Introduce one boot cpu feature per page size, ARM64_USE_PAGE_SIZE_*K. These will enable use of the alternatives framework to patch code based on the page size selected at boot. Additionally, this provides a neat way to figure out what page size is in use during boot from the kernel log. Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@xxxxxxx/ arch/arm64/kernel/cpufeature.c | 25 +++++++++++++++++++++++++ arch/arm64/tools/cpucaps | 3 +++ 2 files changed, 28 insertions(+) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 7705c9c0e7142..e5618423bb99d 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1831,6 +1831,13 @@ static bool has_nv1(const struct arm64_cpu_capabilities *entry, int scope) is_midr_in_range_list(read_cpuid_id(), nv1_ni_list))); } +static bool use_page_size(const struct arm64_cpu_capabilities *entry, int scope) +{ + return (entry->capability == ARM64_USE_PAGE_SIZE_4K && PAGE_SIZE == SZ_4K) || + (entry->capability == ARM64_USE_PAGE_SIZE_16K && PAGE_SIZE == SZ_16K) || + (entry->capability == ARM64_USE_PAGE_SIZE_64K && PAGE_SIZE == SZ_64K); +} + static bool has_lpa2_at_stage1(u64 mmfr0) { unsigned int tgran; @@ -2881,6 +2888,24 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .matches = has_nv1, ARM64_CPUID_FIELDS_NEG(ID_AA64MMFR4_EL1, E2H0, NI_NV1) }, + { + .desc = "4K page size", + .capability = ARM64_USE_PAGE_SIZE_4K, + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE, + .matches = use_page_size, + }, + { + .desc = "16K page size", + .capability = ARM64_USE_PAGE_SIZE_16K, + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE, + .matches = use_page_size, + }, + { + .desc = "64K page size", + .capability = ARM64_USE_PAGE_SIZE_64K, + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE, + .matches = use_page_size, + }, {}, }; diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index ac3429d892b9a..5cb75675303c6 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -71,6 +71,9 @@ SPECTRE_BHB SSBS SVE UNMAP_KERNEL_AT_EL0 +USE_PAGE_SIZE_4K +USE_PAGE_SIZE_16K +USE_PAGE_SIZE_64K WORKAROUND_834220 WORKAROUND_843419 WORKAROUND_845719 -- 2.43.0
