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[4/4] arm64: irqflags: Introduce explicit debugging for IRQ priorities

Message ID 1555424556-46023-5-git-send-email-julien.thierry@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: Fix save/restore with IRQ priority masking | expand

Commit Message

Julien Thierry April 16, 2019, 2:22 p.m. UTC 
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 <julien.thierry@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/Kconfig                 | 11 +++++++++++
 arch/arm64/include/asm/daifflags.h |  9 +++++++++
 arch/arm64/include/asm/irqflags.h  | 23 +++++++++++++++++++++--
 3 files changed, 41 insertions(+), 2 deletions(-)

--
1.9.1
diff mbox series

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7e34b9e..3fb38f3 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1359,6 +1359,17 @@  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/daifflags.h b/arch/arm64/include/asm/daifflags.h
index e575fdb..0a1add9 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(IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) &&
+		system_uses_irq_prio_masking() &&
+		(read_sysreg_s(SYS_ICC_PMR_EL1) & GIC_PRIO_WAIT_GIC_BIT));
+
 	asm volatile(
 		"msr	daifset, #0xf		// local_daif_mask\n"
 		:
@@ -62,6 +66,11 @@  static inline void local_daif_restore(unsigned long flags)
 {
 	bool irq_disabled = flags & PSR_I_BIT;

+	WARN_ON(IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING)
+		&& system_uses_irq_prio_masking()
+		&& (!(read_sysreg(daif) & PSR_I_BIT) ||
+		    read_sysreg_s(SYS_ICC_PMR_EL1) & GIC_PRIO_WAIT_GIC_BIT));
+
 	if (!irq_disabled) {
 		trace_hardirqs_on();

diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h
index 4eeaa65..2cb13a7 100644
--- a/arch/arm64/include/asm/irqflags.h
+++ b/arch/arm64/include/asm/irqflags.h
@@ -40,6 +40,13 @@ 
  */
 static inline void arch_local_irq_enable(void)
 {
+	if (IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) &&
+	    system_uses_irq_prio_masking()) {
+		u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1);
+
+		WARN_ON(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF);
+	}
+
 	asm volatile(ALTERNATIVE(
 		"msr	daifclr, #2		// arch_local_irq_enable\n"
 		"nop",
@@ -51,7 +58,7 @@  static inline void arch_local_irq_enable(void)
 		: "memory");
 }

-static inline void arch_local_irq_disable(void)
+static inline void _arch_local_irq_disable_nocheck(void)
 {
 	asm volatile(ALTERNATIVE(
 		"msr	daifset, #2		// arch_local_irq_disable",
@@ -62,6 +69,18 @@  static inline void arch_local_irq_disable(void)
 		: "memory");
 }

+static inline void arch_local_irq_disable(void)
+{
+	if (IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) &&
+	    system_uses_irq_prio_masking()) {
+		u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1);
+
+		WARN_ON(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF);
+	}
+
+	_arch_local_irq_disable_nocheck();
+}
+
 /*
  * Save the current interrupt enable state.
  */
@@ -86,7 +105,7 @@  static inline unsigned long arch_local_irq_save(void)

 	flags = arch_local_save_flags();

-	arch_local_irq_disable();
+	_arch_local_irq_disable_nocheck();

 	return flags;
 }