diff options
Diffstat (limited to 'arch/powerpc/mm/subpage-prot.c')
| -rw-r--r-- | arch/powerpc/mm/subpage-prot.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c new file mode 100644 index 000000000000..4cafc0c33d0a --- /dev/null +++ b/arch/powerpc/mm/subpage-prot.c @@ -0,0 +1,213 @@ +/* + * Copyright 2007-2008 Paul Mackerras, IBM Corp. + * + * 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; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/gfp.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/mm.h> +#include <linux/hugetlb.h> + +#include <asm/pgtable.h> +#include <asm/uaccess.h> +#include <asm/tlbflush.h> + +/* + * Free all pages allocated for subpage protection maps and pointers. + * Also makes sure that the subpage_prot_table structure is + * reinitialized for the next user. + */ +void subpage_prot_free(pgd_t *pgd) +{ + struct subpage_prot_table *spt = pgd_subpage_prot(pgd); + unsigned long i, j, addr; + u32 **p; + + for (i = 0; i < 4; ++i) { + if (spt->low_prot[i]) { + free_page((unsigned long)spt->low_prot[i]); + spt->low_prot[i] = NULL; + } + } + addr = 0; + for (i = 0; i < 2; ++i) { + p = spt->protptrs[i]; + if (!p) + continue; + spt->protptrs[i] = NULL; + for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr; + ++j, addr += PAGE_SIZE) + if (p[j]) + free_page((unsigned long)p[j]); + free_page((unsigned long)p); + } + spt->maxaddr = 0; +} + +static void hpte_flush_range(struct mm_struct *mm, unsigned long addr, + int npages) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + spinlock_t *ptl; + + pgd = pgd_offset(mm, addr); + if (pgd_none(*pgd)) + return; + pud = pud_offset(pgd, addr); + if (pud_none(*pud)) + return; + pmd = pmd_offset(pud, addr); + if (pmd_none(*pmd)) + return; + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); + arch_enter_lazy_mmu_mode(); + for (; npages > 0; --npages) { + pte_update(mm, addr, pte, 0, 0); + addr += PAGE_SIZE; + ++pte; + } + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(pte - 1, ptl); +} + +/* + * Clear the subpage protection map for an address range, allowing + * all accesses that are allowed by the pte permissions. + */ +static void subpage_prot_clear(unsigned long addr, unsigned long len) +{ + struct mm_struct *mm = current->mm; + struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd); + u32 **spm, *spp; + int i, nw; + unsigned long next, limit; + + down_write(&mm->mmap_sem); + limit = addr + len; + if (limit > spt->maxaddr) + limit = spt->maxaddr; + for (; addr < limit; addr = next) { + next = pmd_addr_end(addr, limit); + if (addr < 0x100000000) { + spm = spt->low_prot; + } else { + spm = spt->protptrs[addr >> SBP_L3_SHIFT]; + if (!spm) + continue; + } + spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)]; + if (!spp) + continue; + spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); + + i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); + nw = PTRS_PER_PTE - i; + if (addr + (nw << PAGE_SHIFT) > next) + nw = (next - addr) >> PAGE_SHIFT; + + memset(spp, 0, nw * sizeof(u32)); + + /* now flush any existing HPTEs for the range */ + hpte_flush_range(mm, addr, nw); + } + up_write(&mm->mmap_sem); +} + +/* + * Copy in a subpage protection map for an address range. + * The map has 2 bits per 4k subpage, so 32 bits per 64k page. + * Each 2-bit field is 0 to allow any access, 1 to prevent writes, + * 2 or 3 to prevent all accesses. + * Note that the normal page protections also apply; the subpage + * protection mechanism is an additional constraint, so putting 0 + * in a 2-bit field won't allow writes to a page that is otherwise + * write-protected. + */ +long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map) +{ + struct mm_struct *mm = current->mm; + struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd); + u32 **spm, *spp; + int i, nw; + unsigned long next, limit; + int err; + + /* Check parameters */ + if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) || + addr >= TASK_SIZE || len >= TASK_SIZE || addr + len > TASK_SIZE) + return -EINVAL; + + if (is_hugepage_only_range(mm, addr, len)) + return -EINVAL; + + if (!map) { + /* Clear out the protection map for the address range */ + subpage_prot_clear(addr, len); + return 0; + } + + if (!access_ok(VERIFY_READ, map, (len >> PAGE_SHIFT) * sizeof(u32))) + return -EFAULT; + + down_write(&mm->mmap_sem); + for (limit = addr + len; addr < limit; addr = next) { + next = pmd_addr_end(addr, limit); + err = -ENOMEM; + if (addr < 0x100000000) { + spm = spt->low_prot; + } else { + spm = spt->protptrs[addr >> SBP_L3_SHIFT]; + if (!spm) { + spm = (u32 **)get_zeroed_page(GFP_KERNEL); + if (!spm) + goto out; + spt->protptrs[addr >> SBP_L3_SHIFT] = spm; + } + } + spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1); + spp = *spm; + if (!spp) { + spp = (u32 *)get_zeroed_page(GFP_KERNEL); + if (!spp) + goto out; + *spm = spp; + } + spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); + + local_irq_disable(); + demote_segment_4k(mm, addr); + local_irq_enable(); + + i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); + nw = PTRS_PER_PTE - i; + if (addr + (nw << PAGE_SHIFT) > next) + nw = (next - addr) >> PAGE_SHIFT; + + up_write(&mm->mmap_sem); + err = -EFAULT; + if (__copy_from_user(spp, map, nw * sizeof(u32))) + goto out2; + map += nw; + down_write(&mm->mmap_sem); + + /* now flush any existing HPTEs for the range */ + hpte_flush_range(mm, addr, nw); + } + if (limit > spt->maxaddr) + spt->maxaddr = limit; + err = 0; + out: + up_write(&mm->mmap_sem); + out2: + return err; +} |