From:   Ard Biesheuvel <ardb@kernel.org>
To:     linux-kernel@vger.kernel.org
Cc:     linux-arm-kernel@lists.infradead.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Ryan Roberts <ryan.roberts@arm.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Kees Cook <keescook@chromium.org>
Subject: [PATCH v3 30/60] arm64: idreg-override: Create a pseudo feature for rodata=off
Date:   Tue,  7 Mar 2023 15:04:52 +0100
Message-Id: <20230307140522.2311461-31-ardb@kernel.org>
In-Reply-To: <20230307140522.2311461-1-ardb@kernel.org>
References: <20230307140522.2311461-1-ardb@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Add rodata=off to the set of kernel command line options that is parsed
early using the CPU feature override detection code, so we can easily
refer to it when creating the kernel mapping.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/include/asm/cpufeature.h   | 1 +
 arch/arm64/kernel/pi/idreg-override.c | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index bc10098901808c00..edc7733aa49846b2 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -16,6 +16,7 @@
 #define cpu_feature(x)		KERNEL_HWCAP_ ## x
 
 #define ARM64_SW_FEATURE_OVERRIDE_NOKASLR	0
+#define ARM64_SW_FEATURE_OVERRIDE_RODATA_OFF	4
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
index 4e76db6eb72c2087..6c547cccaf6a9e9c 100644
--- a/arch/arm64/kernel/pi/idreg-override.c
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -151,6 +151,7 @@ static const struct ftr_set_desc sw_features __prel64_initconst = {
 	.override	= &arm64_sw_feature_override,
 	.fields		= {
 		FIELD("nokaslr", ARM64_SW_FEATURE_OVERRIDE_NOKASLR, NULL),
+		FIELD("rodataoff", ARM64_SW_FEATURE_OVERRIDE_RODATA_OFF, NULL),
 		{}
 	},
 };
@@ -183,6 +184,7 @@ static const struct {
 	  "id_aa64isar2.gpa3=0 id_aa64isar2.apa3=0"	   },
 	{ "arm64.nomte",		"id_aa64pfr1.mte=0" },
 	{ "nokaslr",			"arm64_sw.nokaslr=1" },
+	{ "rodata=off",			"arm64_sw.rodataoff=1" },
 };
 
 static int __init parse_hexdigit(const char *p, u64 *v)
-- 
2.39.2