From: Mark Rutland <mark.rutland@arm.com>
To: Julien Thierry <julien.thierry@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, daniel.thompson@linaro.org,
joel@joelfernandes.org, marc.zyngier@arm.com,
christoffer.dall@arm.com, james.morse@arm.com,
catalin.marinas@arm.com, will.deacon@arm.com
Subject: Re: [PATCH v6 08/24] arm64: Unmask PMR before going idle
Date: Thu, 29 Nov 2018 17:44:37 +0000 [thread overview]
Message-ID: <20181129174436.avqjydyzvv6ubnjd@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <1542023835-21446-9-git-send-email-julien.thierry@arm.com>
On Mon, Nov 12, 2018 at 11:56:59AM +0000, Julien Thierry wrote:
> CPU does not received signals for interrupts with a priority masked by
> ICC_PMR_EL1. This means the CPU might not come back from a WFI
> instruction.
>
> Make sure ICC_PMR_EL1 does not mask interrupts when doing a WFI.
>
> Signed-off-by: Julien Thierry <julien.thierry@arm.com>
> Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/mm/proc.S | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> index 2c75b0b..3c7064c 100644
> --- a/arch/arm64/mm/proc.S
> +++ b/arch/arm64/mm/proc.S
> @@ -20,6 +20,7 @@
>
> #include <linux/init.h>
> #include <linux/linkage.h>
> +#include <linux/irqchip/arm-gic-v3.h>
> #include <asm/assembler.h>
> #include <asm/asm-offsets.h>
> #include <asm/hwcap.h>
> @@ -53,10 +54,27 @@
> * cpu_do_idle()
> *
> * Idle the processor (wait for interrupt).
> + *
> + * If the CPU supports priority masking we must do additional work to
> + * ensure that interrupts are not masked at the PMR (because the core will
> + * not wake up if we block the wake up signal in the interrupt controller).
> */
> ENTRY(cpu_do_idle)
> +alternative_if_not ARM64_HAS_IRQ_PRIO_MASKING
> + dsb sy // WFI may enter a low-power mode
> + wfi
> + ret
> +alternative_else
> + mrs x0, daif // save I bit
> + msr daifset, #2 // set I bit
> + mrs_s x1, SYS_ICC_PMR_EL1 // save PMR
> +alternative_endif
> + mov x2, #GIC_PRIO_IRQON
> + msr_s SYS_ICC_PMR_EL1, x2 // unmask PMR
> dsb sy // WFI may enter a low-power mode
Is the DSB SY sufficient and necessary to synchronise the update of
SYS_ICC_PMR_EL1? We don't need an ISB too?
> wfi
> + msr_s SYS_ICC_PMR_EL1, x1 // restore PMR
Likewise, we don't need any barriers here before we poke DAIF?
> + msr daif, x0 // restore I bit
> ret
> ENDPROC(cpu_do_idle)
If we build without CONFIG_ARM64_PSEUDO_NMI surely we don't want to emit
the alternative?
How about we move this to C, and have something like the below?
For the !CONFIG_ARM64_PSEUDO_NMI case it generates identical assembly to the
existing cpu_do_idle(). Note that I've assumed we don't need barriers, which
(as above) I'm not certain of.
Thanks,
Mark.
---->8----
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 7f1628effe6d..ccd2ad8c5e2f 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -73,6 +73,40 @@ EXPORT_SYMBOL_GPL(pm_power_off);
void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
+static inline void __cpu_do_idle(void)
+{
+ /* WFI may enter a low-power mode */
+ dsb(sy);
+ wfi();
+}
+
+/*
+ * When using priority masking we need to take extra care, etc.
+ */
+static inline void __cpu_do_idle_irqprio(void)
+{
+ unsigned long flags = arch_local_irq_save();
+ unsigned long pmr = gic_read_pmr();
+
+ gic_write_pmr(GIC_PRIO_IRQON);
+
+ __cpu_do_idle();
+
+ gic_write_pmr(pmr);
+ arch_local_irq_enable();
+}
+
+/*
+ * Idle the processor (wait for interrupt).
+ */
+void cpu_do_idle(void)
+{
+ if (system_uses_irq_prio_masking())
+ __cpu_do_idle_irqprio();
+ else
+ __cpu_do_idle();
+}
+
/*
* This is our default idle handler.
*/
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 03646e6a2ef4..38c0171e52e2 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -49,17 +49,6 @@
#define MAIR(attr, mt) ((attr) << ((mt) * 8))
-/*
- * cpu_do_idle()
- *
- * Idle the processor (wait for interrupt).
