diff options
| -rw-r--r-- | arch/arm64/Makefile | 6 | ||||
| -rw-r--r-- | arch/arm64/include/asm/simd.h | 19 |
2 files changed, 11 insertions, 14 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 7976d2d242fa..e7101b19d590 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -60,13 +60,15 @@ ifeq ($(CONFIG_CPU_BIG_ENDIAN), y) KBUILD_CPPFLAGS += -mbig-endian CHECKFLAGS += -D__AARCH64EB__ AS += -EB -LDFLAGS += -EB -maarch64elfb +# We must use the linux target here, since distributions don't tend to package +# the ELF linker scripts with binutils, and this results in a build failure. +LDFLAGS += -EB -maarch64linuxb UTS_MACHINE := aarch64_be else KBUILD_CPPFLAGS += -mlittle-endian CHECKFLAGS += -D__AARCH64EL__ AS += -EL -LDFLAGS += -EL -maarch64elf +LDFLAGS += -EL -maarch64linux # See comment above UTS_MACHINE := aarch64 endif diff --git a/arch/arm64/include/asm/simd.h b/arch/arm64/include/asm/simd.h index fa8b3fe932e6..6495cc51246f 100644 --- a/arch/arm64/include/asm/simd.h +++ b/arch/arm64/include/asm/simd.h @@ -29,20 +29,15 @@ DECLARE_PER_CPU(bool, kernel_neon_busy); static __must_check inline bool may_use_simd(void) { /* - * The raw_cpu_read() is racy if called with preemption enabled. - * This is not a bug: kernel_neon_busy is only set when - * preemption is disabled, so we cannot migrate to another CPU - * while it is set, nor can we migrate to a CPU where it is set. - * So, if we find it clear on some CPU then we're guaranteed to - * find it clear on any CPU we could migrate to. - * - * If we are in between kernel_neon_begin()...kernel_neon_end(), - * the flag will be set, but preemption is also disabled, so we - * can't migrate to another CPU and spuriously see it become - * false. + * kernel_neon_busy is only set while preemption is disabled, + * and is clear whenever preemption is enabled. Since + * this_cpu_read() is atomic w.r.t. preemption, kernel_neon_busy + * cannot change under our feet -- if it's set we cannot be + * migrated, and if it's clear we cannot be migrated to a CPU + * where it is set. */ return !in_irq() && !irqs_disabled() && !in_nmi() && - !raw_cpu_read(kernel_neon_busy); + !this_cpu_read(kernel_neon_busy); } #else /* ! CONFIG_KERNEL_MODE_NEON */ |