GNU Linux-libre 6.7.9-gnu
[releases.git] / arch / powerpc / kernel / vdso.c
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
39 extern char vdso32_start, vdso32_end;
40 extern char vdso64_start, vdso64_end;
41
42 long 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  */
49 static union {
50         struct vdso_arch_data   data;
51         u8                      page[PAGE_SIZE];
52 } vdso_data_store __page_aligned_data;
53 struct vdso_arch_data *vdso_data = &vdso_data_store.data;
54
55 enum vvar_pages {
56         VVAR_DATA_PAGE_OFFSET,
57         VVAR_TIMENS_PAGE_OFFSET,
58         VVAR_NR_PAGES,
59 };
60
61 static 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
74 static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
75 {
76         return vdso_mremap(sm, new_vma, &vdso32_end - &vdso32_start);
77 }
78
79 static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
80 {
81         return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start);
82 }
83
84 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
85                              struct vm_area_struct *vma, struct vm_fault *vmf);
86
87 static struct vm_special_mapping vvar_spec __ro_after_init = {
88         .name = "[vvar]",
89         .fault = vvar_fault,
90 };
91
92 static struct vm_special_mapping vdso32_spec __ro_after_init = {
93         .name = "[vdso]",
94         .mremap = vdso32_mremap,
95 };
96
97 static struct vm_special_mapping vdso64_spec __ro_after_init = {
98         .name = "[vdso]",
99         .mremap = vdso64_mremap,
100 };
101
102 #ifdef CONFIG_TIME_NS
103 struct 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  */
115 int 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, &vvar_spec))
124                         zap_vma_pages(vma);
125         }
126         mmap_read_unlock(mm);
127
128         return 0;
129 }
130 #endif
131
132 static 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, 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  */
170 static 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, vdso_base, vvar_size,
208                                        VM_READ | VM_MAYREAD | VM_IO |
209                                        VM_DONTDUMP | VM_PFNMAP, &vvar_spec);
210         if (IS_ERR(vma))
211                 return PTR_ERR(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, vdso_base + vvar_size, vdso_size,
224                                        VM_READ | VM_EXEC | VM_MAYREAD |
225                                        VM_MAYWRITE | VM_MAYEXEC, vdso_spec);
226         if (IS_ERR(vma))
227                 do_munmap(mm, vdso_base, vvar_size, NULL);
228
229         return PTR_ERR_OR_ZERO(vma);
230 }
231
232 int 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
257 static 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  */
280 static 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
294 int 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 */
317 early_initcall(vdso_getcpu_init);
318 #endif
319
320 static 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(pages + 1, sizeof(struct page *), GFP_KERNEL);
327         if (!pagelist)
328                 panic("%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
336 static 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(&vdso32_start, &vdso32_end);
370
371         if (IS_ENABLED(CONFIG_PPC64))
372                 vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end);
373
374         smp_wmb();
375
376         return 0;
377 }
378 arch_initcall(vdso_init);