From 4a503217ce37e1f4f3d9b681bbcbbac103776bf1 Mon Sep 17 00:00:00 2001 From: Julien Thierry Date: Thu, 31 Jan 2019 14:58:50 +0000 Subject: [PATCH] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking Instead disabling interrupts by setting the PSR.I bit, use a priority higher than the one used for interrupts to mask them via PMR. When using PMR to disable interrupts, the value of PMR will be used instead of PSR.[DAIF] for the irqflags. Signed-off-by: Julien Thierry Suggested-by: Daniel Thompson Acked-by: Ard Biesheuvel Reviewed-by: Catalin Marinas Cc: Will Deacon Cc: Ard Biesheuvel Cc: Oleg Nesterov Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/efi.h | 11 +++++ arch/arm64/include/asm/irqflags.h | 100 +++++++++++++++++++++++++++----------- 2 files changed, 83 insertions(+), 28 deletions(-) diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h index 7ed320895d1f..c9e9a6978e73 100644 --- a/arch/arm64/include/asm/efi.h +++ b/arch/arm64/include/asm/efi.h @@ -44,6 +44,17 @@ efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...); #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) +/* + * Even when Linux uses IRQ priorities for IRQ disabling, EFI does not. + * And EFI shouldn't really play around with priority masking as it is not aware + * which priorities the OS has assigned to its interrupts. + */ +#define arch_efi_save_flags(state_flags) \ + ((void)((state_flags) = read_sysreg(daif))) + +#define arch_efi_restore_flags(state_flags) write_sysreg(state_flags, daif) + + /* arch specific definitions used by the stub code */ /* diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h index 24692edf1a69..d4597b2c5729 100644 --- a/arch/arm64/include/asm/irqflags.h +++ b/arch/arm64/include/asm/irqflags.h @@ -18,7 +18,9 @@ #ifdef __KERNEL__ +#include #include +#include /* * Aarch64 has flags for masking: Debug, Asynchronous (serror), Interrupts and @@ -36,33 +38,27 @@ /* * CPU interrupt mask handling. */ -static inline unsigned long arch_local_irq_save(void) -{ - unsigned long flags; - asm volatile( - "mrs %0, daif // arch_local_irq_save\n" - "msr daifset, #2" - : "=r" (flags) - : - : "memory"); - return flags; -} - static inline void arch_local_irq_enable(void) { - asm volatile( - "msr daifclr, #2 // arch_local_irq_enable" - : + asm volatile(ALTERNATIVE( + "msr daifclr, #2 // arch_local_irq_enable\n" + "nop", + "msr_s " __stringify(SYS_ICC_PMR_EL1) ",%0\n" + "dsb sy", + ARM64_HAS_IRQ_PRIO_MASKING) : + : "r" (GIC_PRIO_IRQON) : "memory"); } static inline void arch_local_irq_disable(void) { - asm volatile( - "msr daifset, #2 // arch_local_irq_disable" - : + asm volatile(ALTERNATIVE( + "msr daifset, #2 // arch_local_irq_disable", + "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0", + ARM64_HAS_IRQ_PRIO_MASKING) : + : "r" (GIC_PRIO_IRQOFF) : "memory"); } @@ -71,12 +67,44 @@ static inline void arch_local_irq_disable(void) */ static inline unsigned long arch_local_save_flags(void) { + unsigned long daif_bits; unsigned long flags; - asm volatile( - "mrs %0, daif // arch_local_save_flags" - : "=r" (flags) - : + + daif_bits = read_sysreg(daif); + + /* + * The asm is logically equivalent to: + * + * if (system_uses_irq_prio_masking()) + * flags = (daif_bits & PSR_I_BIT) ? + * GIC_PRIO_IRQOFF : + * read_sysreg_s(SYS_ICC_PMR_EL1); + * else + * flags = daif_bits; + */ + asm volatile(ALTERNATIVE( + "mov %0, %1\n" + "nop\n" + "nop", + "mrs_s %0, " __stringify(SYS_ICC_PMR_EL1) "\n" + "ands %1, %1, " __stringify(PSR_I_BIT) "\n" + "csel %0, %0, %2, eq", + ARM64_HAS_IRQ_PRIO_MASKING) + : "=&r" (flags), "+r" (daif_bits) + : "r" (GIC_PRIO_IRQOFF) : "memory"); + + return flags; +} + +static inline unsigned long arch_local_irq_save(void) +{ + unsigned long flags; + + flags = arch_local_save_flags(); + + arch_local_irq_disable(); + return flags; } @@ -85,16 +113,32 @@ static inline unsigned long arch_local_save_flags(void) */ static inline void arch_local_irq_restore(unsigned long flags) { - asm volatile( - "msr daif, %0 // arch_local_irq_restore" - : - : "r" (flags) - : "memory"); + asm volatile(ALTERNATIVE( + "msr daif, %0\n" + "nop", + "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0\n" + "dsb sy", + ARM64_HAS_IRQ_PRIO_MASKING) + : "+r" (flags) + : + : "memory"); } static inline int arch_irqs_disabled_flags(unsigned long flags) { - return flags & PSR_I_BIT; + int res; + + asm volatile(ALTERNATIVE( + "and %w0, %w1, #" __stringify(PSR_I_BIT) "\n" + "nop", + "cmp %w1, #" __stringify(GIC_PRIO_IRQOFF) "\n" + "cset %w0, ls", + ARM64_HAS_IRQ_PRIO_MASKING) + : "=&r" (res) + : "r" ((int) flags) + : "memory"); + + return res; } #endif #endif -- 2.11.0