[lttng-modules.git] / lib / ringbuffer / ring_buffer_mmap.c

/*
 * ring_buffer_mmap.c
 *
 * Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
 * Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com>
 * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Re-using content from kernel/relay.c.
 *
 * This file is released under the GPL v2.
 */

#include <linux/module.h>
#include <linux/mm.h>

#include "../../wrapper/ringbuffer/backend.h"
#include "../../wrapper/ringbuffer/frontend.h"
#include "../../wrapper/ringbuffer/vfs.h"

/*
 * fault() vm_op implementation for ring buffer file mapping.
 */
static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct lib_ring_buffer *buf = vma->vm_private_data;
	struct channel *chan = buf->backend.chan;
	const struct lib_ring_buffer_config *config = chan->backend.config;
	pgoff_t pgoff = vmf->pgoff;
	struct page **page;
	void **virt;
	unsigned long offset, sb_bindex;

	if (!buf)
		return VM_FAULT_OOM;

	/*
	 * Verify that faults are only done on the range of pages owned by the
	 * reader.
	 */
	offset = pgoff << PAGE_SHIFT;
	sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id);
	if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset
	      && offset < buf->backend.array[sb_bindex]->mmap_offset +
			  buf->backend.chan->backend.subbuf_size))
		return VM_FAULT_SIGBUS;
	/*
	 * ring_buffer_read_get_page() gets the page in the current reader's
	 * pages.
	 */
	page = lib_ring_buffer_read_get_page(&buf->backend, offset, &virt);
	if (!*page)
		return VM_FAULT_SIGBUS;
	get_page(*page);
	vmf->page = *page;

	return 0;
}

/*
 * vm_ops for ring buffer file mappings.
 */
static const struct vm_operations_struct lib_ring_buffer_mmap_ops = {
	.fault = lib_ring_buffer_fault,
};

/**
 *	lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space
 *	@buf: ring buffer to map
 *	@vma: vm_area_struct describing memory to be mapped
 *
 *	Returns 0 if ok, negative on error
 *
 *	Caller should already have grabbed mmap_sem.
 */
static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf,
				    struct vm_area_struct *vma)
{
	unsigned long length = vma->vm_end - vma->vm_start;
	struct channel *chan = buf->backend.chan;
	const struct lib_ring_buffer_config *config = chan->backend.config;
	unsigned long mmap_buf_len;

	if (config->output != RING_BUFFER_MMAP)
		return -EINVAL;

	if (!buf)
		return -EBADF;

	mmap_buf_len = chan->backend.buf_size;
	if (chan->backend.extra_reader_sb)
		mmap_buf_len += chan->backend.subbuf_size;

	if (length != mmap_buf_len)
		return -EINVAL;

	vma->vm_ops = &lib_ring_buffer_mmap_ops;
	vma->vm_flags |= VM_DONTEXPAND;
	vma->vm_private_data = buf;

	return 0;
}

/**
 *	lib_ring_buffer_mmap - mmap file op
 *	@filp: the file
 *	@vma: the vma describing what to map
 *
 *	Calls upon lib_ring_buffer_mmap_buf() to map the file into user space.
 */
int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma)
{
	struct lib_ring_buffer *buf = filp->private_data;
	return lib_ring_buffer_mmap_buf(buf, vma);
}
EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap);
Commit	Line	Data
f3bc08c5 MD	1	/*
	2	* ring_buffer_mmap.c
	3	*
	4	* Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
	5	* Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com>
	6	* Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	7	*
	8	* Re-using content from kernel/relay.c.
	9	*
	10	* This file is released under the GPL v2.
	11	*/
	12
	13	#include <linux/module.h>
	14	#include <linux/mm.h>
	15
	16	#include "../../wrapper/ringbuffer/backend.h"
	17	#include "../../wrapper/ringbuffer/frontend.h"
	18	#include "../../wrapper/ringbuffer/vfs.h"
	19
	20	/*
	21	* fault() vm_op implementation for ring buffer file mapping.
	22	*/
	23	static int lib_ring_buffer_fault(struct vm_area_struct vma, struct vm_fault vmf)
	24	{
	25	struct lib_ring_buffer *buf = vma->vm_private_data;
	26	struct channel *chan = buf->backend.chan;
	27	const struct lib_ring_buffer_config *config = chan->backend.config;
	28	pgoff_t pgoff = vmf->pgoff;
	29	struct page **page;
	30	void **virt;
	31	unsigned long offset, sb_bindex;
	32
	33	if (!buf)
	34	return VM_FAULT_OOM;
	35
	36	/*
	37	* Verify that faults are only done on the range of pages owned by the
	38	* reader.
	39	*/
	40	offset = pgoff << PAGE_SHIFT;
	41	sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id);
	42	if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset
	43	&& offset < buf->backend.array[sb_bindex]->mmap_offset +
	44	buf->backend.chan->backend.subbuf_size))
	45	return VM_FAULT_SIGBUS;
	46	/*
	47	* ring_buffer_read_get_page() gets the page in the current reader's
	48	* pages.
	49	*/
	50	page = lib_ring_buffer_read_get_page(&buf->backend, offset, &virt);
	51	if (!*page)
	52	return VM_FAULT_SIGBUS;
	53	get_page(*page);
	54	vmf->page = *page;
	55
	56	return 0;
	57	}
	58
	59	/*
	60	* vm_ops for ring buffer file mappings.
	61	*/
	62	static const struct vm_operations_struct lib_ring_buffer_mmap_ops = {
	63	.fault = lib_ring_buffer_fault,
	64	};
65
66	/**
67	* lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space
68	* @buf: ring buffer to map
69	* @vma: vm_area_struct describing memory to be mapped
70	*
71	* Returns 0 if ok, negative on error
72	*
73	* Caller should already have grabbed mmap_sem.
74	*/
75	static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf,
76	struct vm_area_struct *vma)
77	{
78	unsigned long length = vma->vm_end - vma->vm_start;
79	struct channel *chan = buf->backend.chan;
80	const struct lib_ring_buffer_config *config = chan->backend.config;
81	unsigned long mmap_buf_len;
82
83	if (config->output != RING_BUFFER_MMAP)
84	return -EINVAL;
85
86	if (!buf)
87	return -EBADF;
88
89	mmap_buf_len = chan->backend.buf_size;
90	if (chan->backend.extra_reader_sb)
91	mmap_buf_len += chan->backend.subbuf_size;
92
93	if (length != mmap_buf_len)
94	return -EINVAL;
95
96	vma->vm_ops = &lib_ring_buffer_mmap_ops;
97	vma->vm_flags \|= VM_DONTEXPAND;
98	vma->vm_private_data = buf;
99
100	return 0;
101	}
102
103	/**
104	* lib_ring_buffer_mmap - mmap file op
105	* @filp: the file
106	* @vma: the vma describing what to map
107	*
108	* Calls upon lib_ring_buffer_mmap_buf() to map the file into user space.
109	*/
110	int lib_ring_buffer_mmap(struct file filp, struct vm_area_struct vma)
111	{
112	struct lib_ring_buffer *buf = filp->private_data;
113	return lib_ring_buffer_mmap_buf(buf, vma);
114	}
115	EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap);