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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
* <benh@kernel.crashing.org>
* Copyright (C) 2012 ARM Limited
* Copyright (C) 2015 Regents of the University of California
*/
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/err.h>
#include <asm/vdso.h>
extern char vdso_start[], vdso_end[];
static unsigned int vdso_pages;
static struct page **vdso_pagelist;
/*
* The vDSO data page.
*/
static union {
struct vdso_data data;
u8 page[PAGE_SIZE];
} vdso_data_store __page_aligned_data;
static struct vdso_data *vdso_data = &vdso_data_store.data;
static int __init vdso_init(void)
{
unsigned int i;
vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
vdso_pagelist =
kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
if (unlikely(vdso_pagelist == NULL)) {
pr_err("vdso: pagelist allocation failed\n");
return -ENOMEM;
}
for (i = 0; i < vdso_pages; i++) {
struct page *pg;
pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
vdso_pagelist[i] = pg;
}
vdso_pagelist[i] = virt_to_page(vdso_data);
return 0;
}
arch_initcall(vdso_init);
int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long vdso_base, vdso_len;
int ret;
vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
down_write(&mm->mmap_sem);
vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
ret = vdso_base;
goto end;
}
/*
* Put vDSO base into mm struct. We need to do this before calling
* install_special_mapping or the perf counter mmap tracking code
* will fail to recognise it as a vDSO (since arch_vma_name fails).
*/
mm->context.vdso = (void *)vdso_base;
ret = install_special_mapping(mm, vdso_base, vdso_len,
(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
vdso_pagelist);
if (unlikely(ret))
mm->context.vdso = NULL;
end:
up_write(&mm->mmap_sem);
return ret;
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
return "[vdso]";
return NULL;
}
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