On Mon, Nov 14, 2016 at 12:29 PM, Chris Metcalf <[email protected]> wrote: > The tile architecture already marks RO_DATA as read-only in > the kernel, so grouping RO_AFTER_INIT_DATA with RO_DATA, as is > done by default, means the kernel faults in init when it tries > to write to RO_AFTER_INIT_DATA. For now, just arrange that > __ro_after_init is handled like __write_once, i.e. __read_mostly. > > Signed-off-by: Chris Metcalf <[email protected]>
Reviewed-by: Kees Cook <[email protected]> At some point here, I want to collect all the arch maintainers and discuss the options for correctly reflecting the three data memory-protection needs we have: - always read-only - read-only after init - read-only except during rare updates (The latter one doesn't exist all yet...) x86, arm, and arm64 use mark_rodata_ro() after init finishes, so they don't technically implement "always read-only". parisc, tile, powerpc, others have "always read-only", but disable read-only-after-init since they don't use mark_rodata_ro(). I think s390 has recently implemented both, but I have to double-check... -Kees > --- > arch/tile/include/asm/cache.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/tile/include/asm/cache.h b/arch/tile/include/asm/cache.h > index 6160761d5f61..4810e48dbbbf 100644 > --- a/arch/tile/include/asm/cache.h > +++ b/arch/tile/include/asm/cache.h > @@ -61,4 +61,7 @@ > */ > #define __write_once __read_mostly > > +/* __ro_after_init is the generic name for the tile arch __write_once. */ > +#define __ro_after_init __read_mostly > + > #endif /* _ASM_TILE_CACHE_H */ > -- > 2.7.2 > -- Kees Cook Nexus Security
