x86/process: Clone FPU in copy_thread()

mainline inclusion
from mainline-v5.16-rc1
commit 2d16a187
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I590ZC
CVE: NA

Intel-SIG: commit 2d16a187 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: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.780714235@linutronix.deSigned-off-by: NLin Wang <lin.x.wang@intel.com>
Signed-off-by: NAichun Shi <aichun.shi@intel.com>

arch/x86/kernel/process.c

@@ -93,7 +93,7 @@ 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;
 }
 
 /*
@@ -161,6 +161,8 @@ 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();