Using IRQ priority masking to enable/disable interrupts is a bit sensitive as it requires to deal with both ICC_PMR_EL1 and PSR.I.
Introduce some validity checks to both highlight the states in which functions dealing with IRQ enabling/disabling can (not) be called, and bark a warning when called in an unexpected state. Since these checks are done on hotpaths, introduce a build option to choose whether to do the checking. Signed-off-by: Julien Thierry <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> --- arch/arm64/Kconfig | 11 +++++++++++ arch/arm64/include/asm/cpufeature.h | 6 ++++++ arch/arm64/include/asm/daifflags.h | 7 +++++++ arch/arm64/include/asm/irqflags.h | 14 +++++++++++++- 4 files changed, 37 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 697ea05..8acc40e 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1436,6 +1436,17 @@ config ARM64_PSEUDO_NMI If unsure, say N +if ARM64_PSEUDO_NMI +config ARM64_DEBUG_PRIORITY_MASKING + bool "Debug interrupt priority masking" + help + This adds runtime checks to functions enabling/disabling + interrupts when using priority masking. The additional checks verify + the validity of ICC_PMR_EL1 when calling concerned functions. + + If unsure, say N +endif + config RELOCATABLE bool help diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index bc895c8..693a086 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -617,6 +617,12 @@ static inline bool system_uses_irq_prio_masking(void) cpus_have_const_cap(ARM64_HAS_IRQ_PRIO_MASKING); } +static inline bool system_has_prio_mask_debugging(void) +{ + return IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) && + system_uses_irq_prio_masking(); +} + #define ARM64_SSBD_UNKNOWN -1 #define ARM64_SSBD_FORCE_DISABLE 0 #define ARM64_SSBD_KERNEL 1 diff --git a/arch/arm64/include/asm/daifflags.h b/arch/arm64/include/asm/daifflags.h index f93204f..eca5bee 100644 --- a/arch/arm64/include/asm/daifflags.h +++ b/arch/arm64/include/asm/daifflags.h @@ -28,6 +28,10 @@ /* mask/save/unmask/restore all exceptions, including interrupts. */ static inline void local_daif_mask(void) { + WARN_ON(system_has_prio_mask_debugging() && + (read_sysreg_s(SYS_ICC_PMR_EL1) == (GIC_PRIO_IRQOFF | + GIC_PRIO_PSR_I_SET))); + asm volatile( "msr daifset, #0xf // local_daif_mask\n" : @@ -62,6 +66,9 @@ static inline void local_daif_restore(unsigned long flags) { bool irq_disabled = flags & PSR_I_BIT; + WARN_ON(system_has_prio_mask_debugging() && + !(read_sysreg(daif) & PSR_I_BIT)); + if (!irq_disabled) { trace_hardirqs_on(); diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h index b6f757f..cac2d2a 100644 --- a/arch/arm64/include/asm/irqflags.h +++ b/arch/arm64/include/asm/irqflags.h @@ -40,6 +40,12 @@ */ static inline void arch_local_irq_enable(void) { + if (system_has_prio_mask_debugging()) { + u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1); + + WARN_ON_ONCE(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF); + } + asm volatile(ALTERNATIVE( "msr daifclr, #2 // arch_local_irq_enable\n" "nop", @@ -53,6 +59,12 @@ static inline void arch_local_irq_enable(void) static inline void arch_local_irq_disable(void) { + if (system_has_prio_mask_debugging()) { + u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1); + + WARN_ON_ONCE(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF); + } + asm volatile(ALTERNATIVE( "msr daifset, #2 // arch_local_irq_disable", __msr_s(SYS_ICC_PMR_EL1, "%0"), @@ -86,7 +98,7 @@ static inline int arch_irqs_disabled_flags(unsigned long flags) asm volatile(ALTERNATIVE( "and %w0, %w1, #" __stringify(PSR_I_BIT), - "eor %w0, %w1, #" __stringify(GIC_PRIO_IRQOFF), + "eor %w0, %w1, #" __stringify(GIC_PRIO_IRQON), ARM64_HAS_IRQ_PRIO_MASKING) : "=&r" (res) : "r" ((int) flags) -- 1.9.1
