On Thu, Jun 1, 2017 at 6:34 PM, Mark Rutland <mark.rutl...@arm.com> wrote: > On Thu, Jun 01, 2017 at 07:23:37PM +0300, Andrey Ryabinin wrote: >> We used to read several bytes of the shadow memory in advance. >> Therefore additional shadow memory mapped to prevent crash if >> speculative load would happen near the end of the mapped shadow memory. >> >> Now we don't have such speculative loads, so we no longer need to map >> additional shadow memory. > > I see that patch 1 fixed up the Linux helpers for outline > instrumentation. > > Just to check, is it also true that the inline instrumentation never > performs unaligned accesses to the shadow memory?
Inline instrumentation generally accesses only a single byte. > If so, this looks good to me; it also avoids a potential fencepost issue > when memory exists right at the end of the linear map. Assuming that > holds: > > Acked-by: Mark Rutland <mark.rutl...@arm.com> > > Thanks, > Mark. > >> >> Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> >> Cc: Catalin Marinas <catalin.mari...@arm.com> >> Cc: Will Deacon <will.dea...@arm.com> >> Cc: linux-arm-ker...@lists.infradead.org >> --- >> arch/arm64/mm/kasan_init.c | 8 +------- >> 1 file changed, 1 insertion(+), 7 deletions(-) >> >> diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c >> index 687a358a3733..81f03959a4ab 100644 >> --- a/arch/arm64/mm/kasan_init.c >> +++ b/arch/arm64/mm/kasan_init.c >> @@ -191,14 +191,8 @@ void __init kasan_init(void) >> if (start >= end) >> break; >> >> - /* >> - * end + 1 here is intentional. We check several shadow bytes >> in >> - * advance to slightly speed up fastpath. In some rare cases >> - * we could cross boundary of mapped shadow, so we just map >> - * some more here. >> - */ >> vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), >> - (unsigned long)kasan_mem_to_shadow(end) + 1, >> + (unsigned long)kasan_mem_to_shadow(end), >> pfn_to_nid(virt_to_pfn(start))); >> } >> >> -- >> 2.13.0 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-ker...@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > IMPORTANT NOTICE: The contents of this email and any attachments are > confidential and may also be privileged. If you are not the intended > recipient, please notify the sender immediately and do not disclose the > contents to any other person, use it for any purpose, or store or copy the > information in any medium. Thank you.
