since it really shouldn't be sufficiently performance critical that we
actually need to have it inlined move it into a C file, this will save
anyone else scratching their head about why it is defined in the header.
As far as I can see it's only there because it was factored out of the
various callers.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210319174022.33051-1-broonie@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/stacktrace.h

@@ -148,27 +148,7 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
 	return false;
 }
 
-static inline 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;
-}
+void start_backtrace(struct stackframe *frame, unsigned long fp,
+		     unsigned long pc);
 
 #endif	/* __ASM_STACKTRACE_H */

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).
  *