Commit 0ddc312b authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
Browse files

arm64: Turn kaslr_feature_override into a generic SW feature override 



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: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230609162200.2024064-4-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 35230be8

arch/arm64/include/asm/cpufeature.h

+4 −0
Original line number Diff line number Diff line
@@ -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);

arch/arm64/kernel/cpufeature.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

arch/arm64/kernel/idreg-override.c

+6 −10
Original line number Diff line number Diff line
@@ -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)

arch/arm64/kernel/kaslr.c

+3 −3
Original line number Diff line number Diff line
@@ -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;

	}