From 1bd3f93641ec710015fcb3badca07dacd58c91d3 Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Tue, 31 Oct 2017 15:51:11 +0000 Subject: [PATCH] arm64/sve: Preserve SVE registers around kernel-mode NEON use MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Ard Biesheuvel Reviewed-by: Alex BennĂ©e Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon --- 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 715398e91d65..741fbbfa1265 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -886,8 +886,10 @@ 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);