| 1 | /* Copyright (C) 1996-2024 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 <sysdep.h> |
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| 19 | |
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| 20 | /* |
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| 21 | * This is for COMPATIBILITY with Linux/x86 only. Linux/Alpha system |
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| 22 | * calls return an error indication in a3. This allows arbitrary 64bit |
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| 23 | * values to be returned in v0 (because negative values are not |
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| 24 | * mistaken as error numbers). However, C allows only one value to |
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| 25 | * be returned, so the interface below folds the error indication passed in |
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| 26 | * a3 back into v0: it sets v0 to -errno if an error occurs. Thus, |
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| 27 | * no negative 64bit numbers can be returned. To avoid this problem, |
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| 28 | * use assembly stubs wherever possible/convenient. |
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| 29 | * |
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| 30 | * Usage: |
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| 31 | * |
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| 32 | * long syscall(syscall_number, arg1, arg2, arg3, arg4, arg5, arg6) |
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| 33 | * |
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| 34 | * syscall_number = the index of the system call we're invoking |
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| 35 | * arg1-arg6 = up to 6 integer arguments to the system call |
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| 36 | * |
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| 37 | * We need to do some arg shifting: the kernel expects the |
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| 38 | * syscall number in v0 and the first six args in a0-a5. |
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| 39 | * |
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| 40 | */ |
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| 41 | |
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| 42 | |
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| 43 | LEAF(__syscall, 0) |
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| 44 | #ifdef PROF |
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| 45 | ldgp gp, 0(pv) |
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| 46 | .set noat |
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| 47 | lda AT, _mcount |
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| 48 | jsr AT, (AT), _mcount |
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| 49 | .set at |
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| 50 | .prologue 1 |
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| 51 | #else |
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| 52 | .prologue 0 |
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| 53 | #endif |
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| 54 | |
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| 55 | mov a0, v0 /* Syscall number -> v0 */ |
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| 56 | mov a1, a0 /* arg1-arg5 -> a0-a4 */ |
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| 57 | mov a2, a1 |
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| 58 | mov a3, a2 |
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| 59 | mov a4, a3 |
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| 60 | mov a5, a4 |
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| 61 | ldq a5,0(sp) /* arg6 -> a5 */ |
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| 62 | |
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| 63 | call_pal PAL_callsys /* Invoke system call */ |
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| 64 | bne a3, SYSCALL_ERROR_LABEL |
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| 65 | ret |
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| 66 | |
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| 67 | PSEUDO_END(__syscall) |
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| 68 | |
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| 69 | weak_alias (__syscall, syscall) |
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| 70 | |
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