arm64: idreg-override: Create a pseudo feature for rodata=off

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>
Link: https://lore.kernel.org/r/20240214122845.2033971-57-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index e309255..03c3424 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -17,6 +17,7 @@
 
 #define ARM64_SW_FEATURE_OVERRIDE_NOKASLR      0
 #define ARM64_SW_FEATURE_OVERRIDE_HVHE         4
+#define ARM64_SW_FEATURE_OVERRIDE_RODATA_OFF   8
 
 #ifndef __ASSEMBLY__
 

diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
index f9e05c1..e4bcabc 100644 (file)
--- a/arch/arm64/kernel/pi/idreg-override.c
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -159,6 +159,7 @@ static const struct ftr_set_desc sw_features __prel64_initconst = {
        .fields         = {
                FIELD("nokaslr", ARM64_SW_FEATURE_OVERRIDE_NOKASLR, NULL),
                FIELD("hvhe", ARM64_SW_FEATURE_OVERRIDE_HVHE, hvhe_filter),
+               FIELD("rodataoff", ARM64_SW_FEATURE_OVERRIDE_RODATA_OFF, NULL),
                {}
        },
 };
@@ -190,6 +191,7 @@ static const struct {
        { "arm64.nomops",               "id_aa64isar2.mops=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)