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1// SPDX-License-Identifier: GPL-2.0-or-later
2
3/*
4 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
5 * <[email protected]>
6 */
7
8#include <linux/errno.h>
9#include <linux/sched.h>
10#include <linux/kernel.h>
11#include <linux/mm.h>
12#include <linux/smp.h>
13#include <linux/stddef.h>
14#include <linux/unistd.h>
15#include <linux/slab.h>
16#include <linux/user.h>
17#include <linux/elf.h>
18#include <linux/security.h>
19#include <linux/syscalls.h>
20#include <linux/vdso_datastore.h>
21#include <vdso/datapage.h>
22
23#include <asm/syscall.h>
24#include <asm/syscalls.h>
25#include <asm/processor.h>
26#include <asm/mmu.h>
27#include <asm/mmu_context.h>
28#include <asm/machdep.h>
29#include <asm/cputable.h>
30#include <asm/sections.h>
31#include <asm/firmware.h>
32#include <asm/vdso.h>
33#include <asm/vdso_datapage.h>
34#include <asm/setup.h>
35
36static_assert(__VDSO_PAGES == VDSO_NR_PAGES);
37
38/* The alignment of the vDSO */
39#define VDSO_ALIGNMENT (1 << 16)
40
41extern char vdso32_start, vdso32_end;
42extern char vdso64_start, vdso64_end;
43
44static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma,
45 unsigned long text_size)
46{
47 unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
48
49 if (new_size != text_size)
50 return -EINVAL;
51
52 current->mm->context.vdso = (void __user *)new_vma->vm_start;
53
54 return 0;
55}
56
57static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
58{
59 return vdso_mremap(sm, new_vma, &vdso32_end - &vdso32_start);
60}
61
62static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
63{
64 return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start);
65}
66
67static void vdso_close(const struct vm_special_mapping *sm, struct vm_area_struct *vma)
68{
69 struct mm_struct *mm = vma->vm_mm;
70
71 /*
72 * close() is called for munmap() but also for mremap(). In the mremap()
73 * case the vdso pointer has already been updated by the mremap() hook
74 * above, so it must not be set to NULL here.
75 */
76 if (vma->vm_start != (unsigned long)mm->context.vdso)
77 return;
78
79 mm->context.vdso = NULL;
80}
81
82static struct vm_special_mapping vdso32_spec __ro_after_init = {
83 .name = "[vdso]",
84 .mremap = vdso32_mremap,
85 .close = vdso_close,
86};
87
88static struct vm_special_mapping vdso64_spec __ro_after_init = {
89 .name = "[vdso]",
90 .mremap = vdso64_mremap,
91 .close = vdso_close,
92};
93
94/*
95 * This is called from binfmt_elf, we create the special vma for the
96 * vDSO and insert it into the mm struct tree
97 */
98static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
99{
100 unsigned long vdso_size, vdso_base, mappings_size;
101 struct vm_special_mapping *vdso_spec;
102 unsigned long vvar_size = VDSO_NR_PAGES * PAGE_SIZE;
103 struct mm_struct *mm = current->mm;
104 struct vm_area_struct *vma;
105
106 if (is_32bit_task()) {
107 vdso_spec = &vdso32_spec;
108 vdso_size = &vdso32_end - &vdso32_start;
109 } else {
110 vdso_spec = &vdso64_spec;
111 vdso_size = &vdso64_end - &vdso64_start;
112 }
113
114 mappings_size = vdso_size + vvar_size;
115 mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK;
116
117 /*
118 * Pick a base address for the vDSO in process space.
119 * Add enough to the size so that the result can be aligned.
120 */
121 vdso_base = get_unmapped_area(NULL, 0, mappings_size, 0, 0);
122 if (IS_ERR_VALUE(vdso_base))
123 return vdso_base;
124
125 /* Add required alignment. */
126 vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT);
127
128 vma = vdso_install_vvar_mapping(mm, vdso_base);
129 if (IS_ERR(vma))
130 return PTR_ERR(vma);
131
132 /*
133 * our vma flags don't have VM_WRITE so by default, the process isn't
134 * allowed to write those pages.
135 * gdb can break that with ptrace interface, and thus trigger COW on
136 * those pages but it's then your responsibility to never do that on
137 * the "data" page of the vDSO or you'll stop getting kernel updates
138 * and your nice userland gettimeofday will be totally dead.
