[PATCH 5/6] arm64/vdso: Restrict splitting VVAR VMA
From: Andrei Vagin <hidden>
Date: 2020-06-02 18:03:23
Also in:
lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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> Signed-off-by: Andrei Vagin <redacted> --- 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 f3baecd8edfb..8b17d7d10729 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c@@ -235,6 +235,17 @@ 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 arch_vdso_type arch_index, struct mm_struct *mm, struct linux_binprm *bprm,
@@ -317,6 +328,7 @@ static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = { { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, { .name = "[vdso]",
@@ -488,6 +500,7 @@ static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = { { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, { .name = "[vdso]",
--
2.24.1
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