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authorPalmer Dabbelt <palmer@dabbelt.com>2017-07-10 18:06:09 -0700
committerPalmer Dabbelt <palmer@dabbelt.com>2017-09-26 15:26:47 -0700
commit07037db5d479f90377c998259a4f9a469c404edf (patch)
tree31f69eeb15052afe454c49673b6b398692f451d4 /arch/riscv/include/asm/pgtable.h
parent6d60b6ee0c9777b92c47f6dc8aad1dd90612e4fa (diff)
downloadlinux-07037db5d479f90377c998259a4f9a469c404edf.tar.gz
RISC-V: Paging and MMU
This patch contains code to manage the RISC-V MMU, including definitions of the page tables and the page walking code. Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Diffstat (limited to 'arch/riscv/include/asm/pgtable.h')
-rw-r--r--arch/riscv/include/asm/pgtable.h430
1 files changed, 430 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
new file mode 100644
index 000000000000..3399257780b2
--- /dev/null
+++ b/arch/riscv/include/asm/pgtable.h
@@ -0,0 +1,430 @@
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _ASM_RISCV_PGTABLE_H
+#define _ASM_RISCV_PGTABLE_H
+
+#include <linux/mmzone.h>
+
+#include <asm/pgtable-bits.h>
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_MMU
+
+/* Page Upper Directory not used in RISC-V */
+#include <asm-generic/pgtable-nopud.h>
+#include <asm/page.h>
+#include <asm/tlbflush.h>
+#include <linux/mm_types.h>
+
+#ifdef CONFIG_64BIT
+#include <asm/pgtable-64.h>
+#else
+#include <asm/pgtable-32.h>
+#endif /* CONFIG_64BIT */
+
+/* Number of entries in the page global directory */
+#define PTRS_PER_PGD (PAGE_SIZE / sizeof(pgd_t))
+/* Number of entries in the page table */
+#define PTRS_PER_PTE (PAGE_SIZE / sizeof(pte_t))
+
+/* Number of PGD entries that a user-mode program can use */
+#define USER_PTRS_PER_PGD (TASK_SIZE / PGDIR_SIZE)
+#define FIRST_USER_ADDRESS 0
+
+/* Page protection bits */
+#define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_USER)
+
+#define PAGE_NONE __pgprot(0)
+#define PAGE_READ __pgprot(_PAGE_BASE | _PAGE_READ)
+#define PAGE_WRITE __pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_WRITE)
+#define PAGE_EXEC __pgprot(_PAGE_BASE | _PAGE_EXEC)
+#define PAGE_READ_EXEC __pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_EXEC)
+#define PAGE_WRITE_EXEC __pgprot(_PAGE_BASE | _PAGE_READ | \
+ _PAGE_EXEC | _PAGE_WRITE)
+
+#define PAGE_COPY PAGE_READ
+#define PAGE_COPY_EXEC PAGE_EXEC
+#define PAGE_COPY_READ_EXEC PAGE_READ_EXEC
+#define PAGE_SHARED PAGE_WRITE
+#define PAGE_SHARED_EXEC PAGE_WRITE_EXEC
+
+#define _PAGE_KERNEL (_PAGE_READ \
+ | _PAGE_WRITE \
+ | _PAGE_PRESENT \
+ | _PAGE_ACCESSED \
+ | _PAGE_DIRTY)
+
+#define PAGE_KERNEL __pgprot(_PAGE_KERNEL)
+#define PAGE_KERNEL_EXEC __pgprot(_PAGE_KERNEL | _PAGE_EXEC)
+
+extern pgd_t swapper_pg_dir[];
+
+/* MAP_PRIVATE permissions: xwr (copy-on-write) */
+#define __P000 PAGE_NONE
+#define __P001 PAGE_READ
+#define __P010 PAGE_COPY
+#define __P011 PAGE_COPY
+#define __P100 PAGE_EXEC
+#define __P101 PAGE_READ_EXEC
+#define __P110 PAGE_COPY_EXEC
+#define __P111 PAGE_COPY_READ_EXEC
+
+/* MAP_SHARED permissions: xwr */
+#define __S000 PAGE_NONE
+#define __S001 PAGE_READ
+#define __S010 PAGE_SHARED
+#define __S011 PAGE_SHARED
+#define __S100 PAGE_EXEC
+#define __S101 PAGE_READ_EXEC
+#define __S110 PAGE_SHARED_EXEC
+#define __S111 PAGE_SHARED_EXEC
+
+/*
+ * ZERO_PAGE is a global shared page that is always zero,
+ * used for zero-mapped memory areas, etc.
