Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Andrei Vagin <> | Subject | [PATCH 5/6] arm64/vdso: Restrict splitting VVAR VMA | Date | Tue, 16 Jun 2020 00:55:44 -0700 |
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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.
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrei Vagin <avagin@gmail.com> --- arch/arm64/kernel/vdso.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index 21bdd0d74f40..68e021324113 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -226,6 +226,17 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, return vmf_insert_pfn(vma, vmf->address, pfn); } +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; + + if (new_size != VVAR_NR_PAGES * PAGE_SIZE) + return -EINVAL; + + return 0; +} + static int __setup_additional_pages(enum vdso_abi abi, struct mm_struct *mm, struct linux_binprm *bprm, @@ -308,6 +319,7 @@ static struct vm_special_mapping aarch32_vdso_maps[] = { [AA32_MAP_VVAR] = { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, [AA32_MAP_VDSO] = { .name = "[vdso]", @@ -476,6 +488,7 @@ static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { [AA64_MAP_VVAR] = { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, [AA64_MAP_VDSO] = { .name = "[vdso]", -- 2.24.1
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