1 | /* Copyright (C) 2017-2022 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library. If not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <assert.h> |
19 | #include <stdbool.h> |
20 | #include <stdlib.h> |
21 | #include <unistd.h> |
22 | |
23 | |
24 | static long int linux_sysconf (int name); |
25 | |
26 | /* Get the value of the system variable NAME. */ |
27 | long int |
28 | __sysconf (int name) |
29 | { |
30 | unsigned ctr; |
31 | |
32 | /* Unfortunately, the registers that contain the actual cache info |
33 | (CCSIDR_EL1, CLIDR_EL1, and CSSELR_EL1) are protected by the Linux |
34 | kernel (though they need not have been). However, CTR_EL0 contains |
35 | the *minimum* linesize in the entire cache hierarchy, and is |
36 | accessible to userland, for use in __aarch64_sync_cache_range, |
37 | and it is a reasonable assumption that the L1 cache will have that |
38 | minimum line size. */ |
39 | switch (name) |
40 | { |
41 | case _SC_LEVEL1_ICACHE_LINESIZE: |
42 | asm("mrs\t%0, ctr_el0" : "=r" (ctr)); |
43 | return 4 << (ctr & 0xf); |
44 | case _SC_LEVEL1_DCACHE_LINESIZE: |
45 | asm("mrs\t%0, ctr_el0" : "=r" (ctr)); |
46 | return 4 << ((ctr >> 16) & 0xf); |
47 | } |
48 | |
49 | return linux_sysconf (name); |
50 | } |
51 | |
52 | /* Now the generic Linux version. */ |
53 | #undef __sysconf |
54 | #define __sysconf static linux_sysconf |
55 | #include <sysdeps/unix/sysv/linux/sysconf.c> |
56 | |