Commit | Line | Data |
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b7cdc182 | 1 | /* SPDX-License-Identifier: GPL-2.0-only |
9f36eaed | 2 | * |
f3bc08c5 MD |
3 | * ring_buffer_mmap.c |
4 | * | |
5 | * Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp | |
6 | * Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com> | |
886d51a3 | 7 | * Copyright (C) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
f3bc08c5 | 8 | * |
b7cdc182 | 9 | * Re-using code from kernel/relay.c, hence the GPL-2.0-only license for this |
886d51a3 | 10 | * file. |
f3bc08c5 MD |
11 | */ |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/mm.h> | |
15 | ||
b5304713 MD |
16 | #include <ringbuffer/backend.h> |
17 | #include <ringbuffer/frontend.h> | |
18 | #include <ringbuffer/vfs.h> | |
f3bc08c5 MD |
19 | |
20 | /* | |
21 | * fault() vm_op implementation for ring buffer file mapping. | |
22 | */ | |
2ca0c84f | 23 | static vm_fault_t lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) |
f3bc08c5 MD |
24 | { |
25 | struct lib_ring_buffer *buf = vma->vm_private_data; | |
26 | struct channel *chan = buf->backend.chan; | |
5a8fd222 | 27 | const struct lib_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 | 28 | pgoff_t pgoff = vmf->pgoff; |
0112cb7b | 29 | unsigned long *pfnp; |
f3bc08c5 MD |
30 | void **virt; |
31 | unsigned long offset, sb_bindex; | |
32 | ||
f3bc08c5 MD |
33 | /* |
34 | * Verify that faults are only done on the range of pages owned by the | |
35 | * reader. | |
36 | */ | |
37 | offset = pgoff << PAGE_SHIFT; | |
38 | sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id); | |
39 | if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset | |
40 | && offset < buf->backend.array[sb_bindex]->mmap_offset + | |
41 | buf->backend.chan->backend.subbuf_size)) | |
42 | return VM_FAULT_SIGBUS; | |
43 | /* | |
0112cb7b MD |
44 | * ring_buffer_read_get_pfn() gets the page frame number for the |
45 | * current reader's pages. | |
f3bc08c5 | 46 | */ |
0112cb7b MD |
47 | pfnp = lib_ring_buffer_read_get_pfn(&buf->backend, offset, &virt); |
48 | if (!*pfnp) | |
f3bc08c5 | 49 | return VM_FAULT_SIGBUS; |
0112cb7b MD |
50 | get_page(pfn_to_page(*pfnp)); |
51 | vmf->page = pfn_to_page(*pfnp); | |
f3bc08c5 MD |
52 | |
53 | return 0; | |
54 | } | |
55 | ||
2ca0c84f MJ |
56 | static vm_fault_t lib_ring_buffer_fault(struct vm_fault *vmf) |
57 | { | |
58 | struct vm_area_struct *vma = vmf->vma; | |
59 | return lib_ring_buffer_fault_compat(vma, vmf); | |
60 | } | |
52a391bd | 61 | |
f3bc08c5 MD |
62 | /* |
63 | * vm_ops for ring buffer file mappings. | |
64 | */ | |
65 | static const struct vm_operations_struct lib_ring_buffer_mmap_ops = { | |
66 | .fault = lib_ring_buffer_fault, | |
67 | }; | |
68 | ||
69 | /** | |
70 | * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space | |
71 | * @buf: ring buffer to map | |
72 | * @vma: vm_area_struct describing memory to be mapped | |
73 | * | |
74 | * Returns 0 if ok, negative on error | |
75 | * | |
76 | * Caller should already have grabbed mmap_sem. | |
77 | */ | |
78 | static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf, | |
79 | struct vm_area_struct *vma) | |
80 | { | |
81 | unsigned long length = vma->vm_end - vma->vm_start; | |
82 | struct channel *chan = buf->backend.chan; | |
5a8fd222 | 83 | const struct lib_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 MD |
84 | unsigned long mmap_buf_len; |
85 | ||
86 | if (config->output != RING_BUFFER_MMAP) | |
87 | return -EINVAL; | |
88 | ||
f3bc08c5 MD |
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 | ||
d83004aa JD |
103 | int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma, |
104 | struct lib_ring_buffer *buf) | |
105 | { | |
106 | return lib_ring_buffer_mmap_buf(buf, vma); | |
107 | } | |
108 | EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap); | |
109 | ||
f3bc08c5 | 110 | /** |
d83004aa | 111 | * vfs_lib_ring_buffer_mmap - mmap file op |
f3bc08c5 MD |
112 | * @filp: the file |
113 | * @vma: the vma describing what to map | |
114 | * | |
115 | * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space. | |
116 | */ | |
d83004aa | 117 | int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma) |
f3bc08c5 MD |
118 | { |
119 | struct lib_ring_buffer *buf = filp->private_data; | |
d83004aa | 120 | return lib_ring_buffer_mmap(filp, vma, buf); |
f3bc08c5 | 121 | } |
d83004aa | 122 | EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap); |