lkml.org 
[lkml]   [2019]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v3 6/8] 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/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
\
 
 \ /
  Last update: 2019-06-06 11:33    [W:0.144 / U:0.360 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site