Commit 2d299e3d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
Browse files

x86/fpu: Always use memcpy_and_pad() in arch_dup_task_struct() 



It makes no sense to copy the bytes after sizeof(struct task_struct),
FPU state will be initialized in fpu_clone().

A plain memcpy(dst, src, sizeof(struct task_struct)) should work too,
but "_and_pad" looks safer.

[ mingo: Simplify it a bit more. ]

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S . Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250503143850.GA8997@redhat.com
parent 8e269c03

arch/x86/kernel/process.c

+2 −5
Original line number Diff line number Diff line
@@ -93,11 +93,8 @@ EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid); 
 */

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)

{

	/* init_task is not dynamically sized (incomplete FPU state) */

	if (unlikely(src == &init_task))

		memcpy_and_pad(dst, arch_task_struct_size, src, sizeof(init_task), 0);

	else

		memcpy(dst, src, arch_task_struct_size);

	/* fpu_clone() will initialize the "dst_fpu" memory */

	memcpy_and_pad(dst, arch_task_struct_size, src, sizeof(*dst), 0);



#ifdef CONFIG_VM86

	dst->thread.vm86 = NULL;