[PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace
From: Andrei Vagin <hidden>
Date: 2020-06-02 18:03:12
Also in:
lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
The VVAR page layout depends on whether a task belongs to the root or non-root time namespace. Whenever a task changes its namespace, the VVAR page tables are cleared and then they will be re-faulted with a corresponding layout. Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Andrei Vagin <redacted> --- arch/arm64/kernel/vdso.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 031ee1a8d4a8..33df3cdf7982 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c@@ -131,6 +131,38 @@ static int __vdso_init(enum arch_vdso_type arch_index) return 0; } +#ifdef CONFIG_TIME_NS +/* + * The vvar page layout depends on whether a task belongs to the root or + * non-root time namespace. Whenever a task changes its namespace, the VVAR + * page tables are cleared and then they will re-faulted with a + * corresponding layout. + * See also the comment near timens_setup_vdso_data() for details. + */ +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) +{ + struct mm_struct *mm = task->mm; + struct vm_area_struct *vma; + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + for (vma = mm->mmap; vma; vma = vma->vm_next) { + unsigned long size = vma->vm_end - vma->vm_start; + + if (vma_is_special_mapping(vma, vdso_lookup[ARM64_VDSO].dm)) + zap_page_range(vma, vma->vm_start, size); +#ifdef CONFIG_COMPAT_VDSO + if (vma_is_special_mapping(vma, vdso_lookup[ARM64_VDSO32].dm)) + zap_page_range(vma, vma->vm_start, size); +#endif + } + + up_write(&mm->mmap_sem); + return 0; +} +#endif + static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) {
--
2.24.1
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