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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Copyright (c) 2022 Helge Deller <[email protected]>
- *
- * based on arch/s390/kernel/vdso.c which is
- * Copyright IBM Corp. 2008
- * Author(s): Martin Schwidefsky ([email protected])
- */
- #include <linux/kernel.h>
- #include <linux/mm.h>
- #include <linux/slab.h>
- #include <linux/elf.h>
- #include <linux/timekeeper_internal.h>
- #include <linux/compat.h>
- #include <linux/nsproxy.h>
- #include <linux/time_namespace.h>
- #include <linux/random.h>
- #include <asm/pgtable.h>
- #include <asm/page.h>
- #include <asm/sections.h>
- #include <asm/vdso.h>
- #include <asm/cacheflush.h>
- extern char vdso32_start, vdso32_end;
- extern char vdso64_start, vdso64_end;
- static int vdso_mremap(const struct vm_special_mapping *sm,
- struct vm_area_struct *vma)
- {
- current->mm->context.vdso_base = vma->vm_start;
- return 0;
- }
- #ifdef CONFIG_64BIT
- static struct vm_special_mapping vdso64_mapping = {
- .name = "[vdso]",
- .mremap = vdso_mremap,
- };
- #endif
- static struct vm_special_mapping vdso32_mapping = {
- .name = "[vdso]",
- .mremap = vdso_mremap,
- };
- /*
- * This is called from binfmt_elf, we create the special vma for the
- * vDSO and insert it into the mm struct tree
- */
- int arch_setup_additional_pages(struct linux_binprm *bprm,
- int executable_stack)
- {
- unsigned long vdso_text_start, vdso_text_len, map_base;
- struct vm_special_mapping *vdso_mapping;
- struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
- int rc;
- if (mmap_write_lock_killable(mm))
- return -EINTR;
- #ifdef CONFIG_64BIT
- if (!is_compat_task()) {
- vdso_text_len = &vdso64_end - &vdso64_start;
- vdso_mapping = &vdso64_mapping;
- } else
- #endif
- {
- vdso_text_len = &vdso32_end - &vdso32_start;
- vdso_mapping = &vdso32_mapping;
- }
- map_base = mm->mmap_base;
- if (current->flags & PF_RANDOMIZE)
- map_base -= prandom_u32_max(0x20) * PAGE_SIZE;
- vdso_text_start = get_unmapped_area(NULL, map_base, vdso_text_len, 0, 0);
- /* VM_MAYWRITE for COW so gdb can set breakpoints */
- vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdso_mapping);
- if (IS_ERR(vma)) {
- do_munmap(mm, vdso_text_start, PAGE_SIZE, NULL);
- rc = PTR_ERR(vma);
- } else {
- current->mm->context.vdso_base = vdso_text_start;
- rc = 0;
- }
- mmap_write_unlock(mm);
- return rc;
- }
- static struct page ** __init vdso_setup_pages(void *start, void *end)
- {
- int pages = (end - start) >> PAGE_SHIFT;
- struct page **pagelist;
- int i;
- pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL);
- if (!pagelist)
- panic("%s: Cannot allocate page list for VDSO", __func__);
- for (i = 0; i < pages; i++)
- pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
- return pagelist;
- }
- static int __init vdso_init(void)
- {
- #ifdef CONFIG_64BIT
- vdso64_mapping.pages = vdso_setup_pages(&vdso64_start, &vdso64_end);
- #endif
- if (IS_ENABLED(CONFIG_COMPAT) || !IS_ENABLED(CONFIG_64BIT))
- vdso32_mapping.pages = vdso_setup_pages(&vdso32_start, &vdso32_end);
- return 0;
- }
- arch_initcall(vdso_init);
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