Viewing file:  pgtable.h (17.62 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 Regents of the University of California
*/
#ifndef _ASM_RISCV_PGTABLE_H
#define _ASM_RISCV_PGTABLE_H
#include <linux/mmzone.h>
#include <linux/sizes.h>
#include <asm/pgtable-bits.h>
#ifndef CONFIG_MMU
#define KERNEL_LINK_ADDR PAGE_OFFSET
#else
#define ADDRESS_SPACE_END (UL(-1))
#ifdef CONFIG_64BIT
/* Leave 2GB for kernel and BPF at the end of the address space */
#define KERNEL_LINK_ADDR (ADDRESS_SPACE_END - SZ_2G + 1)
#else
#define KERNEL_LINK_ADDR PAGE_OFFSET
#endif
#define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1)
#define VMALLOC_END (PAGE_OFFSET - 1)
#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
#define BPF_JIT_REGION_SIZE (SZ_128M)
#ifdef CONFIG_64BIT
#define BPF_JIT_REGION_START (BPF_JIT_REGION_END - BPF_JIT_REGION_SIZE)
#define BPF_JIT_REGION_END (MODULES_END)
#else
#define BPF_JIT_REGION_START (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
#define BPF_JIT_REGION_END (VMALLOC_END)
#endif
/* Modules always live before the kernel */
#ifdef CONFIG_64BIT
#define MODULES_VADDR (PFN_ALIGN((unsigned long)&_end) - SZ_2G)
#define MODULES_END (PFN_ALIGN((unsigned long)&_start))
#endif
/*
* Roughly size the vmemmap space to be large enough to fit enough
* struct pages to map half the virtual address space. Then
* position vmemmap directly below the VMALLOC region.
*/
#define VMEMMAP_SHIFT \
(CONFIG_VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT)
#define VMEMMAP_SIZE BIT(VMEMMAP_SHIFT)
#define VMEMMAP_END (VMALLOC_START - 1)
#define VMEMMAP_START (VMALLOC_START - VMEMMAP_SIZE)
/*
* Define vmemmap for pfn_to_page & page_to_pfn calls. Needed if kernel
* is configured with CONFIG_SPARSEMEM_VMEMMAP enabled.
*/
#define vmemmap ((struct page *)VMEMMAP_START)
#define PCI_IO_SIZE SZ_16M
#define PCI_IO_END VMEMMAP_START
#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
#define FIXADDR_TOP PCI_IO_START
#ifdef CONFIG_64BIT
#define MAX_FDT_SIZE PMD_SIZE
#define FIX_FDT_SIZE (MAX_FDT_SIZE + SZ_2M)
#define FIXADDR_SIZE (PMD_SIZE + FIX_FDT_SIZE)
#else
#define MAX_FDT_SIZE PGDIR_SIZE
#define FIX_FDT_SIZE MAX_FDT_SIZE
#define FIXADDR_SIZE (PGDIR_SIZE + FIX_FDT_SIZE)
#endif
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
#endif
#ifdef CONFIG_XIP_KERNEL
#define XIP_OFFSET SZ_8M
#else
#define XIP_OFFSET 0
#endif
#ifndef __ASSEMBLY__
/* 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 */
#ifdef CONFIG_XIP_KERNEL
#define XIP_FIXUP(addr) ({ \
uintptr_t __a = (uintptr_t)(addr); \
(__a >= CONFIG_XIP_PHYS_ADDR && __a < CONFIG_XIP_PHYS_ADDR + SZ_16M) ? \
__a - CONFIG_XIP_PHYS_ADDR + CONFIG_PHYS_RAM_BASE - XIP_OFFSET :\
__a; \
})
#else
#define XIP_FIXUP(addr) (addr)
#endif /* CONFIG_XIP_KERNEL */
#ifdef CONFIG_MMU
/* 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)
/* Page protection bits */
#define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_USER)
#define PAGE_NONE __pgprot(_PAGE_PROT_NONE)
#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 \
| _PAGE_GLOBAL)
#define PAGE_KERNEL __pgprot(_PAGE_KERNEL)
#define PAGE_KERNEL_READ __pgprot(_PAGE_KERNEL & ~_PAGE_WRITE)
#define PAGE_KERNEL_EXEC __pgprot(_PAGE_KERNEL | _PAGE_EXEC)
#define PAGE_KERNEL_READ_EXEC __pgprot((_PAGE_KERNEL & ~_PAGE_WRITE) \
| _PAGE_EXEC)
#define PAGE_TABLE __pgprot(_PAGE_TABLE)
/*
* The RISC-V ISA doesn't yet specify how to query or modify PMAs, so we can't
* change the properties of memory regions.
