1// SPDX-License-Identifier: GPL-2.0-or-later
2
3/*
4 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
5 * <benh@kernel.crashing.org>
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/memblock.h>
20#include <linux/syscalls.h>
21#include <linux/time_namespace.h>
22#include <vdso/datapage.h>
23
24#include <asm/syscall.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
36/* The alignment of the vDSO */
37#define VDSO_ALIGNMENT (1 << 16)
38
39extern char vdso32_start, vdso32_end;
40extern char vdso64_start, vdso64_end;
41
42long sys_ni_syscall(void);
43
44/*
45 * The vdso data page (aka. systemcfg for old ppc64 fans) is here.
46 * Once the early boot kernel code no longer needs to muck around
47 * with it, it will become dynamically allocated
48 */
49static union {
50 struct vdso_arch_data data;
51 u8 page[PAGE_SIZE];
52} vdso_data_store __page_aligned_data;
53struct vdso_arch_data *vdso_data = &vdso_data_store.data;
54
55enum vvar_pages {
56 VVAR_DATA_PAGE_OFFSET,
57 VVAR_TIMENS_PAGE_OFFSET,
58 VVAR_NR_PAGES,
59};
60
61static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma,
62 unsigned long text_size)
63{
64 unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
65
66 if (new_size != text_size)
67 return -EINVAL;
68
69 current->mm->context.vdso = (void __user *)new_vma->vm_start;
70
71 return 0;
72}
73
74static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
75{
76 return vdso_mremap(sm, new_vma, text_size: &vdso32_end - &vdso32_start);
77}
78
79static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
80{
81 return vdso_mremap(sm, new_vma, text_size: &vdso64_end - &vdso64_start);
82}
83
84static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
85 struct vm_area_struct *vma, struct vm_fault *vmf);
86
87static struct vm_special_mapping vvar_spec __ro_after_init = {
88 .name = "[vvar]",
89 .fault = vvar_fault,
90};
91
92static struct vm_special_mapping vdso32_spec __ro_after_init = {
93 .name = "[vdso]",
94 .mremap = vdso32_mremap,
95};
96
97static struct vm_special_mapping vdso64_spec __ro_after_init = {
98 .name = "[vdso]",
99 .mremap = vdso64_mremap,
100};
101
102#ifdef CONFIG_TIME_NS
103struct vdso_data *arch_get_vdso_data(void *vvar_page)
104{
105 return ((struct vdso_arch_data *)vvar_page)->data;
106}
107
108/*
109 * The vvar mapping contains data for a specific time namespace, so when a task
110 * changes namespace we must unmap its vvar data for the old namespace.
111 * Subsequent faults will map in data for the new namespace.
112 *
113 * For more details see timens_setup_vdso_data().
114 */
115int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
116{
117 struct mm_struct *mm = task->mm;
118 VMA_ITERATOR(vmi, mm, 0);
119 struct vm_area_struct *vma;
120
121 mmap_read_lock(mm);
122 for_each_vma(vmi, vma) {
123 if (vma_is_special_mapping(vma, sm: &vvar_spec))
124 zap_vma_pages(vma);
125 }
126 mmap_read_unlock(mm);
127
128 return 0;
129}
130#endif
131
132static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
133 struct vm_area_struct *vma, struct vm_fault *vmf)
134{
135 struct page *timens_page = find_timens_vvar_page(vma);
136 unsigned long pfn;
137
138 switch (vmf->pgoff) {
139 case VVAR_DATA_PAGE_OFFSET:
140 if (timens_page)
141 pfn = page_to_pfn(timens_page);
142 else
143 pfn = virt_to_pfn(vdso_data);
144 break;
145#ifdef CONFIG_TIME_NS
146 case VVAR_TIMENS_PAGE_OFFSET:
147 /*
148 * If a task belongs to a time namespace then a namespace
149 * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
150 * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
151 * offset.
152 * See also the comment near timens_setup_vdso_data().
