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[PATCH v2 17/28] arm64/sve: Preserve SVE registers around kernel-mode NEON use
- From: Dave Martin <Dave dot Martin at arm dot com>
- To: linux-arm-kernel at lists dot infradead dot org
- Cc: Catalin Marinas <catalin dot marinas at arm dot com>, Will Deacon <will dot deacon at arm dot com>, Ard Biesheuvel <ard dot biesheuvel at linaro dot org>, Alex Bennée <alex dot bennee at linaro dot org>, Szabolcs Nagy <szabolcs dot nagy at arm dot com>, Richard Sandiford <richard dot sandiford at arm dot com>, kvmarm at lists dot cs dot columbia dot edu, libc-alpha at sourceware dot org, linux-arch at vger dot kernel dot org
- Date: Thu, 31 Aug 2017 18:00:49 +0100
- Subject: [PATCH v2 17/28] arm64/sve: Preserve SVE registers around kernel-mode NEON use
- Authentication-results: sourceware.org; auth=none
- References: <1504198860-12951-1-git-send-email-Dave.Martin@arm.com>
Kernel-mode NEON will corrupt the SVE vector registers, due to the
way they alias the FPSIMD vector registers in the hardware.
This patch ensures that any live SVE register content for the task
is saved by kernel_neon_begin(). The data will be restored in the
usual way on return to userspace.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/kernel/fpsimd.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index cea05a7..dd89acf 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -744,8 +744,10 @@ void kernel_neon_begin(void)
__this_cpu_write(kernel_neon_busy, true);
/* Save unsaved task fpsimd state, if any: */
- if (current->mm && !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
- fpsimd_save_state(¤t->thread.fpsimd_state);
+ if (current->mm) {
+ task_fpsimd_save();
+ set_thread_flag(TIF_FOREIGN_FPSTATE);
+ }
/* Invalidate any task state remaining in the fpsimd regs: */
__this_cpu_write(fpsimd_last_state, NULL);
--
2.1.4