144 lines
3.7 KiB
C
144 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <linux/elf.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/timekeeper_internal.h>
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#include <asm/vdso.h>
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extern char vdso_start, vdso_end;
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static unsigned long vdso_pages;
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static struct page **vdso_pagelist;
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/*
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* The vDSO data page.
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*/
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static union {
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struct vdso_data data;
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u8 page[PAGE_SIZE];
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} vdso_data_store __page_aligned_data;
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struct vdso_data *vdso_data = &vdso_data_store.data;
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static struct vm_special_mapping vdso_spec[2];
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static int __init vdso_init(void)
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{
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int i;
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if (memcmp(&vdso_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_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
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pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
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vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
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/* Allocate the vDSO pagelist, plus a page for the data. */
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vdso_pagelist = kcalloc(vdso_pages + 1, 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 data page. */
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vdso_pagelist[0] = virt_to_page(vdso_data);
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/* Grab the vDSO code pages. */
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for (i = 0; i < vdso_pages; i++)
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vdso_pagelist[i + 1] = virt_to_page(&vdso_start + i * PAGE_SIZE);
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/* Populate the special mapping structures */
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vdso_spec[0] = (struct vm_special_mapping) {
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.name = "[vvar]",
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.pages = vdso_pagelist,
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};
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vdso_spec[1] = (struct vm_special_mapping) {
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.name = "[vdso]",
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.pages = &vdso_pagelist[1],
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};
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return 0;
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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,
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int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
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void *ret;
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vdso_text_len = 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 + PAGE_SIZE;
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if (down_write_killable(&mm->mmap_lock))
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return -EINTR;
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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, PAGE_SIZE,
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VM_READ|VM_MAYREAD,
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&vdso_spec[0]);
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if (IS_ERR(ret))
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goto up_fail;
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vdso_base += 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|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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&vdso_spec[1]);
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if (IS_ERR(ret))
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goto up_fail;
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up_write(&mm->mmap_lock);
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return 0;
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up_fail:
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mm->context.vdso = NULL;
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up_write(&mm->mmap_lock);
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return PTR_ERR(ret);
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}
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void update_vsyscall(struct timekeeper *tk)
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{
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vdso_data_write_begin(vdso_data);
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vdso_data->xtime_sec = tk->xtime_sec;
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vdso_data->xtime_nsec = tk->tkr_mono.xtime_nsec;
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vdso_data->wall_to_mono_sec = tk->wall_to_monotonic.tv_sec;
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vdso_data->wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec;
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vdso_data->cs_shift = tk->tkr_mono.shift;
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vdso_data->cs_mult = tk->tkr_mono.mult;
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vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
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vdso_data->cs_mask = tk->tkr_mono.mask;
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vdso_data_write_end(vdso_data);
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}
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void update_vsyscall_tz(void)
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{
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vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
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vdso_data->tz_dsttime = sys_tz.tz_dsttime;
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}
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