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linux/arch/arm64/include/asm/pgtable.h
Will Deacon a6fadf7e67 arm64: mm: introduce present, faulting entries for PAGE_NONE 
This is mostly a port of dbf62d5006 ("ARM: mm: introduce L_PTE_VALID
for page table entries") and 26ffd0d43b ("ARM: mm: introduce present,
faulting entries for PAGE_NONE") from ARM, which makes use of present,
faulting page table entries for page table entries mapped as PROT_NONE.

The main difference with this implementation is that we can make use of
the two pte type bits in order to avoid allocating a software bit for
identifying PROT_NONE pages, instead reserving the 10b suffix for these
types of mappings.

This is required to prevent users from accessing such pages via syscalls
such as read/write over a pipe.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-01-10 10:48:48 +00:00

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/*
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM_PGTABLE_H
#define __ASM_PGTABLE_H
#include <asm/proc-fns.h>
#include <asm/memory.h>
#include <asm/pgtable-hwdef.h>
/*
* Software defined PTE bits definition.
*/
#define PTE_VALID (_AT(pteval_t, 1) << 0)
#define PTE_PROT_NONE (_AT(pteval_t, 1) << 1) /* only when !PTE_VALID */
#define PTE_FILE (_AT(pteval_t, 1) << 2) /* only when !pte_present() */
#define PTE_DIRTY (_AT(pteval_t, 1) << 55)
#define PTE_SPECIAL (_AT(pteval_t, 1) << 56)
/*
* VMALLOC and SPARSEMEM_VMEMMAP ranges.
*/
#define VMALLOC_START UL(0xffffff8000000000)
#define VMALLOC_END (PAGE_OFFSET - UL(0x400000000) - SZ_64K)
#define vmemmap ((struct page *)(VMALLOC_END + SZ_64K))
#define FIRST_USER_ADDRESS 0
#ifndef __ASSEMBLY__
extern void __pte_error(const char *file, int line, unsigned long val);
extern void __pmd_error(const char *file, int line, unsigned long val);
extern void __pgd_error(const char *file, int line, unsigned long val);
#define pte_ERROR(pte) __pte_error(__FILE__, __LINE__, pte_val(pte))
#ifndef CONFIG_ARM64_64K_PAGES
#define pmd_ERROR(pmd) __pmd_error(__FILE__, __LINE__, pmd_val(pmd))
#endif
#define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd))
/*
* The pgprot_* and protection_map entries will be fixed up at runtime to
* include the cachable and bufferable bits based on memory policy, as well as
* any architecture dependent bits like global/ASID and SMP shared mapping
* bits.
*/
#define _PAGE_DEFAULT PTE_TYPE_PAGE | PTE_AF
extern pgprot_t pgprot_default;
#define __pgprot_modify(prot,mask,bits) \
__pgprot((pgprot_val(prot) & ~(mask)) | (bits))
#define _MOD_PROT(p, b) __pgprot_modify(p, 0, b)
#define PAGE_NONE __pgprot_modify(pgprot_default, PTE_TYPE_MASK, PTE_PROT_NONE)
#define PAGE_SHARED _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define PAGE_SHARED_EXEC _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN)
#define PAGE_COPY _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
#define PAGE_COPY_EXEC _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_RDONLY)
#define PAGE_READONLY _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
#define PAGE_READONLY_EXEC _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_RDONLY)
#define PAGE_KERNEL _MOD_PROT(pgprot_default, PTE_PXN | PTE_UXN | PTE_DIRTY)
#define PAGE_KERNEL_EXEC _MOD_PROT(pgprot_default, PTE_UXN | PTE_DIRTY)
#define __PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE)
#define __PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define __PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
#define __PAGE_COPY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
#define __PAGE_COPY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_RDONLY)
#define __PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
#define __PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_RDONLY)
#endif /* __ASSEMBLY__ */
#define __P000 __PAGE_NONE
#define __P001 __PAGE_READONLY
#define __P010 __PAGE_COPY
#define __P011 __PAGE_COPY
#define __P100 __PAGE_READONLY_EXEC
#define __P101 __PAGE_READONLY_EXEC
#define __P110 __PAGE_COPY_EXEC
#define __P111 __PAGE_COPY_EXEC
#define __S000 __PAGE_NONE
#define __S001 __PAGE_READONLY
#define __S010 __PAGE_SHARED
#define __S011 __PAGE_SHARED
#define __S100 __PAGE_READONLY_EXEC
#define __S101 __PAGE_READONLY_EXEC
#define __S110 __PAGE_SHARED_EXEC
#define __S111 __PAGE_SHARED_EXEC
#ifndef __ASSEMBLY__
/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
extern struct page *empty_zero_page;
#define ZERO_PAGE(vaddr) (empty_zero_page)
#define pte_pfn(pte) ((pte_val(pte) & PHYS_MASK) >> PAGE_SHIFT)
#define pfn_pte(pfn,prot) (__pte(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
#define pte_none(pte) (!pte_val(pte))
#define pte_clear(mm,addr,ptep) set_pte(ptep, __pte(0))
#define pte_page(pte) (pfn_to_page(pte_pfn(pte)))
#define pte_offset_kernel(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))
#define pte_offset_map(dir,addr) pte_offset_kernel((dir), (addr))
#define pte_offset_map_nested(dir,addr) pte_offset_kernel((dir), (addr))
#define pte_unmap(pte) do { } while (0)
