1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2004 Suleiman Souhlal 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/param.h> 30 31 #include <stdarg.h> 32 #include <stdlib.h> 33 #include <unistd.h> 34 #include <stdio.h> 35 #include <ucontext.h> 36 37 __weak_reference(__makecontext, makecontext); 38 39 void _ctx_done(ucontext_t *ucp); 40 void _ctx_start(void); 41 42 void 43 _ctx_done(ucontext_t *ucp) 44 { 45 if (ucp->uc_link == NULL) 46 exit(0); 47 else { 48 /* invalidate context */ 49 ucp->uc_mcontext.mc_len = 0; 50 51 setcontext((const ucontext_t *)ucp->uc_link); 52 53 abort(); /* should never return from above call */ 54 } 55 } 56 57 void 58 __makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...) 59 { 60 mcontext_t *mc; 61 char *sp; 62 va_list ap; 63 int i, regargs, stackargs; 64 65 /* Sanity checks */ 66 if ((ucp == NULL) || (argc < 0) 67 || (ucp->uc_stack.ss_sp == NULL) 68 || (ucp->uc_stack.ss_size < MINSIGSTKSZ)) { 69 /* invalidate context */ 70 ucp->uc_mcontext.mc_len = 0; 71 return; 72 } 73 74 /* 75 * The stack must have space for the frame pointer, saved 76 * link register, overflow arguments, and be 16-byte 77 * aligned. 78 */ 79 stackargs = (argc > 8) ? argc - 8 : 0; 80 sp = (char *) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size 81 - sizeof(uint32_t)*(stackargs + 2); 82 sp = (char *)((uint32_t)sp & ~0x1f); 83 84 mc = &ucp->uc_mcontext; 85 86 /* 87 * Up to 8 register args. Assumes all args are 32-bit and 88 * integer only. Not sure how to cater for floating point, 89 * although 64-bit args will work if aligned correctly 90 * in the arg list. 91 */ 92 regargs = (argc > 8) ? 8 : argc; 93 va_start(ap, argc); 94 for (i = 0; i < regargs; i++) 95 mc->mc_gpr[3 + i] = va_arg(ap, uint32_t); 96 97 /* 98 * Overflow args go onto the stack 99 */ 100 if (argc > 8) { 101 uint32_t *argp; 102 103 /* Skip past frame pointer and saved LR */ 104 argp = (uint32_t *)sp + 2; 105 106 for (i = 0; i < stackargs; i++) 107 *argp++ = va_arg(ap, uint32_t); 108 } 109 va_end(ap); 110 111 /* 112 * Use caller-saved regs 14/15 to hold params that _ctx_start 113 * will use to invoke the user-supplied func 114 */ 115 mc->mc_srr0 = (uint32_t) _ctx_start; 116 mc->mc_gpr[1] = (uint32_t) sp; /* new stack pointer */ 117 mc->mc_gpr[14] = (uint32_t) start; /* r14 <- start */ 118 mc->mc_gpr[15] = (uint32_t) ucp; /* r15 <- ucp */ 119 } 120