From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
This allows us to catch incorrect usage of cpu_has_feature() and
mmu_has_feature() prior to jump labels being initialised.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
arch/powerpc/Kconfig.debug | 10 ++++++++++
arch/powerpc/include/asm/cpu_has_feature.h | 7 +++++++
arch/powerpc/include/asm/mmu.h | 14 ++++++++++++++
arch/powerpc/kernel/process.c | 2 +-
4 files changed, 32 insertions(+), 1 deletion(-)
v3: Use printk() and dump_stack() rather than WARN_ON(), because
WARN_ON() may not work this early in boot.
Rename the Kconfig.
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 2512dac77adb..0108fde08d90 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -69,6 +69,16 @@ config JUMP_LABEL_FEATURE_CHECKS
feature checks. This should generate more optimal code for those
checks.
+config JUMP_LABEL_FEATURE_CHECK_DEBUG
+ bool "Do extra check on feature fixup calls"
+ depends on DEBUG_KERNEL && JUMP_LABEL_FEATURE_CHECKS
+ default n
+ help
+ This tries to catch incorrect usage of cpu_has_feature() and
+ mmu_has_feature() in the code.
+
+ If you don't know what this means, say N.
+
config FTR_FIXUP_SELFTEST
bool "Run self-tests of the feature-fixup code"
depends on DEBUG_KERNEL
diff --git a/arch/powerpc/include/asm/cpu_has_feature.h
b/arch/powerpc/include/asm/cpu_has_feature.h
index 18e60e61bea9..b702a48c438d 100644
--- a/arch/powerpc/include/asm/cpu_has_feature.h
+++ b/arch/powerpc/include/asm/cpu_has_feature.h
@@ -22,6 +22,13 @@ static __always_inline bool cpu_has_feature(unsigned long
feature)
{
int i;
+#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
+ if (!static_key_initialized) {
+ printk("Warning! cpu_has_feature() used prior to jump label
init!\n");
+ dump_stack();
+ return __cpu_has_feature(feature);
+ }
+#endif
if (CPU_FTRS_ALWAYS & feature)
return true;
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 3900cb7fe7cf..50d8c9f78976 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -153,6 +153,13 @@ static __always_inline bool mmu_has_feature(unsigned long
feature)
{
int i;
+#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
+ if (!static_key_initialized) {
+ printk("Warning! mmu_has_feature() used prior to jump label
init!\n");
+ dump_stack();
+ return __mmu_has_feature(feature);
+ }
+#endif
if (!(MMU_FTRS_POSSIBLE & feature))
return false;
@@ -164,6 +171,13 @@ static inline void mmu_clear_feature(unsigned long feature)
{
int i;
+#ifdef CONFIG_FEATURE_FIXUP_DEBUG
+ if (!static_key_initialized) {
+ WARN_ON(1);
+ cur_cpu_spec->mmu_features &= ~feature;
+ return;
+ }
+#endif
i = __builtin_ctzl(feature);
cur_cpu_spec->mmu_features &= ~feature;
static_branch_disable(&mmu_feature_keys[i]);
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