*/
#define _PAGE_IOREMAP _PAGE_KERNEL
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
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline int pmd_present(pmd_t pmd)
{
/*
* Checking for _PAGE_LEAF is needed too because:
* When splitting a THP, split_huge_page() will temporarily clear
* the present bit, in this situation, pmd_present() and
* pmd_trans_huge() still needs to return true.
*/
return (pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROT_NONE | _PAGE_LEAF));
}
#else
static inline int pmd_present(pmd_t pmd)
{
return (pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROT_NONE));
}
#endif
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) || (pmd_val(pmd) & _PAGE_LEAF);
}
#define pmd_leaf pmd_leaf
static inline int pmd_leaf(pmd_t pmd)
{
return pmd_present(pmd) && (pmd_val(pmd) & _PAGE_LEAF);
}
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));
}
static inline unsigned long _pgd_pfn(pgd_t pgd)
{
return pgd_val(pgd) >> _PAGE_PFN_SHIFT;
}
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);
}
static inline pte_t pmd_pte(pmd_t pmd)
{
return __pte(pmd_val(pmd));
}
static inline pte_t pud_pte(pud_t pud)
{
return __pte(pud_val(pud));
}
/* 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));
}
#define mk_pte(page, prot) pfn_pte(page_to_pfn(page), prot)
static inline int pte_present(pte_t pte)
{
return (pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROT_NONE));
}
static inline int pte_none(pte_t pte)
{
return (pte_val(pte) == 0);
}
static inline int pte_write(pte_t pte)
{
return pte_val(pte) & _PAGE_WRITE;
}
static inline int pte_exec(pte_t pte)
{
return pte_val(pte) & _PAGE_EXEC;
}
static inline int pte_huge(pte_t pte)
{
return pte_present(pte) && (pte_val(pte) & _PAGE_LEAF);
}
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);
}
static inline pte_t pte_mkhuge(pte_t pte)
{
return pte;
}
#ifdef CONFIG_NUMA_BALANCING
/*
* See the comment in include/asm-generic/pgtable.h
*/
static inline int pte_protnone(pte_t pte)
{
return (pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROT_NONE)) == _PAGE_PROT_NONE;
}
static inline int pmd_protnone(pmd_t pmd)
{
return pte_protnone(pmd_pte(pmd));
}
#endif
/* 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);
}
static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp)
{
pte_t *ptep = (pte_t *)pmdp;
update_mmu_cache(vma, address, ptep);
}
#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);
}
/*
* 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;
}
void flush_icache_pte(pte_t pte);
static inline void set_pte_at(struct mm_struct *mm,
unsigned long addr, pte_t *ptep, pte_t pteval)
{
if (pte_present(pteval) && pte_exec(pteval))
flush_icache_pte(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));
}
#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);
}
/*
* THP functions
*/
static inline pmd_t pte_pmd(pte_t pte)
{
return __pmd(pte_val(pte));
}
static inline pmd_t pmd_mkhuge(pmd_t pmd)
{
return pmd;
}
static inline pmd_t pmd_mkinvalid(pmd_t pmd)
{
return __pmd(pmd_val(pmd) & ~(_PAGE_PRESENT|_PAGE_PROT_NONE));
}
#define __pmd_to_phys(pmd) (pmd_val(pmd) >> _PAGE_PFN_SHIFT << PAGE_SHIFT)
static inline unsigned long pmd_pfn(pmd_t pmd)
{
return ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT);
}
static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
{
return pte_pmd(pte_modify(pmd_pte(pmd), newprot));
}
