Commit 270de609 authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64: Simplify do_notify_resume() DAIF masking 



In do_notify_resume, we handle _TIF_NEED_RESCHED differently from all
other flags, leaving IRQ+FIQ masked when calling into schedule(). This
masking is a historical artifact, and it is not currently necessary
to mask IRQ+FIQ when calling into schedule (as evidenced by the generic
exit_to_user_mode_loop(), which unmasks IRQs before checking
_TIF_NEED_RESCHED and calling schedule()).

This patch removes the special case for _TIF_NEED_RESCHED, moving this
check into the main loop such that schedule() will be called from a
regular process context with IRQ+FIQ unmasked. This is a minor
simplification to do_notify_resume() and brings it into line with the
generic exit_to_user_mode_loop() logic. This will also aid subsequent
rework of DAIF management.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240206123848.1696480-2-mark.rutland@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Tested-by: default avatarItaru Kitayama <itaru.kitayama@linux.dev>
parent 54be6c6c

arch/arm64/kernel/signal.c

+15 −19
Original line number Diff line number Diff line
@@ -1281,13 +1281,10 @@ static void do_signal(struct pt_regs *regs) 
void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)

{

	do {

		if (thread_flags & _TIF_NEED_RESCHED) {

			/* Unmask Debug and SError for the next task */

			local_daif_restore(DAIF_PROCCTX_NOIRQ);

		local_daif_restore(DAIF_PROCCTX);



		if (thread_flags & _TIF_NEED_RESCHED)

			schedule();

		} else {

			local_daif_restore(DAIF_PROCCTX);



		if (thread_flags & _TIF_UPROBE)

			uprobe_notify_resume(regs);
@@ -1306,7 +1303,6 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) 


		if (thread_flags & _TIF_FOREIGN_FPSTATE)

			fpsimd_restore_current_state();

		}



		local_daif_mask();

		thread_flags = read_thread_flags();