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From: Mark Brown <broonie@kernel.org>
Date: Sat, 03 Feb 2024 12:25:41 +0000
Subject: [PATCH v8 15/38] arm64/idreg: Add overrride for GCS
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To: Catalin Marinas <catalin.marinas@arm.com>, 
 Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>, 
 Andrew Morton <akpm@linux-foundation.org>, Marc Zyngier <maz@kernel.org>, 
 Oliver Upton <oliver.upton@linux.dev>, James Morse <james.morse@arm.com>, 
 Suzuki K Poulose <suzuki.poulose@arm.com>, Arnd Bergmann <arnd@arndb.de>, 
 Oleg Nesterov <oleg@redhat.com>, Eric Biederman <ebiederm@xmission.com>, 
 Kees Cook <keescook@chromium.org>, Shuah Khan <shuah@kernel.org>, 
 "Rick P. Edgecombe" <rick.p.edgecombe@intel.com>, 
 Deepak Gupta <debug@rivosinc.com>, Ard Biesheuvel <ardb@kernel.org>, 
 Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>, 
 Paul Walmsley <paul.walmsley@sifive.com>, 
 Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, 
 Florian Weimer <fweimer@redhat.com>, Christian Brauner <brauner@kernel.org>, 
 Thiago Jung Bauermann <thiago.bauermann@linaro.org>, 
 linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, 
 kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, 
 linux-arch@vger.kernel.org, linux-mm@kvack.org, 
 linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-riscv@lists.infradead.org, Mark Brown <broonie@kernel.org>

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

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
 arch/arm64/kernel/idreg-override.c              | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 31b3a25680d0..e86160251d23 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -429,9 +429,15 @@
 	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
 
+	arm64.nopauth	[ARM64] Unconditionally disable Pointer Authentication
+			support
+
 	arm64.nomte	[ARM64] Unconditionally disable Memory Tagging Extension
 			support
 
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index e30fd9e32ef3..00bcdad53ba9 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -110,6 +110,7 @@ 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),
 		{}
@@ -190,6 +191,7 @@ 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 "

-- 
2.30.2