On 07/15/2015 07:37 PM, Catalin Marinas wrote: > Ok, so simply taking the call out of the loop won't work unless we > conditionally define these functions (wouldn't be too bad since we have > some #if CONFIG_PGTABLE_LEVELS already introduced by this patch but it > would be nicer without). > > Anyway, I think we can keep the current iterations but exit early if > !pud_none() because it means we already populated it (reworked to match > other such patterns throughout the kernel with pgd_populate called from > the pud function; and untested): > > void kasan_early_pmd_populate(pud_t *pud, unsigned long addr, unsigned long > end) > { > pmd_t *pmd; > unsigned long next; > > if (pud_none(*pud)) > pud_populate(&init_mm, pud, kasan_zero_pmd); > > pmd = pmd_offset(pud, addr); > do { > next = pmd_addr_end(addr, end); > kasan_early_pte_populate(pmd, addr, next); > } while (pmd++, addr = next, addr != end && pmd_none(*pmd)); > } > > void kasan_early_pud_populate(pgd_t *pgd, unsigned long addr, unsigned long > end) > { > pud_t *pud; > unsigned long next; > > if (pgd_none(*pgd)) > pgd_populate(&init_mm, pgd, kasan_zero_pud); > > pud = pud_offset(pgd, addr); > do { > next = pud_addr_end(addr, end); > kasan_early_pmd_populate(pud, addr, next); > } while (pud++, addr = next, addr != end && pud_none(*pud)); > } > > Given that we check pud_none() after the first iterations, it covers the > lower levels if needed. >
I think this may work, if pud_none(*pud) will be replaced with !pud_val(*pud). We can't use pud_none() because with 2-level page tables it's always false, so we will never go down to pmd level where swapper_pg_dir populated. But you gave me another idea how we could use p?d_none() and avoid rewriting table entries: void kasan_early_pmd_populate(unsigned long start, unsigned long end, pte_t *pte) { unsigned long addr = start; long next; do { pgd_t *pgd = pgd_offset_k(addr); pud_t *pud = pud_offset(pgd, addr); pmd_t *pmd = pmd_offset(pud, addr); if (!pmd_none(*pmd)) break; pmd_populate_kernel(&init_mm, pmd, pte); next = pgd_addr_end(addr, end); next = pud_addr_end(addr, next) next = pmd_addr_end(addr, next); } while(addr = next, addr != end); } void kasan_early_pud_populate(unsigned long start, unsigned long end, pmd_t *pmd) { unsigned long addr = start; long next; do { pgd_t *pgd = pgd_offset_k(addr); pud_t *pud = pud_offset(pgd, addr); if (!pud_none(*pud)) break; pud_populate(&init_mm, pud, pmd); next = pud_addr_end(addr, pgd_addr_end(addr, end)); } while(addr = next, addr != end); } void kasan_early_pgd_populate(...) { //something similar to above .... } static void __init kasan_map_early_shadow(void) { kasan_early_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, kasan_zero_pud); kasan_early_pud_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, kasan_zero_pmd); kasan_early_pmd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, kasan_zero_pte); kasan_early_pte_populate(); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/