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