Commit d2d92648 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu: Update stale comments 



copy_fpstate_to_sigframe() does not have a slow path anymore. Neither does
the !ia32 restore in __fpu_restore_sig().

Update the comments accordingly.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.493570236@linutronix.de
parent 9568bfb4

arch/x86/kernel/fpu/signal.c

+3 −10
Original line number Diff line number Diff line
@@ -155,10 +155,8 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf) 
 *	buf == buf_fx for 64-bit frames and 32-bit fsave frame.

 *	buf != buf_fx for 32-bit frames with fxstate.

 *

 * Try to save it directly to the user frame with disabled page fault handler.

 * If this fails then do the slow path where the FPU state is first saved to

 * task's fpu->state and then copy it to the user frame pointed to by the

 * aligned pointer 'buf_fx'.

 * Save it directly to the user frame with disabled page fault handler. If

 * that faults, try to clear the frame which handles the page fault.

 *

 * If this is a 32-bit frame with fxstate, put a fsave header before

 * the aligned state at 'buf_fx'.
@@ -334,12 +332,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx, 
	}



	if (likely(!ia32_fxstate)) {

		/*

		 * Attempt to restore the FPU registers directly from user

		 * memory. For that to succeed, the user access cannot cause page

		 * faults. If it does, fall back to the slow path below, going

		 * through the kernel buffer with the enabled pagefault handler.

		 */

		/* Restore the FPU registers directly from user memory. */

		return restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only,

						state_size);

	}