Hey Meelis,
On Mon, 27 Aug 2018, Meelis Roos wrote:
> While trying to compile v4.18-13105-gaba16dc5cf93 with gcc 5.3.1 on a
> 32-bit x86 configured for AMD K6
> CC mm/slub.o
> In file included from ./arch/x86/include/asm/atomic.h:8:0,
> from ./include/linux/atomic.h:7,
> from ./arch/x86/include/asm/thread_info.h:54,
> from ./include/linux/thread_info.h:38,
> from ./arch/x86/include/asm/preempt.h:7,
> from ./include/linux/preempt.h:81,
> from ./include/linux/spinlock.h:51,
> from ./include/linux/mmzone.h:8,
> from ./include/linux/gfp.h:6,
> from ./include/linux/mm.h:10,
> from mm/slub.c:13:
> mm/slub.c: In function ‘__slab_free’:
> ./arch/x86/include/asm/cmpxchg.h:245:2: error: ‘asm’ operand has
impossible constraints
> asm volatile(pfx "cmpxchg%c4b %2; sete %0" \
Could you give the attched patch a try? I've been hit by this issue
via kbuild robot complaining about one of my patches which didn't
touch the asm stuff above.
I suspect the "=a" contraint of the outputs and "a" of the inputs
are the culprit. You could save me from having to search through
all the debian repos for a gcc showing that issue...
Juergen
>From 252450d28ffc8fbfd5b332d0b97990ae12a207d9 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgr...@suse.com>
Date: Wed, 5 Sep 2018 11:32:26 +0200
Subject: [PATCH] x86: correct inline asm constraints in __cmpxchg_double()
Specifying "=a" for output constraints and "a" for input seems to be
wrong. Instead "0" should be used for the input constraint.
Fixes: cdcd629869fab ("x86: Fix and improve cmpxchg_double{,_local}()")
Cc: sta...@vger.kernel.org
Signed-off-by: Juergen Gross <jgr...@suse.com>
---
arch/x86/include/asm/cmpxchg.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index a55d79b233d3..b3b4d61a8969 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -245,7 +245,7 @@ extern void __add_wrong_size(void)
asm volatile(pfx "cmpxchg%c4b %2; sete %0" \
: "=a" (__ret), "+d" (__old2), \
"+m" (*(p1)), "+m" (*(p2)) \
- : "i" (2 * sizeof(long)), "a" (__old1), \
+ : "i" (2 * sizeof(long)), "0" (__old1), \
"b" (__new1), "c" (__new2)); \
__ret; \
})
--
2.16.4
