[PATCH 2/3] arm64: vdso: move to _install_special_mapping and remove arch_vma_name

[Will Deacon]

_install_special_mapping replaces install_special_mapping and removes
the need to detect special VMA in arch_vma_name.

This patch moves the vdso and compat vectors page code over to the new
API.

Cc: Andy Lutomirski <luto at amacapital.net>
Signed-off-by: Will Deacon <will.deacon at arm.com>
---
 arch/arm64/kernel/vdso.c | 80 +++++++++++++++++++++---------------------------
 1 file changed, 35 insertions(+), 45 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 84cafbc3eb54..60ae12087d9f 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -88,22 +88,29 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 {
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = AARCH32_VECTORS_BASE;
-	int ret;
+	static struct vm_special_mapping spec = {
+		.name	= "[vectors]",
+		.pages	= vectors_page,
+
+	};
+	void *ret;
 
 	down_write(&mm->mmap_sem);
 	current->mm->context.vdso = (void *)addr;
 
 	/* Map vectors page at the high address. */
-	ret = install_special_mapping(mm, addr, PAGE_SIZE,
-				      VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
-				      vectors_page);
+	ret = _install_special_mapping(mm, addr, PAGE_SIZE,
+				       VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
+				       &spec);
 
 	up_write(&mm->mmap_sem);
 
-	return ret;
+	return PTR_ERR_OR_ZERO(ret);
 }
 #endif /* CONFIG_COMPAT */
 
+static struct vm_special_mapping vdso_spec[2];
+
 static int __init vdso_init(void)
 {
 	int i;
@@ -130,6 +137,17 @@ static int __init vdso_init(void)
 	/* Grab the vDSO data page. */
 	vdso_pagelist[i] = virt_to_page(vdso_data);
 
+	/* Populate the special mapping structures */
+	vdso_spec[0] = (struct vm_special_mapping) {
+		.name	= "[vdso]",
+		.pages	= vdso_pagelist,
+	};
+
+	vdso_spec[1] = (struct vm_special_mapping) {
+		.name	= "[vvar]",
+		.pages	= vdso_pagelist + vdso_pages,
+	};
+
 	return 0;
 }
 arch_initcall(vdso_init);
@@ -139,7 +157,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
 {
 	struct mm_struct *mm = current->mm;
 	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
-	int ret;
+	void *ret;
 
 	vdso_text_len = vdso_pages << PAGE_SHIFT;
 	/* Be sure to map the data page */
@@ -148,23 +166,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
 	down_write(&mm->mmap_sem);
 	vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
 	if (IS_ERR_VALUE(vdso_base)) {
-		ret = vdso_base;
+		ret = ERR_PTR(vdso_base);
 		goto up_fail;
 	}
 	mm->context.vdso = (void *)vdso_base;
 
-	ret = install_special_mapping(mm, vdso_base, vdso_text_len,
-				      VM_READ|VM_EXEC|
-				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-				      vdso_pagelist);
-	if (ret)
+	ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
+				       VM_READ|VM_EXEC|
+				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+				       &vdso_spec[0]);
+	if (IS_ERR(ret))
 		goto up_fail;
 
 	vdso_base += vdso_text_len;
-	ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
-				      VM_READ|VM_MAYREAD,
-				      vdso_pagelist + vdso_pages);
-	if (ret)
+	ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
+				       VM_READ|VM_MAYREAD,
+				       &vdso_spec[1]);
+	if (IS_ERR(ret))
 		goto up_fail;
 
 	up_write(&mm->mmap_sem);
@@ -173,35 +191,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
 up_fail:
 	mm->context.vdso = NULL;
 	up_write(&mm->mmap_sem);
-	return ret;
-}
-
-const char *arch_vma_name(struct vm_area_struct *vma)
-{
-	unsigned long vdso_text;
-
-	if (!vma->vm_mm)
-		return NULL;
-
-	vdso_text = (unsigned long)vma->vm_mm->context.vdso;
-
-	/*
-	 * We can re-use the vdso pointer in mm_context_t for identifying
-	 * the vectors page for compat applications. The vDSO will always
-	 * sit above TASK_UNMAPPED_BASE and so we don't need to worry about
-	 * it conflicting with the vectors base.
-	 */
-	if (vma->vm_start == vdso_text) {
-#ifdef CONFIG_COMPAT
-		if (vma->vm_start == AARCH32_VECTORS_BASE)
-			return "[vectors]";
-#endif
-		return "[vdso]";
-	} else if (vma->vm_start == (vdso_text + (vdso_pages << PAGE_SHIFT))) {
-		return "[vvar]";
-	}
-
-	return NULL;
+	return PTR_ERR(ret);
 }
 
 /*
-- 
2.0.0