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arm64: Turn kaslr_feature_override into a generic SW feature override

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Disabling KASLR from the command line is implemented as a feature
override. Repaint it slightly so that it can further be used as
more generic infrastructure for SW override purposes.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230609162200.2024064-4-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Marc Zyngier 2023-06-09 17:21:46 +01:00 committed by Oliver Upton
parent 35230be87e
commit 0ddc312b7c
4 changed files with 15 additions and 13 deletions
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4
arch/arm64/include/asm/cpufeature.h
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@ -15,6 +15,8 @@
#define MAX_CPU_FEATURES 128
#define cpu_feature(x) KERNEL_HWCAP_ ## x
#define ARM64_SW_FEATURE_OVERRIDE_NOKASLR 0
#ifndef __ASSEMBLY__
#include <linux/bug.h>
@ -925,6 +927,8 @@ extern struct arm64_ftr_override id_aa64smfr0_override;
extern struct arm64_ftr_override id_aa64isar1_override;
extern struct arm64_ftr_override id_aa64isar2_override;
extern struct arm64_ftr_override arm64_sw_feature_override;
u32 get_kvm_ipa_limit(void);
void dump_cpu_features(void);

2
arch/arm64/kernel/cpufeature.c
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@ -664,6 +664,8 @@ struct arm64_ftr_override __ro_after_init id_aa64smfr0_override;
struct arm64_ftr_override __ro_after_init id_aa64isar1_override;
struct arm64_ftr_override __ro_after_init id_aa64isar2_override;
struct arm64_ftr_override arm64_sw_feature_override;
static const struct __ftr_reg_entry {
u32 sys_id;
struct arm64_ftr_reg *reg;

16
arch/arm64/kernel/idreg-override.c
View File

@ -138,15 +138,11 @@ static const struct ftr_set_desc smfr0 __initconst = {
},
};
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
static const struct ftr_set_desc sw_features __initconst = {
.name = "arm64_sw",
.override = &arm64_sw_feature_override,
.fields = {
FIELD("disabled", 0, NULL),
FIELD("nokaslr", ARM64_SW_FEATURE_OVERRIDE_NOKASLR, NULL),
{}
},
};
@ -158,7 +154,7 @@ static const struct ftr_set_desc * const regs[] __initconst = {
&isar1,
&isar2,
&smfr0,
&kaslr,
&sw_features,
};
static const struct {
@ -175,7 +171,7 @@ static const struct {
"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" },
{ "nokaslr", "arm64_sw.nokaslr=1" },
};
static int __init parse_nokaslr(char *unused)

6
arch/arm64/kernel/kaslr.c
View File

@ -23,8 +23,6 @@
u64 __ro_after_init module_alloc_base;
u16 __initdata memstart_offset_seed;
struct arm64_ftr_override kaslr_feature_override __initdata;
static int __init kaslr_init(void)
{
u64 module_range;
@ -36,7 +34,9 @@ static int __init kaslr_init(void)
*/
module_alloc_base = (u64)_etext - MODULES_VSIZE;
if (kaslr_feature_override.val & kaslr_feature_override.mask & 0xf) {
if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val &
arm64_sw_feature_override.mask,
ARM64_SW_FEATURE_OVERRIDE_NOKASLR)) {
pr_info("KASLR disabled on command line\n");
return 0;
}