#define pte_unmap_nested(pte) do { } while (0)
/*
* The following only work if pte_present(). Undefined behaviour otherwise.
*/
#define pte_present(pte) (pte_val(pte) & (PTE_VALID | PTE_PROT_NONE))
#define pte_dirty(pte) (pte_val(pte) & PTE_DIRTY)
#define pte_young(pte) (pte_val(pte) & PTE_AF)
#define pte_special(pte) (pte_val(pte) & PTE_SPECIAL)
#define pte_write(pte) (!(pte_val(pte) & PTE_RDONLY))
#define pte_exec(pte) (!(pte_val(pte) & PTE_UXN))
#define pte_valid_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
#define PTE_BIT_FUNC(fn,op) \
static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
PTE_BIT_FUNC(wrprotect, |= PTE_RDONLY);
PTE_BIT_FUNC(mkwrite, &= ~PTE_RDONLY);
PTE_BIT_FUNC(mkclean, &= ~PTE_DIRTY);
PTE_BIT_FUNC(mkdirty, |= PTE_DIRTY);
PTE_BIT_FUNC(mkold, &= ~PTE_AF);
PTE_BIT_FUNC(mkyoung, |= PTE_AF);
PTE_BIT_FUNC(mkspecial, |= PTE_SPECIAL);
static inline void set_pte(pte_t *ptep, pte_t pte)
{
*ptep = pte;
}
extern void __sync_icache_dcache(pte_t pteval, unsigned long addr);
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
if (pte_valid_user(pte)) {
if (pte_exec(pte))
__sync_icache_dcache(pte, addr);
if (!pte_dirty(pte))
pte = pte_wrprotect(pte);
}
set_pte(ptep, pte);
}
/*
* Huge pte definitions.
*/
#define pte_huge(pte) ((pte_val(pte) & PTE_TYPE_MASK) == PTE_TYPE_HUGEPAGE)
#define pte_mkhuge(pte) (__pte((pte_val(pte) & ~PTE_TYPE_MASK) | PTE_TYPE_HUGEPAGE))
#define __HAVE_ARCH_PTE_SPECIAL
/*
* Mark the prot value as uncacheable and unbufferable.
*/
#define pgprot_noncached(prot) \
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRnE))
#define pgprot_writecombine(prot) \
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_GRE))
#define pgprot_dmacoherent(prot) \
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC))
#define __HAVE_PHYS_MEM_ACCESS_PROT
struct file;
extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot);
#define pmd_none(pmd) (!pmd_val(pmd))
#define pmd_present(pmd) (pmd_val(pmd))
#define pmd_bad(pmd) (!(pmd_val(pmd) & 2))
static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
{
*pmdp = pmd;
dsb();
}
static inline void pmd_clear(pmd_t *pmdp)
{
set_pmd(pmdp, __pmd(0));
}
static inline pte_t *pmd_page_vaddr(pmd_t pmd)
{
return __va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
}
#define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define mk_pte(page,prot) pfn_pte(page_to_pfn(page),prot)
#ifndef CONFIG_ARM64_64K_PAGES
#define pud_none(pud) (!pud_val(pud))
#define pud_bad(pud) (!(pud_val(pud) & 2))
#define pud_present(pud) (pud_val(pud))
static inline void set_pud(pud_t *pudp, pud_t pud)
{
*pudp = pud;
dsb();
}
static inline void pud_clear(pud_t *pudp)
{
set_pud(pudp, __pud(0));
}
static inline pmd_t *pud_page_vaddr(pud_t pud)
{
return __va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
}
#endif /* CONFIG_ARM64_64K_PAGES */
/* to find an entry in a page-table-directory */
#define pgd_index(addr) (((addr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
#define pgd_offset(mm, addr) ((mm)->pgd+pgd_index(addr))
/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(addr) pgd_offset(&init_mm, addr)
/* Find an entry in the second-level page table.. */
#ifndef CONFIG_ARM64_64K_PAGES
#define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
{
return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
}
#endif
/* Find an entry in the third-level page table.. */
#define __pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY |
PTE_PROT_NONE | PTE_VALID;
pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
return pte;
}
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
#define SWAPPER_DIR_SIZE (3 * PAGE_SIZE)
#define IDMAP_DIR_SIZE (2 * PAGE_SIZE)
/*
* Encode and decode a swap entry:
* bits 0-1: present (must be zero)
* bit 2: PTE_FILE
* bits 3-8: swap type
* bits 9-63: swap offset
*/
#define __SWP_TYPE_SHIFT 3
#define __SWP_TYPE_BITS 6
#define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1)
#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)
#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(swp) ((pte_t) { (swp).val })
/*
* Ensure that there are not more swap files than can be encoded in the kernel
* the PTEs.
*/
#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP_TYPE_BITS)
/*
* Encode and decode a file entry:
* bits 0-1: present (must be zero)
* bit 2: PTE_FILE
* bits 3-63: file offset / PAGE_SIZE
*/
#define pte_file(pte) (pte_val(pte) & PTE_FILE)
#define pte_to_pgoff(x) (pte_val(x) >> 3)
#define pgoff_to_pte(x) __pte(((x) << 3) | PTE_FILE)
#define PTE_FILE_MAX_BITS 61
extern int kern_addr_valid(unsigned long addr);
#include <asm-generic/pgtable.h>
/*
* remap a physical page `pfn' of size `size' with page protection `prot'
* into virtual address `from'
*/
#define io_remap_pfn_range(vma,from,pfn,size,prot) \
remap_pfn_range(vma, from, pfn, size, prot)
#define pgtable_cache_init() do { } while (0)
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_PGTABLE_H */
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