From 17ce302f3117e9518395847a3120c8a108b587b8 Mon Sep 17 00:00:00 2001 From: Julien Thierry Date: Tue, 11 Jun 2019 10:38:09 +0100 Subject: [PATCH] arm64: Fix interrupt tracing in the presence of NMIs In the presence of any form of instrumentation, nmi_enter() should be done before calling any traceable code and any instrumentation code. Currently, nmi_enter() is done in handle_domain_nmi(), which is much too late as instrumentation code might get called before. Move the nmi_enter/exit() calls to the arch IRQ vector handler. On arm64, it is not possible to know if the IRQ vector handler was called because of an NMI before acknowledging the interrupt. However, It is possible to know whether normal interrupts could be taken in the interrupted context (i.e. if taking an NMI in that context could introduce a potential race condition). When interrupting a context with IRQs disabled, call nmi_enter() as soon as possible. In contexts with IRQs enabled, defer this to the interrupt controller, which is in a better position to know if an interrupt taken is an NMI. Fixes: bc3c03ccb464 ("arm64: Enable the support of pseudo-NMIs") Cc: # 5.1.x- Cc: Will Deacon Cc: Thomas Gleixner Cc: Jason Cooper Cc: Mark Rutland Reviewed-by: Marc Zyngier Signed-off-by: Julien Thierry Signed-off-by: Catalin Marinas --- arch/arm64/kernel/entry.S | 46 ++++++++++++++++++++++++++---------- arch/arm64/kernel/irq.c | 17 +++++++++++++ drivers/irqchip/irq-gic-v3.c | 7 ++++++ kernel/irq/irqdesc.c | 8 +++++-- 4 files changed, 64 insertions(+), 14 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 89ab6bd896c4..6d5966346710 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -435,6 +435,20 @@ tsk .req x28 // current thread_info irq_stack_exit .endm +#ifdef CONFIG_ARM64_PSEUDO_NMI + /* + * Set res to 0 if irqs were unmasked in interrupted context. + * Otherwise set res to non-0 value. + */ + .macro test_irqs_unmasked res:req, pmr:req +alternative_if ARM64_HAS_IRQ_PRIO_MASKING + sub \res, \pmr, #GIC_PRIO_IRQON +alternative_else + mov \res, xzr +alternative_endif + .endm +#endif + .text /* @@ -631,21 +645,21 @@ ENDPROC(el1_sync) el1_irq: kernel_entry 1 enable_da_f -#ifdef CONFIG_TRACE_IRQFLAGS + #ifdef CONFIG_ARM64_PSEUDO_NMI alternative_if ARM64_HAS_IRQ_PRIO_MASKING ldr x20, [sp, #S_PMR_SAVE] -alternative_else - mov x20, #GIC_PRIO_IRQON -alternative_endif - cmp x20, #GIC_PRIO_IRQOFF - /* Irqs were disabled, don't trace */ - b.ls 1f -#endif - bl trace_hardirqs_off +alternative_else_nop_endif + test_irqs_unmasked res=x0, pmr=x20 + cbz x0, 1f + bl asm_nmi_enter 1: #endif +#ifdef CONFIG_TRACE_IRQFLAGS + bl trace_hardirqs_off +#endif + irq_handler #ifdef CONFIG_PREEMPT @@ -662,14 +676,22 @@ alternative_else_nop_endif bl preempt_schedule_irq // irq en/disable is done inside 1: #endif -#ifdef CONFIG_TRACE_IRQFLAGS + #ifdef CONFIG_ARM64_PSEUDO_NMI /* * if IRQs were disabled when we received the interrupt, we have an NMI * and we are not re-enabling interrupt upon eret. Skip tracing. */ - cmp x20, #GIC_PRIO_IRQOFF - b.ls 1f + test_irqs_unmasked res=x0, pmr=x20 + cbz x0, 1f + bl asm_nmi_exit +1: +#endif + +#ifdef CONFIG_TRACE_IRQFLAGS +#ifdef CONFIG_ARM64_PSEUDO_NMI + test_irqs_unmasked res=x0, pmr=x20 + cbnz x0, 1f #endif bl trace_hardirqs_on 1: diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index 92fa81798fb9..fdd9cb27fed5 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -27,8 +27,10 @@ #include #include #include +#include #include #include +#include #include unsigned long irq_err_count; @@ -76,3 +78,18 @@ void __init init_IRQ(void) if (!handle_arch_irq) panic("No interrupt controller found."); } + +/* + * Stubs to make nmi_enter/exit() code callable from ASM + */ +asmlinkage void notrace asm_nmi_enter(void) +{ + nmi_enter(); +} +NOKPROBE_SYMBOL(asm_nmi_enter); + +asmlinkage void notrace asm_nmi_exit(void) +{ + nmi_exit(); +} +NOKPROBE_SYMBOL(asm_nmi_exit); diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index f44cd89cfc40..b176700bb387 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -472,8 +472,12 @@ static void gic_deactivate_unhandled(u32 irqnr) static inline void gic_handle_nmi(u32 irqnr, struct pt_regs *regs) { + bool irqs_enabled = interrupts_enabled(regs); int err; + if (irqs_enabled) + nmi_enter(); + if (static_branch_likely(&supports_deactivate_key)) gic_write_eoir(irqnr); /* @@ -485,6 +489,9 @@ static inline void gic_handle_nmi(u32 irqnr, struct pt_regs *regs) err = handle_domain_nmi(gic_data.domain, irqnr, regs); if (err) gic_deactivate_unhandled(irqnr); + + if (irqs_enabled) + nmi_exit(); } static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs) diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index c52b737ab8e3..a92b33593b8d 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -680,6 +680,8 @@ int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq, * @hwirq: The HW irq number to convert to a logical one * @regs: Register file coming from the low-level handling code * + * This function must be called from an NMI context. + * * Returns: 0 on success, or -EINVAL if conversion has failed */ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq, @@ -689,7 +691,10 @@ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq, unsigned int irq; int ret = 0; - nmi_enter(); + /* + * NMI context needs to be setup earlier in order to deal with tracing. + */ + WARN_ON(!in_nmi()); irq = irq_find_mapping(domain, hwirq); @@ -702,7 +707,6 @@ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq, else ret = -EINVAL; - nmi_exit(); set_irq_regs(old_regs); return ret; }