diff options
| -rw-r--r-- | arch/arm64/include/asm/rwonce.h | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/rwonce.h b/arch/arm64/include/asm/rwonce.h index fc0fb42b0b64..9fd24cef3376 100644 --- a/arch/arm64/include/asm/rwonce.h +++ b/arch/arm64/include/asm/rwonce.h @@ -20,6 +20,17 @@ ARM64_HAS_LDAPR) /* + * Replace this with typeof_unqual() when minimum compiler versions are + * increased to GCC 14 and Clang 19. For the time being, we need this + * workaround, which relies on function return values dropping qualifiers. + */ +#define __rwonce_typeof_unqual(x) typeof(({ \ + __diag_push() \ + __diag_ignore_all("-Wignored-qualifiers", "") \ + ((typeof(x)(*)(void))0)(); \ + __diag_pop() })) + +/* * When building with LTO, there is an increased risk of the compiler * converting an address dependency headed by a READ_ONCE() invocation * into a control dependency and consequently allowing for harmful @@ -32,8 +43,7 @@ #define __READ_ONCE(x) \ ({ \ typeof(&(x)) __x = &(x); \ - int atomic = 1; \ - union { __unqual_scalar_typeof(*__x) __val; char __c[1]; } __u; \ + union { __rwonce_typeof_unqual(*__x) __val; char __c[1]; } __u; \ switch (sizeof(x)) { \ case 1: \ asm volatile(__LOAD_RCPC(b, %w0, %1) \ @@ -56,9 +66,9 @@ : "Q" (*__x) : "memory"); \ break; \ default: \ - atomic = 0; \ + __u.__val = *(volatile typeof(*__x) *)__x; \ } \ - atomic ? (typeof(*__x))__u.__val : (*(volatile typeof(*__x) *)__x);\ + __u.__val; \ }) #endif /* !BUILD_VDSO */ |