153 */
154 if (!timens_page)
155 return VM_FAULT_SIGBUS;
156 pfn = virt_to_pfn(vdso_data);
157 break;
158#endif /* CONFIG_TIME_NS */
159 default:
160 return VM_FAULT_SIGBUS;
161 }
162
163 return vmf_insert_pfn(vma, addr: vmf->address, pfn);
164}
165
166/*
167 * This is called from binfmt_elf, we create the special vma for the
168 * vDSO and insert it into the mm struct tree
169 */
170static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
171{
172 unsigned long vdso_size, vdso_base, mappings_size;
173 struct vm_special_mapping *vdso_spec;
174 unsigned long vvar_size = VVAR_NR_PAGES * PAGE_SIZE;
175 struct mm_struct *mm = current->mm;
176 struct vm_area_struct *vma;
177
178 if (is_32bit_task()) {
179 vdso_spec = &vdso32_spec;
180 vdso_size = &vdso32_end - &vdso32_start;
181 } else {
182 vdso_spec = &vdso64_spec;
183 vdso_size = &vdso64_end - &vdso64_start;
184 }
185
186 mappings_size = vdso_size + vvar_size;
187 mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK;
188
189 /*
190 * Pick a base address for the vDSO in process space.
191 * Add enough to the size so that the result can be aligned.
192 */
193 vdso_base = get_unmapped_area(NULL, 0, mappings_size, 0, 0);
194 if (IS_ERR_VALUE(vdso_base))
195 return vdso_base;
196
197 /* Add required alignment. */
198 vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT);
199
200 /*
201 * Put vDSO base into mm struct. We need to do this before calling
202 * install_special_mapping or the perf counter mmap tracking code
203 * will fail to recognise it as a vDSO.
204 */
205 mm->context.vdso = (void __user *)vdso_base + vvar_size;
206
207 vma = _install_special_mapping(mm, addr: vdso_base, len: vvar_size,
208 VM_READ | VM_MAYREAD | VM_IO |
209 VM_DONTDUMP | VM_PFNMAP, spec: &vvar_spec);
210 if (IS_ERR(ptr: vma))
211 return PTR_ERR(ptr: vma);
212
213 /*
214 * our vma flags don't have VM_WRITE so by default, the process isn't
215 * allowed to write those pages.
216 * gdb can break that with ptrace interface, and thus trigger COW on
217 * those pages but it's then your responsibility to never do that on
218 * the "data" page of the vDSO or you'll stop getting kernel updates
219 * and your nice userland gettimeofday will be totally dead.
220 * It's fine to use that for setting breakpoints in the vDSO code
221 * pages though.
222 */
223 vma = _install_special_mapping(mm, addr: vdso_base + vvar_size, len: vdso_size,
224 VM_READ | VM_EXEC | VM_MAYREAD |
225 VM_MAYWRITE | VM_MAYEXEC, spec: vdso_spec);
226 if (IS_ERR(ptr: vma))
227 do_munmap(mm, vdso_base, vvar_size, NULL);
228
229 return PTR_ERR_OR_ZERO(ptr: vma);
230}
231
232int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
233{
234 struct mm_struct *mm = current->mm;
235 int rc;
236
237 mm->context.vdso = NULL;
238
239 if (mmap_write_lock_killable(mm))
240 return -EINTR;
241
242 rc = __arch_setup_additional_pages(bprm, uses_interp);
243 if (rc)
244 mm->context.vdso = NULL;
245
246 mmap_write_unlock(mm);
247 return rc;
248}
249
250#define VDSO_DO_FIXUPS(type, value, bits, sec) do { \
251 void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start); \
252 void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end); \
253 \
254 do_##type##_fixups((value), __start, __end); \
255} while (0)
256
257static void __init vdso_fixup_features(void)
258{
259#ifdef CONFIG_PPC64
260 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup);
261 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup);
262 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup);
263 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup);
264#endif /* CONFIG_PPC64 */
265
266#ifdef CONFIG_VDSO32
267 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup);
268 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup);
269#ifdef CONFIG_PPC64
270 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup);
271#endif /* CONFIG_PPC64 */
272 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup);
273#endif
274}
275
276/*
277 * Called from setup_arch to initialize the bitmap of available
278 * syscalls in the systemcfg page
279 */
280static void __init vdso_setup_syscall_map(void)
281{
282 unsigned int i;
283
284 for (i = 0; i < NR_syscalls; i++) {
285 if (sys_call_table[i] != (void *)&sys_ni_syscall)
286 vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
287 if (IS_ENABLED(CONFIG_COMPAT) &&
288 compat_sys_call_table[i] != (void *)&sys_ni_syscall)
289 vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
290 }
291}
292
293#ifdef CONFIG_PPC64
294int vdso_getcpu_init(void)
295{
296 unsigned long cpu, node, val;
297
298 /*
299 * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node
300 * in the next 16 bits. The VDSO uses this to implement getcpu().
