323 lines
7.2 KiB
C
323 lines
7.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Early cpufeature override framework
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*
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* Copyright (C) 2020 Google LLC
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* Author: Marc Zyngier <maz@kernel.org>
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*/
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#include <linux/ctype.h>
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#include <linux/kernel.h>
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#include <linux/libfdt.h>
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#include <asm/cacheflush.h>
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#include <asm/cpufeature.h>
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#include <asm/setup.h>
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#define FTR_DESC_NAME_LEN 20
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#define FTR_DESC_FIELD_LEN 10
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#define FTR_ALIAS_NAME_LEN 30
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#define FTR_ALIAS_OPTION_LEN 116
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static u64 __boot_status __initdata;
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struct ftr_set_desc {
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char name[FTR_DESC_NAME_LEN];
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struct arm64_ftr_override *override;
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struct {
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char name[FTR_DESC_FIELD_LEN];
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u8 shift;
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u8 width;
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bool (*filter)(u64 val);
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} fields[];
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};
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#define FIELD(n, s, f) { .name = n, .shift = s, .width = 4, .filter = f }
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static bool __init mmfr1_vh_filter(u64 val)
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{
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/*
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* If we ever reach this point while running VHE, we're
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* guaranteed to be on one of these funky, VHE-stuck CPUs. If
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* the user was trying to force nVHE on us, proceed with
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* attitude adjustment.
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*/
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return !(__boot_status == (BOOT_CPU_FLAG_E2H | BOOT_CPU_MODE_EL2) &&
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val == 0);
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}
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static const struct ftr_set_desc mmfr1 __initconst = {
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.name = "id_aa64mmfr1",
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.override = &id_aa64mmfr1_override,
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.fields = {
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FIELD("vh", ID_AA64MMFR1_EL1_VH_SHIFT, mmfr1_vh_filter),
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{}
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},
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};
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static bool __init pfr0_sve_filter(u64 val)
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{
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/*
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* Disabling SVE also means disabling all the features that
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* are associated with it. The easiest way to do it is just to
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* override id_aa64zfr0_el1 to be 0.
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*/
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if (!val) {
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id_aa64zfr0_override.val = 0;
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id_aa64zfr0_override.mask = GENMASK(63, 0);
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}
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return true;
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}
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static const struct ftr_set_desc pfr0 __initconst = {
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.name = "id_aa64pfr0",
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.override = &id_aa64pfr0_override,
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.fields = {
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FIELD("sve", ID_AA64PFR0_EL1_SVE_SHIFT, pfr0_sve_filter),
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{}
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},
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};
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static bool __init pfr1_sme_filter(u64 val)
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{
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/*
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* Similarly to SVE, disabling SME also means disabling all
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* the features that are associated with it. Just set
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* id_aa64smfr0_el1 to 0 and don't look back.
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*/
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if (!val) {
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id_aa64smfr0_override.val = 0;
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id_aa64smfr0_override.mask = GENMASK(63, 0);
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}
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return true;
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}
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static const struct ftr_set_desc pfr1 __initconst = {
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.name = "id_aa64pfr1",
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.override = &id_aa64pfr1_override,
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.fields = {
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FIELD("bt", ID_AA64PFR1_EL1_BT_SHIFT, NULL ),
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FIELD("mte", ID_AA64PFR1_EL1_MTE_SHIFT, NULL),
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FIELD("sme", ID_AA64PFR1_EL1_SME_SHIFT, pfr1_sme_filter),
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{}
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},
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};
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static const struct ftr_set_desc isar1 __initconst = {
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.name = "id_aa64isar1",
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.override = &id_aa64isar1_override,
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.fields = {
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FIELD("gpi", ID_AA64ISAR1_EL1_GPI_SHIFT, NULL),
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FIELD("gpa", ID_AA64ISAR1_EL1_GPA_SHIFT, NULL),
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FIELD("api", ID_AA64ISAR1_EL1_API_SHIFT, NULL),
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FIELD("apa", ID_AA64ISAR1_EL1_APA_SHIFT, NULL),
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{}
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},
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};
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static const struct ftr_set_desc isar2 __initconst = {
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.name = "id_aa64isar2",
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.override = &id_aa64isar2_override,
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.fields = {
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FIELD("gpa3", ID_AA64ISAR2_EL1_GPA3_SHIFT, NULL),
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FIELD("apa3", ID_AA64ISAR2_EL1_APA3_SHIFT, NULL),
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{}
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},
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};
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static const struct ftr_set_desc smfr0 __initconst = {
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.name = "id_aa64smfr0",
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.override = &id_aa64smfr0_override,
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.fields = {
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FIELD("smever", ID_AA64SMFR0_EL1_SMEver_SHIFT, NULL),
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/* FA64 is a one bit field... :-/ */
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{ "fa64", ID_AA64SMFR0_EL1_FA64_SHIFT, 1, },
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{}
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},
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};
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extern struct arm64_ftr_override kaslr_feature_override;
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static const struct ftr_set_desc kaslr __initconst = {
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.name = "kaslr",
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#ifdef CONFIG_RANDOMIZE_BASE
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.override = &kaslr_feature_override,
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#endif
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.fields = {
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FIELD("disabled", 0, NULL),
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{}
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},
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};
