[PATCH v10 15/40] arm64/idreg: Add overrride for GCS

Mark Brown
2024-08-01T12:59:02Z

Hook up an override for GCS, allowing it to be disabled from the command
line by specifying arm64.nogcs in case there are problems.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 3 +++
arch/arm64/kernel/pi/idreg-override.c | 2 ++
2 files changed, 5 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f1384c7b59c9..3006c1bd1af0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -441,6 +441,9 @@
arm64.nobti [ARM64] Unconditionally disable Branch Target
Identification support

+ arm64.nogcs [ARM64] Unconditionally disable Guarded Control Stack
+ support
+
arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory
Set instructions support

diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
index 29d4b6244a6f..2bb709d78405 100644
--- a/arch/arm64/kernel/pi/idreg-override.c
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -133,6 +133,7 @@ static const struct ftr_set_desc pfr1 __prel64_initconst = {
.override = &id_aa64pfr1_override,
.fields = {
FIELD("bt", ID_AA64PFR1_EL1_BT_SHIFT, NULL ),
+ FIELD("gcs", ID_AA64PFR1_EL1_GCS_SHIFT, NULL),
FIELD("mte", ID_AA64PFR1_EL1_MTE_SHIFT, NULL),
FIELD("sme", ID_AA64PFR1_EL1_SME_SHIFT, pfr1_sme_filter),
{}
@@ -215,6 +216,7 @@ static const struct {
{ "arm64.nosve", "id_aa64pfr0.sve=0" },
{ "arm64.nosme", "id_aa64pfr1.sme=0" },
{ "arm64.nobti", "id_aa64pfr1.bt=0" },
+ { "arm64.nogcs", "id_aa64pfr1.gcs=0" },
{ "arm64.nopauth",
"id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
"id_aa64isar1.api=0 id_aa64isar1.apa=0 "

--
2.39.2