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 arnd@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)