[PATCH for-4.8 V2 10/10] powerpc/mm: Catch the usage of cpu/mmu_has_feature before jump label init

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

This enable us to catch the wrong usage of cpu_has_feature and
mmu_has_feature in the code. We need to use the feature bit based
check in show_regs because that is used in the reporting code.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/Kconfig.debug             | 11 +++++++++++
 arch/powerpc/include/asm/cpufeatures.h |  6 ++++++
 arch/powerpc/include/asm/mmu.h         | 13 +++++++++++++
 arch/powerpc/kernel/process.c          |  2 +-
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 8243ada23237..e4da4e4985fe 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -60,6 +60,17 @@ config CODE_PATCHING_SELFTEST
 	depends on DEBUG_KERNEL
 	default n
 
+config FEATURE_FIXUP_DEBUG
+	bool "Do extra check on feature fixup calls"
+	depends on DEBUG_KERNEL
+	default n
+	help
+	  This catch the wrong 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/cpufeatures.h b/arch/powerpc/include/asm/cpufeatures.h
index 4a4a0b898463..93e7e3e87af4 100644
--- a/arch/powerpc/include/asm/cpufeatures.h
+++ b/arch/powerpc/include/asm/cpufeatures.h
@@ -22,6 +22,12 @@ static __always_inline bool cpu_has_feature(unsigned long feature)
 {
 	int i;
 
+#ifdef CONFIG_FEATURE_FIXUP_DEBUG
+	if (!static_key_initialized) {
+		WARN_ON(1);
+		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 3726161f6a8d..5c1f3a4cb99f 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -152,6 +152,12 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
 {
 	int i;
 
+#ifdef CONFIG_FEATURE_FIXUP_DEBUG
+	if (!static_key_initialized) {
+		WARN_ON(1);
+		return __mmu_has_feature(feature);
+	}
+#endif
 	if (!(MMU_FTRS_POSSIBLE & feature))
 		return false;
 
@@ -163,6 +169,13 @@ 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_feat_keys[i]);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 75611b984faa..5a08cff6621c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1315,7 +1315,7 @@ void show_regs(struct pt_regs * regs)
 	print_msr_bits(regs->msr);
 	printk("  CR: %08lx  XER: %08lx\n", regs->ccr, regs->xer);
 	trap = TRAP(regs);
-	if ((regs->trap != 0xc00) && cpu_has_feature(CPU_FTR_CFAR))
+	if ((regs->trap != 0xc00) && __cpu_has_feature(CPU_FTR_CFAR))
 		printk("CFAR: "REG" ", regs->orig_gpr3);
 	if (trap == 0x200 || trap == 0x300 || trap == 0x600)
 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
-- 
2.7.4