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1 | /* Create new context. |
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2 | Copyright (C) 2022-2024 Free Software Foundation, Inc. |
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3 | |
| 4 | This file is part of the GNU C Library. |
| 5 | |
| 6 | The GNU C Library is free software; you can redistribute it and/or |
| 7 | modify it under the terms of the GNU Lesser General Public |
| 8 | License as published by the Free Software Foundation; either |
| 9 | version 2.1 of the License, or (at your option) any later version. |
| 10 | |
| 11 | The GNU C Library is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | Lesser General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU Lesser General Public |
| 17 | License along with the GNU C Library. If not, see |
| 18 | <https://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include <sysdep.h> |
| 21 | #include <sys/asm.h> |
| 22 | #include <sys/ucontext.h> |
| 23 | #include <stdarg.h> |
| 24 | #include <assert.h> |
| 25 | |
| 26 | void |
| 27 | __makecontext (ucontext_t *ucp, void (*func) (void), int argc, long int a0, |
| 28 | long int a1, long int a2, long int a3, long int a4, ...) |
| 29 | { |
| 30 | extern void __start_context (void) attribute_hidden; |
| 31 | unsigned long int *sp; |
| 32 | |
| 33 | _Static_assert(LARCH_REG_NARGS == 8, |
| 34 | "__makecontext assumes 8 argument registers"); |
| 35 | |
| 36 | /* Set up the stack. */ |
| 37 | sp = (unsigned long int *) |
| 38 | (((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ALMASK); |
| 39 | |
| 40 | /* Set up the register context. |
| 41 | ra = s0 = 0, terminating the stack for backtracing purposes. |
| 42 | s1 = the function we must call. |
| 43 | s2 = the subsequent context to run. */ |
| 44 | ucp->uc_mcontext.__gregs[LARCH_REG_RA] = (uintptr_t) 0; |
| 45 | ucp->uc_mcontext.__gregs[LARCH_REG_S0] = (uintptr_t) 0; |
| 46 | ucp->uc_mcontext.__gregs[LARCH_REG_S1] = (uintptr_t) func; |
| 47 | ucp->uc_mcontext.__gregs[LARCH_REG_S2] = (uintptr_t) ucp->uc_link; |
| 48 | ucp->uc_mcontext.__gregs[LARCH_REG_SP] = (uintptr_t) sp; |
| 49 | ucp->uc_mcontext.__pc = (uintptr_t) &__start_context; |
| 50 | |
| 51 | /* Put args in a0-a7, then put any remaining args on the stack. */ |
| 52 | ucp->uc_mcontext.__gregs[LARCH_REG_A0 + 0] = (uintptr_t) a0; |
| 53 | ucp->uc_mcontext.__gregs[LARCH_REG_A0 + 1] = (uintptr_t) a1; |
| 54 | ucp->uc_mcontext.__gregs[LARCH_REG_A0 + 2] = (uintptr_t) a2; |
| 55 | ucp->uc_mcontext.__gregs[LARCH_REG_A0 + 3] = (uintptr_t) a3; |
| 56 | ucp->uc_mcontext.__gregs[LARCH_REG_A0 + 4] = (uintptr_t) a4; |
| 57 | |
| 58 | if (__glibc_unlikely (argc > 5)) |
| 59 | { |
| 60 | va_list vl; |
| 61 | va_start (vl, a4); |
| 62 | |
| 63 | long int reg_args = argc < LARCH_REG_NARGS ? argc : LARCH_REG_NARGS; |
| 64 | for (long int i = 5; i < reg_args; i++) |
| 65 | ucp->uc_mcontext.__gregs[LARCH_REG_A0 + i] = va_arg (vl, unsigned long int); |
| 66 | |
| 67 | long int stack_args = argc - reg_args; |
| 68 | if (stack_args > 0) |
| 69 | { |
| 70 | sp = (unsigned long int *) |
| 71 | (((uintptr_t) sp - stack_args * sizeof (long int)) & ALMASK); |
| 72 | ucp->uc_mcontext.__gregs[LARCH_REG_SP] = (uintptr_t) sp; |
| 73 | for (long int i = 0; i < stack_args; i++) |
| 74 | sp[i] = va_arg (vl, unsigned long int); |
| 75 | } |
| 76 | |
| 77 | va_end (vl); |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | weak_alias (__makecontext, makecontext) |
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