lkml.org 
[lkml]   [2019]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 4/5] arm64: irqflags: Introduce explicit debugging for IRQ priorities
Date
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 | 14 ++++++++++++++
3 files changed, 34 insertions(+)

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 a32ece9..9512968 100644
--- a/arch/arm64/include/asm/daifflags.h
+++ b/arch/arm64/include/asm/daifflags.h
@@ -28,6 +28,11 @@
/* 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_IRQOFF |
+ GIC_PRIO_IGNORE_PMR)));
+
asm volatile(
"msr daifset, #0xf // local_daif_mask\n"
:
@@ -62,6 +67,10 @@ 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));
+
if (!irq_disabled) {
trace_hardirqs_on();

diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h
index 516cdfc..a40abc2 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",
@@ -53,6 +60,13 @@ static inline void arch_local_irq_enable(void)

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);
+ }
+
asm volatile(ALTERNATIVE(
"msr daifset, #2 // arch_local_irq_disable",
"msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0",
--
1.9.1
\
 
 \ /
  Last update: 2019-04-29 18:01    [W:1.830 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site