From: Christopher Covington <cov@codeaurora.org>
To: criu@openvz.org, Will Deacon <will.deacon@arm.com>,
linux-mm@kvack.org, Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Christopher Covington <cov@codeaurora.org>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC v2 1/7] mm: Provide generic VDSO unmap and remap functions
Date: Tue, 1 Nov 2016 11:10:55 -0600 [thread overview]
Message-ID: <20161101171101.24704-1-cov@codeaurora.org> (raw)
When Address Space Layout Randomization (ASLR, randmaps) is enabled, the
address of the VDSO fluctuates from one process to the next. If
Checkpoint/Restore In Userspace (CRIU) is to fully replicate the memory map
of a previous process, it must be able to remap the VDSO of a new process
to the address used by the previous process. Historically this has been
implemented in architecture-specific code for PowerPC and x86. In order to
support 32-bit and 64-bit ARM without further duplication of code, copy
Laurent Dufour's implementation for PowerPC with slight modifications to a
generic location. This is hopefully the beginning of a long process of VDSO
code de-duplication between architectures.
Signed-off-by: Christopher Covington <cov@codeaurora.org>
---
include/asm-generic/mm_hooks.h | 35 ++++++++++++++++++++++++++++++++---
1 file changed, 32 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/mm_hooks.h b/include/asm-generic/mm_hooks.h
index cc5d9a1..73f09f1 100644
--- a/include/asm-generic/mm_hooks.h
+++ b/include/asm-generic/mm_hooks.h
@@ -1,7 +1,17 @@
/*
- * Define generic no-op hooks for arch_dup_mmap, arch_exit_mmap
- * and arch_unmap to be included in asm-FOO/mmu_context.h for any
- * arch FOO which doesn't need to hook these.
+ * Define generic hooks for arch_dup_mmap, arch_exit_mmap and arch_unmap to be
+ * included in asm-FOO/mmu_context.h for any arch FOO which doesn't need to
+ * specially hook these.
+ *
+ * arch_remap originally from include/linux-mm-arch-hooks.h
+ * arch_unmap originally from arch/powerpc/include/asm/mmu_context.h
+ * Copyright (C) 2015, IBM Corporation
+ * Author: Laurent Dufour <ldufour@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
*/
#ifndef _ASM_GENERIC_MM_HOOKS_H
#define _ASM_GENERIC_MM_HOOKS_H
@@ -19,6 +29,25 @@ static inline void arch_unmap(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
+#ifdef CONFIG_GENERIC_VDSO
+ if (start <= mm->context.vdso && mm->context.vdso < end)
+ mm->context.vdso = 0;
+#endif /* CONFIG_GENERIC_VDSO */
+}
+
+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)
+{
+#ifdef CONFIG_GENERIC_VDSO
+ /*
+ * mremap() doesn't allow moving multiple vmas so we can limit the
+ * check to old_addr == vdso.
+ */
+ if (old_addr == mm->context.vdso)
+ mm->context.vdso = new_addr;
+
+#endif /* CONFIG_GENERIC_VDSO */
}
static inline void arch_bprm_mm_init(struct mm_struct *mm,
--
Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
next reply other threads:[~2016-11-01 17:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-01 17:10 Christopher Covington [this message]
2016-11-01 17:10 ` [RFC v2 2/7] arm: Use generic VDSO unmap and remap Christopher Covington
2016-11-01 17:18 ` Russell King - ARM Linux
2016-11-01 17:10 ` [RFC v2 3/7] arm64: Use unsigned long for VDSO Christopher Covington
2016-11-01 17:10 ` [RFC v2 4/7] arm64: Use generic VDSO unmap and remap functions Christopher Covington
2016-11-01 17:10 ` [RFC v2 5/7] powerpc: Rename context.vdso_base to context.vdso Christopher Covington
[not found] ` <87r36rn8nl.fsf@concordia.ellerman.id.au>
2016-11-04 20:13 ` Will Deacon
2016-11-07 8:01 ` Michael Ellerman
2016-11-01 17:11 ` [RFC v2 6/7] mm/powerpc: Use generic VDSO remap and unmap functions Christopher Covington
2016-11-04 4:59 ` Michael Ellerman
2016-11-07 20:20 ` Laurent Dufour
2016-11-07 23:51 ` Michael Ellerman
2016-11-01 17:23 ` [RFC v2 1/7] mm: Provide generic VDSO unmap and remap functions Dmitry Safonov
2016-11-02 0:23 ` Christopher Covington
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