Subject: [PATCH] ARM: allow unwinder to unwind recursive functions

From: Russell King <[email-masked]>
Date: Mon, 10 Feb 2020 10:15:29 +0000

Allow the unwinder to unwind recursive functions if the stack makes
progress, even if the PC is the same. This allows tracing through
recursive __switchdev_handle_port_attr_set() and similar.

Signed-off-by: Russell King <[email-masked]>
---
 arch/arm/kernel/unwind.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 4574e6aea0a5..11a964fd66f4 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -444,7 +444,7 @@ int unwind_frame(struct stackframe *frame)
 		ctrl.vrs[PC] = ctrl.vrs[LR];
 
 	/* check for infinite loop */
-	if (frame->pc == ctrl.vrs[PC])
+	if (frame->pc == ctrl.vrs[PC] && frame->sp == ctrl.vrs[SP])
 		return -URC_FAILURE;
 
 	frame->fp = ctrl.vrs[FP];
-- 
2.20.1

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