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* [PATCH] m68k: Fix asm register constraints for atomic ops
@ 2021-07-25 10:46 Geert Uytterhoeven
  2021-07-25 14:24 ` Andreas Schwab
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Geert Uytterhoeven @ 2021-07-25 10:46 UTC (permalink / raw)
  To: Greg Ungerer, Will Deacon, Peter Zijlstra, Boqun Feng
  Cc: Brendan Jackman, kernel test robot, Arnd Bergmann,
	Alexander Viro, linux-m68k, linux-kernel, Geert Uytterhoeven

Depending on register assignment by the compiler:

    {standard input}:3084: Error: operands mismatch -- statement `andl %a1,%d1' ignored
    {standard input}:3145: Error: operands mismatch -- statement `orl %a1,%d1' ignored
    {standard input}:3195: Error: operands mismatch -- statement `eorl %a1,%d1' ignored

Indeed, the first operand must not be an address register.  Fix this by
adjusting the register constraint from "g" (general purpose register) to
"d" (data register).

Fixes: e39d88ea3ce4a471 ("locking/atomic, arch/m68k: Implement atomic_fetch_{add,sub,and,or,xor}()")
Fixes: d839bae4269aea46 ("locking,arch,m68k: Fold atomic_ops")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
Personally, I have never seen this failure in an 68020+ build, but I can
reproduce it on Coldfire with the config provided by lkp (with bogus
CONFIG_RMW_INSNS=y).

Technically, the issue was present before, but I doubt adding pre-v3.18
Fixes tags would make any difference for stable...
---
 arch/m68k/include/asm/atomic.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/include/asm/atomic.h b/arch/m68k/include/asm/atomic.h
index 8637bf8a2f652009..2d5a6e556754290b 100644
--- a/arch/m68k/include/asm/atomic.h
+++ b/arch/m68k/include/asm/atomic.h
@@ -48,7 +48,7 @@ static inline int arch_atomic_##op##_return(int i, atomic_t *v)		\
 			"	casl %2,%1,%0\n"			\
 			"	jne 1b"					\
 			: "+m" (*v), "=&d" (t), "=&d" (tmp)		\
-			: "g" (i), "2" (arch_atomic_read(v)));		\
+			: "d" (i), "2" (arch_atomic_read(v)));		\
 	return t;							\
 }
 
@@ -63,7 +63,7 @@ static inline int arch_atomic_fetch_##op(int i, atomic_t *v)		\
 			"	casl %2,%1,%0\n"			\
 			"	jne 1b"					\
 			: "+m" (*v), "=&d" (t), "=&d" (tmp)		\
-			: "g" (i), "2" (arch_atomic_read(v)));		\
+			: "d" (i), "2" (arch_atomic_read(v)));		\
 	return tmp;							\
 }
 
-- 
2.25.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-07-26  7:40 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-25 10:46 [PATCH] m68k: Fix asm register constraints for atomic ops Geert Uytterhoeven
2021-07-25 14:24 ` Andreas Schwab
2021-07-26  7:29   ` Geert Uytterhoeven
2021-07-25 15:26 ` Arnd Bergmann
2021-07-25 23:44 ` Finn Thain
2021-07-26  7:34   ` Geert Uytterhoeven
2021-07-26  7:39     ` Arnd Bergmann

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