arm64: cpufeature: Fix CLRBHB and BC detection

ClearBHB support is indicated by the CLRBHB field in ID_AA64ISAR2_EL1.
Following some refactoring the kernel incorrectly checks the BC field
instead. Fix the detection to use the right field.

(Note: The original ClearBHB support had it as FTR_HIGHER_SAFE, but this
patch uses FTR_LOWER_SAFE, which seems more correct.)

Also fix the detection of BC (hinted conditional branches) to use
FTR_LOWER_SAFE, so that it is not reported on mismatched systems.

Fixes: 356137e68a9f ("arm64/sysreg: Make BHB clear feature defines match the architecture")
Fixes: 8fcc8285c0e3 ("arm64/sysreg: Convert ID_AA64ISAR2_EL1 to automatic generation")
Cc: stable@vger.kernel.org
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230912133429.2606875-1-kristina.martsenko@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 96e50227f940..5bba39376055 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -663,7 +663,7 @@ static inline bool supports_clearbhb(int scope)
 		isar2 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR2_EL1);
 
 	return cpuid_feature_extract_unsigned_field(isar2,
-						    ID_AA64ISAR2_EL1_BC_SHIFT);
+						    ID_AA64ISAR2_EL1_CLRBHB_SHIFT);
 }
 
 const struct cpumask *system_32bit_el0_cpumask(void);