From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 15 Oct 2021 03:16:04 +0200
Subject: x86/process: Clone FPU in copy_thread()
Git-commit: 2d16a1876f20218f8970ea4b7f679cead1cdb510
Patch-mainline: v5.15 or v5.15-rc8 (next release)
References: jsc#SLE-18931
There is no reason to clone FPU in arch_dup_task_struct(). Quite the
contrary - it prevents optimizations. Move it to copy_thread().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.780714235@linutronix.de
---
arch/x86/kernel/process.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 1d9463e3096b..d2227c55e683 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -87,7 +87,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
#ifdef CONFIG_VM86
dst->thread.vm86 = NULL;
#endif
- return fpu_clone(dst);
+ return 0;
}
/*
@@ -154,6 +154,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
frame->flags = X86_EFLAGS_FIXED;
#endif
+ fpu_clone(p);
+
/* Kernel thread ? */
if (unlikely(p->flags & PF_KTHREAD)) {
p->thread.pkru = pkru_get_init_value();