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/*
* 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) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; only version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Re-using code from kernel/relay.c, hence the GPLv2 license for this
* file.
*/
#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;
/*
* 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;
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;
}
int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma,
struct lib_ring_buffer *buf)
{
return lib_ring_buffer_mmap_buf(buf, vma);
}
EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap);
/**
* vfs_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 vfs_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(filp, vma, buf);
}
EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap);
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