linux-kernel - [PATCH v4 1/2] mm: Introducing arch

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Date:	Thu, 26 Mar 2015 18:37:52 +0100
From:	Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Jeff Dike <jdike@...toit.com>,
	Richard Weinberger <richard@....at>,
	Guan Xuetao <gxt@...c.pku.edu.cn>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Arnd Bergmann <arnd@...db.de>, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	user-mode-linux-devel@...ts.sourceforge.net,
	user-mode-linux-user@...ts.sourceforge.net,
	linux-arch@...r.kernel.org, linux-mm@...ck.org
Cc:	cov@...eaurora.org, criu@...nvz.org
Subject: [PATCH v4 1/2] mm: Introducing arch_remap hook

Some architecture would like to be triggered when a memory area is moved
through the mremap system call.

This patch is introducing a new arch_remap mm hook which is placed in the
path of mremap, and is called before the old area is unmapped (and the
arch_unmap hook is called).

The architectures which need to call this hook should define
__HAVE_ARCH_REMAP in their asm/mmu_context.h and provide the arch_remap
service with the following prototype:
void arch_remap(struct mm_struct *mm,
                unsigned long old_start, unsigned long old_end,
                unsigned long new_start, unsigned long new_end);

Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
---
 mm/mremap.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 57dadc025c64..bafc234db45c 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -25,6 +25,7 @@
 
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
 
 #include "internal.h"
 
@@ -286,8 +287,14 @@ static unsigned long move_vma(struct vm_area_struct *vma,
 		old_len = new_len;
 		old_addr = new_addr;
 		new_addr = -ENOMEM;
-	} else if (vma->vm_file && vma->vm_file->f_op->mremap)
-		vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+	} else {
+		if (vma->vm_file && vma->vm_file->f_op->mremap)
+			vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+#ifdef __HAVE_ARCH_REMAP
+		arch_remap(mm, old_addr, old_addr+old_len,
+			   new_addr, new_addr+new_len);
+#endif
+	}
 
 	/* Conceal VM_ACCOUNT so old reservation is not undone */
 	if (vm_flags & VM_ACCOUNT) {
-- 
1.9.1

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