[PATCH v3 20/21] powerpc/mm: Catch usage of cpu/mmu_has_feature() before jump label init
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-07-27 14:18:57
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
From: "Aneesh Kumar K.V" <redacted>
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 <redacted>
Signed-off-by: Michael Ellerman <mpe@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]);