Messages in this thread | | | From | Ard Biesheuvel <> | Date | Mon, 17 Apr 2023 16:30:32 +0200 | Subject | Re: [PATCH v3 30/60] arm64: idreg-override: Create a pseudo feature for rodata=off |
| |
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.
| |