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Commit 206cb636 authored by Stephen Wilson's avatar Stephen Wilson Committed by Al Viro
Browse files

mm: factor out main logic of access_process_vm 



Introduce an internal helper __access_remote_vm and base access_process_vm on
top of it.  This new method may be called with a NULL task_struct if page fault
accounting is not desired.  This code will be shared with a new address space
accessor that is independent of task_struct.

Signed-off-by: default avatarStephen Wilson <wilsons@start.ca>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e7f22e20

mm/memory.c

+25 −10
Original line number Diff line number Diff line
@@ -3650,20 +3650,15 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 
#endif



/*

 * Access another process' address space.

 * Source/target buffer must be kernel space,

 * Do not walk the page table directly, use get_user_pages

 * Access another process' address space as given in mm.  If non-NULL, use the

 * given task for page fault accounting.

 */

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 mm_struct *mm;

	struct vm_area_struct *vma;

	void *old_buf = buf;



	mm = get_task_mm(tsk);

	if (!mm)

		return 0;



	down_read(&mm->mmap_sem);

	/* ignore errors, just check how much was successfully transferred */

	while (len) {
@@ -3712,11 +3707,31 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in 
		addr += bytes;

	}

	up_read(&mm->mmap_sem);

	mmput(mm);



	return buf - old_buf;

}



/*

 * Access another process' address space.

 * Source/target buffer must be kernel space,

 * Do not walk the page table directly, use get_user_pages

 */

int access_process_vm(struct task_struct *tsk, unsigned long addr,

		void *buf, int len, int write)

{

	struct mm_struct *mm;

	int ret;



	mm = get_task_mm(tsk);

	if (!mm)

		return 0;



	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);

	mmput(mm);



	return ret;

}



/*

 * Print the name of a VMA.

 */