blob: e30fd9e32ef3a1e308ad8dec3722c454eb7deb0f [file] [log] [blame]
// 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;
// temporary __prel64 related definitions
// to be removed when this code is moved under pi/
#define __prel64_initconst __initconst
#define PREL64(type, name) union { type *name; }
#define prel64_pointer(__d) (__d)
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 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),
{}
},
};
static const
PREL64(const struct ftr_set_desc, reg) regs[] __prel64_initconst = {
{ &mmfr1 },
{ &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" },
};
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(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)
{
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();
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));
}
}