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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 | */ | |
2ca0c84f MJ |
23 | #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0)) |
24 | static vm_fault_t lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) | |
25 | #else | |
52a391bd | 26 | static int lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) |
2ca0c84f | 27 | #endif |
f3bc08c5 MD |
28 | { |
29 | struct lib_ring_buffer *buf = vma->vm_private_data; | |
30 | struct channel *chan = buf->backend.chan; | |
5a8fd222 | 31 | const struct lib_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 | 32 | pgoff_t pgoff = vmf->pgoff; |
0112cb7b | 33 | unsigned long *pfnp; |
f3bc08c5 MD |
34 | void **virt; |
35 | unsigned long offset, sb_bindex; | |
36 | ||
f3bc08c5 MD |
37 | /* |
38 | * Verify that faults are only done on the range of pages owned by the | |
39 | * reader. | |
40 | */ | |
41 | offset = pgoff << PAGE_SHIFT; | |
42 | sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id); | |
43 | if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset | |
44 | && offset < buf->backend.array[sb_bindex]->mmap_offset + | |
45 | buf->backend.chan->backend.subbuf_size)) | |
46 | return VM_FAULT_SIGBUS; | |
47 | /* | |
0112cb7b MD |
48 | * ring_buffer_read_get_pfn() gets the page frame number for the |
49 | * current reader's pages. | |
f3bc08c5 | 50 | */ |
0112cb7b MD |
51 | pfnp = lib_ring_buffer_read_get_pfn(&buf->backend, offset, &virt); |
52 | if (!*pfnp) | |
f3bc08c5 | 53 | return VM_FAULT_SIGBUS; |
0112cb7b MD |
54 | get_page(pfn_to_page(*pfnp)); |
55 | vmf->page = pfn_to_page(*pfnp); | |
f3bc08c5 MD |
56 | |
57 | return 0; | |
58 | } | |
59 | ||
2ca0c84f MJ |
60 | #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0)) |
61 | static vm_fault_t lib_ring_buffer_fault(struct vm_fault *vmf) | |
62 | { | |
63 | struct vm_area_struct *vma = vmf->vma; | |
64 | return lib_ring_buffer_fault_compat(vma, vmf); | |
65 | } | |
66 | #elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) | |
52a391bd FD |
67 | static int lib_ring_buffer_fault(struct vm_fault *vmf) |
68 | { | |
69 | struct vm_area_struct *vma = vmf->vma; | |
70 | return lib_ring_buffer_fault_compat(vma, vmf); | |
71 | } | |
72 | #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */ | |
73 | static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
74 | { | |
75 | return lib_ring_buffer_fault_compat(vma, vmf); | |
76 | } | |
77 | #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */ | |
78 | ||
f3bc08c5 MD |
79 | /* |
80 | * vm_ops for ring buffer file mappings. | |
81 | */ | |
82 | static const struct vm_operations_struct lib_ring_buffer_mmap_ops = { | |
83 | .fault = lib_ring_buffer_fault, | |
84 | }; | |
85 | ||
86 | /** | |
87 | * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space | |
88 | * @buf: ring buffer to map | |
89 | * @vma: vm_area_struct describing memory to be mapped | |
90 | * | |
91 | * Returns 0 if ok, negative on error | |
92 | * | |
93 | * Caller should already have grabbed mmap_sem. | |
94 | */ | |
95 | static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf, | |
96 | struct vm_area_struct *vma) | |
97 | { | |
98 | unsigned long length = vma->vm_end - vma->vm_start; | |
99 | struct channel *chan = buf->backend.chan; | |
5a8fd222 | 100 | const struct lib_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 MD |
101 | unsigned long mmap_buf_len; |
102 | ||
103 | if (config->output != RING_BUFFER_MMAP) | |
104 | return -EINVAL; | |
105 | ||
f3bc08c5 MD |
106 | mmap_buf_len = chan->backend.buf_size; |
107 | if (chan->backend.extra_reader_sb) | |
108 | mmap_buf_len += chan->backend.subbuf_size; | |
109 | ||
110 | if (length != mmap_buf_len) | |
111 | return -EINVAL; | |
112 | ||
113 | vma->vm_ops = &lib_ring_buffer_mmap_ops; | |
114 | vma->vm_flags |= VM_DONTEXPAND; | |
115 | vma->vm_private_data = buf; | |
116 | ||
117 | return 0; | |
118 | } | |
119 | ||
d83004aa JD |
120 | int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma, |
121 | struct lib_ring_buffer *buf) | |
122 | { | |
123 | return lib_ring_buffer_mmap_buf(buf, vma); | |
124 | } | |
125 | EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap); | |
126 | ||
f3bc08c5 | 127 | /** |
d83004aa | 128 | * vfs_lib_ring_buffer_mmap - mmap file op |
f3bc08c5 MD |
129 | * @filp: the file |
130 | * @vma: the vma describing what to map | |
131 | * | |
132 | * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space. | |
133 | */ | |
d83004aa | 134 | int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma) |
f3bc08c5 MD |
135 | { |
136 | struct lib_ring_buffer *buf = filp->private_data; | |
d83004aa | 137 | return lib_ring_buffer_mmap(filp, vma, buf); |
f3bc08c5 | 138 | } |
d83004aa | 139 | EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap); |