From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Date: Sat, 23 Jul 2016 09:12:43 +0000 (+0530)
Subject: powerpc/mm: Catch usage of cpu/mmu_has_feature() before jump label init
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c812c7d8f1470ac9c8aa6d7e29b56e5845ee05fc;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

powerpc/mm: Catch usage of cpu/mmu_has_feature() before jump label init

This allows us to catch incorrect usage of cpu_has_feature() and
mmu_has_feature() prior to jump labels being initialised.

mpe: Use printk() and dump_stack() rather than WARN_ON(), because
WARN_ON() may not work this early in boot. Rename the Kconfig.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 36d7e345f599..63292f64b25a 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 039c011b4252..2ef55f8968a2 100644
--- a/arch/powerpc/include/asm/cpu_has_feature.h
+++ b/arch/powerpc/include/asm/cpu_has_feature.h
@@ -25,6 +25,14 @@ static __always_inline bool cpu_has_feature(unsigned long feature)
 
 	BUILD_BUG_ON(!__builtin_constant_p(feature));
 
+#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 early_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 1bf919aafd50..e2fb408f8398 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -156,6 +156,14 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
 
 	BUILD_BUG_ON(!__builtin_constant_p(feature));
 
+#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 early_mmu_has_feature(feature);
+	}
+#endif
+
 	if (!(MMU_FTRS_POSSIBLE & feature))
 		return false;