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arm64: Simplify do_notify_resume() DAIF masking

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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: Mark 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: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240206123848.1696480-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Itaru Kitayama <itaru.kitayama@linux.dev>
This commit is contained in:
Mark Rutland 2024-02-06 12:38:46 +00:00 committed by Catalin Marinas
parent 54be6c6c5a
commit 270de609ae
1 changed files with 17 additions and 21 deletions
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10
arch/arm64/kernel/signal.c
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@ -1281,14 +1281,11 @@ 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);
schedule();
} else {
local_daif_restore(DAIF_PROCCTX);
if (thread_flags & _TIF_NEED_RESCHED)
schedule();
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();