linux-kernel - [PATCH v3 21/21] arm64: cpufeatures: Allow disabling of Pointer Auth from the command-line

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210111132811.2455113-22-maz@kernel.org>
Date:   Mon, 11 Jan 2021 13:28:11 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Brazdil <dbrazdil@...gle.com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Jing Zhang <jingzhangos@...gle.com>,
        Ajay Patil <pajay@....qualcomm.com>,
        Prasad Sodagudi <psodagud@...eaurora.org>,
        Srinivas Ramana <sramana@...eaurora.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kernel-team@...roid.com
Subject: [PATCH v3 21/21] arm64: cpufeatures: Allow disabling of Pointer Auth from the command-line

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@...nel.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  3 +++
 arch/arm64/include/asm/cpufeature.h             |  2 ++
 arch/arm64/kernel/cpufeature.c                  |  5 ++++-
 arch/arm64/kernel/idreg-override.c              | 17 +++++++++++++++++
 4 files changed, 26 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 d3e0f6dd43c4..9d8dcf380ad5 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -818,6 +818,8 @@ extern u64 id_aa64mmfr1_val;
 extern u64 id_aa64mmfr1_mask;
 extern u64 id_aa64pfr1_val;
 extern u64 id_aa64pfr1_mask;
+extern u64 id_aa64isar1_val;
+extern u64 id_aa64isar1_mask;
 
 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 48dc0333bb4b..894af60b9669 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -559,6 +559,8 @@ u64 id_aa64mmfr1_val;
 u64 id_aa64mmfr1_mask;
 u64 id_aa64pfr1_val;
 u64 id_aa64pfr1_mask;
+u64 id_aa64isar1_val;
+u64 id_aa64isar1_mask;
 
 static const struct __ftr_reg_entry {
 	u32			sys_id;
@@ -604,7 +606,8 @@ 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_val, &id_aa64isar1_mask),
 
 	/* 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 a9e3ed193fd4..7037c9b214d0 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -43,6 +43,19 @@ static const struct reg_desc pfr1 __initdata = {
 	},
 };
 
+static const struct reg_desc isar1 __initdata = {
+	.name		= "id_aa64isar1",
+	.val		= &id_aa64isar1_val,
+	.mask		= &id_aa64isar1_mask,
+	.fields		= {
+	        { "gpi", ID_AA64ISAR1_GPI_SHIFT },
+	        { "gpa", ID_AA64ISAR1_GPA_SHIFT },
+	        { "api", ID_AA64ISAR1_API_SHIFT },
+	        { "apa", ID_AA64ISAR1_APA_SHIFT },
+		{}
+	},
+};
+
 extern u64 kaslr_feature_val;
 extern u64 kaslr_feature_mask;
 
@@ -61,6 +74,7 @@ static const struct reg_desc kaslr __initdata = {
 static const struct reg_desc * const regs[] __initdata = {
 	&mmfr1,
 	&pfr1,
+	&isar1,
 	&kaslr,
 };
 
@@ -71,6 +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