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* Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
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* Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com>
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* Copyright (C) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; only version 2 of the License.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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* Re-using code from kernel/relay.c, hence the GPLv2 license for this
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#include <linux/module.h>
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#include "../../wrapper/ringbuffer/backend.h"
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#include "../../wrapper/ringbuffer/frontend.h"
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#include "../../wrapper/ringbuffer/vfs.h"
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* fault() vm_op implementation for ring buffer file mapping.
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static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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struct lib_ring_buffer *buf = vma->vm_private_data;
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struct channel *chan = buf->backend.chan;
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const struct lib_ring_buffer_config *config = &chan->backend.config;
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pgoff_t pgoff = vmf->pgoff;
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unsigned long offset, sb_bindex;
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* Verify that faults are only done on the range of pages owned by the
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offset = pgoff << PAGE_SHIFT;
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sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id);
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if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset
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&& offset < buf->backend.array[sb_bindex]->mmap_offset +
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buf->backend.chan->backend.subbuf_size))
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return VM_FAULT_SIGBUS;
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* ring_buffer_read_get_page() gets the page in the current reader's
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page = lib_ring_buffer_read_get_page(&buf->backend, offset, &virt);
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return VM_FAULT_SIGBUS;
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* vm_ops for ring buffer file mappings.
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static const struct vm_operations_struct lib_ring_buffer_mmap_ops = {
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.fault = lib_ring_buffer_fault,
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* lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space
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* @buf: ring buffer to map
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* @vma: vm_area_struct describing memory to be mapped
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* Returns 0 if ok, negative on error
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* Caller should already have grabbed mmap_sem.
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static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf,
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struct vm_area_struct *vma)
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unsigned long length = vma->vm_end - vma->vm_start;
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struct channel *chan = buf->backend.chan;
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const struct lib_ring_buffer_config *config = &chan->backend.config;
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unsigned long mmap_buf_len;
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if (config->output != RING_BUFFER_MMAP)
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mmap_buf_len = chan->backend.buf_size;
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if (chan->backend.extra_reader_sb)
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mmap_buf_len += chan->backend.subbuf_size;
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if (length != mmap_buf_len)
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vma->vm_ops = &lib_ring_buffer_mmap_ops;
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vma->vm_flags |= VM_DONTEXPAND;
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vma->vm_private_data = buf;
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int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma,
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struct lib_ring_buffer *buf)
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return lib_ring_buffer_mmap_buf(buf, vma);
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EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap);
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* vfs_lib_ring_buffer_mmap - mmap file op
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* @vma: the vma describing what to map
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* Calls upon lib_ring_buffer_mmap_buf() to map the file into user space.
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int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma)
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struct lib_ring_buffer *buf = filp->private_data;
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return lib_ring_buffer_mmap(filp, vma, buf);
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EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap);