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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 | ||
24591303 MD |
16 | #include <ringbuffer/backend.h> |
17 | #include <ringbuffer/frontend.h> | |
18 | #include <ringbuffer/vfs.h> | |
f3bc08c5 | 19 | |
23d91ab1 MJ |
20 | #include <wrapper/mm.h> |
21 | ||
f3bc08c5 MD |
22 | /* |
23 | * fault() vm_op implementation for ring buffer file mapping. | |
24 | */ | |
05355f0b MJ |
25 | #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,1,0) || \ |
26 | LTTNG_RHEL_KERNEL_RANGE(4,18,0,193,0,0, 4,19,0,0,0,0)) | |
2ca0c84f MJ |
27 | static vm_fault_t lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) |
28 | #else | |
52a391bd | 29 | static int lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) |
2ca0c84f | 30 | #endif |
f3bc08c5 | 31 | { |
e20c0fec | 32 | struct lttng_kernel_ring_buffer *buf = vma->vm_private_data; |
860c213b | 33 | struct lttng_kernel_ring_buffer_channel *chan = buf->backend.chan; |
e20c0fec | 34 | const struct lttng_kernel_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 | 35 | pgoff_t pgoff = vmf->pgoff; |
0112cb7b | 36 | unsigned long *pfnp; |
f3bc08c5 MD |
37 | void **virt; |
38 | unsigned long offset, sb_bindex; | |
39 | ||
f3bc08c5 MD |
40 | /* |
41 | * Verify that faults are only done on the range of pages owned by the | |
42 | * reader. | |
43 | */ | |
44 | offset = pgoff << PAGE_SHIFT; | |
45 | sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id); | |
46 | if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset | |
47 | && offset < buf->backend.array[sb_bindex]->mmap_offset + | |
48 | buf->backend.chan->backend.subbuf_size)) | |
49 | return VM_FAULT_SIGBUS; | |
50 | /* | |
0112cb7b MD |
51 | * ring_buffer_read_get_pfn() gets the page frame number for the |
52 | * current reader's pages. | |
f3bc08c5 | 53 | */ |
0112cb7b MD |
54 | pfnp = lib_ring_buffer_read_get_pfn(&buf->backend, offset, &virt); |
55 | if (!*pfnp) | |
f3bc08c5 | 56 | return VM_FAULT_SIGBUS; |
0112cb7b MD |
57 | get_page(pfn_to_page(*pfnp)); |
58 | vmf->page = pfn_to_page(*pfnp); | |
f3bc08c5 MD |
59 | |
60 | return 0; | |
61 | } | |
62 | ||
05355f0b MJ |
63 | #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,1,0) || \ |
64 | LTTNG_RHEL_KERNEL_RANGE(4,18,0,193,0,0, 4,19,0,0,0,0)) | |
2ca0c84f MJ |
65 | static vm_fault_t lib_ring_buffer_fault(struct vm_fault *vmf) |
66 | { | |
67 | struct vm_area_struct *vma = vmf->vma; | |
68 | return lib_ring_buffer_fault_compat(vma, vmf); | |
69 | } | |
5f4c791e | 70 | #elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,11,0)) |
52a391bd FD |
71 | static int lib_ring_buffer_fault(struct vm_fault *vmf) |
72 | { | |
73 | struct vm_area_struct *vma = vmf->vma; | |
74 | return lib_ring_buffer_fault_compat(vma, vmf); | |
75 | } | |
5f4c791e | 76 | #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,11,0)) */ |
52a391bd FD |
77 | static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
78 | { | |
79 | return lib_ring_buffer_fault_compat(vma, vmf); | |
80 | } | |
5f4c791e | 81 | #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,11,0)) */ |
52a391bd | 82 | |
f3bc08c5 MD |
83 | /* |
84 | * vm_ops for ring buffer file mappings. | |
85 | */ | |
86 | static const struct vm_operations_struct lib_ring_buffer_mmap_ops = { | |
87 | .fault = lib_ring_buffer_fault, | |
88 | }; | |
89 | ||
90 | /** | |
91 | * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space | |
92 | * @buf: ring buffer to map | |
93 | * @vma: vm_area_struct describing memory to be mapped | |
94 | * | |
95 | * Returns 0 if ok, negative on error | |
96 | * | |
97 | * Caller should already have grabbed mmap_sem. | |
98 | */ | |
e20c0fec | 99 | static int lib_ring_buffer_mmap_buf(struct lttng_kernel_ring_buffer *buf, |
f3bc08c5 MD |
100 | struct vm_area_struct *vma) |
101 | { | |
102 | unsigned long length = vma->vm_end - vma->vm_start; | |
860c213b | 103 | struct lttng_kernel_ring_buffer_channel *chan = buf->backend.chan; |
e20c0fec | 104 | const struct lttng_kernel_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 MD |
105 | unsigned long mmap_buf_len; |
106 | ||
107 | if (config->output != RING_BUFFER_MMAP) | |
108 | return -EINVAL; | |
109 | ||
f3bc08c5 MD |
110 | mmap_buf_len = chan->backend.buf_size; |
111 | if (chan->backend.extra_reader_sb) | |
112 | mmap_buf_len += chan->backend.subbuf_size; | |
113 | ||
114 | if (length != mmap_buf_len) | |
115 | return -EINVAL; | |
116 | ||
117 | vma->vm_ops = &lib_ring_buffer_mmap_ops; | |
23d91ab1 | 118 | wrapper_vm_flags_set(vma, VM_DONTEXPAND); |
f3bc08c5 MD |
119 | vma->vm_private_data = buf; |
120 | ||
121 | return 0; | |
122 | } | |
123 | ||
d83004aa | 124 | int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma, |
e20c0fec | 125 | struct lttng_kernel_ring_buffer *buf) |
d83004aa JD |
126 | { |
127 | return lib_ring_buffer_mmap_buf(buf, vma); | |
128 | } | |
129 | EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap); | |
130 | ||
f3bc08c5 | 131 | /** |
d83004aa | 132 | * vfs_lib_ring_buffer_mmap - mmap file op |
f3bc08c5 MD |
133 | * @filp: the file |
134 | * @vma: the vma describing what to map | |
135 | * | |
136 | * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space. | |
137 | */ | |
d83004aa | 138 | int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma) |
f3bc08c5 | 139 | { |
e20c0fec | 140 | struct lttng_kernel_ring_buffer *buf = filp->private_data; |
d83004aa | 141 | return lib_ring_buffer_mmap(filp, vma, buf); |
f3bc08c5 | 142 | } |
d83004aa | 143 | EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap); |