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2023-12-09 b22da3d8526a935aa31e086e63f60ff3246cb61c 
 kernel/arch/x86/entry/vdso/vma.c
....@@ -1,6 +1,6 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * Copyright 2007 Andi Kleen, SUSE Labs.
3
- * Subject to the GPL, v.2
44  *
55  * This contains most of the x86 vDSO kernel-side code.
66  */
....@@ -14,15 +14,31 @@
1414 #include <linux/elf.h>
1515 #include <linux/cpu.h>
1616 #include <linux/ptrace.h>
17
+#include <linux/time_namespace.h>
18
+
1719 #include <asm/pvclock.h>
1820 #include <asm/vgtod.h>
1921 #include <asm/proto.h>
2022 #include <asm/vdso.h>
2123 #include <asm/vvar.h>
24
+#include <asm/tlb.h>
2225 #include <asm/page.h>
2326 #include <asm/desc.h>
2427 #include <asm/cpufeature.h>
25
-#include <asm/mshyperv.h>
28
+#include <clocksource/hyperv_timer.h>
29
+
30
+#undef _ASM_X86_VVAR_H
31
+#define EMIT_VVAR(name, offset)	\
32
+	const size_t name ## _offset = offset;
33
+#include <asm/vvar.h>
34
+
35
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
36
+{
37
+	return (struct vdso_data *)(vvar_page + _vdso_data_offset);
38
+}
39
+#undef EMIT_VVAR
40
+
41
+unsigned int vclocks_used __read_mostly;
2642 
2743 #if defined(CONFIG_X86_64)
2844 unsigned int __read_mostly vdso64_enabled = 1;
....@@ -37,9 +53,10 @@
3753 						image->alt_len));
3854 }
3955 
56
+static const struct vm_special_mapping vvar_mapping;
4057 struct linux_binprm;
4158 
42
-static int vdso_fault(const struct vm_special_mapping *sm,
59
+static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
4360 		      struct vm_area_struct *vma, struct vm_fault *vmf)
4461 {
4562 	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
....@@ -84,12 +101,74 @@
84101 	return 0;
85102 }
86103 
87
-static int vvar_fault(const struct vm_special_mapping *sm,
104
+static int vvar_mremap(const struct vm_special_mapping *sm,
105
+		struct vm_area_struct *new_vma)
106
+{
107
+	const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;
108
+	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
109
+
110
+	if (new_size != -image->sym_vvar_start)
111
+		return -EINVAL;
112
+
113
+	return 0;
114
+}
115
+
116
+#ifdef CONFIG_TIME_NS
117
+static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
118
+{
119
+	if (likely(vma->vm_mm == current->mm))
120
+		return current->nsproxy->time_ns->vvar_page;
121
+
122
+	/*
123
+	 * VM_PFNMAP | VM_IO protect .fault() handler from being called
124
+	 * through interfaces like /proc/$pid/mem or
125
+	 * process_vm_{readv,writev}() as long as there's no .access()
126
+	 * in special_mapping_vmops().
127
+	 * For more details check_vma_flags() and __access_remote_vm()
128
+	 */
129
+
130
+	WARN(1, "vvar_page accessed remotely");
131
+
132
+	return NULL;
133
+}
134
+
135
+/*
136
+ * The vvar page layout depends on whether a task belongs to the root or
137
+ * non-root time namespace. Whenever a task changes its namespace, the VVAR
138
+ * page tables are cleared and then they will re-faulted with a
139
+ * corresponding layout.
140
+ * See also the comment near timens_setup_vdso_data() for details.
141
+ */
142
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
143
+{
144
+	struct mm_struct *mm = task->mm;
145
+	struct vm_area_struct *vma;
146
+
147
+	mmap_read_lock(mm);
148
+
149
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
150
+		unsigned long size = vma->vm_end - vma->vm_start;
151
+
152
+		if (vma_is_special_mapping(vma, &vvar_mapping))
153
+			zap_page_range(vma, vma->vm_start, size);
154
+	}
155
+
156
+	mmap_read_unlock(mm);
157
+	return 0;
158
+}
159
+#else
160
+static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
161
+{
162
+	return NULL;
163
+}
164
+#endif
165
+
166
+static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
88167 		      struct vm_area_struct *vma, struct vm_fault *vmf)
89168 {
90169 	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
170
+	unsigned long pfn;
91171 	long sym_offset;
92
-	int ret = -EFAULT;
93172 
94173 	if (!image)
95174 		return VM_FAULT_SIGBUS;
....@@ -108,28 +187,59 @@
108187 		return VM_FAULT_SIGBUS;
109188 
110189 	if (sym_offset == image->sym_vvar_page) {
111
-		ret = vm_insert_pfn(vma, vmf->address,
112
-				    __pa_symbol(&__vvar_page) >> PAGE_SHIFT);
190
+		struct page *timens_page = find_timens_vvar_page(vma);
191
+
192
+		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
193
+
194
+		/*
195
+		 * If a task belongs to a time namespace then a namespace
196
+		 * specific VVAR is mapped with the sym_vvar_page offset and
197
+		 * the real VVAR page is mapped with the sym_timens_page
198
+		 * offset.
