linux-kernel - [PATCH 3.16 067/157] xtensa: fix return

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Message-ID: <lsq.1565469607.887281316@decadent.org.uk>
Date:   Sat, 10 Aug 2019 21:40:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Max Filippov" <jcmvbkbc@...il.com>
Subject: [PATCH 3.16 067/157] xtensa: fix return_address

3.16.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Max Filippov <jcmvbkbc@...il.com>

commit ada770b1e74a77fff2d5f539bf6c42c25f4784db upstream.

return_address returns the address that is one level higher in the call
stack than requested in its argument, because level 0 corresponds to its
caller's return address. Use requested level as the number of stack
frames to skip.

This fixes the address reported by might_sleep and friends.

Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/xtensa/kernel/stacktrace.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/arch/xtensa/kernel/stacktrace.c
+++ b/arch/xtensa/kernel/stacktrace.c
@@ -107,10 +107,14 @@ static int return_address_cb(struct stac
 	return 1;
 }
 
+/*
+ * level == 0 is for the return address from the caller of this function,
+ * not from this function itself.
+ */
 unsigned long return_address(unsigned level)
 {
 	struct return_addr_data r = {
-		.skip = level + 1,
+		.skip = level,
 	};
 	walk_stackframe(stack_pointer(NULL), return_address_cb, &r);
 	return r.addr;