diff options
| author | Peter Collingbourne <pcc@google.com> | 2021-06-02 16:52:29 -0700 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2021-06-04 19:32:21 +0100 |
| commit | 013bb59dbb7cf876449df860946458a595a96d51 (patch) | |
| tree | 2c086b293dc8c5d6e33881248aa49b0dbe698808 /include/linux/highmem.h | |
| parent | 7a3b835371883558eb63e069d891bd87f562380d (diff) | |
| download | linux-013bb59dbb7cf876449df860946458a595a96d51.tar.gz | |
arm64: mte: handle tags zeroing at page allocation time
Currently, on an anonymous page fault, the kernel allocates a zeroed
page and maps it in user space. If the mapping is tagged (PROT_MTE),
set_pte_at() additionally clears the tags. It is, however, more
efficient to clear the tags at the same time as zeroing the data on
allocation. To avoid clearing the tags on any page (which may not be
mapped as tagged), only do this if the vma flags contain VM_MTE. This
requires introducing a new GFP flag that is used to determine whether
to clear the tags.
The DC GZVA instruction with a 0 top byte (and 0 tag) requires
top-byte-ignore. Set the TCR_EL1.{TBI1,TBID1} bits irrespective of
whether KASAN_HW is enabled.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://linux-review.googlesource.com/id/Id46dc94e30fe11474f7e54f5d65e7658dbdddb26
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20210602235230.3928842-4-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'include/linux/highmem.h')
| -rw-r--r-- | include/linux/highmem.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 54d0643b8fcfb5..8c6e8e996c8754 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -185,6 +185,14 @@ static inline void clear_highpage(struct page *page) kunmap_atomic(kaddr); } +#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE + +static inline void tag_clear_highpage(struct page *page) +{ +} + +#endif + /* * If we pass in a base or tail page, we can zero up to PAGE_SIZE. * If we pass in a head page, we can zero up to the size of the compound page. |