On Tue, Nov 06, 2018 at 06:30:22PM +0100, Andrey Konovalov wrote: > A tag-based KASAN shadow memory cell contains a memory tag, that > corresponds to the tag in the top byte of the pointer, that points to that > memory. The native top byte value of kernel pointers is 0xff, so with > tag-based KASAN we need to initialize shadow memory to 0xff. > > Reviewed-by: Andrey Ryabinin <[email protected]> > Reviewed-by: Dmitry Vyukov <[email protected]> > Signed-off-by: Andrey Konovalov <[email protected]> > --- > arch/arm64/mm/kasan_init.c | 16 ++++++++++++++-- > include/linux/kasan.h | 8 ++++++++ > mm/kasan/common.c | 3 ++- > 3 files changed, 24 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > index 63527e585aac..18ebc8994a7b 100644 > --- a/arch/arm64/mm/kasan_init.c > +++ b/arch/arm64/mm/kasan_init.c > @@ -43,6 +43,15 @@ static phys_addr_t __init kasan_alloc_zeroed_page(int node) > return __pa(p); > } > > +static phys_addr_t __init kasan_alloc_raw_page(int node) > +{ > + void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE, > + __pa(MAX_DMA_ADDRESS), > + MEMBLOCK_ALLOC_ACCESSIBLE, > + node); > + return __pa(p); > +} > + > static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int > node, > bool early) > { > @@ -88,7 +97,9 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned > long addr, > > do { > phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page) > - : kasan_alloc_zeroed_page(node); > + : kasan_alloc_raw_page(node); > + if (!early) > + memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); > next = addr + PAGE_SIZE; > set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); > } while (ptep++, addr = next, addr != end && > pte_none(READ_ONCE(*ptep))); > @@ -138,6 +149,7 @@ asmlinkage void __init kasan_early_init(void) > KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); > BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); > BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); > + > kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, > true); > } > @@ -234,7 +246,7 @@ void __init kasan_init(void) > set_pte(&kasan_zero_pte[i], > pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO)); > > - memset(kasan_zero_page, 0, PAGE_SIZE); > + memset(kasan_zero_page, KASAN_SHADOW_INIT, PAGE_SIZE);
If this isn't going to contain zero, can we please have a preparatory patch renaming this to something which isn't misleading? Perhaps kasan_common_shadow_page? Thanks, Mark.
