| 1 | /* Copyright (C) 2017-2024 Free Software Foundation, Inc. |
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| 2 | This file is part of the GNU C Library. |
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| 3 | |
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| 4 | The GNU C Library is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU Lesser General Public |
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| 6 | License as published by the Free Software Foundation; either |
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| 7 | version 2.1 of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | The GNU C Library is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | Lesser General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with the GNU C Library. If not, see |
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| 16 | <https://www.gnu.org/licenses/>. */ |
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| 17 | |
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| 18 | #include <assert.h> |
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| 19 | #include <stdbool.h> |
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| 20 | #include <stdlib.h> |
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| 21 | #include <unistd.h> |
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| 22 | |
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| 23 | |
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| 24 | static long int linux_sysconf (int name); |
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| 25 | |
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| 26 | /* Get the value of the system variable NAME. */ |
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| 27 | long int |
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| 28 | __sysconf (int name) |
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| 29 | { |
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| 30 | unsigned ctr; |
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| 31 | |
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| 32 | /* Unfortunately, the registers that contain the actual cache info |
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| 33 | (CCSIDR_EL1, CLIDR_EL1, and CSSELR_EL1) are protected by the Linux |
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| 34 | kernel (though they need not have been). However, CTR_EL0 contains |
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| 35 | the *minimum* linesize in the entire cache hierarchy, and is |
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| 36 | accessible to userland, for use in __aarch64_sync_cache_range, |
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| 37 | and it is a reasonable assumption that the L1 cache will have that |
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| 38 | minimum line size. */ |
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| 39 | switch (name) |
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| 40 | { |
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| 41 | case _SC_LEVEL1_ICACHE_LINESIZE: |
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| 42 | asm("mrs\t%0, ctr_el0" : "=r" (ctr)); |
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| 43 | return 4 << (ctr & 0xf); |
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| 44 | case _SC_LEVEL1_DCACHE_LINESIZE: |
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| 45 | asm("mrs\t%0, ctr_el0" : "=r" (ctr)); |
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| 46 | return 4 << ((ctr >> 16) & 0xf); |
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| 47 | } |
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| 48 | |
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| 49 | return linux_sysconf (name); |
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| 50 | } |
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| 51 | |
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| 52 | /* Now the generic Linux version. */ |
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| 53 | #undef __sysconf |
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| 54 | #define __sysconf static linux_sysconf |
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| 55 | #include <sysdeps/unix/sysv/linux/sysconf.c> |
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| 56 | |
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