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Commit 66c3ec5a authored by Dave Martin's avatar Dave Martin Committed by Catalin Marinas
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arm64: neon: Forbid when irqs are disabled 



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.

Acked-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 11cefd5a

arch/arm64/include/asm/simd.h

+3 −1
Original line number Original line Diff line number Diff line
@@ -10,6 +10,7 @@ 
#define __ASM_SIMD_H

#define __ASM_SIMD_H





#include <linux/compiler.h>

#include <linux/compiler.h>

#include <linux/irqflags.h>

#include <linux/percpu.h>

#include <linux/percpu.h>

#include <linux/preempt.h>

#include <linux/preempt.h>

#include <linux/types.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

	 * can't migrate to another CPU and spuriously see it become

	 * false.

	 * 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 */

#else /* ! CONFIG_KERNEL_MODE_NEON */