From: Dmitry Safonov Date: Tue, 12 Nov 2019 01:27:08 +0000 (+0000) Subject: x86/vdso: Restrict splitting VVAR VMA X-Git-Tag: v5.10.7~3409^2~25 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6f74acfde20af1eb2178d0bd846bfd8f50b3be32;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: Andrei Vagin Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20191112012724.250792-20-dima@arista.com --- 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, }; /*