From: Jiri Slaby <jslaby@suse.cz>
To: stable@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>,
linux-metag@vger.kernel.org, Jiri Slaby <jslaby@suse.cz>
Subject: [patch added to 3.12-stable] metag: Fix __cmpxchg_u32 asm constraint for CMP
Date: Fri, 19 Aug 2016 08:52:58 +0200 [thread overview]
Message-ID: <20160819065308.14409-3-jslaby@suse.cz> (raw)
In-Reply-To: <20160819065308.14409-1-jslaby@suse.cz>
From: James Hogan <james.hogan@imgtec.com>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
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@imgtec.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
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 0154e2807ebb..2369ad394876 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"
);
--
2.9.3
parent reply other threads:[~2016-08-19 6:52 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20160819065308.14409-1-jslaby@suse.cz>]
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