From 2dde02ab6d1a725ddccc7144ff6bf5f55d37f916 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Wed, 30 Sep 2020 18:58:50 -0700 Subject: ARC: mm: support 3 levels of page tables ARCv2 MMU is software walked and Linux implements 2 levels of paging: pgd/pte. Forthcoming hw will have multiple levels, so this change preps mm code for same. It is also fun to try multi levels even on soft-walked code to ensure generic mm code is robust to handle. overview ________ 2 levels {pgd, pte} : pmd is folded but pmd_* macros are valid and operate on pgd 3 levels {pgd, pmd, pte}: - pud is folded and pud_* macros point to pgd - pmd_* macros operate on actual pmd code changes ____________ 1. #include 2. Define CONFIG_PGTABLE_LEVELS 3 3a. Define PMD_SHIFT, PMD_SIZE, PMD_MASK, pmd_t 3b. Define pmd_val() which actually deals with pmd (pmd_offset(), pmd_index() are provided by generic code) 3c. pmd_alloc_one()/pmd_free() also provided by generic code (pmd_populate/pmd_free already exist) 4. Define pud_none(), pud_bad() macros based on generic pud_val() which internally pertains to pgd now. 4b. define pud_populate() to just setup pgd Acked-by: Mike Rapoport Signed-off-by: Vineet Gupta --- arch/arc/mm/init.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arc/mm/init.c') diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c index 46ad9aee7a73..f7ba2a5d5ec8 100644 --- a/arch/arc/mm/init.c +++ b/arch/arc/mm/init.c @@ -191,6 +191,7 @@ void __init mem_init(void) highmem_init(); BUILD_BUG_ON((PTRS_PER_PGD * sizeof(pgd_t)) > PAGE_SIZE); + BUILD_BUG_ON((PTRS_PER_PMD * sizeof(pmd_t)) > PAGE_SIZE); BUILD_BUG_ON((PTRS_PER_PTE * sizeof(pte_t)) > PAGE_SIZE); } -- cgit v1.2.3