Messages in this thread | | | Date | Mon, 17 Apr 2023 15:33:53 +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 17/04/2023 15:30, Ard Biesheuvel wrote: > On Mon, 17 Apr 2023 at 16:28, Ryan Roberts <ryan.roberts@arm.com> wrote: >> >> 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? >> > > This (ab)uses the CPU feature framework, which is based on 4-bit > quantities. I don't remember if it matters or not, but IIRC the > default macros use 4-bit wide values.
OK, thanks.
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