On Thu, Oct 29, 2020 at 02:16:43PM +0100, Marco Elver wrote: > Add architecture specific implementation details for KFENCE and enable > KFENCE for the arm64 architecture. In particular, this implements the > required interface in <asm/kfence.h>. > > KFENCE requires that attributes for pages from its memory pool can > individually be set. Therefore, force the entire linear map to be mapped > at page granularity. Doing so may result in extra memory allocated for > page tables in case rodata=full is not set; however, currently > CONFIG_RODATA_FULL_DEFAULT_ENABLED=y is the default, and the common case > is therefore not affected by this change. > > Reviewed-by: Dmitry Vyukov <dvyu...@google.com> > Co-developed-by: Alexander Potapenko <gli...@google.com> > Signed-off-by: Alexander Potapenko <gli...@google.com> > Signed-off-by: Marco Elver <el...@google.com> > --- > v5: > * Move generic page allocation code to core.c [suggested by Jann Horn]. > * Remove comment about HAVE_ARCH_KFENCE_STATIC_POOL, since we no longer > support static pools. > * Force page granularity for the linear map [suggested by Mark Rutland]. > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/kfence.h | 19 +++++++++++++++++++ > arch/arm64/mm/fault.c | 4 ++++ > arch/arm64/mm/mmu.c | 7 ++++++- > 4 files changed, 30 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/include/asm/kfence.h > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index f858c352f72a..2f8b32dddd8b 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -135,6 +135,7 @@ config ARM64 > select HAVE_ARCH_JUMP_LABEL_RELATIVE > select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48) > select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN > + select HAVE_ARCH_KFENCE if (!ARM64_16K_PAGES && !ARM64_64K_PAGES)
Why does this depend on the page size? If this is functional, but has a larger overhead on 16K or 64K, I'd suggest removing the dependency, and just updating the Kconfig help text to explain that. Otherwise, this patch looks fine to me. Thanks, Mark.