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static const struct ftr_set_desc * const regs[] __initconst = {
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&mmfr1,
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&pfr0,
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&pfr1,
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&isar1,
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&isar2,
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&smfr0,
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&kaslr,
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};
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static const struct {
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char alias[FTR_ALIAS_NAME_LEN];
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char feature[FTR_ALIAS_OPTION_LEN];
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} aliases[] __initconst = {
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{ "kvm-arm.mode=nvhe", "id_aa64mmfr1.vh=0" },
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{ "kvm-arm.mode=protected", "id_aa64mmfr1.vh=0" },
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{ "arm64.nosve", "id_aa64pfr0.sve=0 id_aa64pfr1.sme=0" },
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{ "arm64.nosme", "id_aa64pfr1.sme=0" },
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{ "arm64.nobti", "id_aa64pfr1.bt=0" },
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{ "arm64.nopauth",
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"id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
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"id_aa64isar1.api=0 id_aa64isar1.apa=0 "
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"id_aa64isar2.gpa3=0 id_aa64isar2.apa3=0" },
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{ "arm64.nomte", "id_aa64pfr1.mte=0" },
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{ "nokaslr", "kaslr.disabled=1" },
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};
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static int __init find_field(const char *cmdline,
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const struct ftr_set_desc *reg, int f, u64 *v)
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{
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char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2];
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int len;
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len = snprintf(opt, ARRAY_SIZE(opt), "%s.%s=",
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reg->name, reg->fields[f].name);
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if (!parameqn(cmdline, opt, len))
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return -1;
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return kstrtou64(cmdline + len, 0, v);
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}
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static void __init match_options(const char *cmdline)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(regs); i++) {
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int f;
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if (!regs[i]->override)
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continue;
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for (f = 0; strlen(regs[i]->fields[f].name); f++) {
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u64 shift = regs[i]->fields[f].shift;
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u64 width = regs[i]->fields[f].width ?: 4;
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u64 mask = GENMASK_ULL(shift + width - 1, shift);
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u64 v;
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if (find_field(cmdline, regs[i], f, &v))
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continue;
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/*
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* If an override gets filtered out, advertise
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* it by setting the value to the all-ones while
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* clearing the mask... Yes, this is fragile.
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*/
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if (regs[i]->fields[f].filter &&
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!regs[i]->fields[f].filter(v)) {
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regs[i]->override->val |= mask;
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regs[i]->override->mask &= ~mask;
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continue;
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}
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regs[i]->override->val &= ~mask;
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regs[i]->override->val |= (v << shift) & mask;
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regs[i]->override->mask |= mask;
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return;
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}
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}
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}
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static __init void __parse_cmdline(const char *cmdline, bool parse_aliases)
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{
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do {
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char buf[256];
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size_t len;
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int i;
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cmdline = skip_spaces(cmdline);
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for (len = 0; cmdline[len] && !isspace(cmdline[len]); len++);
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if (!len)
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return;
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len = min(len, ARRAY_SIZE(buf) - 1);
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strncpy(buf, cmdline, len);
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buf[len] = 0;
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if (strcmp(buf, "--") == 0)
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return;
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cmdline += len;
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match_options(buf);
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for (i = 0; parse_aliases && i < ARRAY_SIZE(aliases); i++)
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if (parameq(buf, aliases[i].alias))
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__parse_cmdline(aliases[i].feature, false);
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} while (1);
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}
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static __init const u8 *get_bootargs_cmdline(void)
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{
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const u8 *prop;
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void *fdt;
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int node;
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fdt = get_early_fdt_ptr();
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if (!fdt)
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return NULL;
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node = fdt_path_offset(fdt, "/chosen");
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if (node < 0)
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return NULL;
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prop = fdt_getprop(fdt, node, "bootargs", NULL);
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if (!prop)
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return NULL;
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return strlen(prop) ? prop : NULL;
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}
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static __init void parse_cmdline(void)
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{
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const u8 *prop = get_bootargs_cmdline();
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if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop)
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__parse_cmdline(CONFIG_CMDLINE, true);
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if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop)
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__parse_cmdline(prop, true);
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}
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/* Keep checkers quiet */
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void init_feature_override(u64 boot_status);
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asmlinkage void __init init_feature_override(u64 boot_status)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(regs); i++) {
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if (regs[i]->override) {
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regs[i]->override->val = 0;
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regs[i]->override->mask = 0;
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}
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}
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__boot_status = boot_status;
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parse_cmdline();
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for (i = 0; i < ARRAY_SIZE(regs); i++) {
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if (regs[i]->override)
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dcache_clean_inval_poc((unsigned long)regs[i]->override,
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(unsigned long)regs[i]->override +
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sizeof(*regs[i]->override));
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}
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}
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