From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 15 Oct 2021 01:16:04 +0000 (+0200)
Subject: x86/process: Clone FPU in copy_thread()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2d16a1876f20218f8970ea4b7f679cead1cdb510;p=linux.git

x86/process: Clone FPU in copy_thread()

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
---

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 1d9463e3096b6..d2227c55e6838 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();