From f2c281204b47309534f26dc63cee2a130c2b497b Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Mon, 7 Mar 2022 18:08:59 +0000 Subject: [PATCH] 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: Marc Zyngier Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20220307180900.3045812-1-broonie@kernel.org Signed-off-by: Will Deacon --- arch/arm64/include/asm/cpufeature.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 2728abd..2b407fb 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -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); -- 2.7.4