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Revert "mm: protect against PTE changes done by dup_mmap()"

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This reverts commit a9e3a1ab5d.

Reason for revert: remove SPF non upstream code
Bug: 140544941
Test: boot
Change-Id: I912a8891ac6cf3e72c7b7aa27df2922554b31491
Signed-off-by: Martin Liu <liumartin@google.com>
[dereference23: Forward port to msm-5.4]
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>
This commit is contained in:
Martin Liu 2020-04-12 01:32:15 +08:00 • committed by Alexander Winkowski
commit 37d40ca049
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GPG key ID: 72762A66704CDE44
1 changed files with 2 additions and 28 deletions
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30
kernel/fork.c
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@ -486,7 +486,7 @@ EXPORT_SYMBOL(free_task);
static __latent_entropy int dup_mmap(struct mm_struct *mm,
struct mm_struct *oldmm)
{
struct vm_area_struct *mpnt, *tmp, *prev, **pprev, *last = NULL;
struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
struct rb_node **rb_link, *rb_parent;
int retval;
unsigned long charge;
@ -605,18 +605,8 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
rb_parent = &tmp->vm_rb;
mm->map_count++;
if (!(tmp->vm_flags & VM_WIPEONFORK)) {
if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT)) {
/*
* Mark this VMA as changing to prevent the
* speculative page fault hanlder to process
* it until the TLB are flushed below.
*/
last = mpnt;
vm_write_begin(mpnt);
}
if (!(tmp->vm_flags & VM_WIPEONFORK))
retval = copy_page_range(mm, oldmm, mpnt);
}
if (tmp->vm_ops && tmp->vm_ops->open)
tmp->vm_ops->open(tmp);
@ -629,22 +619,6 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
out:
up_write(&mm->mmap_sem);
flush_tlb_mm(oldmm);
if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT)) {
/*
* Since the TLB has been flush, we can safely unmark the
* copied VMAs and allows the speculative page fault handler to
* process them again.
* Walk back the VMA list from the last marked VMA.
*/
for (; last; last = last->vm_prev) {
if (last->vm_flags & VM_DONTCOPY)
continue;
if (!(last->vm_flags & VM_WIPEONFORK))
vm_write_end(last);
}
}
up_write(&oldmm->mmap_sem);
dup_userfaultfd_complete(&uf);
fail_uprobe_end: