| Message ID | 1546956464-48825-10-git-send-email-julien.thierry@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: provide pseudo NMI with GICv3 | expand |
On Tue, Jan 08, 2019 at 02:07:27PM +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. > > Since the logic of cpu_do_idle is becoming a bit more complex than just > two instructions, lets turn it from ASM to C. I haven't checked all the call paths, so asking here: does the core code normally call arch_cpu_idle() with IRQs off?
On 18/01/2019 16:23, Catalin Marinas wrote: > On Tue, Jan 08, 2019 at 02:07:27PM +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. >> >> Since the logic of cpu_do_idle is becoming a bit more complex than just >> two instructions, lets turn it from ASM to C. > > I haven't checked all the call paths, so asking here: does the core code > normally call arch_cpu_idle() with IRQs off? > If you look at do_idle() in kernel/sched/idle.c, it does: while (!need_resched()) { [...] local_irq_disable(); arch_cpu_idle_enter(); [...] } else { cpuidle_idle_call(); } } Then cpuidle_idle_call() will call default_idle_call() (which calls arch_cpu_idle()) either directly or via the cpuidle driver. My understanding is that it always does the call with interrupts disabled. Thanks,
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 6d410fc..f05b63f 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -51,6 +51,7 @@ #include <linux/thread_info.h> #include <asm/alternative.h> +#include <asm/arch_gicv3.h> #include <asm/compat.h> #include <asm/cacheflush.h> #include <asm/exec.h> @@ -74,6 +75,50 @@ void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd); +static inline void __cpu_do_idle(void) +{ + dsb(sy); + wfi(); +} + +static inline void __cpu_do_idle_irqprio(void) +{ + unsigned long pmr; + unsigned long daif_bits; + + daif_bits = read_sysreg(daif); + write_sysreg(daif_bits | PSR_I_BIT, daif); + + /* + * Unmask PMR before going idle to make sure interrupts can + * be raised. + */ + pmr = gic_read_pmr(); + gic_write_pmr(GIC_PRIO_IRQON); + + __cpu_do_idle(); + + gic_write_pmr(pmr); + write_sysreg(daif_bits, daif); +} + +/* + * 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). + */ +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 73886a5..3ea4f3b 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -55,17 +55,6 @@ #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
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. Since the logic of cpu_do_idle is becoming a bit more complex than just two instructions, lets turn it from ASM to C. 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/kernel/process.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ arch/arm64/mm/proc.S | 11 ----------- 2 files changed, 45 insertions(+), 11 deletions(-)