Commit f2c28120 authored by Mark Brown's avatar Mark Brown Committed by Will Deacon
Browse files

arm64: cpufeature: Warn if we attempt to read a zero width field 



Add a WARN_ON_ONCE() when extracting a field if no width is specified. This
should never happen outside of development since it will be triggered with
or without the feature so long as the relevant ID register is present.  If
the warning triggers hope that the field was the standard 4 bits wide and
soldier on.

Suggested-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220307180900.3045812-1-broonie@kernel.org


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent b8fc7801

arch/arm64/include/asm/cpufeature.h

+2 −0
Original line number Diff line number Diff line
@@ -577,6 +577,8 @@ static inline u64 arm64_ftr_reg_user_value(const struct arm64_ftr_reg *reg) 
static inline int __attribute_const__

cpuid_feature_extract_field_width(u64 features, int field, int width, bool sign)

{

	if (WARN_ON_ONCE(!width))

		width = 4;

	return (sign) ?

		cpuid_feature_extract_signed_field_width(features, field, width) :

		cpuid_feature_extract_unsigned_field_width(features, field, width);