From: Willy Tarreau <w@1wt.eu>
To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>,
linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org#3.9.x-,
Willy Tarreau <w@1wt.eu>
Subject: [PATCH 3.10 168/180] metag: Fix __cmpxchg_u32 asm constraint for CMP
Date: Sun, 21 Aug 2016 17:31:38 +0200 [thread overview]
Message-ID: <1471793510-13022-169-git-send-email-w@1wt.eu> (raw)
In-Reply-To: <1471793510-13022-1-git-send-email-w-K+wRfnb2/UA@public.gmane.org>
From: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
commit 6154c187b97ee7513046bb4eb317a89f738f13ef upstream.
The LNKGET based atomic sequence in __cmpxchg_u32 has slightly incorrect
constraints for the return value which under certain circumstances can
allow an address unit register to be used as the first operand of a CMP
instruction. This isn't a valid instruction however as the encodings
only allow a data unit to be specified. This would result in an
assembler error like the following:
Error: failed to assemble instruction: "CMP A0.2,D0Ar6"
Fix by changing the constraint from "=&da" (assigned, early clobbered,
data or address unit register) to "=&d" (data unit register only).
The constraint for the second operand, "bd" (an op2 register where op1
is a data unit register and the instruction supports O2R) is already
correct assuming the first operand is a data unit register.
Other cases of CMP in inline asm have had their constraints checked, and
appear to all be fine.
Fixes: 6006c0d8ce94 ("metag: Atomics, locks and bitops")
Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
Cc: linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> # 3.9.x-
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
arch/metag/include/asm/cmpxchg_lnkget.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/metag/include/asm/cmpxchg_lnkget.h b/arch/metag/include/asm/cmpxchg_lnkget.h
index 0154e28..2369ad3 100644
--- a/arch/metag/include/asm/cmpxchg_lnkget.h
+++ b/arch/metag/include/asm/cmpxchg_lnkget.h
@@ -73,7 +73,7 @@ static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old,
" DCACHE [%2], %0\n"
#endif
"2:\n"
- : "=&d" (temp), "=&da" (retval)
+ : "=&d" (temp), "=&d" (retval)
: "da" (m), "bd" (old), "da" (new)
: "cc"
);
--
2.8.0.rc2.1.gbe9624a
parent reply other threads:[~2016-08-21 15:31 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <1471793510-13022-1-git-send-email-w-K+wRfnb2/UA@public.gmane.org>]
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