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Subject[RFC 12/20] x86/vdso: Look for vvar vma to purge timens page
Date
As vvar vma may be moved away from vdso, let's search it, rather than
calculate purge address from vdso position.

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
arch/x86/entry/vdso/vma.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 90eadcfcb7f5..d1e2392a4905 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -159,7 +159,18 @@ static int vvar_fault(const struct vm_special_mapping *sm,
return VM_FAULT_SIGBUS;
}

-static void clear_flush_timens_pte(struct mm_struct *mm, unsigned long addr)
+static const struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ .fault = vdso_fault,
+ .mremap = vdso_mremap,
+};
+static const struct vm_special_mapping vvar_mapping = {
+ .name = "[vvar]",
+ .fault = vvar_fault,
+ .mremap = vvar_mremap,
+};
+
+static void vvar_flush_timens_pte(struct mm_struct *mm, unsigned long addr)
{
spinlock_t *ptl;
pte_t *ptep;
@@ -175,31 +186,31 @@ int vvar_purge_timens(struct task_struct *task)
{
struct mm_struct *mm = task->mm;
const struct vdso_image *image;
+ struct vm_area_struct *vma;
unsigned long addr;

if (down_write_killable(&mm->mmap_sem))
return -EINTR;

+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma_is_special_mapping(vma, &vvar_mapping))
+ break;
+ }
+
+ /* vvar is unmapped */
+ if (!vma || !vma_is_special_mapping(vma, &vvar_mapping))
+ goto out;
+
image = mm->context.vdso_image;

- addr = (unsigned long)mm->context.vdso + image->sym_timens_page;
- clear_flush_timens_pte(mm, addr);
+ addr = vma->vm_end + image->sym_timens_page;
+ vvar_flush_timens_pte(mm, addr);

+out:
up_write(&mm->mmap_sem);
return 0;
}

-static const struct vm_special_mapping vdso_mapping = {
- .name = "[vdso]",
- .fault = vdso_fault,
- .mremap = vdso_mremap,
-};
-static const struct vm_special_mapping vvar_mapping = {
- .name = "[vvar]",
- .fault = vvar_fault,
- .mremap = vvar_mremap,
-};
-
/*
* Add vdso and vvar mappings to current process.
* @image - blob to map
--
2.13.6
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