From 0698ae6597067c2ea04564cb61eeb5c3ccd95438 Mon Sep 17 00:00:00 2001 From: Janet Liu Date: Thu, 11 Jun 2015 12:04:32 +0800 Subject: arm64: kernel thread don't need to save fpsimd context. kernel thread's default fpsimd state is zero. When fork a thread, if parent is kernel thread, and save hardware context to parent's fpsimd state, but this hardware context is user process's context, because kernel thread don't use fpsimd, it will not introduce issue, it add a little cost. Change-Id: I292c0b328983b1ecaf642503183473c12bb1207b Signed-off-by: Janet Liu Signed-off-by: Chunyan Zhang Signed-off-by: Catalin Marinas Git-commit: 6eb6c80187c55b7f95683bc6502dccac54b95b92 Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git Signed-off-by: Se Wang (Patrick) Oh Signed-off-by: franciscofranco --- arch/arm64/kernel/process.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index ad14dbc07..0e3a980d0 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -385,7 +385,8 @@ void release_thread(struct task_struct *dead_task) int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { - fpsimd_preserve_current_state(); + if (current->mm) + fpsimd_preserve_current_state(); *dst = *src; return 0; } -- cgit v1.2.3