301 */
302 cpu = get_cpu();
303 WARN_ON_ONCE(cpu > 0xffff);
304
305 node = cpu_to_node(cpu);
306 WARN_ON_ONCE(node > 0xffff);
307
308 val = (cpu & 0xffff) | ((node & 0xffff) << 16);
309 mtspr(SPRN_SPRG_VDSO_WRITE, val);
310 get_paca()->sprg_vdso = val;
311
312 put_cpu();
313
314 return 0;
315}
316/* We need to call this before SMP init */
317early_initcall(vdso_getcpu_init);
318#endif
319
320static struct page ** __init vdso_setup_pages(void *start, void *end)
321{
322 int i;
323 struct page **pagelist;
324 int pages = (end - start) >> PAGE_SHIFT;
325
326 pagelist = kcalloc(n: pages + 1, size: sizeof(struct page *), GFP_KERNEL);
327 if (!pagelist)
328 panic(fmt: "%s: Cannot allocate page list for VDSO", __func__);
329
330 for (i = 0; i < pages; i++)
331 pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
332
333 return pagelist;
334}
335
336static int __init vdso_init(void)
337{
338#ifdef CONFIG_PPC64
339 /*
340 * Fill up the "systemcfg" stuff for backward compatibility
341 */
342 strcpy((char *)vdso_data->eye_catcher, "SYSTEMCFG:PPC64");
343 vdso_data->version.major = SYSTEMCFG_MAJOR;
344 vdso_data->version.minor = SYSTEMCFG_MINOR;
345 vdso_data->processor = mfspr(SPRN_PVR);
346 /*
347 * Fake the old platform number for pSeries and add
348 * in LPAR bit if necessary
349 */
350 vdso_data->platform = 0x100;
351 if (firmware_has_feature(FW_FEATURE_LPAR))
352 vdso_data->platform |= 1;
353 vdso_data->physicalMemorySize = memblock_phys_mem_size();
354 vdso_data->dcache_size = ppc64_caches.l1d.size;
355 vdso_data->dcache_line_size = ppc64_caches.l1d.line_size;
356 vdso_data->icache_size = ppc64_caches.l1i.size;
357 vdso_data->icache_line_size = ppc64_caches.l1i.line_size;
358 vdso_data->dcache_block_size = ppc64_caches.l1d.block_size;
359 vdso_data->icache_block_size = ppc64_caches.l1i.block_size;
360 vdso_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size;
361 vdso_data->icache_log_block_size = ppc64_caches.l1i.log_block_size;
362#endif /* CONFIG_PPC64 */
363
364 vdso_setup_syscall_map();
365
366 vdso_fixup_features();
367
368 if (IS_ENABLED(CONFIG_VDSO32))
369 vdso32_spec.pages = vdso_setup_pages(start: &vdso32_start, end: &vdso32_end);
370
371 if (IS_ENABLED(CONFIG_PPC64))
372 vdso64_spec.pages = vdso_setup_pages(start: &vdso64_start, end: &vdso64_end);
373
374 smp_wmb();
375
376 return 0;
377}
378arch_initcall(vdso_init);
379

source code of linux/arch/powerpc/kernel/vdso.c