Hi Pavel, On Wed, Sep 20, 2017 at 04:17:11PM -0400, Pavel Tatashin wrote: > During early boot, kasan uses vmemmap_populate() to establish its shadow > memory. But, that interface is intended for struct pages use. > > Because of the current project, vmemmap won't be zeroed during allocation, > but kasan expects that memory to be zeroed. We are adding a new > kasan_map_populate() function to resolve this difference. Thanks for putting this together. I've given this a spin on arm64, and can confirm that it works. Given that this involes redundant walking of page tables, I still think it'd be preferable to have some common *_populate() helper that took a gfp argument, but I guess it's not the end of the world. I'll leave it to Will and Catalin to say whether they're happy with the page table walking and the new p{u,m}d_large() helpers added to arm64. Thanks, Mark. > > Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> > --- > arch/arm64/include/asm/pgtable.h | 3 ++ > include/linux/kasan.h | 2 ++ > mm/kasan/kasan_init.c | 67 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 72 insertions(+) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index bc4e92337d16..d89713f04354 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -381,6 +381,9 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > PUD_TYPE_TABLE) > #endif > > +#define pmd_large(pmd) pmd_sect(pmd) > +#define pud_large(pud) pud_sect(pud) > + > static inline void set_pmd(pmd_t *pmdp, pmd_t pmd) > { > *pmdp = pmd; > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > index a5c7046f26b4..7e13df1722c2 100644 > --- a/include/linux/kasan.h > +++ b/include/linux/kasan.h > @@ -78,6 +78,8 @@ size_t kasan_metadata_size(struct kmem_cache *cache); > > bool kasan_save_enable_multi_shot(void); > void kasan_restore_multi_shot(bool enabled); > +int __meminit kasan_map_populate(unsigned long start, unsigned long end, > + int node); > > #else /* CONFIG_KASAN */ > > diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c > index 554e4c0f23a2..57a973f05f63 100644 > --- a/mm/kasan/kasan_init.c > +++ b/mm/kasan/kasan_init.c > @@ -197,3 +197,70 @@ void __init kasan_populate_zero_shadow(const void *shadow_start, > zero_p4d_populate(pgd, addr, next); > } while (pgd++, addr = next, addr != end); > } > + > +/* Creates mappings for kasan during early boot. The mapped memory is zeroed */ > +int __meminit kasan_map_populate(unsigned long start, unsigned long end, > + int node) > +{ > + unsigned long addr, pfn, next; > + unsigned long long size; > + pgd_t *pgd; > + p4d_t *p4d; > + pud_t *pud; > + pmd_t *pmd; > + pte_t *pte; > + int ret; > + > + ret = vmemmap_populate(start, end, node); > + /* > + * We might have partially populated memory, so check for no entries, > + * and zero only those that actually exist. > + */ > + for (addr = start; addr < end; addr = next) { > + pgd = pgd_offset_k(addr); > + if (pgd_none(*pgd)) { > + next = pgd_addr_end(addr, end); > + continue; > + } > + > + p4d = p4d_offset(pgd, addr); > + if (p4d_none(*p4d)) { > + next = p4d_addr_end(addr, end); > + continue; > + } > + > + pud = pud_offset(p4d, addr); > + if (pud_none(*pud)) { > + next = pud_addr_end(addr, end); > + continue; > + } > + if (pud_large(*pud)) { > + /* This is PUD size page */ > + next = pud_addr_end(addr, end); > + size = PUD_SIZE; > + pfn = pud_pfn(*pud); > + } else { > + pmd = pmd_offset(pud, addr); > + if (pmd_none(*pmd)) { > + next = pmd_addr_end(addr, end); > + continue; > + } > + if (pmd_large(*pmd)) { > + /* This is PMD size page */ > + next = pmd_addr_end(addr, end); > + size = PMD_SIZE; > + pfn = pmd_pfn(*pmd); > + } else { > + pte = pte_offset_kernel(pmd, addr); > + next = addr + PAGE_SIZE; > + if (pte_none(*pte)) > + continue; > + /* This is base size page */ > + size = PAGE_SIZE; > + pfn = pte_pfn(*pte); > + } > + } > + memset(phys_to_virt(PFN_PHYS(pfn)), 0, size); > + } > + return ret; > +} > -- > 2.14.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html