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9f36eaed MJ |
1 | /* SPDX-License-Identifier: GPL-2.0 |
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 | * |
9f36eaed | 9 | * Re-using code from kernel/relay.c, hence the GPL-2.0 license for this |
886d51a3 | 10 | * file. |
f3bc08c5 MD |
11 | */ |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/mm.h> | |
15 | ||
c075712b MD |
16 | #include <wrapper/ringbuffer/backend.h> |
17 | #include <wrapper/ringbuffer/frontend.h> | |
18 | #include <wrapper/ringbuffer/vfs.h> | |
f3bc08c5 MD |
19 | |
20 | /* | |
21 | * fault() vm_op implementation for ring buffer file mapping. | |
22 | */ | |
52a391bd | 23 | static int 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 | ||
52a391bd FD |
56 | #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) |
57 | static int lib_ring_buffer_fault(struct vm_fault *vmf) | |
58 | { | |
59 | struct vm_area_struct *vma = vmf->vma; | |
60 | return lib_ring_buffer_fault_compat(vma, vmf); | |
61 | } | |
62 | #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */ | |
63 | static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
64 | { | |
65 | return lib_ring_buffer_fault_compat(vma, vmf); | |
66 | } | |
67 | #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */ | |
68 | ||
f3bc08c5 MD |
69 | /* |
70 | * vm_ops for ring buffer file mappings. | |
71 | */ | |
72 | static const struct vm_operations_struct lib_ring_buffer_mmap_ops = { | |
73 | .fault = lib_ring_buffer_fault, | |
74 | }; | |
75 | ||
76 | /** | |
77 | * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space | |
78 | * @buf: ring buffer to map | |
79 | * @vma: vm_area_struct describing memory to be mapped | |
80 | * | |
81 | * Returns 0 if ok, negative on error | |
82 | * | |
83 | * Caller should already have grabbed mmap_sem. | |
84 | */ | |
85 | static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf, | |
86 | struct vm_area_struct *vma) | |
87 | { | |
88 | unsigned long length = vma->vm_end - vma->vm_start; | |
89 | struct channel *chan = buf->backend.chan; | |
5a8fd222 | 90 | const struct lib_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 MD |
91 | unsigned long mmap_buf_len; |
92 | ||
93 | if (config->output != RING_BUFFER_MMAP) | |
94 | return -EINVAL; | |
95 | ||
f3bc08c5 MD |
96 | mmap_buf_len = chan->backend.buf_size; |
97 | if (chan->backend.extra_reader_sb) | |
98 | mmap_buf_len += chan->backend.subbuf_size; | |
99 | ||
100 | if (length != mmap_buf_len) | |
101 | return -EINVAL; | |
102 | ||
103 | vma->vm_ops = &lib_ring_buffer_mmap_ops; | |
104 | vma->vm_flags |= VM_DONTEXPAND; | |
105 | vma->vm_private_data = buf; | |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
d83004aa JD |
110 | int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma, |
111 | struct lib_ring_buffer *buf) | |
112 | { | |
113 | return lib_ring_buffer_mmap_buf(buf, vma); | |
114 | } | |
115 | EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap); | |
116 | ||
f3bc08c5 | 117 | /** |
d83004aa | 118 | * vfs_lib_ring_buffer_mmap - mmap file op |
f3bc08c5 MD |
119 | * @filp: the file |
120 | * @vma: the vma describing what to map | |
121 | * | |
122 | * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space. | |
123 | */ | |
d83004aa | 124 | int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma) |
f3bc08c5 MD |
125 | { |
126 | struct lib_ring_buffer *buf = filp->private_data; | |
d83004aa | 127 | return lib_ring_buffer_mmap(filp, vma, buf); |
f3bc08c5 | 128 | } |
d83004aa | 129 | EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap); |