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2024-11-01 2f529f9b558ca1c1bd74be7437a84e4711743404

 kernel/arch/arm/kernel/vdso.c
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@@ -32,7 +32,10 @@
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 extern char vdso_start[], vdso_end[];
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-/* Total number of pages needed for the data and text portions of the VDSO. */
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+/*
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+ * Total number of pages needed for the data, private and text
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+ * portions of the VDSO.
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+ */
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 unsigned int vdso_total_pages __ro_after_init;
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 /*
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@@ -53,8 +56,8 @@
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 	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
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 	unsigned long vdso_size;
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-	/* without VVAR page */
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-	vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT;
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+	/* without VVAR and VPRIV pages */
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+	vdso_size = (vdso_total_pages - 2) << PAGE_SHIFT;
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 	if (vdso_size != new_size)
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 		return -EINVAL;
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@@ -180,8 +183,10 @@
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 	/* If the virtual counter is absent or non-functional we don't
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 	 * want programs to incur the slight additional overhead of
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 	 * dispatching through the VDSO only to fall back to syscalls.
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+	 * However, if clocksources supporting generic MMIO access can
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+	 * be reached via the vDSO, keep this fast path enabled.
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 	 */
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-	if (!cntvct_ok) {
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+	if (!cntvct_ok && !IS_ENABLED(CONFIG_GENERIC_CLOCKSOURCE_VDSO)) {
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 		vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
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 		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
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 		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
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@@ -219,16 +224,26 @@
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 	vdso_text_mapping.pages = vdso_text_pagelist;
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-	vdso_total_pages = 1; /* for the data/vvar page */
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+	vdso_total_pages = 2; /* for the data/vvar and vpriv pages */
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 	vdso_total_pages += text_pages;
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 	cntvct_ok = cntvct_functional();
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 	patch_vdso(vdso_start);
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+#ifdef CONFIG_GENERIC_CLOCKSOURCE_VDSO
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+	vdso_data->cs_type_seq = CLOCKSOURCE_VDSO_NONE << 16 | 1;
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+#endif
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 	return 0;
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 }
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 arch_initcall(vdso_init);
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+
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+static int install_vpriv(struct mm_struct *mm, unsigned long addr)
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+{
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+	return mmap_region(NULL, addr, PAGE_SIZE,
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+			  VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
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+			   0, NULL) != addr ? -EINVAL : 0;
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+}
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 static int install_vvar(struct mm_struct *mm, unsigned long addr)
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 {
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@@ -237,8 +252,13 @@
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 	vma = _install_special_mapping(mm, addr, PAGE_SIZE,
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 				       VM_READ | VM_MAYREAD,
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 				       &vdso_data_mapping);
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+	if (IS_ERR(vma))
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+		return PTR_ERR(vma);
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-	return PTR_ERR_OR_ZERO(vma);
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+	if (cache_is_vivt())
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+		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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+
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+	return vma->vm_start != addr ? -EINVAL : 0;
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 }
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 /* assumes mmap_lock is write-locked */
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@@ -252,18 +272,29 @@
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 	if (vdso_text_pagelist == NULL)
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 		return;
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-	if (install_vvar(mm, addr))
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+	if (install_vpriv(mm, addr)) {
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+		pr_err("cannot map VPRIV at expected address!\n");
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 		return;
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+	}
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-	/* Account for vvar page. */
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+	/* Account for the private storage. */
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 	addr += PAGE_SIZE;
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-	len = (vdso_total_pages - 1) << PAGE_SHIFT;
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+	if (install_vvar(mm, addr)) {
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+		WARN(1, "cannot map VVAR at expected address!\n");
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+		return;
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+	}
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+
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+	/* Account for vvar and vpriv pages. */
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+	addr += PAGE_SIZE;
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+	len = (vdso_total_pages - 2) << PAGE_SHIFT;
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 	vma = _install_special_mapping(mm, addr, len,
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 		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
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 		&vdso_text_mapping);
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-	if (!IS_ERR(vma))
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+	if (IS_ERR(vma) || vma->vm_start != addr)
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+		WARN(1, "cannot map VDSO at expected address!\n");
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+	else
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 		mm->context.vdso = addr;
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 }
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