#define pmd_write pmd_write
static inline int pmd_write(pmd_t pmd)
{
return pte_write(pmd_pte(pmd));
}
static inline int pmd_dirty(pmd_t pmd)
{
return pte_dirty(pmd_pte(pmd));
}
static inline int pmd_young(pmd_t pmd)
{
return pte_young(pmd_pte(pmd));
}
static inline pmd_t pmd_mkold(pmd_t pmd)
{
return pte_pmd(pte_mkold(pmd_pte(pmd)));
}
static inline pmd_t pmd_mkyoung(pmd_t pmd)
{
return pte_pmd(pte_mkyoung(pmd_pte(pmd)));
}
static inline pmd_t pmd_mkwrite(pmd_t pmd)
{
return pte_pmd(pte_mkwrite(pmd_pte(pmd)));
}
static inline pmd_t pmd_wrprotect(pmd_t pmd)
{
return pte_pmd(pte_wrprotect(pmd_pte(pmd)));
}
static inline pmd_t pmd_mkclean(pmd_t pmd)
{
return pte_pmd(pte_mkclean(pmd_pte(pmd)));
}
static inline pmd_t pmd_mkdirty(pmd_t pmd)
{
return pte_pmd(pte_mkdirty(pmd_pte(pmd)));
}
static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t pmd)
{
return set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd));
}
static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
pud_t *pudp, pud_t pud)
{
return set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud));
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline int pmd_trans_huge(pmd_t pmd)
{
return pmd_leaf(pmd);
}
#define __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp,
pmd_t entry, int dirty)
{
return ptep_set_access_flags(vma, address, (pte_t *)pmdp, pmd_pte(entry), dirty);
}
#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp)
{
return ptep_test_and_clear_young(vma, address, (pte_t *)pmdp);
}
#define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
return pte_pmd(ptep_get_and_clear(mm, address, (pte_t *)pmdp));
}
#define __HAVE_ARCH_PMDP_SET_WRPROTECT
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
ptep_set_wrprotect(mm, address, (pte_t *)pmdp);
}
#define pmdp_establish pmdp_establish
static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp, pmd_t pmd)
{
return __pmd(atomic_long_xchg((atomic_long_t *)pmdp, pmd_val(pmd)));
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/*
* Encode and decode a swap entry
*
* Format of swap PTE:
* bit 0: _PAGE_PRESENT (zero)
* bit 1: _PAGE_PROT_NONE (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 })
/*
* In the RV64 Linux scheme, we give the user half of the virtual-address space
* and give the kernel the other (upper) half.
*/
#ifdef CONFIG_64BIT
#define KERN_VIRT_START (-(BIT(CONFIG_VA_BITS)) + TASK_SIZE)
#else
#define KERN_VIRT_START FIXADDR_START
#endif
/*
* Task size is 0x4000000000 for RV64 or 0x9fc00000 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 FIXADDR_START
#endif
#else /* CONFIG_MMU */
#define PAGE_SHARED __pgprot(0)
#define PAGE_KERNEL __pgprot(0)
#define swapper_pg_dir NULL
#define TASK_SIZE 0xffffffffUL
#define VMALLOC_START 0
#define VMALLOC_END TASK_SIZE
#endif /* !CONFIG_MMU */
#define kern_addr_valid(addr) (1) /* FIXME */
extern char _start[];
extern void *_dtb_early_va;
extern uintptr_t _dtb_early_pa;
#if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_MMU)
#define dtb_early_va (*(void **)XIP_FIXUP(&_dtb_early_va))
#define dtb_early_pa (*(uintptr_t *)XIP_FIXUP(&_dtb_early_pa))
#else
#define dtb_early_va _dtb_early_va
#define dtb_early_pa _dtb_early_pa
#endif /* CONFIG_XIP_KERNEL */
void paging_init(void);
void misc_mem_init(void);
/*
* 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))
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_RISCV_PGTABLE_H */
|