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712676ea2b
Hook up the generic vDSO implementation to the aarch64 vDSO data page. The _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a offset larger than the vdso_data. The vDSO function requires a ChaCha20 implementation that does not write to the stack, and that can do an entire ChaCha20 permutation. The one provided uses NEON on the permute operation, with a fallback to the syscall for chips that do not support AdvSIMD. This also passes the vdso_test_chacha test along with vdso_test_getrandom. The vdso_test_getrandom bench-single result on Neoverse-N1 shows: vdso: 25000000 times in 0.783884250 seconds libc: 25000000 times in 8.780275399 seconds syscall: 25000000 times in 8.786581518 seconds A small fixup to arch/arm64/include/asm/mman.h was required to avoid pulling kernel code into the vDSO, similar to what's already done in arch/arm64/include/asm/rwonce.h. Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
442 lines
10 KiB
C
442 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* VDSO implementations.
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*
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* Copyright (C) 2012 ARM Limited
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*
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* Author: Will Deacon <will.deacon@arm.com>
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*/
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#include <linux/cache.h>
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#include <linux/clocksource.h>
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#include <linux/elf.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/gfp.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/signal.h>
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#include <linux/slab.h>
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#include <linux/time_namespace.h>
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#include <linux/timekeeper_internal.h>
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#include <linux/vmalloc.h>
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#include <vdso/datapage.h>
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#include <vdso/helpers.h>
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#include <vdso/vsyscall.h>
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#include <asm/cacheflush.h>
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#include <asm/signal32.h>
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#include <asm/vdso.h>
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enum vdso_abi {
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VDSO_ABI_AA64,
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VDSO_ABI_AA32,
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};
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struct vdso_abi_info {
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const char *name;
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const char *vdso_code_start;
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const char *vdso_code_end;
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unsigned long vdso_pages;
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/* Data Mapping */
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struct vm_special_mapping *dm;
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/* Code Mapping */
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struct vm_special_mapping *cm;
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};
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static struct vdso_abi_info vdso_info[] __ro_after_init = {
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[VDSO_ABI_AA64] = {
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.name = "vdso",
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.vdso_code_start = vdso_start,
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.vdso_code_end = vdso_end,
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},
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#ifdef CONFIG_COMPAT_VDSO
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[VDSO_ABI_AA32] = {
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.name = "vdso32",
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.vdso_code_start = vdso32_start,
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.vdso_code_end = vdso32_end,
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},
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#endif /* CONFIG_COMPAT_VDSO */
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};
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/*
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* The vDSO data page.
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*/
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static union vdso_data_store vdso_data_store __page_aligned_data;
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struct vdso_data *vdso_data = vdso_data_store.data;
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static int vdso_mremap(const struct vm_special_mapping *sm,
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struct vm_area_struct *new_vma)
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{
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current->mm->context.vdso = (void *)new_vma->vm_start;
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return 0;
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}
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static int __init __vdso_init(enum vdso_abi abi)
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{
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int i;
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struct page **vdso_pagelist;
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unsigned long pfn;
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if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) {
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pr_err("vDSO is not a valid ELF object!\n");
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return -EINVAL;
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}
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vdso_info[abi].vdso_pages = (
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vdso_info[abi].vdso_code_end -
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vdso_info[abi].vdso_code_start) >>
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PAGE_SHIFT;
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vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages,
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sizeof(struct page *),
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GFP_KERNEL);
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if (vdso_pagelist == NULL)
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return -ENOMEM;
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/* Grab the vDSO code pages. */
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pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
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for (i = 0; i < vdso_info[abi].vdso_pages; i++)
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vdso_pagelist[i] = pfn_to_page(pfn + i);
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vdso_info[abi].cm->pages = vdso_pagelist;
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return 0;
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}
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#ifdef CONFIG_TIME_NS
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struct vdso_data *arch_get_vdso_data(void *vvar_page)
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{
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return (struct vdso_data *)(vvar_page);
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}
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/*
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* The vvar mapping contains data for a specific time namespace, so when a task
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* changes namespace we must unmap its vvar data for the old namespace.
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* Subsequent faults will map in data for the new namespace.
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*
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* For more details see timens_setup_vdso_data().
