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hc
2024-11-15 a46a1ad097419aeea7350987dd95230f50d90392 
 kernel/arch/arm/kernel/vdso.c
....@@ -32,7 +32,10 @@
3232 
3333 extern char vdso_start[], vdso_end[];
3434 
35
-/* Total number of pages needed for the data and text portions of the VDSO. */
35
+/*
36
+ * Total number of pages needed for the data, private and text
37
+ * portions of the VDSO.
38
+ */
3639 unsigned int vdso_total_pages __ro_after_init;
3740 
3841 /*
....@@ -53,8 +56,8 @@
5356 	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
5457 	unsigned long vdso_size;
5558 
56
-	/* without VVAR page */
57
-	vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT;
59
+	/* without VVAR and VPRIV pages */
60
+	vdso_size = (vdso_total_pages - 2) << PAGE_SHIFT;
5861 
5962 	if (vdso_size != new_size)
6063 		return -EINVAL;
....@@ -180,8 +183,10 @@
180183 	/* If the virtual counter is absent or non-functional we don't
181184 	 * want programs to incur the slight additional overhead of
182185 	 * dispatching through the VDSO only to fall back to syscalls.
186
+	 * However, if clocksources supporting generic MMIO access can
187
+	 * be reached via the vDSO, keep this fast path enabled.
183188 	 */
184
-	if (!cntvct_ok) {
189
+	if (!cntvct_ok && !IS_ENABLED(CONFIG_GENERIC_CLOCKSOURCE_VDSO)) {
185190 		vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
186191 		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
187192 		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
....@@ -219,16 +224,26 @@
219224 
220225 	vdso_text_mapping.pages = vdso_text_pagelist;
221226 
222
-	vdso_total_pages = 1; /* for the data/vvar page */
227
+	vdso_total_pages = 2; /* for the data/vvar and vpriv pages */
223228 	vdso_total_pages += text_pages;
224229 
225230 	cntvct_ok = cntvct_functional();
226231 
227232 	patch_vdso(vdso_start);
233
+#ifdef CONFIG_GENERIC_CLOCKSOURCE_VDSO
234
+	vdso_data->cs_type_seq = CLOCKSOURCE_VDSO_NONE << 16 | 1;
235
+#endif
228236 
229237 	return 0;
230238 }
231239 arch_initcall(vdso_init);
240
+
241
+static int install_vpriv(struct mm_struct *mm, unsigned long addr)
242
+{
243
+	return mmap_region(NULL, addr, PAGE_SIZE,
244
+			  VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
245
+			   0, NULL) != addr ? -EINVAL : 0;
246
+}
232247 
233248 static int install_vvar(struct mm_struct *mm, unsigned long addr)
234249 {
....@@ -237,8 +252,13 @@
237252 	vma = _install_special_mapping(mm, addr, PAGE_SIZE,
238253 				       VM_READ | VM_MAYREAD,
239254 				       &vdso_data_mapping);
255
+	if (IS_ERR(vma))
256
+		return PTR_ERR(vma);
240257 
241
-	return PTR_ERR_OR_ZERO(vma);
258
+	if (cache_is_vivt())
259
+		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
260
+
261
+	return vma->vm_start != addr ? -EINVAL : 0;
242262 }
243263 
244264 /* assumes mmap_lock is write-locked */
....@@ -252,18 +272,29 @@
252272 	if (vdso_text_pagelist == NULL)
253273 		return;
254274 
255
-	if (install_vvar(mm, addr))
275
+	if (install_vpriv(mm, addr)) {
276
+		pr_err("cannot map VPRIV at expected address!\n");
256277 		return;
278
+	}
257279 
258
-	/* Account for vvar page. */
280
+	/* Account for the private storage. */
259281 	addr += PAGE_SIZE;
260
-	len = (vdso_total_pages - 1) << PAGE_SHIFT;
282
+	if (install_vvar(mm, addr)) {
283
+		WARN(1, "cannot map VVAR at expected address!\n");
284
+		return;
285
+	}
286
+
287
+	/* Account for vvar and vpriv pages. */
288
+	addr += PAGE_SIZE;
289
+	len = (vdso_total_pages - 2) << PAGE_SHIFT;
261290 
262291 	vma = _install_special_mapping(mm, addr, len,
263292 		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
264293 		&vdso_text_mapping);
265294 
266
-	if (!IS_ERR(vma))
295
+	if (IS_ERR(vma) || vma->vm_start != addr)
296
+		WARN(1, "cannot map VDSO at expected address!\n");
297
+	else
267298 		mm->context.vdso = addr;
268299 }
269300