139 * It's fine to use that for setting breakpoints in the vDSO code
140 * pages though.
141 */
142 vma = _install_special_mapping(mm, vdso_base + vvar_size, vdso_size,
143 VM_READ | VM_EXEC | VM_MAYREAD |
144 VM_MAYWRITE | VM_MAYEXEC, vdso_spec);
145 if (IS_ERR(vma)) {
146 do_munmap(mm, vdso_base, vvar_size, NULL);
147 return PTR_ERR(vma);
148 }
149
150 // Now that the mappings are in place, set the mm VDSO pointer
151 mm->context.vdso = (void __user *)vdso_base + vvar_size;
152
153 return 0;
154}
155
156int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
157{
158 struct mm_struct *mm = current->mm;
159 int rc;
160
161 mm->context.vdso = NULL;
162
163 if (mmap_write_lock_killable(mm))
164 return -EINTR;
165
166 rc = __arch_setup_additional_pages(bprm, uses_interp);
167
168 mmap_write_unlock(mm);
169 return rc;
170}
171
172#define VDSO_DO_FIXUPS(type, value, bits, sec) do { \
173 void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start); \
174 void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end); \
175 \
176 do_##type##_fixups((value), __start, __end); \
177} while (0)
178
179static void __init vdso_fixup_features(void)
180{
181#ifdef CONFIG_PPC64
182 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup);
183 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup);
184 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup);
185 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup);
186#endif /* CONFIG_PPC64 */
187
188#ifdef CONFIG_VDSO32
189 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup);
190 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup);
191#ifdef CONFIG_PPC64
192 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup);
193#endif /* CONFIG_PPC64 */
194 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup);
195#endif
196}
197
198/*
199 * Called from setup_arch to initialize the bitmap of available
200 * syscalls in the systemcfg page
201 */
202static void __init vdso_setup_syscall_map(void)
203{
204 unsigned int i;
205
206 for (i = 0; i < NR_syscalls; i++) {
207 if (sys_call_table[i] != (void *)&sys_ni_syscall)
208 vdso_k_arch_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
209 if (IS_ENABLED(CONFIG_COMPAT) &&
210 compat_sys_call_table[i] != (void *)&sys_ni_syscall)
211 vdso_k_arch_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
212 }
213}
214
215#ifdef CONFIG_PPC64
216int vdso_getcpu_init(void)
217{
218 unsigned long cpu, node, val;
219
220 /*
221 * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node
222 * in the next 16 bits. The VDSO uses this to implement getcpu().
223 */
224 cpu = get_cpu();
225 WARN_ON_ONCE(cpu > 0xffff);
226
227 node = cpu_to_node(cpu);
228 WARN_ON_ONCE(node > 0xffff);
229
230 val = (cpu & 0xffff) | ((node & 0xffff) << 16);
231 mtspr(SPRN_SPRG_VDSO_WRITE, val);
232 get_paca()->sprg_vdso = val;
233
234 put_cpu();
235
236 return 0;
237}
238/* We need to call this before SMP init */
239early_initcall(vdso_getcpu_init);
240#endif
241
242static struct page ** __init vdso_setup_pages(void *start, void *end)
243{
244 int i;
245 struct page **pagelist;
246 int pages = (end - start) >> PAGE_SHIFT;
247
248 pagelist = kzalloc_objs(struct page *, pages + 1);
249 if (!pagelist)
250 panic("%s: Cannot allocate page list for VDSO", __func__);
251
252 for (i = 0; i < pages; i++)
253 pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
254
255 return pagelist;
256}
257
258static int __init vdso_init(void)
259{
260#ifdef CONFIG_PPC64
261 vdso_k_arch_data->dcache_block_size = ppc64_caches.l1d.block_size;
262 vdso_k_arch_data->icache_block_size = ppc64_caches.l1i.block_size;
263 vdso_k_arch_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size;
264 vdso_k_arch_data->icache_log_block_size = ppc64_caches.l1i.log_block_size;
265#endif /* CONFIG_PPC64 */
266
267 vdso_setup_syscall_map();
268
269 vdso_fixup_features();
270
271 if (IS_ENABLED(CONFIG_VDSO32))
272 vdso32_spec.pages = vdso_setup_pages(&vdso32_start, &vdso32_end);
273
274 if (IS_ENABLED(CONFIG_PPC64))
275 vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end);
276
277 smp_wmb();
278
279 return 0;
280}
281arch_initcall(vdso_init);