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*/
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int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
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{
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struct mm_struct *mm = task->mm;
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struct vm_area_struct *vma;
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VMA_ITERATOR(vmi, mm, 0);
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mmap_read_lock(mm);
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for_each_vma(vmi, vma) {
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if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA64].dm))
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zap_vma_pages(vma);
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#ifdef CONFIG_COMPAT_VDSO
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if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA32].dm))
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zap_vma_pages(vma);
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#endif
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}
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mmap_read_unlock(mm);
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return 0;
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}
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#endif
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static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
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struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct page *timens_page = find_timens_vvar_page(vma);
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unsigned long pfn;
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switch (vmf->pgoff) {
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case VVAR_DATA_PAGE_OFFSET:
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if (timens_page)
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pfn = page_to_pfn(timens_page);
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else
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pfn = sym_to_pfn(vdso_data);
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break;
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#ifdef CONFIG_TIME_NS
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case VVAR_TIMENS_PAGE_OFFSET:
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/*
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* If a task belongs to a time namespace then a namespace
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* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
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* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
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* offset.
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* See also the comment near timens_setup_vdso_data().
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*/
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if (!timens_page)
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return VM_FAULT_SIGBUS;
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pfn = sym_to_pfn(vdso_data);
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break;
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#endif /* CONFIG_TIME_NS */
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default:
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return VM_FAULT_SIGBUS;
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}
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return vmf_insert_pfn(vma, vmf->address, pfn);
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}
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static int __setup_additional_pages(enum vdso_abi abi,
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struct mm_struct *mm,
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struct linux_binprm *bprm,
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int uses_interp)
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{
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unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
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unsigned long gp_flags = 0;
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void *ret;
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BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
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vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
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/* Be sure to map the data page */
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vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE;
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vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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ret = ERR_PTR(vdso_base);
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goto up_fail;
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}
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ret = _install_special_mapping(mm, vdso_base, VVAR_NR_PAGES * PAGE_SIZE,
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VM_READ|VM_MAYREAD|VM_PFNMAP,
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vdso_info[abi].dm);
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if (IS_ERR(ret))
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goto up_fail;
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if (system_supports_bti_kernel())
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gp_flags = VM_ARM64_BTI;
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vdso_base += VVAR_NR_PAGES * PAGE_SIZE;
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mm->context.vdso = (void *)vdso_base;
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ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
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VM_READ|VM_EXEC|gp_flags|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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vdso_info[abi].cm);
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if (IS_ERR(ret))
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goto up_fail;
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return 0;
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up_fail:
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mm->context.vdso = NULL;
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return PTR_ERR(ret);
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}
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#ifdef CONFIG_COMPAT
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/*
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* Create and map the vectors page for AArch32 tasks.
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*/
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enum aarch32_map {
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AA32_MAP_VECTORS, /* kuser helpers */
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AA32_MAP_SIGPAGE,
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AA32_MAP_VVAR,
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AA32_MAP_VDSO,
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};
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static struct page *aarch32_vectors_page __ro_after_init;
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static struct page *aarch32_sig_page __ro_after_init;
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static int aarch32_sigpage_mremap(const struct vm_special_mapping *sm,
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struct vm_area_struct *new_vma)
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{
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current->mm->context.sigpage = (void *)new_vma->vm_start;
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return 0;
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}
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static struct vm_special_mapping aarch32_vdso_maps[] = {
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[AA32_MAP_VECTORS] = {
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.name = "[vectors]", /* ABI */
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.pages = &aarch32_vectors_page,
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},
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[AA32_MAP_SIGPAGE] = {
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.name = "[sigpage]", /* ABI */
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.pages = &aarch32_sig_page,
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.mremap = aarch32_sigpage_mremap,
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},
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[AA32_MAP_VVAR] = {
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.name = "[vvar]",
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.fault = vvar_fault,
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},
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[AA32_MAP_VDSO] = {
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.name = "[vdso]",
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.mremap = vdso_mremap,
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},
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};
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static int aarch32_alloc_kuser_vdso_page(void)
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{
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extern char __kuser_helper_start[], __kuser_helper_end[];
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int kuser_sz = __kuser_helper_end - __kuser_helper_start;
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unsigned long vdso_page;
