Re: [PATCHv2 4/5] irqchip/GICv3: let gic_handle_irq() utilize irqentry on arm64
From: Mark Rutland <mark.rutland@arm.com>
Date: 2021-09-28 09:11:02
Also in:
lkml
On Fri, Sep 24, 2021 at 09:28:36PM +0800, Pingfan Liu wrote:
The call to rcu_irq_enter() originated from gic_handle_irq() is redundant now, since arm64 has enter_from_kernel_mode() akin to irqenter_entry(), which has already called rcu_irq_enter().
Here I think you're referring to the call in handle_domain_irq(), but that isn't clear from the commit message.
Based on code analysis, the redundant can raise some mistake, e.g. rcu_data->dynticks_nmi_nesting inc 2, which causes rcu_is_cpu_rrupt_from_idle() unexpected. So eliminate the call to irq_enter() in handle_domain_irq(). And accordingly supplementing irq_enter_rcu().
We support many more irqchips on arm64, and GICv3 can be used on regular
32-bit arm, so this isn't right. Moving the irq_enter_rcu() call
into the GICv3 driver specifically breaks other drivers on arm64 by
removing the call, and breaks the GICv3 driver on arm by adding a
duplicate call.
It looks like this should live in do_interrupt_handler() in
arch/arm64/kernel/entry-common.c, e.g.
| static void do_interrupt_handler(struct pt_regs *regs,
| void (*handler)(struct pt_regs *))
| {
| irq_enter_rcu();
| if (on_thread_stack())
| call_on_irq_stack(regs, handler);
| else
| handler(regs);
| irq_exit_rcu();
| }
... unless there's some problem with that?
Thanks,
Mark.
quoted hunk ↗ jump to hunk
Signed-off-by: Pingfan Liu <redacted> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Joey Gouly <joey.gouly@arm.com> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Julien Thierry <redacted> Cc: Thomas Gleixner <redacted> Cc: Yuichi Ito <redacted> Cc: linux-kernel@vger.kernel.org To: linux-arm-kernel@lists.infradead.org --- arch/arm64/Kconfig | 1 + drivers/irqchip/irq-gic-v3.c | 2 ++ 2 files changed, 3 insertions(+)diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 5c7ae4c3954b..d29bae38a951 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig@@ -98,6 +98,7 @@ config ARM64 select ARCH_HAS_UBSAN_SANITIZE_ALL select ARM_AMBA select ARM_ARCH_TIMER + select HAVE_ARCH_IRQENTRY select ARM_GIC select AUDIT_ARCH_COMPAT_GENERIC select ARM_GIC_V2M if PCIdiff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index 89dcec902a82..906538fa8771 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c@@ -729,10 +729,12 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs else isb(); + irq_enter_rcu(); if (handle_domain_irq(gic_data.domain, irqnr, regs)) { WARN_ONCE(true, "Unexpected interrupt received!\n"); gic_deactivate_unhandled(irqnr); } + irq_exit_rcu(); } static u32 gic_get_pribits(void)-- 2.31.1
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