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Diffstat (limited to 'arch/arm64/kernel/pi/idreg-override.c')
-rw-r--r--arch/arm64/kernel/pi/idreg-override.c403
1 files changed, 403 insertions, 0 deletions
diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
new file mode 100644
index 000000000000..bccfee34f62f
--- /dev/null
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -0,0 +1,403 @@
+// 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>
+
+#include "pi.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;
+
+typedef bool filter_t(u64 val);
+
+struct ftr_set_desc {
+ char name[FTR_DESC_NAME_LEN];
+ PREL64(struct arm64_ftr_override, override);
+ struct {
+ char name[FTR_DESC_FIELD_LEN];
+ u8 shift;
+ u8 width;
+ PREL64(filter_t, filter);
+ } 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 __prel64_initconst = {
+ .name = "id_aa64mmfr1",
+ .override = &id_aa64mmfr1_override,
+ .fields = {
+ FIELD("vh", ID_AA64MMFR1_EL1_VH_SHIFT, mmfr1_vh_filter),
+ {}
+ },
+};
+
+
+static bool __init mmfr2_varange_filter(u64 val)
+{
+ int __maybe_unused feat;
+
+ if (val)
+ return false;
+
+#ifdef CONFIG_ARM64_LPA2
+ feat = cpuid_feature_extract_signed_field(read_sysreg(id_aa64mmfr0_el1),
+ ID_AA64MMFR0_EL1_TGRAN_SHIFT);
+ if (feat >= ID_AA64MMFR0_EL1_TGRAN_LPA2) {
+ id_aa64mmfr0_override.val |=
+ (ID_AA64MMFR0_EL1_TGRAN_LPA2 - 1) << ID_AA64MMFR0_EL1_TGRAN_SHIFT;
+ id_aa64mmfr0_override.mask |= 0xfU << ID_AA64MMFR0_EL1_TGRAN_SHIFT;
+ }
+#endif
+ return true;
+}
+
+static const struct ftr_set_desc mmfr2 __prel64_initconst = {
+ .name = "id_aa64mmfr2",
+ .override = &id_aa64mmfr2_override,
+ .fields = {
+ FIELD("varange", ID_AA64MMFR2_EL1_VARange_SHIFT, mmfr2_varange_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 __prel64_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 __prel64_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 __prel64_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 __prel64_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),
+ FIELD("mops", ID_AA64ISAR2_EL1_MOPS_SHIFT, NULL),
+ {}
+ },
+};
+
+static const struct ftr_set_desc smfr0 __prel64_initconst = {
+ .name = "id_aa64smfr0",
+ .override = &id_aa64smfr0_override,
+ .fields = {
+ FIELD("smever", ID_AA64SMFR0_EL1_SMEver_SHIFT, NULL),
+ /* FA64 is a one bit field... :-/ */
+ { "fa64", ID_AA64SMFR0_EL1_FA64_SHIFT, 1, },
+ {}
+ },
+};
+
+static bool __init hvhe_filter(u64 val)
+{
+ u64 mmfr1 = read_sysreg(id_aa64mmfr1_el1);
+
+ return (val == 1 &&
+ lower_32_bits(__boot_status) == BOOT_CPU_MODE_EL2 &&
+ cpuid_feature_extract_unsigned_field(mmfr1,
+ ID_AA64MMFR1_EL1_VH_SHIFT));
+}
+
+static const struct ftr_set_desc sw_features __prel64_initconst = {
+ .name = "arm64_sw",
+ .override = &arm64_sw_feature_override,
+ .fields = {
+ FIELD("nokaslr", ARM64_SW_FEATURE_OVERRIDE_NOKASLR, NULL),
+ FIELD("hvhe", ARM64_SW_FEATURE_OVERRIDE_HVHE, hvhe_filter),
+ FIELD("rodataoff", ARM64_SW_FEATURE_OVERRIDE_RODATA_OFF, NULL),
+ FIELD("nowxn", ARM64_SW_FEATURE_OVERRIDE_NOWXN, NULL),
+ {}
+ },
+};
+
+static const
+PREL64(const struct ftr_set_desc, reg) regs[] __prel64_initconst = {
+ { &mmfr1 },
+ { &mmfr2 },
+ { &pfr0 },
+ { &pfr1 },
+ { &isar1 },
+ { &isar2 },
+ { &smfr0 },
+ { &sw_features },
+};
+
+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" },
+ { "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.nomops", "id_aa64isar2.mops=0" },
+ { "arm64.nomte", "id_aa64pfr1.mte=0" },
+ { "nokaslr", "arm64_sw.nokaslr=1" },
+ { "rodata=off", "arm64_sw.rodataoff=1 arm64_sw.nowxn=1" },
+ { "arm64.nolva", "id_aa64mmfr2.varange=0" },
+ { "arm64.nowxn", "arm64_sw.nowxn=1" },
+};
+
+static int __init parse_hexdigit(const char *p, u64 *v)
