From bcf996434240c611f0fdab2c18cd75dd59cfa3c2 Mon Sep 17 00:00:00 2001 From: Andrei Vagin Date: Wed, 24 Jun 2020 01:33:20 -0700 Subject: [PATCH] arm64/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. Signed-off-by: Andrei Vagin Reviewed-by: Vincenzo Frascino Reviewed-by: Dmitry Safonov Link: https://lore.kernel.org/r/20200624083321.144975-6-avagin@gmail.com Signed-off-by: Catalin Marinas --- 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 c11ee18e3e79..d4202a32abc9 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -223,6 +223,17 @@ 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, @@ -302,6 +313,7 @@ static struct vm_special_mapping aarch32_vdso_maps[] = { [AA32_MAP_VVAR] = { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, [AA32_MAP_VDSO] = { .name = "[vdso]", @@ -468,6 +480,7 @@ 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]",