[PATCH 10/15] irq: arm64: perform irqentry in entry code

Mark Rutland
2021-10-21T18:03:45Z

In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/arm64
perform all the irqentry accounting in its entry code.

As arch/arm64 already performs portions of the irqentry logic in
enter_from_kernel_mode() and exit_to_kernel_mode(), including
rcu_irq_{enter,exit}(), the only additional calls that need to be made
are to irq_{enter,exit}_rcu(). Removing the calls to
rcu_irq_{enter,exit}() from handle_domain_irq() ensures that we inform
RCU once per IRQ entry and will correctly identify quiescent periods.

Since we should not call irq_{enter,exit}_rcu() when entering a
pseudo-NMI, el1_interrupt() is reworked to have separate __el1_irq() and
__el1_pnmi() paths for regular IRQ and psuedo-NMI entry, with
irq_{enter,exit}_irq() only called for the former.

In preparation for removing HANDLE_DOMAIN_IRQ, the irq regs are managed
in do_interrupt_handler() for both regular IRQ and pseudo-NMI. This is
currently redundant, but not harmful.

For clarity the preemption logic is moved into __el1_irq(). We should
never preempt within a pseudo-NMI, and arm64_enter_nmi() already
enforces this by incrementing the preempt_count, but it's clearer if we
never invoke the preemption logic when entering a pseudo-NMI.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/Kconfig | 1 -
arch/arm64/kernel/entry-common.c | 52 ++++++++++++++++++++++++----------------
2 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 553239a5a5f7..5c7ae4c3954b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -134,7 +134,6 @@ config ARM64
select GENERIC_GETTIMEOFDAY
select GENERIC_VDSO_TIME_NS
select HANDLE_DOMAIN_IRQ
- select HANDLE_DOMAIN_IRQ_IRQENTRY
select HARDIRQS_SW_RESEND
select HAVE_MOVE_PMD
select HAVE_MOVE_PUD
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 32f9796c4ffe..f7408edf8571 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -17,6 +17,7 @@
#include <asm/daifflags.h>
#include <asm/esr.h>
#include <asm/exception.h>
+#include <asm/irq_regs.h>
#include <asm/kprobes.h>
#include <asm/mmu.h>
#include <asm/processor.h>
@@ -219,22 +220,6 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
lockdep_hardirqs_on(CALLER_ADDR0);
}

-static void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
-{
- if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
- arm64_enter_nmi(regs);
- else
- enter_from_kernel_mode(regs);
-}
-
-static void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
-{
- if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
- arm64_exit_nmi(regs);
- else
- exit_to_kernel_mode(regs);
-}
-
static void __sched arm64_preempt_schedule_irq(void)
{
lockdep_assert_irqs_disabled();
@@ -263,10 +248,14 @@ static void __sched arm64_preempt_schedule_irq(void)
static void do_interrupt_handler(struct pt_regs *regs,
void (*handler)(struct pt_regs *))
{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+
if (on_thread_stack())
call_on_irq_stack(regs, handler);
else
handler(regs);
+
+ set_irq_regs(old_regs);
}

extern void (*handle_arch_irq)(struct pt_regs *);
@@ -432,13 +421,22 @@ asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
}
}

-static void noinstr el1_interrupt(struct pt_regs *regs,
- void (*handler)(struct pt_regs *))
+static __always_inline void __el1_pnmi(struct pt_regs *regs,
+ void (*handler)(struct pt_regs *))
{
- write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
+ arm64_enter_nmi(regs);
+ do_interrupt_handler(regs, handler);
+ arm64_exit_nmi(regs);
+}
+
+static __always_inline void __el1_irq(struct pt_regs *regs,
+ void (*handler)(struct pt_regs *))
+{
+ enter_from_kernel_mode(regs);

- enter_el1_irq_or_nmi(regs);
+ irq_enter_rcu();
do_interrupt_handler(regs, handler);
+ irq_exit_rcu();

/*
* Note: thread_info::preempt_count includes both thread_info::count
@@ -449,7 +447,17 @@ static void noinstr el1_interrupt(struct pt_regs *regs,
READ_ONCE(current_thread_info()->preempt_count) == 0)
arm64_preempt_schedule_irq();

- exit_el1_irq_or_nmi(regs);
+ exit_to_kernel_mode(regs);
+}
+static void noinstr el1_interrupt(struct pt_regs *regs,
+ void (*handler)(struct pt_regs *))
+{
+ write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
+
+ if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
+ __el1_pnmi(regs, handler);
+ else
+ __el1_irq(regs, handler);
}

asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)
@@ -667,7 +675,9 @@ static void noinstr el0_interrupt(struct pt_regs *regs,
if (regs->pc & BIT(55))
arm64_apply_bp_hardening();

+ irq_enter_rcu();
do_interrupt_handler(regs, handler);
+ irq_exit_rcu();

exit_to_user_mode(regs);
}
--
2.11.0