+ */
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
+#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
+
+static inline int pmd_present(pmd_t pmd)
+{
+ return (pmd_val(pmd) & _PAGE_PRESENT);
+}
+
+static inline int pmd_none(pmd_t pmd)
+{
+ return (pmd_val(pmd) == 0);
+}
+
+static inline int pmd_bad(pmd_t pmd)
+{
+ return !pmd_present(pmd);
+}
+
+static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
+{
+ *pmdp = pmd;
+}
+
+static inline void pmd_clear(pmd_t *pmdp)
+{
+ set_pmd(pmdp, __pmd(0));
+}
+
+
+static inline pgd_t pfn_pgd(unsigned long pfn, pgprot_t prot)
+{
+ return __pgd((pfn << _PAGE_PFN_SHIFT) | pgprot_val(prot));
+}
+
+#define pgd_index(addr) (((addr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
+
+/* Locate an entry in the page global directory */
+static inline pgd_t *pgd_offset(const struct mm_struct *mm, unsigned long addr)
+{
+ return mm->pgd + pgd_index(addr);
+}
+/* Locate an entry in the kernel page global directory */
+#define pgd_offset_k(addr) pgd_offset(&init_mm, (addr))
+
+static inline struct page *pmd_page(pmd_t pmd)
+{
+ return pfn_to_page(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
+}
+
+static inline unsigned long pmd_page_vaddr(pmd_t pmd)
+{
+ return (unsigned long)pfn_to_virt(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
+}
+
+/* Yields the page frame number (PFN) of a page table entry */
+static inline unsigned long pte_pfn(pte_t pte)
+{
+ return (pte_val(pte) >> _PAGE_PFN_SHIFT);
+}
+
+#define pte_page(x) pfn_to_page(pte_pfn(x))
+
+/* Constructs a page table entry */
+static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot)
+{
+ return __pte((pfn << _PAGE_PFN_SHIFT) | pgprot_val(prot));
+}
+
+static inline pte_t mk_pte(struct page *page, pgprot_t prot)
+{
+ return pfn_pte(page_to_pfn(page), prot);
+}
+
+#define pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
+
+static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long addr)
+{
+ return (pte_t *)pmd_page_vaddr(*pmd) + pte_index(addr);
+}
+
+#define pte_offset_map(dir, addr) pte_offset_kernel((dir), (addr))
+#define pte_unmap(pte) ((void)(pte))
+
+/*
+ * Certain architectures need to do special things when PTEs within
+ * a page table are directly modified. Thus, the following hook is
+ * made available.
+ */
+static inline void set_pte(pte_t *ptep, pte_t pteval)
+{
+ *ptep = pteval;
+}
+
+static inline void set_pte_at(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep, pte_t pteval)
+{
+ set_pte(ptep, pteval);
+}
+
+static inline void pte_clear(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep)
+{
+ set_pte_at(mm, addr, ptep, __pte(0));
+}
+
+static inline int pte_present(pte_t pte)
+{
+ return (pte_val(pte) & _PAGE_PRESENT);
+}
+
+static inline int pte_none(pte_t pte)
+{
+ return (pte_val(pte) == 0);
+}
+
+/* static inline int pte_read(pte_t pte) */
+
+static inline int pte_write(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_WRITE;
+}
+
+static inline int pte_huge(pte_t pte)
+{
+ return pte_present(pte)
+ && (pte_val(pte) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
+}
+
+/* static inline int pte_exec(pte_t pte) */
+
+static inline int pte_dirty(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_DIRTY;
+}
+
+static inline int pte_young(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_ACCESSED;
+}
+
+static inline int pte_special(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_SPECIAL;
+}
+
+/* static inline pte_t pte_rdprotect(pte_t pte) */
+
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+ return __pte(pte_val(pte) & ~(_PAGE_WRITE));
+}
+
+/* static inline pte_t pte_mkread(pte_t pte) */
+
+static inline pte_t pte_mkwrite(pte_t pte)
+{
+ return __pte(pte_val(pte) | _PAGE_WRITE);
+}
+
+/* static inline pte_t pte_mkexec(pte_t pte) */
+
+static inline pte_t pte_mkdirty(pte_t pte)
+{
+ return __pte(pte_val(pte) | _PAGE_DIRTY);
+}
+
+static inline pte_t pte_mkclean(pte_t pte)
+{
+ return __pte(pte_val(pte) & ~(_PAGE_DIRTY));
+}
+
+static inline pte_t pte_mkyoung(pte_t pte)
+{
+ return __pte(pte_val(pte) | _PAGE_ACCESSED);
+}
+
+static inline pte_t pte_mkold(pte_t pte)
+{
+ return __pte(pte_val(pte) & ~(_PAGE_ACCESSED));
+}
+
+static inline pte_t pte_mkspecial(pte_t pte)
+{
+ return __pte(pte_val(pte) | _PAGE_SPECIAL);
+}
+
+/* Modify page protection bits */
+static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
+{
+ return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
+}
+
+#define pgd_ERROR(e) \
+ pr_err("%s:%d: bad pgd " PTE_FMT ".\n", __FILE__, __LINE__, pgd_val(e))
+
+
+/* Commit new configuration to MMU hardware */
+static inline void update_mmu_cache(struct vm_area_struct *vma,
+ unsigned long address, pte_t *ptep)
+{
+ /*
+ * The kernel assumes that TLBs don't cache invalid entries, but
+ * in RISC-V, SFENCE.VMA specifies an ordering constraint, not a
+ * cache flush; it is necessary even after writing invalid entries.
