Messages in this thread | | | From | Barry Song <> | Date | Wed, 21 Sep 2022 21:00:28 +1200 | Subject | Re: [PATCH] arm64/mm: fold check for KFENCE into can_set_direct_map() |
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On Wed, Sep 21, 2022 at 8:26 PM Mike Rapoport <rppt@kernel.org> wrote: > > From: Mike Rapoport <rppt@linux.ibm.com> > > KFENCE requires linear map to be mapped at page granularity, so that it > is possible to protect/unprotect single pages, just like with > rodata_full and DEBUG_PAGEALLOC. > > Instead of repating > > can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE) > > make can_set_direct_map() handle the KFENCE case. > > This also prevents potential false positives in kernel_page_present() > that may return true for non-present page if CONFIG_KFENCE is enabled. > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> > --- > arch/arm64/mm/mmu.c | 8 ++------ > arch/arm64/mm/pageattr.c | 8 +++++++- > 2 files changed, 9 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index e7ad44585f40..c5065abec55a 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -535,7 +535,7 @@ static void __init map_mem(pgd_t *pgdp) > */ > BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end)); > > - if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) > + if (can_set_direct_map()) > flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; > > /* > @@ -1547,11 +1547,7 @@ int arch_add_memory(int nid, u64 start, u64 size, > > VM_BUG_ON(!mhp_range_allowed(start, size, true)); > > - /* > - * KFENCE requires linear map to be mapped at page granularity, so that > - * it is possible to protect/unprotect single pages in the KFENCE pool. > - */ > - if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) > + if (can_set_direct_map()) > flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; > > __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index 64e985eaa52d..d107c3d434e2 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -21,7 +21,13 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED > > bool can_set_direct_map(void) > { > - return rodata_full || debug_pagealloc_enabled(); > + /* > + * rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be > + * mapped at page granularity, so that it is possible to > + * protect/unprotect single pages. > + */ > + return rodata_full || debug_pagealloc_enabled() || > + IS_ENABLED(CONFIG_KFENCE);
might be irrelevant, i wonder if rodata_full is too strict as rodata_full is almost always true since RODATA_FULL_DEFAULT_ENABLED is default true.
> } > > static int change_page_range(pte_t *ptep, unsigned long addr, void *data) > -- > 2.35.3 >
Thanks Barry
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