[PATCHv5 21/37] x86/vdso: Restrict splitting VVAR VMA
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STALE2633d
SUPERSEDED
From: Dmitry Safonov <hidden>
Date: 2019-07-29 21:58:36
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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
Revision v5 of 7 in this series.
Revisions (7)
Although, time namespace can work with VVAR VMA split, it seems worth to forbid splitting VVAR resulting in stricter ABI and reducing amount of corner-cases to consider while working further on VDSO. I don't think there is any use-case for partial mremap() of vvar, but if there is any - this patch can be easily reverted. Co-developed-by: Andrei Vagin <redacted> Signed-off-by: Andrei Vagin <redacted> Signed-off-by: Dmitry Safonov <redacted> --- arch/x86/entry/vdso/vma.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 349a61d8bf34..3f05418642a8 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c@@ -84,6 +84,18 @@ static int vdso_mremap(const struct vm_special_mapping *sm, return 0; } +static int vvar_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) +{ + unsigned long new_size = new_vma->vm_end - new_vma->vm_start; + const struct vdso_image *image = new_vma->vm_mm->context.vdso_image; + + if (new_size != -image->sym_vvar_start) + return -EINVAL; + + return 0; +} + static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) {
@@ -136,6 +148,7 @@ static const struct vm_special_mapping vdso_mapping = { static const struct vm_special_mapping vvar_mapping = { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }; /*
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2.22.0