On Fri, 30 Oct 2020 at 16:47, Mark Rutland <mark.rutland@xxxxxxx> wrote: > > 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 <dvyukov@xxxxxxxxxx> > > Co-developed-by: Alexander Potapenko <glider@xxxxxxxxxx> > > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > > Signed-off-by: Marco Elver <elver@xxxxxxxxxx> > > --- > > 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. Good point, I don't think anything is requiring us to force 4K pages. Let's remove it. Thanks, -- Marco > Otherwise, this patch looks fine to me. > > Thanks, > Mark.
