1 | /* |
2 | * QEMU access to the auxiliary vector |
3 | * |
4 | * Copyright (C) 2013 Red Hat, Inc |
5 | * |
6 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
7 | * of this software and associated documentation files (the "Software"), to deal |
8 | * in the Software without restriction, including without limitation the rights |
9 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
10 | * copies of the Software, and to permit persons to whom the Software is |
11 | * furnished to do so, subject to the following conditions: |
12 | * |
13 | * The above copyright notice and this permission notice shall be included in |
14 | * all copies or substantial portions of the Software. |
15 | * |
16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
21 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
22 | * THE SOFTWARE. |
23 | */ |
24 | |
25 | #include "qemu/osdep.h" |
26 | |
27 | #ifdef CONFIG_GETAUXVAL |
28 | /* Don't inline this in qemu/osdep.h, because pulling in <sys/auxv.h> for |
29 | the system declaration of getauxval pulls in the system <elf.h>, which |
30 | conflicts with qemu's version. */ |
31 | |
32 | #include <sys/auxv.h> |
33 | |
34 | unsigned long qemu_getauxval(unsigned long key) |
35 | { |
36 | return getauxval(key); |
37 | } |
38 | #elif defined(__linux__) |
39 | #include "elf.h" |
40 | |
41 | /* Our elf.h doesn't contain Elf32_auxv_t and Elf64_auxv_t, which is ok because |
42 | that just makes it easier to define it properly for the host here. */ |
43 | typedef struct { |
44 | unsigned long a_type; |
45 | unsigned long a_val; |
46 | } ElfW_auxv_t; |
47 | |
48 | static const ElfW_auxv_t *auxv; |
49 | |
50 | static const ElfW_auxv_t *qemu_init_auxval(void) |
51 | { |
52 | ElfW_auxv_t *a; |
53 | ssize_t size = 512, r, ofs; |
54 | int fd; |
55 | |
56 | /* Allocate some initial storage. Make sure the first entry is set |
57 | to end-of-list, so that we've got a valid list in case of error. */ |
58 | auxv = a = g_malloc(size); |
59 | a[0].a_type = 0; |
60 | a[0].a_val = 0; |
61 | |
62 | fd = open("/proc/self/auxv" , O_RDONLY); |
63 | if (fd < 0) { |
64 | return a; |
65 | } |
66 | |
67 | /* Read the first SIZE bytes. Hopefully, this covers everything. */ |
68 | r = read(fd, a, size); |
69 | |
70 | if (r == size) { |
71 | /* Continue to expand until we do get a partial read. */ |
72 | do { |
73 | ofs = size; |
74 | size *= 2; |
75 | auxv = a = g_realloc(a, size); |
76 | r = read(fd, (char *)a + ofs, ofs); |
77 | } while (r == ofs); |
78 | } |
79 | |
80 | close(fd); |
81 | return a; |
82 | } |
83 | |
84 | unsigned long qemu_getauxval(unsigned long type) |
85 | { |
86 | const ElfW_auxv_t *a = auxv; |
87 | |
88 | if (unlikely(a == NULL)) { |
89 | a = qemu_init_auxval(); |
90 | } |
91 | |
92 | for (; a->a_type != 0; a++) { |
93 | if (a->a_type == type) { |
94 | return a->a_val; |
95 | } |
96 | } |
97 | |
98 | return 0; |
99 | } |
100 | |
101 | #else |
102 | |
103 | unsigned long qemu_getauxval(unsigned long type) |
104 | { |
105 | return 0; |
106 | } |
107 | |
108 | #endif |
109 | |