From fe6c1b8611aa3a79a937a5e3b85a16576b6ad159 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 8 Jul 2014 18:43:47 +0530 Subject: ARCv2: mm: THP support MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP support. Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a new bit "SZ" in TLB page desciptor to distinguish between them. Super Page size is configurable in hardware (4K to 16M), but fixed once RTL builds. The exact THP size a Linx configuration will support is a function of: - MMU page size (typical 8K, RTL fixed) - software page walker address split between PGD:PTE:PFN (typical 11:8:13, but can be changed with 1 line) So for above default, THP size supported is 8K * 256 = 2M Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime reduces to 1 level (as PTE is folded into PGD and canonically referred to as PMD). Thus thp PMD accessors are implemented in terms of PTE (just like sparc) Signed-off-by: Vineet Gupta --- arch/arc/mm/tlb.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++ arch/arc/mm/tlbex.S | 19 ++++++++++--- 2 files changed, 96 insertions(+), 4 deletions(-) (limited to 'arch/arc/mm') diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c index 2c7ce8b..eb1bdc4 100644 --- a/arch/arc/mm/tlb.c +++ b/arch/arc/mm/tlb.c @@ -256,6 +256,18 @@ noinline void local_flush_tlb_all(void) write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite); } + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { + const int stlb_idx = 0x800; + + /* Blank sTLB entry */ + write_aux_reg(ARC_REG_TLBPD0, _PAGE_HW_SZ); + + for (entry = stlb_idx; entry < stlb_idx + 16; entry++) { + write_aux_reg(ARC_REG_TLBINDEX, entry); + write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite); + } + } + utlb_invalidate(); local_irq_restore(flags); @@ -580,6 +592,75 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned, } } +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + +/* + * MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP + * support. + * + * Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a + * new bit "SZ" in TLB page desciptor to distinguish between them. + * Super Page size is configurable in hardware (4K to 16M), but fixed once + * RTL builds. + * + * The exact THP size a Linx configuration will support is a function of: + * - MMU page size (typical 8K, RTL fixed) + * - software page walker address split between PGD:PTE:PFN (typical + * 11:8:13, but can be changed with 1 line) + * So for above default, THP size supported is 8K * (2^8) = 2M + * + * Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime + * reduces to 1 level (as PTE is folded into PGD and canonically referred + * to as PMD). + * Thus THP PMD accessors are implemented in terms of PTE (just like sparc) + */ + +void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmd) +{ + pte_t pte = __pte(pmd_val(*pmd)); + update_mmu_cache(vma, addr, &pte); +} + +void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, + pgtable_t pgtable) +{ + struct list_head *lh = (struct list_head *) pgtable; + + assert_spin_locked(&mm->page_table_lock); + + /* FIFO */ + if (!pmd_huge_pte(mm, pmdp)) + INIT_LIST_HEAD(lh); + else + list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp)); + pmd_huge_pte(mm, pmdp) = pgtable; +} + +pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp) +{ + struct list_head *lh; + pgtable_t pgtable; + + assert_spin_locked(&mm->page_table_lock); + + pgtable = pmd_huge_pte(mm, pmdp); + lh = (struct list_head *) pgtable; + if (list_empty(lh)) + pmd_huge_pte(mm, pmdp) = NULL; + else { + pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next; + list_del(lh); + } + + pte_val(pgtable[0]) = 0; + pte_val(pgtable[1]) = 0; + + return pgtable; +} + +#endif + /* Read the Cache Build Confuration Registers, Decode them and save into * the cpuinfo structure for later use. * No Validation is done here, simply read/convert the BCRs diff --git a/arch/arc/mm/tlbex.S b/arch/arc/mm/tlbex.S index b8b014c..5525948 100644 --- a/arch/arc/mm/tlbex.S +++ b/arch/arc/mm/tlbex.S @@ -205,10 +205,18 @@ ex_saved_reg1: #endif lsr r0, r2, PGDIR_SHIFT ; Bits for indexing into PGD - ld.as r1, [r1, r0] ; PGD entry corresp to faulting addr - and.f r1, r1, PAGE_MASK ; Ignoring protection and other flags - ; contains Ptr to Page Table - bz.d do_slow_path_pf ; if no Page Table, do page fault + ld.as r3, [r1, r0] ; PGD entry corresp to faulting addr + tst r3, r3 + bz do_slow_path_pf ; if no Page Table, do page fault + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + and.f 0, r3, _PAGE_HW_SZ ; Is this Huge PMD (thp) + add2.nz r1, r1, r0 + bnz.d 2f ; YES: PGD == PMD has THP PTE: stop pgd walk + mov.nz r0, r3 + +#endif + and r1, r3, PAGE_MASK ; Get the PTE entry: The idea is ; (1) x = addr >> PAGE_SHIFT -> masks page-off bits from @fault-addr @@ -219,6 +227,9 @@ ex_saved_reg1: lsr r0, r2, (PAGE_SHIFT - 2) and r0, r0, ( (PTRS_PER_PTE - 1) << 2) ld.aw r0, [r1, r0] ; get PTE and PTE ptr for fault addr + +2: + #ifdef CONFIG_ARC_DBG_TLB_MISS_COUNT and.f 0, r0, _PAGE_PRESENT bz 1f -- cgit v1.1