In order to be able to disable Pointer Authentication at runtime,
whether it is for testing purposes, or to work around HW issues,
let's add support for overriding the ID_AA64ISAR1_EL1.{GPI,GPA,API,APA}
fields.
This is further mapped on the arm64.nopauth command-line alias.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: David Brazdil <dbrazdil@xxxxxxxxxx>
Tested-by: Srinivas Ramana <sramana@xxxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 3 +++
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/kernel/cpufeature.c | 4 +++-
arch/arm64/kernel/idreg-override.c | 16 ++++++++++++++++
4 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7599fd0f1ad7..f9cb28a39bd0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -376,6 +376,9 @@
arm64.nobti [ARM64] Unconditionally disable Branch Target
Identification support
+ arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication
+ support
+
ataflop= [HW,M68k]
atarimouse= [HW,MOUSE] Atari Mouse
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 30917b9a760b..61177bac49fa 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -820,6 +820,7 @@ static inline unsigned int get_vmid_bits(u64 mmfr1)
extern struct arm64_ftr_override id_aa64mmfr1_override;
extern struct arm64_ftr_override id_aa64pfr1_override;
+extern struct arm64_ftr_override id_aa64isar1_override;
u32 get_kvm_ipa_limit(void);
void dump_cpu_features(void);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 7fbeab497adb..3bce87a03717 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -559,6 +559,7 @@ static const struct arm64_ftr_bits ftr_raz[] = {
struct arm64_ftr_override __ro_after_init id_aa64mmfr1_override;
struct arm64_ftr_override __ro_after_init id_aa64pfr1_override;
+struct arm64_ftr_override __ro_after_init id_aa64isar1_override;
static const struct __ftr_reg_entry {
u32 sys_id;
@@ -604,7 +605,8 @@ static const struct __ftr_reg_entry {
/* Op1 = 0, CRn = 0, CRm = 6 */
ARM64_FTR_REG(SYS_ID_AA64ISAR0_EL1, ftr_id_aa64isar0),
- ARM64_FTR_REG(SYS_ID_AA64ISAR1_EL1, ftr_id_aa64isar1),
+ ARM64_FTR_REG_OVERRIDE(SYS_ID_AA64ISAR1_EL1, ftr_id_aa64isar1,
+ &id_aa64isar1_override),
/* Op1 = 0, CRn = 0, CRm = 7 */
ARM64_FTR_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0),
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index d691e9015c62..dffb16682330 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -46,6 +46,18 @@ static const struct ftr_set_desc pfr1 __initconst = {
},
};
+static const struct ftr_set_desc isar1 __initconst = {
+ .name = "id_aa64isar1",
+ .override = &id_aa64isar1_override,
+ .fields = {
+ { "gpi", ID_AA64ISAR1_GPI_SHIFT },
+ { "gpa", ID_AA64ISAR1_GPA_SHIFT },
+ { "api", ID_AA64ISAR1_API_SHIFT },
+ { "apa", ID_AA64ISAR1_APA_SHIFT },
+ {}
+ },
+};
+
extern struct arm64_ftr_override kaslr_feature_override;
static const struct ftr_set_desc kaslr __initconst = {
@@ -62,6 +74,7 @@ static const struct ftr_set_desc kaslr __initconst = {
static const struct ftr_set_desc * const regs[] __initconst = {
&mmfr1,
&pfr1,
+ &isar1,
&kaslr,
};
@@ -72,6 +85,9 @@ static const struct {
{ "kvm-arm.mode=nvhe", "id_aa64mmfr1.vh=0" },
{ "kvm-arm.mode=protected", "id_aa64mmfr1.vh=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" },
{ "nokaslr", "kaslr.disabled=1" },
};
--
2.29.2
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