| Date | Mon, 17 Apr 2023 15:28:47 +0100 | Subject | Re: [PATCH v3 30/60] arm64: idreg-override: Create a pseudo feature for rodata=off | From | Ryan Roberts <> |
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On 07/03/2023 14:04, Ard Biesheuvel wrote: > 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
I assume these are bit numbers? Why not just use the next available bit (bit 1) for this new flag?
> > #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)
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