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if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
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return 0;
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vdso_page = get_zeroed_page(GFP_KERNEL);
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if (!vdso_page)
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return -ENOMEM;
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memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start,
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kuser_sz);
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aarch32_vectors_page = virt_to_page((void *)vdso_page);
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return 0;
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}
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#define COMPAT_SIGPAGE_POISON_WORD 0xe7fddef1
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static int aarch32_alloc_sigpage(void)
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{
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extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
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int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
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__le32 poison = cpu_to_le32(COMPAT_SIGPAGE_POISON_WORD);
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void *sigpage;
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sigpage = (void *)__get_free_page(GFP_KERNEL);
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if (!sigpage)
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return -ENOMEM;
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memset32(sigpage, (__force u32)poison, PAGE_SIZE / sizeof(poison));
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memcpy(sigpage, __aarch32_sigret_code_start, sigret_sz);
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aarch32_sig_page = virt_to_page(sigpage);
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return 0;
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}
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static int __init __aarch32_alloc_vdso_pages(void)
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{
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if (!IS_ENABLED(CONFIG_COMPAT_VDSO))
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return 0;
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vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR];
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vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO];
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return __vdso_init(VDSO_ABI_AA32);
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}
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static int __init aarch32_alloc_vdso_pages(void)
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{
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int ret;
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ret = __aarch32_alloc_vdso_pages();
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if (ret)
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return ret;
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ret = aarch32_alloc_sigpage();
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if (ret)
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return ret;
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return aarch32_alloc_kuser_vdso_page();
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}
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arch_initcall(aarch32_alloc_vdso_pages);
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static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
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{
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void *ret;
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if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
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return 0;
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/*
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* Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's
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* not safe to CoW the page containing the CPU exception vectors.
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*/
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ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE,
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VM_READ | VM_EXEC |
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VM_MAYREAD | VM_MAYEXEC,
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&aarch32_vdso_maps[AA32_MAP_VECTORS]);
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return PTR_ERR_OR_ZERO(ret);
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}
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static int aarch32_sigreturn_setup(struct mm_struct *mm)
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{
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unsigned long addr;
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void *ret;
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
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if (IS_ERR_VALUE(addr)) {
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ret = ERR_PTR(addr);
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goto out;
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}
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/*
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* VM_MAYWRITE is required to allow gdb to Copy-on-Write and
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* set breakpoints.
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*/
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ret = _install_special_mapping(mm, addr, PAGE_SIZE,
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VM_READ | VM_EXEC | VM_MAYREAD |
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VM_MAYWRITE | VM_MAYEXEC,
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&aarch32_vdso_maps[AA32_MAP_SIGPAGE]);
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if (IS_ERR(ret))
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goto out;
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mm->context.sigpage = (void *)addr;
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out:
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return PTR_ERR_OR_ZERO(ret);
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}
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int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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int ret;
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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ret = aarch32_kuser_helpers_setup(mm);
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if (ret)
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goto out;
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if (IS_ENABLED(CONFIG_COMPAT_VDSO)) {
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ret = __setup_additional_pages(VDSO_ABI_AA32, mm, bprm,
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uses_interp);
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if (ret)
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goto out;
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}
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ret = aarch32_sigreturn_setup(mm);
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out:
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mmap_write_unlock(mm);
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return ret;
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}
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#endif /* CONFIG_COMPAT */
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enum aarch64_map {
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AA64_MAP_VVAR,
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AA64_MAP_VDSO,
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};
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static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = {
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[AA64_MAP_VVAR] = {
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.name = "[vvar]",
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.fault = vvar_fault,
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},
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[AA64_MAP_VDSO] = {
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.name = "[vdso]",
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.mremap = vdso_mremap,
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},
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};
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static int __init vdso_init(void)
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{
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vdso_info[VDSO_ABI_AA64].dm = &aarch64_vdso_maps[AA64_MAP_VVAR];
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vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_maps[AA64_MAP_VDSO];
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return __vdso_init(VDSO_ABI_AA64);
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}
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arch_initcall(vdso_init);
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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int ret;
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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ret = __setup_additional_pages(VDSO_ABI_AA64, mm, bprm, uses_interp);
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mmap_write_unlock(mm);
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return ret;
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}
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