[RFC 12/20] x86/vdso: Look for vvar vma to purge timens page
From: Dmitry Safonov <hidden>
Date: 2018-09-19 20:51:02
Also in:
lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), x86 entry code, x86 vdso · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski
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 <redacted> --- 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