Re: [PATCH] NOMMU: implement access_remote_vm

From: Greg Ungerer
Date: Tue Mar 29 2011 - 06:21:25 EST


On 26/03/11 06:32, Mike Frysinger wrote:
Recent vm changes brought in a new function which the core procfs code
utilizes. So implement it for nommu systems too to avoid link failures.

Signed-off-by: Mike Frysinger<vapier@xxxxxxxxxx>

Looks good.

Acked-by: Greg Ungerer <gerg@xxxxxxxxxxx>


---
mm/nommu.c | 52 +++++++++++++++++++++++++++++++++++++++-------------
1 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index cb86e7d..c4c542c 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1971,21 +1971,10 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
}
EXPORT_SYMBOL(filemap_fault);

-/*
- * Access another process' address space.
- * - source/target buffer must be kernel space
- */
-int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long addr, void *buf, int len, int write)
{
struct vm_area_struct *vma;
- struct mm_struct *mm;
-
- if (addr + len< addr)
- return 0;
-
- mm = get_task_mm(tsk);
- if (!mm)
- return 0;

down_read(&mm->mmap_sem);

@@ -2010,6 +1999,43 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
}

up_read(&mm->mmap_sem);
+
+ return len;
+}
+
+/**
+ * @access_remote_vm - access another process' address space
+ * @mm: the mm_struct of the target address space
+ * @addr: start address to access
+ * @buf: source or destination buffer
+ * @len: number of bytes to transfer
+ * @write: whether the access is a write
+ *
+ * The caller must hold a reference on @mm.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+ void *buf, int len, int write)
+{
+ return __access_remote_vm(NULL, mm, addr, buf, len, write);
+}
+
+/*
+ * Access another process' address space.
+ * - source/target buffer must be kernel space
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+{
+ struct mm_struct *mm;
+
+ if (addr + len< addr)
+ return 0;
+
+ mm = get_task_mm(tsk);
+ if (!mm)
+ return 0;
+
+ len = __access_remote_vm(tsk, mm, addr, buf, len, write);
+
mmput(mm);
return len;
}


--
------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg@xxxxxxxxxxxx
SnapGear Group, McAfee PHONE: +61 7 3435 2888
8 Gardner Close FAX: +61 7 3217 5323
Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com
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