199
+		 * See also the comment near timens_setup_vdso_data().
200
+		 */
201
+		if (timens_page) {
202
+			unsigned long addr;
203
+			vm_fault_t err;
204
+
205
+			/*
206
+			 * Optimization: inside time namespace pre-fault
207
+			 * VVAR page too. As on timens page there are only
208
+			 * offsets for clocks on VVAR, it'll be faulted
209
+			 * shortly by VDSO code.
210
+			 */
211
+			addr = vmf->address + (image->sym_timens_page - sym_offset);
212
+			err = vmf_insert_pfn(vma, addr, pfn);
213
+			if (unlikely(err & VM_FAULT_ERROR))
214
+				return err;
215
+
216
+			pfn = page_to_pfn(timens_page);
217
+		}
218
+
219
+		return vmf_insert_pfn(vma, vmf->address, pfn);
113220 	} else if (sym_offset == image->sym_pvclock_page) {
114221 		struct pvclock_vsyscall_time_info *pvti =
115222 			pvclock_get_pvti_cpu0_va();
116
-		if (pvti && vclock_was_used(VCLOCK_PVCLOCK)) {
117
-			ret = vm_insert_pfn_prot(
118
-				vma,
119
-				vmf->address,
120
-				__pa(pvti) >> PAGE_SHIFT,
121
-				pgprot_decrypted(vma->vm_page_prot));
223
+		if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK)) {
224
+			return vmf_insert_pfn_prot(vma, vmf->address,
225
+					__pa(pvti) >> PAGE_SHIFT,
226
+					pgprot_decrypted(vma->vm_page_prot));
122227 		}
123228 	} else if (sym_offset == image->sym_hvclock_page) {
124229 		struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page();
125230 
126
-		if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
127
-			ret = vm_insert_pfn(vma, vmf->address,
128
-					    vmalloc_to_pfn(tsc_pg));
129
-	}
231
+		if (tsc_pg && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
232
+			return vmf_insert_pfn(vma, vmf->address,
233
+					virt_to_phys(tsc_pg) >> PAGE_SHIFT);
234
+	} else if (sym_offset == image->sym_timens_page) {
235
+		struct page *timens_page = find_timens_vvar_page(vma);
130236 
131
-	if (ret == 0 || ret == -EBUSY)
132
-		return VM_FAULT_NOPAGE;
237
+		if (!timens_page)
238
+			return VM_FAULT_SIGBUS;
239
+
240
+		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
241
+		return vmf_insert_pfn(vma, vmf->address, pfn);
242
+	}
133243 
134244 	return VM_FAULT_SIGBUS;
135245 }
....@@ -142,6 +252,7 @@
142252 static const struct vm_special_mapping vvar_mapping = {
143253 	.name = "[vvar]",
144254 	.fault = vvar_fault,
255
+	.mremap = vvar_mremap,
145256 };
146257 
147258 /*
....@@ -156,7 +267,7 @@
156267 	unsigned long text_start;
157268 	int ret = 0;
158269 
159
-	if (down_write_killable(&mm->mmap_sem))
270
+	if (mmap_write_lock_killable(mm))
160271 		return -EINTR;
161272 
162273 	addr = get_unmapped_area(NULL, addr,
....@@ -199,7 +310,7 @@
199310 	}
200311 
201312 up_fail:
202
-	up_write(&mm->mmap_sem);
313
+	mmap_write_unlock(mm);
203314 	return ret;
204315 }
205316 
....@@ -261,22 +372,22 @@
261372 	struct mm_struct *mm = current->mm;
262373 	struct vm_area_struct *vma;
263374 
264
-	down_write(&mm->mmap_sem);
375
+	mmap_write_lock(mm);
265376 	/*
266377 	 * Check if we have already mapped vdso blob - fail to prevent
267378 	 * abusing from userspace install_speciall_mapping, which may
268379 	 * not do accounting and rlimit right.
269380 	 * We could search vma near context.vdso, but it's a slowpath,
270
-	 * so let's explicitely check all VMAs to be completely sure.
381
+	 * so let's explicitly check all VMAs to be completely sure.
271382 	 */
272383 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
273384 		if (vma_is_special_mapping(vma, &vdso_mapping) ||
274385 				vma_is_special_mapping(vma, &vvar_mapping)) {
275
-			up_write(&mm->mmap_sem);
386
+			mmap_write_unlock(mm);
276387 			return -EEXIST;
277388 		}
278389 	}
279
-	up_write(&mm->mmap_sem);
390
+	mmap_write_unlock(mm);
280391 
281392 	return map_vdso(image, addr);
282393 }
....@@ -329,12 +440,14 @@
329440 static __init int vdso_setup(char *s)
330441 {
331442 	vdso64_enabled = simple_strtoul(s, NULL, 0);
332
-	return 0;
443
+	return 1;
333444 }
334445 __setup("vdso=", vdso_setup);
335446 
336447 static int __init init_vdso(void)
337448 {
449
+	BUILD_BUG_ON(VDSO_CLOCKMODE_MAX >= 32);
450
+
338451 	init_vdso_image(&vdso_image_64);
339452 
340453 #ifdef CONFIG_X86_X32_ABI