+ * Relying on flush_tlb_fix_spurious_fault would suffice, but
+ * the extra traps reduce performance. So, eagerly SFENCE.VMA.
+ */
+ local_flush_tlb_page(address);
+}
+
+#define __HAVE_ARCH_PTE_SAME
+static inline int pte_same(pte_t pte_a, pte_t pte_b)
+{
+ return pte_val(pte_a) == pte_val(pte_b);
+}
+
+#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
+static inline int ptep_set_access_flags(struct vm_area_struct *vma,
+ unsigned long address, pte_t *ptep,
+ pte_t entry, int dirty)
+{
+ if (!pte_same(*ptep, entry))
+ set_pte_at(vma->vm_mm, address, ptep, entry);
+ /*
+ * update_mmu_cache will unconditionally execute, handling both
+ * the case that the PTE changed and the spurious fault case.
+ */
+ return true;
+}
+
+#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
+static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
+ unsigned long address, pte_t *ptep)
+{
+ return __pte(atomic_long_xchg((atomic_long_t *)ptep, 0));
+}
+
+#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
+static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
+ unsigned long address,
+ pte_t *ptep)
+{
+ if (!pte_young(*ptep))
+ return 0;
+ return test_and_clear_bit(_PAGE_ACCESSED_OFFSET, &pte_val(*ptep));
+}
+
+#define __HAVE_ARCH_PTEP_SET_WRPROTECT
+static inline void ptep_set_wrprotect(struct mm_struct *mm,
+ unsigned long address, pte_t *ptep)
+{
+ atomic_long_and(~(unsigned long)_PAGE_WRITE, (atomic_long_t *)ptep);
+}
+
+#define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
+static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pte_t *ptep)
+{
+ /*
+ * This comment is borrowed from x86, but applies equally to RISC-V:
+ *
+ * Clearing the accessed bit without a TLB flush
+ * doesn't cause data corruption. [ It could cause incorrect
+ * page aging and the (mistaken) reclaim of hot pages, but the
+ * chance of that should be relatively low. ]
+ *
+ * So as a performance optimization don't flush the TLB when
+ * clearing the accessed bit, it will eventually be flushed by
+ * a context switch or a VM operation anyway. [ In the rare
+ * event of it not getting flushed for a long time the delay
+ * shouldn't really matter because there's no real memory
+ * pressure for swapout to react to. ]
+ */
+ return ptep_test_and_clear_young(vma, address, ptep);
+}
+
+/*
+ * Encode and decode a swap entry
+ *
+ * Format of swap PTE:
+ * bit 0: _PAGE_PRESENT (zero)
+ * bit 1: reserved for future use (zero)
+ * bits 2 to 6: swap type
+ * bits 7 to XLEN-1: swap offset
+ */
+#define __SWP_TYPE_SHIFT 2
+#define __SWP_TYPE_BITS 5
+#define __SWP_TYPE_MASK ((1UL << __SWP_TYPE_BITS) - 1)
+#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)
+
+#define MAX_SWAPFILES_CHECK() \
+ BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP_TYPE_BITS)
+
+#define __swp_type(x) (((x).val >> __SWP_TYPE_SHIFT) & __SWP_TYPE_MASK)
+#define __swp_offset(x) ((x).val >> __SWP_OFFSET_SHIFT)
+#define __swp_entry(type, offset) ((swp_entry_t) \
+ { ((type) << __SWP_TYPE_SHIFT) | ((offset) << __SWP_OFFSET_SHIFT) })
+
+#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
+#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
+
+#ifdef CONFIG_FLATMEM
+#define kern_addr_valid(addr) (1) /* FIXME */
+#endif
+
+extern void paging_init(void);
+
+static inline void pgtable_cache_init(void)
+{
+ /* No page table caches to initialize */
+}
+
+#endif /* CONFIG_MMU */
+
+#define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1)
+#define VMALLOC_END (PAGE_OFFSET - 1)
+#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
+
+/*
+ * Task size is 0x40000000000 for RV64 or 0xb800000 for RV32.
+ * Note that PGDIR_SIZE must evenly divide TASK_SIZE.
+ */
+#ifdef CONFIG_64BIT
+#define TASK_SIZE (PGDIR_SIZE * PTRS_PER_PGD / 2)
+#else
+#define TASK_SIZE VMALLOC_START
+#endif
+
+#include <asm-generic/pgtable.h>
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* _ASM_RISCV_PGTABLE_H */