vdso.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Author: Huacai Chen <chenhuacai@loongson.cn>
  4 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
  5 */
  6
  7#include <linux/binfmts.h>
  8#include <linux/elf.h>
  9#include <linux/err.h>
 10#include <linux/init.h>
 11#include <linux/ioport.h>
 12#include <linux/kernel.h>
 13#include <linux/mm.h>
 14#include <linux/random.h>
 15#include <linux/sched.h>
 16#include <linux/slab.h>
 17#include <linux/vdso_datastore.h>
 18
 19#include <asm/page.h>
 20#include <asm/vdso.h>
 21#include <vdso/helpers.h>
 22#include <vdso/vsyscall.h>
 23#include <vdso/datapage.h>
 24#include <generated/vdso-offsets.h>
 25
 26extern char vdso_start[], vdso_end[];
 27
 28static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
 29{
 30	current->mm->context.vdso = (void *)(new_vma->vm_start);
 31
 32	return 0;
 33}
 34
 35struct loongarch_vdso_info vdso_info = {
 36	.vdso = vdso_start,
 37	.code_mapping = {
 38		.name = "[vdso]",
 39		.mremap = vdso_mremap,
 40	},
 41	.offset_sigreturn = vdso_offset_sigreturn,
 42};
 43
 44static int __init init_vdso(void)
 45{
 46	unsigned long i, cpu, pfn;
 47
 48	BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
 49
 50	for_each_possible_cpu(cpu)
 51		vdso_k_arch_data->pdata[cpu].node = cpu_to_node(cpu);
 52
 53	vdso_info.size = PAGE_ALIGN(vdso_end - vdso_start);
 54	vdso_info.code_mapping.pages =
 55		kcalloc(vdso_info.size / PAGE_SIZE, sizeof(struct page *), GFP_KERNEL);
 56
 57	if (!vdso_info.code_mapping.pages)
 58		return -ENOMEM;
 59
 60	pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
 61	for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
 62		vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
 63
 64	return 0;
 65}
 66subsys_initcall(init_vdso);
 67
 68static unsigned long vdso_base(void)
 69{
 70	unsigned long base = STACK_TOP;
 71
 72	if (current->flags & PF_RANDOMIZE) {
 73		base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
 74		base = PAGE_ALIGN(base);
 75	}
 76
 77	return base;
 78}
 79
 80int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 81{
 82	int ret;
 83	unsigned long size, data_addr, vdso_addr;
 84	struct mm_struct *mm = current->mm;
 85	struct vm_area_struct *vma;
 86	struct loongarch_vdso_info *info = current->thread.vdso;
 87
 88	if (mmap_write_lock_killable(mm))
 89		return -EINTR;
 90
 91	/*
 92	 * Determine total area size. This includes the VDSO data itself
 93	 * and the data pages.
 94	 */
 95	size = VVAR_SIZE + info->size;
 96
 97	data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
 98	if (IS_ERR_VALUE(data_addr)) {
 99		ret = data_addr;
100		goto out;
101	}
102
103	vma = vdso_install_vvar_mapping(mm, data_addr);
104	if (IS_ERR(vma)) {
105		ret = PTR_ERR(vma);
106		goto out;
107	}
108
109	vdso_addr = data_addr + VVAR_SIZE;
110	vma = _install_special_mapping(mm, vdso_addr, info->size,
111				       VM_READ | VM_EXEC |
112				       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC |
113				       VM_SEALED_SYSMAP,
114				       &info->code_mapping);
115	if (IS_ERR(vma)) {
116		ret = PTR_ERR(vma);
117		goto out;
118	}
119
120	mm->context.vdso = (void *)vdso_addr;
121	ret = 0;
122
123out:
124	mmap_write_unlock(mm);
125	return ret;
126}