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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2022 Helge Deller <deller@gmx.de>
*
* based on arch/s390/kernel/vdso.c which is
* Copyright IBM Corp. 2008
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#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 -= get_random_u32_below(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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