mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

arm64: mm: ensure that the zero page is visible to the page table walker 

In paging_init, we allocate the zero page, memset it to zero and then
point TTBR0 to it in order to avoid speculative fetches through the
identity mapping.

In order to guarantee that the freshly zeroed page is indeed visible to
the page table walker, we need to execute a dsb instruction prior to
writing the TTBR.

Cc: <stable@vger.kernel.org> # v3.14+, for older kernels need to drop the 'ishst'
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2015-12-10 16:05:36 +00:00
parent 9cb9c9e5ba
commit 32d6397805
1 changed files with 3 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/arm64/mm/mmu.c
View File

@ -464,6 +464,9 @@ void __init paging_init(void)
empty_zero_page = virt_to_page(zero_page);
/* Ensure the zero page is visible to the page table walker */
dsb(ishst);
/*
* TTBR0 is only used for the identity mapping at this stage. Make it
* point to zero page to avoid speculatively fetching new entries.