linux-kernel - [PATCH 05/13] csky: Fixup kprobes handler couldn't change pc

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Message-Id: <1596244453-98575-6-git-send-email-guoren@kernel.org>
Date:   Sat,  1 Aug 2020 01:14:05 +0000
From:   guoren@...nel.org
To:     guoren@...nel.org, arnd@...db.de
Cc:     linux-kernel@...r.kernel.org, linux-csky@...r.kernel.org,
        linux-arch@...r.kernel.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH 05/13] csky: Fixup kprobes handler couldn't change pc

From: Guo Ren <guoren@...ux.alibaba.com>

The "Changing Execution Path" section in the Documentation/kprobes.txt
said:

Since kprobes can probe into a running kernel code, it can change the
register set, including instruction pointer.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Cc: Arnd Bergmann <arnd@...db.de>
---
 arch/csky/abiv2/mcount.S | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/csky/abiv2/mcount.S b/arch/csky/abiv2/mcount.S
index 911512b..d745e10 100644
--- a/arch/csky/abiv2/mcount.S
+++ b/arch/csky/abiv2/mcount.S
@@ -55,7 +55,9 @@
 
 .macro mcount_exit_regs
 	RESTORE_REGS_FTRACE
-	ldw	t1, (sp, 0)
+	subi	sp, 152
+	ldw	t1, (sp, 4)
+	addi	sp, 152
 	ldw	r8, (sp, 4)
 	ldw	lr, (sp, 8)
 	addi	sp, 12
-- 
2.7.4