+{
+ // skip "0x" if it comes next
+ if (p[0] == '0' && tolower(p[1]) == 'x')
+ p += 2;
+
+ // check whether the RHS is a single hex digit
+ if (!isxdigit(p[0]) || (p[1] && !isspace(p[1])))
+ return -EINVAL;
+
+ *v = tolower(*p) - (isdigit(*p) ? '0' : 'a' - 10);
+ return 0;
+}
+
+static int __init find_field(const char *cmdline, char *opt, int len,
+ const struct ftr_set_desc *reg, int f, u64 *v)
+{
+ int flen = strlen(reg->fields[f].name);
+
+ // append '<fieldname>=' to obtain '<name>.<fieldname>='
+ memcpy(opt + len, reg->fields[f].name, flen);
+ len += flen;
+ opt[len++] = '=';
+
+ if (memcmp(cmdline, opt, len))
+ return -1;
+
+ return parse_hexdigit(cmdline + len, v);
+}
+
+static void __init match_options(const char *cmdline)
+{
+ char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2];
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(regs); i++) {
+ const struct ftr_set_desc *reg = prel64_pointer(regs[i].reg);
+ struct arm64_ftr_override *override;
+ int len = strlen(reg->name);
+ int f;
+
+ override = prel64_pointer(reg->override);
+
+ // set opt[] to '<name>.'
+ memcpy(opt, reg->name, len);
+ opt[len++] = '.';
+
+ for (f = 0; reg->fields[f].name[0] != '\0'; f++) {
+ u64 shift = reg->fields[f].shift;
+ u64 width = reg->fields[f].width ?: 4;
+ u64 mask = GENMASK_ULL(shift + width - 1, shift);
+ bool (*filter)(u64 val);
+ u64 v;
+
+ if (find_field(cmdline, opt, len, reg, 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.
+ */
+ filter = prel64_pointer(reg->fields[f].filter);
+ if (filter && !filter(v)) {
+ override->val |= mask;
+ override->mask &= ~mask;
+ continue;
+ }
+
+ override->val &= ~mask;
+ override->val |= (v << shift) & mask;
+ 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);
+
+ /* terminate on "--" appearing on the command line by itself */
+ if (cmdline[0] == '-' && cmdline[1] == '-' && isspace(cmdline[2]))
+ return;
+
+ for (len = 0; cmdline[len] && !isspace(cmdline[len]); len++) {
+ if (len >= sizeof(buf) - 1)
+ break;
+ if (cmdline[len] == '-')
+ buf[len] = '_';
+ else
+ buf[len] = cmdline[len];
+ }
+ if (!len)
+ return;
+
+ buf[len] = 0;
+
+ cmdline += len;
+
+ match_options(buf);
+
+ for (i = 0; parse_aliases && i < ARRAY_SIZE(aliases); i++)
+ if (!memcmp(buf, aliases[i].alias, len + 1))
+ __parse_cmdline(aliases[i].feature, false);
+ } while (1);
+}
+
+static __init const u8 *get_bootargs_cmdline(const void *fdt, int node)
+{
+ static char const bootargs[] __initconst = "bootargs";
+ const u8 *prop;
+
+ 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(const void *fdt, int chosen)
+{
+ static char const cmdline[] __initconst = CONFIG_CMDLINE;
+ const u8 *prop = get_bootargs_cmdline(fdt, chosen);
+
+ if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop)
+ __parse_cmdline(cmdline, true);
+
+ if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop)
+ __parse_cmdline(prop, true);
+}
+
+void __init init_feature_override(u64 boot_status, const void *fdt,
+ int chosen)
+{
+ struct arm64_ftr_override *override;
+ const struct ftr_set_desc *reg;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(regs); i++) {
+ reg = prel64_pointer(regs[i].reg);
+ override = prel64_pointer(reg->override);
+
+ override->val = 0;
+ override->mask = 0;
+ }
+
+ __boot_status = boot_status;
+
+ parse_cmdline(fdt, chosen);
+
+ for (i = 0; i < ARRAY_SIZE(regs); i++) {
+ reg = prel64_pointer(regs[i].reg);
+ override = prel64_pointer(reg->override);
+ dcache_clean_inval_poc((unsigned long)override,
+ (unsigned long)(override + 1));
+ }
+}
+
+char * __init skip_spaces(const char *str)
+{
+ while (isspace(*str))
+ ++str;
+ return (char *)str;
+}