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Diffstat (limited to 'mm/mprotect.c')
-rw-r--r--mm/mprotect.c266
1 files changed, 213 insertions, 53 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 653b8571c1e..c43d557941f 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -4,13 +4,12 @@
* (C) Copyright 1994 Linus Torvalds
* (C) Copyright 2002 Christoph Hellwig
*
- * Address space accounting code <alan@redhat.com>
+ * Address space accounting code <alan@lxorguk.ukuu.org.uk>
* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
*/
#include <linux/mm.h>
#include <linux/hugetlb.h>
-#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/fs.h>
@@ -19,86 +18,245 @@
#include <linux/mempolicy.h>
#include <linux/personality.h>
#include <linux/syscalls.h>
-
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
+#include <linux/migrate.h>
+#include <linux/perf_event.h>
+#include <linux/ksm.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
-static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
- unsigned long addr, unsigned long end, pgprot_t newprot)
+#ifndef pgprot_modify
+static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
+{
+ return newprot;
+}
+#endif
+
+/*
+ * For a prot_numa update we only hold mmap_sem for read so there is a
+ * potential race with faulting where a pmd was temporarily none. This
+ * function checks for a transhuge pmd under the appropriate lock. It
+ * returns a pte if it was successfully locked or NULL if it raced with
+ * a transhuge insertion.
+ */
+static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, int prot_numa, spinlock_t **ptl)
{
pte_t *pte;
+ spinlock_t *pmdl;
+
+ /* !prot_numa is protected by mmap_sem held for write */
+ if (!prot_numa)
+ return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
+
+ pmdl = pmd_lock(vma->vm_mm, pmd);
+ if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
+ spin_unlock(pmdl);
+ return NULL;
+ }
+
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
+ spin_unlock(pmdl);
+ return pte;
+}
+
+static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, unsigned long end, pgprot_t newprot,
+ int dirty_accountable, int prot_numa)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pte_t *pte, oldpte;
spinlock_t *ptl;
+ unsigned long pages = 0;
- pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
+ if (!pte)
+ return 0;
+
+ arch_enter_lazy_mmu_mode();
do {
- if (pte_present(*pte)) {
+ oldpte = *pte;
+ if (pte_present(oldpte)) {
pte_t ptent;
-
- /* Avoid an SMP race with hardware updated dirty/clean
- * bits by wiping the pte and then setting the new pte
- * into place.
- */
- ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot);
- set_pte_at(mm, addr, pte, ptent);
- lazy_mmu_prot_update(ptent);
+ bool updated = false;
+
+ if (!prot_numa) {
+ ptent = ptep_modify_prot_start(mm, addr, pte);
+ if (pte_numa(ptent))
+ ptent = pte_mknonnuma(ptent);
+ ptent = pte_modify(ptent, newprot);
+ /*
+ * Avoid taking write faults for pages we
+ * know to be dirty.
+ */
+ if (dirty_accountable && pte_dirty(ptent))
+ ptent = pte_mkwrite(ptent);
+ ptep_modify_prot_commit(mm, addr, pte, ptent);
+ updated = true;
+ } else {
+ struct page *page;
+
+ page = vm_normal_page(vma, addr, oldpte);
+ if (page && !PageKsm(page)) {
+ if (!pte_numa(oldpte)) {
+ ptep_set_numa(mm, addr, pte);
+ updated = true;
+ }
+ }
+ }
+ if (updated)
+ pages++;
+ } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
+ swp_entry_t entry = pte_to_swp_entry(oldpte);
+
+ if (is_write_migration_entry(entry)) {
+ pte_t newpte;
+ /*
+ * A protection check is difficult so
+ * just be safe and disable write
+ */
+ make_migration_entry_read(&entry);
+ newpte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(oldpte))
+ newpte = pte_swp_mksoft_dirty(newpte);
+ set_pte_at(mm, addr, pte, newpte);
+
+ pages++;
+ }
}
} while (pte++, addr += PAGE_SIZE, addr != end);
+ arch_leave_lazy_mmu_mode();
pte_unmap_unlock(pte - 1, ptl);
+
+ return pages;
}
-static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
- unsigned long addr, unsigned long end, pgprot_t newprot)
+static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
+ pud_t *pud, unsigned long addr, unsigned long end,
+ pgprot_t newprot, int dirty_accountable, int prot_numa)
{
pmd_t *pmd;
+ struct mm_struct *mm = vma->vm_mm;
unsigned long next;
+ unsigned long pages = 0;
+ unsigned long nr_huge_updates = 0;
+ unsigned long mni_start = 0;
pmd = pmd_offset(pud, addr);
do {
+ unsigned long this_pages;
+
next = pmd_addr_end(addr, end);
- if (pmd_none_or_clear_bad(pmd))
+ if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
continue;
- change_pte_range(mm, pmd, addr, next, newprot);
+
+ /* invoke the mmu notifier if the pmd is populated */
+ if (!mni_start) {
+ mni_start = addr;
+ mmu_notifier_invalidate_range_start(mm, mni_start, end);
+ }
+
+ if (pmd_trans_huge(*pmd)) {
+ if (next - addr != HPAGE_PMD_SIZE)
+ split_huge_page_pmd(vma, addr, pmd);
+ else {
+ int nr_ptes = change_huge_pmd(vma, pmd, addr,
+ newprot, prot_numa);
+
+ if (nr_ptes) {
+ if (nr_ptes == HPAGE_PMD_NR) {
+ pages += HPAGE_PMD_NR;
+ nr_huge_updates++;
+ }
+
+ /* huge pmd was handled */
+ continue;
+ }
+ }
+ /* fall through, the trans huge pmd just split */
+ }
+ this_pages = change_pte_range(vma, pmd, addr, next, newprot,
+ dirty_accountable, prot_numa);
+ pages += this_pages;
} while (pmd++, addr = next, addr != end);
+
+ if (mni_start)
+ mmu_notifier_invalidate_range_end(mm, mni_start, end);
+
+ if (nr_huge_updates)
+ count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
+ return pages;
}
-static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
- unsigned long addr, unsigned long end, pgprot_t newprot)
+static inline unsigned long change_pud_range(struct vm_area_struct *vma,
+ pgd_t *pgd, unsigned long addr, unsigned long end,
+ pgprot_t newprot, int dirty_accountable, int prot_numa)
{
pud_t *pud;
unsigned long next;
+ unsigned long pages = 0;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
- change_pmd_range(mm, pud, addr, next, newprot);
+ pages += change_pmd_range(vma, pud, addr, next, newprot,
+ dirty_accountable, prot_numa);
} while (pud++, addr = next, addr != end);
+
+ return pages;
}
-static void change_protection(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end, pgprot_t newprot)
+static unsigned long change_protection_range(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end, pgprot_t newprot,
+ int dirty_accountable, int prot_numa)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
unsigned long next;
unsigned long start = addr;
+ unsigned long pages = 0;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
flush_cache_range(vma, addr, end);
+ set_tlb_flush_pending(mm);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
- change_pud_range(mm, pgd, addr, next, newprot);
+ pages += change_pud_range(vma, pgd, addr, next, newprot,
+ dirty_accountable, prot_numa);
} while (pgd++, addr = next, addr != end);
- flush_tlb_range(vma, start, end);
+
+ /* Only flush the TLB if we actually modified any entries: */
+ if (pages)
+ flush_tlb_range(vma, start, end);
+ clear_tlb_flush_pending(mm);
+
+ return pages;
+}
+
+unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, pgprot_t newprot,
+ int dirty_accountable, int prot_numa)
+{
+ unsigned long pages;
+
+ if (is_vm_hugetlb_page(vma))
+ pages = hugetlb_change_protection(vma, start, end, newprot);
+ else
+ pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
+
+ return pages;
}
-static int
+int
mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
unsigned long start, unsigned long end, unsigned long newflags)
{
@@ -106,9 +264,9 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
unsigned long oldflags = vma->vm_flags;
long nrpages = (end - start) >> PAGE_SHIFT;
unsigned long charged = 0;
- pgprot_t newprot;
pgoff_t pgoff;
int error;
+ int dirty_accountable = 0;
if (newflags == oldflags) {
*pprev = vma;
@@ -118,22 +276,19 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
/*
* If we make a private mapping writable we increase our commit;
* but (without finer accounting) cannot reduce our commit if we
- * make it unwritable again.
- *
- * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
- * a MAP_NORESERVE private mapping to writable will now reserve.
+ * make it unwritable again. hugetlb mapping were accounted for
+ * even if read-only so there is no need to account for them here
*/
if (newflags & VM_WRITE) {
- if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) {
+ if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
+ VM_SHARED|VM_NORESERVE))) {
charged = nrpages;
- if (security_vm_enough_memory(charged))
+ if (security_vm_enough_memory_mm(mm, charged))
return -ENOMEM;
newflags |= VM_ACCOUNT;
}
}
- newprot = protection_map[newflags & 0xf];
-
/*
* First try to merge with previous and/or next vma.
*/
@@ -165,10 +320,20 @@ success:
* held in write mode.
*/
vma->vm_flags = newflags;
- vma->vm_page_prot = newprot;
- change_protection(vma, start, end, newprot);
+ vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
+ vm_get_page_prot(newflags));
+
+ if (vma_wants_writenotify(vma)) {
+ vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
+ dirty_accountable = 1;
+ }
+
+ change_protection(vma, start, end, vma->vm_page_prot,
+ dirty_accountable, 0);
+
vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
vm_stat_account(mm, newflags, vma->vm_file, nrpages);
+ perf_event_mmap(vma);
return 0;
fail:
@@ -176,8 +341,8 @@ fail:
return error;
}
-asmlinkage long
-sys_mprotect(unsigned long start, size_t len, unsigned long prot)
+SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
+ unsigned long, prot)
{
unsigned long vm_flags, nstart, end, tmp, reqprot;
struct vm_area_struct *vma, *prev;
@@ -195,25 +360,25 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot)
end = start + len;
if (end <= start)
return -ENOMEM;
- if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM))
+ if (!arch_validate_prot(prot))
return -EINVAL;
reqprot = prot;
/*
* Does the application expect PROT_READ to imply PROT_EXEC:
*/
- if (unlikely((prot & PROT_READ) &&
- (current->personality & READ_IMPLIES_EXEC)))
+ if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
prot |= PROT_EXEC;
vm_flags = calc_vm_prot_bits(prot);
down_write(&current->mm->mmap_sem);
- vma = find_vma_prev(current->mm, start, &prev);
+ vma = find_vma(current->mm, start);
error = -ENOMEM;
if (!vma)
goto out;
+ prev = vma->vm_prev;
if (unlikely(grows & PROT_GROWSDOWN)) {
if (vma->vm_start >= end)
goto out;
@@ -221,8 +386,7 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot)
error = -EINVAL;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto out;
- }
- else {
+ } else {
if (vma->vm_start > start)
goto out;
if (unlikely(grows & PROT_GROWSUP)) {
@@ -238,14 +402,10 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot)
for (nstart = start ; ; ) {
unsigned long newflags;
- /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
-
- if (is_vm_hugetlb_page(vma)) {
- error = -EACCES;
- goto out;
- }
+ /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
- newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
+ newflags = vm_flags;
+ newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
/* newflags >> 4 shift VM_MAY% in place of VM_% */
if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-12-05 17:26:22 +0000