259 lines
6.4 KiB
C
259 lines
6.4 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* vdso setup for s390
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*/
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#include <linux/binfmts.h>
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#include <linux/compat.h>
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#include <linux/elf.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/smp.h>
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#include <linux/time_namespace.h>
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#include <linux/random.h>
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#include <vdso/datapage.h>
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#include <asm/vdso.h>
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extern char vdso64_start[], vdso64_end[];
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extern char vdso32_start[], vdso32_end[];
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static struct vm_special_mapping vvar_mapping;
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static union {
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struct vdso_data data[CS_BASES];
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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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enum vvar_pages {
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VVAR_DATA_PAGE_OFFSET,
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VVAR_TIMENS_PAGE_OFFSET,
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VVAR_NR_PAGES,
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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 page layout depends on whether a task belongs to the root or
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* non-root time namespace. Whenever a task changes its namespace, the VVAR
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* page tables are cleared and then they will be re-faulted with a
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* corresponding layout.
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* See also the comment near timens_setup_vdso_data() for details.
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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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VMA_ITERATOR(vmi, mm, 0);
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struct vm_area_struct *vma;
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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, &vvar_mapping))
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continue;
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zap_vma_pages(vma);
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break;
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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 addr, pfn;
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vm_fault_t err;
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switch (vmf->pgoff) {
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case VVAR_DATA_PAGE_OFFSET:
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pfn = virt_to_pfn(vdso_data);
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if (timens_page) {
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/*
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* Fault in VVAR page too, since it will be accessed
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* to get clock data anyway.
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*/
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addr = vmf->address + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE;
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err = vmf_insert_pfn(vma, addr, pfn);
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if (unlikely(err & VM_FAULT_ERROR))
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return err;
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pfn = page_to_pfn(timens_page);
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}
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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 = virt_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 vdso_mremap(const struct vm_special_mapping *sm,
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struct vm_area_struct *vma)
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{
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current->mm->context.vdso_base = vma->vm_start;
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return 0;
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}
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static struct vm_special_mapping vvar_mapping = {
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.name = "[vvar]",
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.fault = vvar_fault,
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};
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static struct vm_special_mapping vdso64_mapping = {
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.name = "[vdso]",
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.mremap = vdso_mremap,
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};
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static struct vm_special_mapping vdso32_mapping = {
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.name = "[vdso]",
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.mremap = vdso_mremap,
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};
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int vdso_getcpu_init(void)
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{
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set_tod_programmable_field(smp_processor_id());
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return 0;
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}
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early_initcall(vdso_getcpu_init); /* Must be called before SMP init */
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static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
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{
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unsigned long vvar_start, vdso_text_start, vdso_text_len;
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struct vm_special_mapping *vdso_mapping;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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int rc;
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BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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if (is_compat_task()) {
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vdso_text_len = vdso32_end - vdso32_start;
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vdso_mapping = &vdso32_mapping;
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} else {
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vdso_text_len = vdso64_end - vdso64_start;
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vdso_mapping = &vdso64_mapping;
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}
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vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
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rc = vvar_start;
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if (IS_ERR_VALUE(vvar_start))
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goto out;
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vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE,
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VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
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VM_PFNMAP,
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&vvar_mapping);
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rc = PTR_ERR(vma);
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if (IS_ERR(vma))
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goto out;
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vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE;
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/* VM_MAYWRITE for COW so gdb can set breakpoints */
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vma = _install_special_mapping(mm, vdso_text_start, 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_mapping);
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if (IS_ERR(vma)) {
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do_munmap(mm, vvar_start, PAGE_SIZE, NULL);
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rc = PTR_ERR(vma);
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} else {
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current->mm->context.vdso_base = vdso_text_start;
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rc = 0;
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}
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out:
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mmap_write_unlock(mm);
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return rc;
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}
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static unsigned long vdso_addr(unsigned long start, unsigned long len)
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{
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unsigned long addr, end, offset;
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/*
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* Round up the start address. It can start out unaligned as a result
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* of stack start randomization.
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*/
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start = PAGE_ALIGN(start);
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/* Round the lowest possible end address up to a PMD boundary. */
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end = (start + len + PMD_SIZE - 1) & PMD_MASK;
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if (end >= VDSO_BASE)
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end = VDSO_BASE;
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end -= len;
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if (end > start) {
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offset = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1);
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addr = start + (offset << PAGE_SHIFT);
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} else {
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addr = start;
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}
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return addr;
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}
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unsigned long vdso_size(void)
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{
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unsigned long size = VVAR_NR_PAGES * PAGE_SIZE;
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if (is_compat_task())
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size += vdso32_end - vdso32_start;
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else
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size += vdso64_end - vdso64_start;
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return PAGE_ALIGN(size);
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}
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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unsigned long addr = VDSO_BASE;
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unsigned long size = vdso_size();
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if (current->flags & PF_RANDOMIZE)
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addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size);
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return map_vdso(addr, size);
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}
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static struct page ** __init vdso_setup_pages(void *start, void *end)
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{
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int pages = (end - start) >> PAGE_SHIFT;
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struct page **pagelist;
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int i;
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pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL);
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if (!pagelist)
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panic("%s: Cannot allocate page list for VDSO", __func__);
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for (i = 0; i < pages; i++)
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pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
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return pagelist;
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}
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static int __init vdso_init(void)
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{
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vdso64_mapping.pages = vdso_setup_pages(vdso64_start, vdso64_end);
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if (IS_ENABLED(CONFIG_COMPAT))
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vdso32_mapping.pages = vdso_setup_pages(vdso32_start, vdso32_end);
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return 0;
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}
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arch_initcall(vdso_init);
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