| Date | Tue, 14 Jan 2020 13:02:16 -0000 | From | "tip-bot2 for Dmitry Safonov" <> | Subject | [tip: timers/core] x86/vdso: Restrict splitting VVAR VMA |
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The following commit has been merged into the timers/core branch of tip:
Commit-ID: 6f74acfde20af1eb2178d0bd846bfd8f50b3be32 Gitweb: https://git.kernel.org/tip/6f74acfde20af1eb2178d0bd846bfd8f50b3be32 Author: Dmitry Safonov <dima@arista.com> AuthorDate: Tue, 12 Nov 2019 01:27:08 Committer: Thomas Gleixner <tglx@linutronix.de> CommitterDate: Tue, 14 Jan 2020 12:20:56 +01:00
x86/vdso: Restrict splitting VVAR VMA
Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the amount of corner-cases to consider while working further on VDSO time namespace support.
As the offset from timens to VVAR page is computed compile-time, the pages in VVAR should stay together and not being partically mremap()'ed.
Co-developed-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20191112012724.250792-20-dima@arista.com
--- 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 f593774..76cbe54 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) +{ + const struct vdso_image *image = new_vma->vm_mm->context.vdso_image; + unsigned long new_size = new_vma->vm_end - new_vma->vm_start; + + 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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