On Monday 16 November 2015 19:05:05 Olof's autobuilder wrote:
>
> Errors:
>
> arm64.allmodconfig:
> arch/arm64/include/asm/barrier.h:71:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:75:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:79:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:83:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:71:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:75:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:79:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:83:3: error: read-only variable '___p1' used
> as 'asm' output
> arch/arm64/include/asm/barrier.h:71:3: error: read-only variable '___p1' used
> as 'asm' output
The patch below seems to fix it. Please review/apply.
8<----
Subject: ARM64: make smp_load_acquire() work with const arguments
smp_load_acquire() uses typeof() to declare a local variable for temporarily
storing the output of the memory access. This fails when the argument is
constant, because the assembler complains about using a constant register
as output:
arch/arm64/include/asm/barrier.h:71:3: error: read-only variable '___p1' used
as 'asm' output
This changes the implementation to use an 'unsigned long' for the temporary
value
and only cast it to the original type in the end.
Signed-off-by: Arnd Bergmann <a...@arndb.de>
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 624f9679f4b0..05fa329467f6 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -64,7 +64,7 @@ do {
\
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1; \
+ unsigned long ___p1; \
compiletime_assert_atomic_type(*p); \
switch (sizeof(*p)) { \
case 1: \
@@ -84,7 +84,7 @@ do {
\
: "=r" (___p1) : "Q" (*p) : "memory"); \
break; \
} \
- ___p1; \
+ (typeof(*p))___p1;
\
})
#define read_barrier_depends() do { } while(0)
--
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