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) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; only version 2 of the License.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
21 * Re-using code from kernel/relay.c, hence the GPLv2 license for this
25 #include <linux/module.h>
28 #include <wrapper/ringbuffer/backend.h>
29 #include <wrapper/ringbuffer/frontend.h>
30 #include <wrapper/ringbuffer/vfs.h>
33 * fault() vm_op implementation for ring buffer file mapping.
35 static int lib_ring_buffer_fault_compat(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
37 struct lib_ring_buffer
*buf
= vma
->vm_private_data
;
38 struct channel
*chan
= buf
->backend
.chan
;
39 const struct lib_ring_buffer_config
*config
= &chan
->backend
.config
;
40 pgoff_t pgoff
= vmf
->pgoff
;
43 unsigned long offset
, sb_bindex
;
46 * Verify that faults are only done on the range of pages owned by the
49 offset
= pgoff
<< PAGE_SHIFT
;
50 sb_bindex
= subbuffer_id_get_index(config
, buf
->backend
.buf_rsb
.id
);
51 if (!(offset
>= buf
->backend
.array
[sb_bindex
]->mmap_offset
52 && offset
< buf
->backend
.array
[sb_bindex
]->mmap_offset
+
53 buf
->backend
.chan
->backend
.subbuf_size
))
54 return VM_FAULT_SIGBUS
;
56 * ring_buffer_read_get_pfn() gets the page frame number for the
57 * current reader's pages.
59 pfnp
= lib_ring_buffer_read_get_pfn(&buf
->backend
, offset
, &virt
);
61 return VM_FAULT_SIGBUS
;
62 get_page(pfn_to_page(*pfnp
));
63 vmf
->page
= pfn_to_page(*pfnp
);
68 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0))
69 static int lib_ring_buffer_fault(struct vm_fault
*vmf
)
71 struct vm_area_struct
*vma
= vmf
->vma
;
72 return lib_ring_buffer_fault_compat(vma
, vmf
);
74 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */
75 static int lib_ring_buffer_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
77 return lib_ring_buffer_fault_compat(vma
, vmf
);
79 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */
82 * vm_ops for ring buffer file mappings.
84 static const struct vm_operations_struct lib_ring_buffer_mmap_ops
= {
85 .fault
= lib_ring_buffer_fault
,
89 * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space
90 * @buf: ring buffer to map
91 * @vma: vm_area_struct describing memory to be mapped
93 * Returns 0 if ok, negative on error
95 * Caller should already have grabbed mmap_sem.
97 static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer
*buf
,
98 struct vm_area_struct
*vma
)
100 unsigned long length
= vma
->vm_end
- vma
->vm_start
;
101 struct channel
*chan
= buf
->backend
.chan
;
102 const struct lib_ring_buffer_config
*config
= &chan
->backend
.config
;
103 unsigned long mmap_buf_len
;
105 if (config
->output
!= RING_BUFFER_MMAP
)
108 mmap_buf_len
= chan
->backend
.buf_size
;
109 if (chan
->backend
.extra_reader_sb
)
110 mmap_buf_len
+= chan
->backend
.subbuf_size
;
112 if (length
!= mmap_buf_len
)
115 vma
->vm_ops
= &lib_ring_buffer_mmap_ops
;
116 vma
->vm_flags
|= VM_DONTEXPAND
;
117 vma
->vm_private_data
= buf
;
122 int lib_ring_buffer_mmap(struct file
*filp
, struct vm_area_struct
*vma
,
123 struct lib_ring_buffer
*buf
)
125 return lib_ring_buffer_mmap_buf(buf
, vma
);
127 EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap
);
130 * vfs_lib_ring_buffer_mmap - mmap file op
132 * @vma: the vma describing what to map
134 * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space.
136 int vfs_lib_ring_buffer_mmap(struct file
*filp
, struct vm_area_struct
*vma
)
138 struct lib_ring_buffer
*buf
= filp
->private_data
;
139 return lib_ring_buffer_mmap(filp
, vma
, buf
);
141 EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap
);