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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/arm64/kernel/idreg-override.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm64/kernel/idreg-override.c')
-rw-r--r-- | arch/arm64/kernel/idreg-override.c | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c new file mode 100644 index 000000000..95133765e --- /dev/null +++ b/arch/arm64/kernel/idreg-override.c @@ -0,0 +1,321 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Early cpufeature override framework + * + * Copyright (C) 2020 Google LLC + * Author: Marc Zyngier <maz@kernel.org> + */ + +#include <linux/ctype.h> +#include <linux/kernel.h> +#include <linux/libfdt.h> + +#include <asm/cacheflush.h> +#include <asm/cpufeature.h> +#include <asm/setup.h> + +#define FTR_DESC_NAME_LEN 20 +#define FTR_DESC_FIELD_LEN 10 +#define FTR_ALIAS_NAME_LEN 30 +#define FTR_ALIAS_OPTION_LEN 116 + +static u64 __boot_status __initdata; + +struct ftr_set_desc { + char name[FTR_DESC_NAME_LEN]; + struct arm64_ftr_override *override; + struct { + char name[FTR_DESC_FIELD_LEN]; + u8 shift; + u8 width; + bool (*filter)(u64 val); + } fields[]; +}; + +#define FIELD(n, s, f) { .name = n, .shift = s, .width = 4, .filter = f } + +static bool __init mmfr1_vh_filter(u64 val) +{ + /* + * If we ever reach this point while running VHE, we're + * guaranteed to be on one of these funky, VHE-stuck CPUs. If + * the user was trying to force nVHE on us, proceed with + * attitude adjustment. + */ + return !(__boot_status == (BOOT_CPU_FLAG_E2H | BOOT_CPU_MODE_EL2) && + val == 0); +} + +static const struct ftr_set_desc mmfr1 __initconst = { + .name = "id_aa64mmfr1", + .override = &id_aa64mmfr1_override, + .fields = { + FIELD("vh", ID_AA64MMFR1_EL1_VH_SHIFT, mmfr1_vh_filter), + {} + }, +}; + +static bool __init pfr0_sve_filter(u64 val) +{ + /* + * Disabling SVE also means disabling all the features that + * are associated with it. The easiest way to do it is just to + * override id_aa64zfr0_el1 to be 0. + */ + if (!val) { + id_aa64zfr0_override.val = 0; + id_aa64zfr0_override.mask = GENMASK(63, 0); + } + + return true; +} + +static const struct ftr_set_desc pfr0 __initconst = { + .name = "id_aa64pfr0", + .override = &id_aa64pfr0_override, + .fields = { + FIELD("sve", ID_AA64PFR0_EL1_SVE_SHIFT, pfr0_sve_filter), + {} + }, +}; + +static bool __init pfr1_sme_filter(u64 val) +{ + /* + * Similarly to SVE, disabling SME also means disabling all + * the features that are associated with it. Just set + * id_aa64smfr0_el1 to 0 and don't look back. + */ + if (!val) { + id_aa64smfr0_override.val = 0; + id_aa64smfr0_override.mask = GENMASK(63, 0); + } + + return true; +} + +static const struct ftr_set_desc pfr1 __initconst = { + .name = "id_aa64pfr1", + .override = &id_aa64pfr1_override, + .fields = { + FIELD("bt", ID_AA64PFR1_EL1_BT_SHIFT, NULL ), + FIELD("mte", ID_AA64PFR1_EL1_MTE_SHIFT, NULL), + FIELD("sme", ID_AA64PFR1_EL1_SME_SHIFT, pfr1_sme_filter), + {} + }, +}; + +static const struct ftr_set_desc isar1 __initconst = { + .name = "id_aa64isar1", + .override = &id_aa64isar1_override, + .fields = { + FIELD("gpi", ID_AA64ISAR1_EL1_GPI_SHIFT, NULL), + FIELD("gpa", ID_AA64ISAR1_EL1_GPA_SHIFT, NULL), + FIELD("api", ID_AA64ISAR1_EL1_API_SHIFT, NULL), + FIELD("apa", ID_AA64ISAR1_EL1_APA_SHIFT, NULL), + {} + }, +}; + +static const struct ftr_set_desc isar2 __initconst = { + .name = "id_aa64isar2", + .override = &id_aa64isar2_override, + .fields = { + FIELD("gpa3", ID_AA64ISAR2_EL1_GPA3_SHIFT, NULL), + FIELD("apa3", ID_AA64ISAR2_EL1_APA3_SHIFT, NULL), + {} + }, +}; + +static const struct ftr_set_desc smfr0 __initconst = { + .name = "id_aa64smfr0", + .override = &id_aa64smfr0_override, + .fields = { + /* FA64 is a one bit field... :-/ */ + { "fa64", ID_AA64SMFR0_EL1_FA64_SHIFT, 1, }, + {} + }, +}; + +extern struct arm64_ftr_override kaslr_feature_override; + +static const struct ftr_set_desc kaslr __initconst = { + .name = "kaslr", +#ifdef CONFIG_RANDOMIZE_BASE + .override = &kaslr_feature_override, +#endif + .fields = { + FIELD("disabled", 0, NULL), + {} + }, +}; + +static const struct ftr_set_desc * const regs[] __initconst = { + &mmfr1, + &pfr0, + &pfr1, + &isar1, + &isar2, + &smfr0, + &kaslr, +}; + +static const struct { + char alias[FTR_ALIAS_NAME_LEN]; + char feature[FTR_ALIAS_OPTION_LEN]; +} aliases[] __initconst = { + { "kvm-arm.mode=nvhe", "id_aa64mmfr1.vh=0" }, + { "kvm-arm.mode=protected", "id_aa64mmfr1.vh=0" }, + { "arm64.nosve", "id_aa64pfr0.sve=0 id_aa64pfr1.sme=0" }, + { "arm64.nosme", "id_aa64pfr1.sme=0" }, + { "arm64.nobti", "id_aa64pfr1.bt=0" }, + { "arm64.nopauth", + "id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 " + "id_aa64isar1.api=0 id_aa64isar1.apa=0 " + "id_aa64isar2.gpa3=0 id_aa64isar2.apa3=0" }, + { "arm64.nomte", "id_aa64pfr1.mte=0" }, + { "nokaslr", "kaslr.disabled=1" }, +}; + +static int __init find_field(const char *cmdline, + const struct ftr_set_desc *reg, int f, u64 *v) +{ + char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2]; + int len; + + len = snprintf(opt, ARRAY_SIZE(opt), "%s.%s=", + reg->name, reg->fields[f].name); + + if (!parameqn(cmdline, opt, len)) + return -1; + + return kstrtou64(cmdline + len, 0, v); +} + +static void __init match_options(const char *cmdline) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + int f; + + if (!regs[i]->override) + continue; + + for (f = 0; strlen(regs[i]->fields[f].name); f++) { + u64 shift = regs[i]->fields[f].shift; + u64 width = regs[i]->fields[f].width ?: 4; + u64 mask = GENMASK_ULL(shift + width - 1, shift); + u64 v; + + if (find_field(cmdline, regs[i], f, &v)) + continue; + + /* + * If an override gets filtered out, advertise + * it by setting the value to the all-ones while + * clearing the mask... Yes, this is fragile. + */ + if (regs[i]->fields[f].filter && + !regs[i]->fields[f].filter(v)) { + regs[i]->override->val |= mask; + regs[i]->override->mask &= ~mask; + continue; + } + + regs[i]->override->val &= ~mask; + regs[i]->override->val |= (v << shift) & mask; + regs[i]->override->mask |= mask; + + return; + } + } +} + +static __init void __parse_cmdline(const char *cmdline, bool parse_aliases) +{ + do { + char buf[256]; + size_t len; + int i; + + cmdline = skip_spaces(cmdline); + + for (len = 0; cmdline[len] && !isspace(cmdline[len]); len++); + if (!len) + return; + + len = min(len, ARRAY_SIZE(buf) - 1); + strncpy(buf, cmdline, len); + buf[len] = 0; + + if (strcmp(buf, "--") == 0) + return; + + cmdline += len; + + match_options(buf); + + for (i = 0; parse_aliases && i < ARRAY_SIZE(aliases); i++) + if (parameq(buf, aliases[i].alias)) + __parse_cmdline(aliases[i].feature, false); + } while (1); +} + +static __init const u8 *get_bootargs_cmdline(void) +{ + const u8 *prop; + void *fdt; + int node; + + fdt = get_early_fdt_ptr(); + if (!fdt) + return NULL; + + node = fdt_path_offset(fdt, "/chosen"); + if (node < 0) + return NULL; + + prop = fdt_getprop(fdt, node, "bootargs", NULL); + if (!prop) + return NULL; + + return strlen(prop) ? prop : NULL; +} + +static __init void parse_cmdline(void) +{ + const u8 *prop = get_bootargs_cmdline(); + + if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop) + __parse_cmdline(CONFIG_CMDLINE, true); + + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop) + __parse_cmdline(prop, true); +} + +/* Keep checkers quiet */ +void init_feature_override(u64 boot_status); + +asmlinkage void __init init_feature_override(u64 boot_status) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + if (regs[i]->override) { + regs[i]->override->val = 0; + regs[i]->override->mask = 0; + } + } + + __boot_status = boot_status; + + parse_cmdline(); + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + if (regs[i]->override) + dcache_clean_inval_poc((unsigned long)regs[i]->override, + (unsigned long)regs[i]->override + + sizeof(*regs[i]->override)); + } +} |