cpu_has_feature()/mmu_has_feature() are only able to check a single
feature at a time, but there is no enforcement of that.
In fact, as fixed in the previous commit, there was code that was
passing multiple values to cpu_has_feature().
So add a check that only a single feature is passed using popcount.
Note that the test allows 0 or 1 bits to be set, because some code
relies on cpu_has_feature(0) being false, the check with
CPU_FTRS_POSSIBLE ensures that. See for example CPU_FTR_PPC_LE.
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
arch/powerpc/include/asm/cpu_has_feature.h | 1 +
arch/powerpc/include/asm/mmu.h | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/powerpc/include/asm/cpu_has_feature.h
b/arch/powerpc/include/asm/cpu_has_feature.h
index 92e24e979954..bf8a228229fa 100644
--- a/arch/powerpc/include/asm/cpu_has_feature.h
+++ b/arch/powerpc/include/asm/cpu_has_feature.h
@@ -25,6 +25,7 @@ static __always_inline bool cpu_has_feature(unsigned long
feature)
int i;
BUILD_BUG_ON(!__builtin_constant_p(feature));
+ BUILD_BUG_ON(__builtin_popcountl(feature) > 1);
#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
if (!static_key_feature_checks_initialized) {
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 4ab9a630d943..eb3065692055 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -247,6 +247,7 @@ static __always_inline bool mmu_has_feature(unsigned long
feature)
int i;
BUILD_BUG_ON(!__builtin_constant_p(feature));
+ BUILD_BUG_ON(__builtin_popcountl(feature) > 1);
#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
if (!static_key_feature_checks_initialized) {
--
2.45.0
