From a1c76574f345342d23836b520ce44674d23bc267 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 27 Jan 2015 16:36:30 +0000 Subject: [PATCH] arm64: mm: use *_sect to check for section maps The {pgd,pud,pmd}_bad family of macros have slightly fuzzy cross-architecture semantics, and seem to imply a populated entry that is not a next-level table, rather than a particular type of entry (e.g. a section map). In arm64 code, for those cases where we care about whether an entry is a section mapping, we can instead use the {pud,pmd}_sect macros to explicitly check for this case. This helps to document precisely what we care about, making the code easier to read, and allows for future relaxation of the *_bad macros to check for other "bad" entries. To that end this patch updates the table dumping and initial table setup to check for section mappings with {pud,pmd}_sect, and adds/restores BUG_ON(*_bad((*p)) checks after we've handled the *_sect and *_none cases so as to catch remaining "bad" cases. In the fault handling code, show_pte is left with *_bad checks as it only cares about whether it can walk the next level table, and this path is used for both kernel and userspace fault handling. The former case will be followed by a die() where we'll report the address that triggered the fault, which can be useful context for debugging. Signed-off-by: Mark Rutland Acked-by: Steve Capper Cc: Ard Biesheuvel Cc: Kees Cook Cc: Laura Abbott Cc: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/mm/dump.c | 18 ++++++++++++------ arch/arm64/mm/mmu.c | 6 ++++-- 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c index bbc5a29ecaaf..612965375473 100644 --- a/arch/arm64/mm/dump.c +++ b/arch/arm64/mm/dump.c @@ -249,10 +249,12 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { addr = start + i * PMD_SIZE; - if (pmd_none(*pmd) || pmd_sect(*pmd) || pmd_bad(*pmd)) + if (pmd_none(*pmd) || pmd_sect(*pmd)) { note_page(st, addr, 3, pmd_val(*pmd)); - else + } else { + BUG_ON(pmd_bad(*pmd)); walk_pte(st, pmd, addr); + } } } @@ -264,10 +266,12 @@ static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start) for (i = 0; i < PTRS_PER_PUD; i++, pud++) { addr = start + i * PUD_SIZE; - if (pud_none(*pud) || pud_sect(*pud) || pud_bad(*pud)) + if (pud_none(*pud) || pud_sect(*pud)) { note_page(st, addr, 2, pud_val(*pud)); - else + } else { + BUG_ON(pud_bad(*pud)); walk_pmd(st, pud, addr); + } } } @@ -279,10 +283,12 @@ static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long st for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { addr = start + i * PGDIR_SIZE; - if (pgd_none(*pgd) || pgd_bad(*pgd)) + if (pgd_none(*pgd)) { note_page(st, addr, 1, pgd_val(*pgd)); - else + } else { + BUG_ON(pgd_bad(*pgd)); walk_pud(st, pgd, addr); + } } } diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index a421f535d351..2eeac10aa0cf 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -90,13 +90,14 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr, { pte_t *pte; - if (pmd_none(*pmd) || pmd_bad(*pmd)) { + if (pmd_none(*pmd) || pmd_sect(*pmd)) { pte = alloc(PTRS_PER_PTE * sizeof(pte_t)); if (pmd_sect(*pmd)) split_pmd(pmd, pte); __pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE); flush_tlb_all(); } + BUG_ON(pmd_bad(*pmd)); pte = pte_offset_kernel(pmd, addr); do { @@ -128,7 +129,7 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud, /* * Check for initial section mappings in the pgd/pud and remove them. */ - if (pud_none(*pud) || pud_bad(*pud)) { + if (pud_none(*pud) || pud_sect(*pud)) { pmd = alloc(PTRS_PER_PMD * sizeof(pmd_t)); if (pud_sect(*pud)) { /* @@ -140,6 +141,7 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud, pud_populate(mm, pud, pmd); flush_tlb_all(); } + BUG_ON(pud_bad(*pud)); pmd = pmd_offset(pud, addr); do { -- 2.34.1