1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2015 Imagination Technologies
4 * Author: Alex Smith <alex.smith@imgtec.com>
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/timekeeper_internal.h>
18
19#include <asm/abi.h>
20#include <asm/mips-cps.h>
21#include <asm/page.h>
22#include <asm/vdso.h>
23#include <vdso/helpers.h>
24#include <vdso/vsyscall.h>
25
26/* Kernel-provided data used by the VDSO. */
27static union vdso_data_store mips_vdso_data __page_aligned_data;
28struct vdso_data *vdso_data = mips_vdso_data.data;
29
30/*
31 * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
32 * what we map and where within the area they are mapped is determined at
33 * runtime.
34 */
35static struct page *no_pages[] = { NULL };
36static struct vm_special_mapping vdso_vvar_mapping = {
37	.name = "[vvar]",
38	.pages = no_pages,
39};
40
41static void __init init_vdso_image(struct mips_vdso_image *image)
42{
43	unsigned long num_pages, i;
44	unsigned long data_pfn;
45
46	BUG_ON(!PAGE_ALIGNED(image->data));
47	BUG_ON(!PAGE_ALIGNED(image->size));
48
49	num_pages = image->size / PAGE_SIZE;
50
51	data_pfn = __phys_to_pfn(__pa_symbol(image->data));
52	for (i = 0; i < num_pages; i++)
53		image->mapping.pages[i] = pfn_to_page(data_pfn + i);
54}
55
56static int __init init_vdso(void)
57{
58	init_vdso_image(&vdso_image);
59
60#ifdef CONFIG_MIPS32_O32
61	init_vdso_image(&vdso_image_o32);
62#endif
63
64#ifdef CONFIG_MIPS32_N32
65	init_vdso_image(&vdso_image_n32);
66#endif
67
68	return 0;
69}
70subsys_initcall(init_vdso);
71
72static unsigned long vdso_base(void)
73{
74	unsigned long base = STACK_TOP;
75
76	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
77		/* Skip the delay slot emulation page */
78		base += PAGE_SIZE;
79	}
80
81	if (current->flags & PF_RANDOMIZE) {
82		base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
83		base = PAGE_ALIGN(base);
84	}
85
86	return base;
87}
88
89int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
90{
91	struct mips_vdso_image *image = current->thread.abi->vdso;
92	struct mm_struct *mm = current->mm;
93	unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base;
94	struct vm_area_struct *vma;
95	int ret;
96
97	if (mmap_write_lock_killable(mm))
98		return -EINTR;
99
100	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
101		/* Map delay slot emulation page */
102		base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
103				VM_READ | VM_EXEC |
104				VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
105				0, NULL);
106		if (IS_ERR_VALUE(base)) {
107			ret = base;
108			goto out;
109		}
110	}
111
112	/*
113	 * Determine total area size. This includes the VDSO data itself, the
114	 * data page, and the GIC user page if present. Always create a mapping
115	 * for the GIC user area if the GIC is present regardless of whether it
116	 * is the current clocksource, in case it comes into use later on. We
117	 * only map a page even though the total area is 64K, as we only need
118	 * the counter registers at the start.
119	 */
120	gic_size = mips_gic_present() ? PAGE_SIZE : 0;
121	vvar_size = gic_size + PAGE_SIZE;
122	size = vvar_size + image->size;
123
124	/*
125	 * Find a region that's large enough for us to perform the
126	 * colour-matching alignment below.
127	 */
128	if (cpu_has_dc_aliases)
129		size += shm_align_mask + 1;
130
131	base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
132	if (IS_ERR_VALUE(base)) {
133		ret = base;
134		goto out;
135	}
136
137	/*
138	 * If we suffer from dcache aliasing, ensure that the VDSO data page
139	 * mapping is coloured the same as the kernel's mapping of that memory.
140	 * This ensures that when the kernel updates the VDSO data userland
141	 * will observe it without requiring cache invalidations.
142	 */
143	if (cpu_has_dc_aliases) {
144		base = __ALIGN_MASK(base, shm_align_mask);
145		base += ((unsigned long)vdso_data - gic_size) & shm_align_mask;
146	}
147
148	data_addr = base + gic_size;
149	vdso_addr = data_addr + PAGE_SIZE;
150
151	vma = _install_special_mapping(mm, base, vvar_size,
152				       VM_READ | VM_MAYREAD,
153				       &vdso_vvar_mapping);
154	if (IS_ERR(vma)) {
155		ret = PTR_ERR(vma);
156		goto out;
157	}
158
159	/* Map GIC user page. */
160	if (gic_size) {
161		gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS;
162		gic_pfn = PFN_DOWN(__pa(gic_base));
163
164		ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
165					 pgprot_noncached(vma->vm_page_prot));
166		if (ret)
167			goto out;
168	}
169
170	/* Map data page. */
171	ret = remap_pfn_range(vma, data_addr,
172			      virt_to_phys(vdso_data) >> PAGE_SHIFT,
173			      PAGE_SIZE, vma->vm_page_prot);
174	if (ret)
175		goto out;
176
177	/* Map VDSO image. */
178	vma = _install_special_mapping(mm, vdso_addr, image->size,
179				       VM_READ | VM_EXEC |
180				       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
181				       &image->mapping);
182	if (IS_ERR(vma)) {
183		ret = PTR_ERR(vma);
184		goto out;
185	}
186
187	mm->context.vdso = (void *)vdso_addr;
188	ret = 0;
189
190out:
191	mmap_write_unlock(mm);
192	return ret;
193}
194