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| author | Dmitry Safonov <dima@arista.com> | 2019-11-12 04:27:08 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-01-14 14:20:56 +0300 |
| commit | 6f74acfde20af1eb2178d0bd846bfd8f50b3be32 (patch) | |
| tree | 39f484ecd89b581b003acd14be07293da887bbba /arch/x86/entry/vdso/vma.c | |
| parent | 0efc8bb0bb5fdfd529a23073ee15478b5d5e3839 (diff) | |
| download | linux-6f74acfde20af1eb2178d0bd846bfd8f50b3be32.tar.xz | |
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
Diffstat (limited to 'arch/x86/entry/vdso/vma.c')
| -rw-r--r-- | arch/x86/entry/vdso/vma.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index f5937742b290..76cbe54e0c39 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, }; /* |