linux-kernel - [PATCH v1 6/9] powerpc/vdso: Provide vdso

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Message-Id: <09497ca1607b62029e46b321bac0732864503323.1598363608.git.christophe.leroy@csgroup.eu>
Date:   Tue, 25 Aug 2020 13:54:04 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v1 6/9] powerpc/vdso: Provide vdso_remap()

Provide vdso_remap() through _install_special_mapping() and
drop arch_remap().

This adds a test of the size and returns -EINVAL if the size
is not correct.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/mm-arch-hooks.h | 25 ---------------------
 arch/powerpc/kernel/vdso.c               | 28 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 25 deletions(-)
 delete mode 100644 arch/powerpc/include/asm/mm-arch-hooks.h

diff --git a/arch/powerpc/include/asm/mm-arch-hooks.h b/arch/powerpc/include/asm/mm-arch-hooks.h
deleted file mode 100644
index dce274be824a..000000000000
--- a/arch/powerpc/include/asm/mm-arch-hooks.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Architecture specific mm hooks
- *
- * Copyright (C) 2015, IBM Corporation
- * Author: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
- */
-
-#ifndef _ASM_POWERPC_MM_ARCH_HOOKS_H
-#define _ASM_POWERPC_MM_ARCH_HOOKS_H
-
-static inline void arch_remap(struct mm_struct *mm,
-			      unsigned long old_start, unsigned long old_end,
-			      unsigned long new_start, unsigned long new_end)
-{
-	/*
-	 * mremap() doesn't allow moving multiple vmas so we can limit the
-	 * check to old_start == vdso_base.
-	 */
-	if (old_start == mm->context.vdso_base)
-		mm->context.vdso_base = new_start;
-}
-#define arch_remap arch_remap
-
-#endif /* _ASM_POWERPC_MM_ARCH_HOOKS_H */
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 4ccfc0dc96b5..b9270923452e 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -114,13 +114,41 @@ struct lib64_elfinfo
 	unsigned long	text;
 };
 
+static int vdso_mremap(unsigned long vdso_pages,
+		       const struct vm_special_mapping *sm,
+		       struct vm_area_struct *new_vma)
+{
+	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+	unsigned long vdso_size = (vdso_pages + 1) << PAGE_SHIFT;
+
+	if (new_size != vdso_size)
+		return -EINVAL;
+
+	current->mm->context.vdso_base = (unsigned long)new_vma->vm_start;
+
+	return 0;
+}
+
+static int vdso32_mremap(const struct vm_special_mapping *sm,
+			 struct vm_area_struct *new_vma)
+{
+	return vdso_mremap(vdso32_pages, sm, new_vma);
+}
+
+static int vdso64_mremap(const struct vm_special_mapping *sm,
+			 struct vm_area_struct *new_vma)
+{
+	return vdso_mremap(vdso64_pages, sm, new_vma);
+}
 
 static struct vm_special_mapping vdso32_spec __ro_after_init = {
 	.name = "[vdso]",
+	.mremap = vdso32_mremap,
 };
 
 static struct vm_special_mapping vdso64_spec __ro_after_init = {
 	.name = "[vdso]",
+	.mremap = vdso64_mremap,
 };
 
 /*
-- 
2.25.0