Re: READ_ONCE() + STACKPROTECTOR_STRONG == :/ (was Re: [GIT PULL] Please pull powerpc/linux.git powerpc-5.5-2 tag (topic/kasan-bitops))
From: Luc Van Oostenryck <hidden>
Date: 2019-12-13 20:37:48
Also in:
linux-arch, lkml
On Fri, Dec 13, 2019 at 01:56:18PM +0100, Peter Zijlstra wrote:
Excellent! I had to change it to something like:
#define unqual_typeof(x) typeof(({_Atomic typeof(x) ___x __maybe_unused; ___x; }))
but that does indeed work!
Now I suppose we should wrap that in a symbol that indicates our
compiler does indeed support _Atomic, otherwise things will come apart.
That is, my gcc-4.6 doesn't seem to have it, while gcc-4.8 does, which
is exactly the range that needs the daft READ_ONCE() construct, how
convenient :/
Something a little like this perhaps?Yes, this looks good to me. Just a small nit here below.
quoted hunk ↗ jump to hunk
---diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 7d9cc5ec4971..c389af602da8 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h@@ -75,9 +75,9 @@ static inline unsigned long array_index_mask_nospec(unsigned long idx, #define __smp_store_release(p, v) \ do { \ - typeof(p) __p = (p); \ - union { typeof(*p) __val; char __c[1]; } __u = \ - { .__val = (__force typeof(*p)) (v) }; \ + unqual_typeof(p) __p = (p); \ + union { unqual_typeof(*p) __val; char __c[1]; } __u = \ + { .__val = (__force unqual_typeof(*p)) (v) }; \
The 2 two trailing backslashes are now off by one tab. -- Luc