- */
-ENTRY(cpu_do_idle)
- dsb sy // WFI may enter a low-power mode
- wfi
- ret
-ENDPROC(cpu_do_idle)
-
#ifdef CONFIG_CPU_PM
/**
* cpu_do_suspend - save CPU registers context
next prev parent reply other threads:[~2018-11-29 17:44 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 11:56 [PATCH v6 00/24] arm64: provide pseudo NMI with GICv3 Julien Thierry
2018-11-12 11:56 ` [PATCH v6 01/24] arm64: Remove unused daif related functions/macros Julien Thierry
2018-11-29 16:26 ` Mark Rutland
2018-11-30 18:03 ` Catalin Marinas
2018-11-12 11:56 ` [PATCH v6 02/24] arm64: cpufeature: Set SYSREG_GIC_CPUIF as a boot system feature Julien Thierry
2018-11-12 18:00 ` Suzuki K Poulose
2018-11-29 16:27 ` Mark Rutland
2018-11-30 18:07 ` Catalin Marinas
2018-11-12 11:56 ` [PATCH v6 03/24] arm64: cpufeature: Add cpufeature for IRQ priority masking Julien Thierry
2018-11-12 18:02 ` Suzuki K Poulose
2018-11-29 17:12 ` Mark Rutland
2018-12-03 10:33 ` Julien Thierry
2018-11-30 18:07 ` Catalin Marinas
2018-11-12 11:56 ` [PATCH v6 04/24] arm/arm64: gic-v3: Add PMR and RPR accessors Julien Thierry
2018-11-29 16:32 ` Mark Rutland
2018-11-30 18:07 ` Catalin Marinas
2018-11-12 11:56 ` [PATCH v6 05/24] irqchip/gic-v3: Switch to PMR masking before calling IRQ handler Julien Thierry
2018-11-29 18:12 ` Mark Rutland
2018-11-30 9:18 ` Julien Thierry
2018-12-04 16:21 ` Catalin Marinas
2018-11-12 11:56 ` [PATCH v6 06/24] arm64: ptrace: Provide definitions for PMR values Julien Thierry
2018-11-29 16:40 ` Mark Rutland
2018-11-30 8:53 ` Julien Thierry
2018-11-30 10:38 ` Daniel Thompson
2018-11-30 11:03 ` Julien Thierry
2018-11-12 11:56 ` [PATCH v6 07/24] arm64: Make PMR part of task context Julien Thierry
2018-11-29 16:46 ` Mark Rutland
2018-11-30 9:25 ` Julien Thierry
2018-12-04 17:09 ` Catalin Marinas
2018-12-04 17:30 ` Julien Thierry
2018-11-12 11:56 ` [PATCH v6 08/24] arm64: Unmask PMR before going idle Julien Thierry
2018-11-29 17:44 ` Mark Rutland [this message]
2018-11-30 10:55 ` Julien Thierry
2018-11-30 13:37 ` Mark Rutland
2018-12-03 10:38 ` Julien Thierry
2018-11-12 11:57 ` [PATCH v6 09/24] arm64: kvm: Unmask PMR before entering guest Julien Thierry
2018-11-12 11:57 ` [PATCH v6 10/24] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking Julien Thierry
2018-12-04 17:36 ` Catalin Marinas
2018-12-05 16:55 ` Julien Thierry
2018-12-05 18:26 ` Catalin Marinas
2018-12-06 9:50 ` Julien Thierry
2018-12-10 14:39 ` Catalin Marinas
2018-11-12 11:57 ` [PATCH v6 11/24] arm64: daifflags: Include PMR in daifflags restore operations Julien Thierry
2018-11-12 11:57 ` [PATCH v6 12/24] arm64: alternative: Allow alternative status checking per cpufeature Julien Thierry
2018-11-12 11:57 ` [PATCH v6 13/24] arm64: alternative: Apply alternatives early in boot process Julien Thierry
2018-11-12 11:57 ` [PATCH v6 14/24] irqchip/gic-v3: Factor group0 detection into functions Julien Thierry
2018-11-12 11:57 ` [PATCH v6 15/24] arm64: Switch to PMR masking when starting CPUs Julien Thierry
2018-12-04 17:51 ` Catalin Marinas
2018-12-04 18:11 ` Julien Thierry
2018-11-12 11:57 ` [PATCH v6 16/24] arm64: gic-v3: Implement arch support for priority masking Julien Thierry
2018-11-12 11:57 ` [PATCH v6 17/24] irqchip/gic-v3: Detect if GIC can support pseudo-NMIs Julien Thierry
2018-11-12 11:57 ` [PATCH v6 18/24] irqchip/gic-v3: Handle pseudo-NMIs Julien Thierry
2018-11-12 11:57 ` [PATCH v6 19/24] irqchip/gic: Add functions to access irq priorities Julien Thierry
2018-11-12 11:57 ` [PATCH v6 20/24] irqchip/gic-v3: Allow interrupts to be set as pseudo-NMI Julien Thierry
2018-11-12 11:57 ` [PATCH v6 21/24] arm64: Handle serror in NMI context Julien Thierry
2018-12-04 18:09 ` Catalin Marinas
2018-12-05 13:02 ` James Morse
2018-11-12 11:57 ` [PATCH v6 22/24] arm64: Skip preemption when exiting an NMI Julien Thierry
2018-11-12 11:57 ` [PATCH v6 23/24] arm64: Skip irqflags tracing for NMI in IRQs disabled context Julien Thierry
2018-11-12 11:57 ` [PATCH v6 24/24] arm64: Enable the support of pseudo-NMIs Julien Thierry
2018-11-12 12:00 ` [PATCH v6 00/24] arm64: provide pseudo NMI with GICv3 Julien Thierry
2018-11-13 14:43 ` Julien Thierry
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