| Message ID | 1502275408-16982-1-git-send-email-Dave.Martin@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 9 August 2017 at 11:43, Dave Martin <Dave.Martin@arm.com> wrote: > Currently, may_use_simd() can return true if IRQs are disabled. If > the caller goes ahead and calls kernel_neon_begin(), this can > result in use of local_bh_enable() in an unsafe context. > > In particular, __efi_fpsimd_begin() may do this when calling EFI as > part of system shutdown. > > This patch ensures that callers don't think they can use > kernel_neon_begin() in such a context. > > Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > arch/arm64/include/asm/simd.h | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/simd.h b/arch/arm64/include/asm/simd.h > index 5a1a927..fa8b3fe 100644 > --- a/arch/arm64/include/asm/simd.h > +++ b/arch/arm64/include/asm/simd.h > @@ -10,6 +10,7 @@ > #define __ASM_SIMD_H > > #include <linux/compiler.h> > +#include <linux/irqflags.h> > #include <linux/percpu.h> > #include <linux/preempt.h> > #include <linux/types.h> > @@ -40,7 +41,8 @@ static __must_check inline bool may_use_simd(void) > * can't migrate to another CPU and spuriously see it become > * false. > */ > - return !in_irq() && !in_nmi() && !raw_cpu_read(kernel_neon_busy); > + return !in_irq() && !irqs_disabled() && !in_nmi() && > + !raw_cpu_read(kernel_neon_busy); > } > > #else /* ! CONFIG_KERNEL_MODE_NEON */ > -- > 2.1.4 >
On Wed, Aug 09, 2017 at 11:43:28AM +0100, Dave P Martin wrote: > Currently, may_use_simd() can return true if IRQs are disabled. If > the caller goes ahead and calls kernel_neon_begin(), this can > result in use of local_bh_enable() in an unsafe context. > > In particular, __efi_fpsimd_begin() may do this when calling EFI as > part of system shutdown. > > This patch ensures that callers don't think they can use > kernel_neon_begin() in such a context. > > Signed-off-by: Dave Martin <Dave.Martin@arm.com> Thanks. I pushed it out to the for-next/kernel-mode-neon branch.
diff --git a/arch/arm64/include/asm/simd.h b/arch/arm64/include/asm/simd.h index 5a1a927..fa8b3fe 100644 --- a/arch/arm64/include/asm/simd.h +++ b/arch/arm64/include/asm/simd.h @@ -10,6 +10,7 @@ #define __ASM_SIMD_H #include <linux/compiler.h> +#include <linux/irqflags.h> #include <linux/percpu.h> #include <linux/preempt.h> #include <linux/types.h> @@ -40,7 +41,8 @@ static __must_check inline bool may_use_simd(void) * can't migrate to another CPU and spuriously see it become * false. */ - return !in_irq() && !in_nmi() && !raw_cpu_read(kernel_neon_busy); + return !in_irq() && !irqs_disabled() && !in_nmi() && + !raw_cpu_read(kernel_neon_busy); } #else /* ! CONFIG_KERNEL_MODE_NEON */
Currently, may_use_simd() can return true if IRQs are disabled. If the caller goes ahead and calls kernel_neon_begin(), this can result in use of local_bh_enable() in an unsafe context. In particular, __efi_fpsimd_begin() may do this when calling EFI as part of system shutdown. This patch ensures that callers don't think they can use kernel_neon_begin() in such a context. Signed-off-by: Dave Martin <Dave.Martin@arm.com> --- arch/arm64/include/asm/simd.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)