From: Mark Rutland Date: Mon, 7 Jun 2021 09:46:09 +0000 (+0100) Subject: arm64: entry: move NMI preempt logic to C X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=101a5b665dcdff169ae7ad90556604c483d9027e;p=linux.git arm64: entry: move NMI preempt logic to C Currently portions of our preempt logic are written in C while other parts are written in assembly. Let's clean this up a little bit by moving the NMI preempt checks to C. For now, the preempt count (and need_resched) checking is left in assembly, and will be converted with the body of the IRQ handler in subsequent patches. Other than the increased lockdep coverage there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Acked-by: Catalin Marinas Acked-by: Marc Zyngier Reviewed-by: Joey Gouly Cc: James Morse Cc: Will Deacon Link: https://lore.kernel.org/r/20210607094624.34689-6-mark.rutland@arm.com Signed-off-by: Will Deacon --- diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index 1fe60578e5566..08d17eb0ce13a 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -121,6 +121,15 @@ asmlinkage void __sched arm64_preempt_schedule_irq(void) { lockdep_assert_irqs_disabled(); + /* + * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC + * priority masking is used the GIC irqchip driver will clear DAIF.IF + * using gic_arch_enable_irqs() for normal IRQs. If anything is set in + * DAIF we must have handled an NMI, so skip preemption. + */ + if (system_uses_irq_prio_masking() && read_sysreg(daif)) + return; + /* * Preempting a task from an IRQ means we leave copies of PSTATE * on the stack. cpufeature's enable calls may modify PSTATE, but diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 656f3129bfefe..449628290ce8f 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -562,17 +562,7 @@ tsk .req x28 // current thread_info #ifdef CONFIG_PREEMPTION ldr x24, [tsk, #TSK_TI_PREEMPT] // get preempt count -alternative_if ARM64_HAS_IRQ_PRIO_MASKING - /* - * DA were cleared at start of handling, and IF are cleared by - * the GIC irqchip driver using gic_arch_enable_irqs() for - * normal IRQs. If anything is set, it means we come back from - * an NMI instead of a normal IRQ, so skip preemption - */ - mrs x0, daif - orr x24, x24, x0 -alternative_else_nop_endif - cbnz x24, 1f // preempt count != 0 || NMI return path + cbnz x24, 1f // preempt count != 0 bl arm64_preempt_schedule_irq // irq en/disable is done inside 1: #endif