Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2021-06-04 03:03:15
Also in:
linux-mm
On Wed, 2 Jun 2021 16:52:26 -0700 Peter Collingbourne [off-list ref] wrote:
Currently we can end up touching PROT_MTE user pages twice on fault and once on unmap. On fault, with KASAN disabled we first clear data and then set tags to 0, and with KASAN enabled we simultaneously clear data and set tags to the KASAN random tag, and then set tags again to 0. On unmap, we poison the page by setting tags, but this is less likely to find a bug than poisoning kernel pages. This patch series fixes these inefficiencies by only touching the pages once on fault using the DC GZVA instruction to clear both data and tags, and avoiding poisoning user pages on free. ... arch/alpha/include/asm/page.h | 6 +-- arch/arm64/include/asm/mte.h | 4 ++ arch/arm64/include/asm/page.h | 10 +++-- arch/arm64/lib/mte.S | 20 ++++++++++ arch/arm64/mm/fault.c | 26 +++++++++++++ arch/arm64/mm/proc.S | 10 +++-- arch/ia64/include/asm/page.h | 6 +-- arch/m68k/include/asm/page_no.h | 6 +-- arch/s390/include/asm/page.h | 6 +-- arch/x86/include/asm/page.h | 6 +-- include/linux/gfp.h | 18 +++++++-- include/linux/highmem.h | 43 ++++++++------------- include/linux/kasan.h | 64 +++++++++++++++++++------------- include/linux/page-flags.h | 9 +++++ include/trace/events/mmflags.h | 9 ++++- mm/kasan/common.c | 4 +- mm/kasan/hw_tags.c | 32 ++++++++++++++++ mm/mempool.c | 6 ++- mm/page_alloc.c | 66 +++++++++++++++++++-------------- 19 files changed, 242 insertions(+), 109 deletions(-)
This is more MMish than ARMish, but I expect it will get more exposure in an ARM tree than in linux-next alone. I'll grab them for now, but in the hope that they will appear in -next via an ARM tree so I get to drop them again. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel