[PATCH 1/2] lib/mpi: avoid assembler warning

From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	[PATCH 1/2] lib/mpi: avoid assembler warning
Date	2016-02-26 13:50 +0100
Message-ID	<r6q0i-3i6-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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A wrapper around the umull assembly instruction might reuse
the input register as an output, which is undefined on
some ARM machines, as pointed out by this assembler warning:

  CC      lib/mpi/generic_mpih-mul1.o
/tmp/ccxJuxIy.s: Assembler messages:
/tmp/ccxJuxIy.s:53: rdhi, rdlo and rm must all be different
  CC      lib/mpi/generic_mpih-mul2.o
/tmp/ccI0scAD.s: Assembler messages:
/tmp/ccI0scAD.s:53: rdhi, rdlo and rm must all be different
  CC      lib/mpi/generic_mpih-mul3.o
/tmp/ccMvVQcp.s: Assembler messages:
/tmp/ccMvVQcp.s:53: rdhi, rdlo and rm must all be different

This changes the constraints to force different registers to
be used as output.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 lib/mpi/longlong.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/mpi/longlong.h b/lib/mpi/longlong.h
index b90e255c2a68..93336502af08 100644
--- a/lib/mpi/longlong.h
+++ b/lib/mpi/longlong.h
@@ -216,7 +216,7 @@ extern UDItype __udiv_qrnnd(UDItype *, UDItype, UDItype, UDItype);
 	__asm__ ("%@ Inlined umul_ppmm\n" \
 		"umull %r1, %r0, %r2, %r3" \
 	: "=&r" ((USItype)(xh)), \
-			"=r" ((USItype)(xl)) \
+			"=&r" ((USItype)(xl)) \
 	: "r" ((USItype)(a)), \
 			"r" ((USItype)(b)) \
 	: "r0", "r1")
-- 
2.7.0

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[PATCH 1/2] lib/mpi: avoid assembler warning Arnd Bergmann <arnd@arndb.de> - 2016-02-26 13:50 +0100
  [PATCH 2/2] lib/mpi: use "static inline" instead of "extern inline" Arnd Bergmann <arnd@arndb.de> - 2016-02-26 13:50 +0100
  Re: [PATCH 1/2] lib/mpi: avoid assembler warning Herbert Xu <herbert@gondor.apana.org.au> - 2016-02-27 20:40 +0100

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