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[L,1/1] s390/uaccess: add missing earlyclobber annotations to __clear_user()

Message ID 20230328175820.76363-2-frank.heimes@canonical.com
State New
Headers show
Series kernel: fix __clear_user() inline assembly constraints (LP: 2013088) | expand

Commit Message

Frank Heimes March 28, 2023, 5:58 p.m. UTC 
From: Heiko Carstens <hca@linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/2013088

Add missing earlyclobber annotation to size, to, and tmp2 operands of the
__clear_user() inline assembly since they are modified or written to before
the last usage of all input operands. This can lead to incorrect register
allocation for the inline assembly.

Fixes: 6c2a9e6df604 ("[S390] Use alternative user-copy operations for new hardware.")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/all/20230321122514.1743889-3-mark.rutland@arm.com/
Cc: stable@vger.kernel.org
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
(cherry picked from commit 89aba4c26fae4e459f755a18912845c348ee48f3 linux-next)
Signed-off-by: Frank Heimes <frank.heimes@canonical.com>
---
 arch/s390/lib/uaccess.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
index 720036fb1924..d44214072779 100644
--- a/arch/s390/lib/uaccess.c
+++ b/arch/s390/lib/uaccess.c
@@ -172,7 +172,7 @@  unsigned long __clear_user(void __user *to, unsigned long size)
 		"4: slgr  %0,%0\n"
 		"5:\n"
 		EX_TABLE(0b,2b) EX_TABLE(6b,2b) EX_TABLE(3b,5b) EX_TABLE(7b,5b)
-		: "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)
+		: "+&a" (size), "+&a" (to), "+a" (tmp1), "=&a" (tmp2)
 		: "a" (empty_zero_page), [spec] "d" (spec.val)
 		: "cc", "memory", "0");
 	return size;