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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-20 01:49:48 +07:00
f226650494
The GICv3 architecture specification is incredibly misleading when it comes to PMR and the requirement for a DSB. It turns out that this DSB is only required if the CPU interface sends an Upstream Control message to the redistributor in order to update the RD's view of PMR. This message is only sent when ICC_CTLR_EL1.PMHE is set, which isn't the case in Linux. It can still be set from EL3, so some special care is required. But the upshot is that in the (hopefuly large) majority of the cases, we can drop the DSB altogether. This relies on a new static key being set if the boot CPU has PMHE set. The drawback is that this static key has to be exported to modules. Cc: Will Deacon <will@kernel.org> Cc: James Morse <james.morse@arm.com> Cc: Julien Thierry <julien.thierry.kdev@gmail.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
131 lines
2.8 KiB
C
131 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2012 ARM Ltd.
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*/
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#ifndef __ASM_IRQFLAGS_H
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#define __ASM_IRQFLAGS_H
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#include <asm/alternative.h>
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#include <asm/barrier.h>
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#include <asm/ptrace.h>
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#include <asm/sysreg.h>
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/*
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* Aarch64 has flags for masking: Debug, Asynchronous (serror), Interrupts and
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* FIQ exceptions, in the 'daif' register. We mask and unmask them in 'dai'
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* order:
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* Masking debug exceptions causes all other exceptions to be masked too/
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* Masking SError masks irq, but not debug exceptions. Masking irqs has no
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* side effects for other flags. Keeping to this order makes it easier for
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* entry.S to know which exceptions should be unmasked.
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*
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* FIQ is never expected, but we mask it when we disable debug exceptions, and
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* unmask it at all other times.
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*/
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/*
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* CPU interrupt mask handling.
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*/
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static inline void arch_local_irq_enable(void)
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{
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if (system_has_prio_mask_debugging()) {
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u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1);
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WARN_ON_ONCE(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF);
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}
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asm volatile(ALTERNATIVE(
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"msr daifclr, #2 // arch_local_irq_enable",
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__msr_s(SYS_ICC_PMR_EL1, "%0"),
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ARM64_HAS_IRQ_PRIO_MASKING)
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:
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: "r" ((unsigned long) GIC_PRIO_IRQON)
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: "memory");
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pmr_sync();
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}
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static inline void arch_local_irq_disable(void)
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{
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if (system_has_prio_mask_debugging()) {
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u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1);
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WARN_ON_ONCE(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF);
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}
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asm volatile(ALTERNATIVE(
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"msr daifset, #2 // arch_local_irq_disable",
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__msr_s(SYS_ICC_PMR_EL1, "%0"),
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ARM64_HAS_IRQ_PRIO_MASKING)
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:
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: "r" ((unsigned long) GIC_PRIO_IRQOFF)
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: "memory");
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}
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/*
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* Save the current interrupt enable state.
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*/
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static inline unsigned long arch_local_save_flags(void)
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{
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unsigned long flags;
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asm volatile(ALTERNATIVE(
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"mrs %0, daif",
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__mrs_s("%0", SYS_ICC_PMR_EL1),
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ARM64_HAS_IRQ_PRIO_MASKING)
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: "=&r" (flags)
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:
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: "memory");
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return flags;
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}
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static inline int arch_irqs_disabled_flags(unsigned long flags)
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{
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int res;
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asm volatile(ALTERNATIVE(
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"and %w0, %w1, #" __stringify(PSR_I_BIT),
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"eor %w0, %w1, #" __stringify(GIC_PRIO_IRQON),
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ARM64_HAS_IRQ_PRIO_MASKING)
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: "=&r" (res)
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: "r" ((int) flags)
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: "memory");
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return res;
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}
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static inline unsigned long arch_local_irq_save(void)
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{
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unsigned long flags;
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flags = arch_local_save_flags();
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/*
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* There are too many states with IRQs disabled, just keep the current
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* state if interrupts are already disabled/masked.
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*/
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if (!arch_irqs_disabled_flags(flags))
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arch_local_irq_disable();
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return flags;
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}
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/*
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* restore saved IRQ state
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*/
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static inline void arch_local_irq_restore(unsigned long flags)
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{
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asm volatile(ALTERNATIVE(
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"msr daif, %0",
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__msr_s(SYS_ICC_PMR_EL1, "%0"),
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ARM64_HAS_IRQ_PRIO_MASKING)
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:
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: "r" (flags)
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: "memory");
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pmr_sync();
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}
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#endif /* __ASM_IRQFLAGS_H */
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