Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/mips/mips/stack_machdep.c
Version:
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2005 Antoine Brodin 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/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/lock.h> 35 #include <sys/mutex.h> 36 #include <sys/proc.h> 37 #include <sys/stack.h> 38 39 #include <machine/mips_opcode.h> 40 41 #include <machine/pcb.h> 42 #include <machine/regnum.h> 43 44 #define VALID_PC(addr) ((addr) >= (uintptr_t)btext && (addr) % 4 == 0) 45 46 static void 47 stack_capture(struct stack *st, struct thread *td, uintptr_t pc, uintptr_t sp) 48 { 49 u_register_t ra; 50 uintptr_t i, ra_addr; 51 int ra_stack_pos, stacksize; 52 InstFmt insn; 53 54 stack_zero(st); 55 56 for (;;) { 57 if (!VALID_PC(pc)) 58 break; 59 60 /* 61 * Walk backward from the PC looking for the function 62 * start. Assume a subtraction from SP is the start 63 * of a function. Hope that we find the store of RA 64 * into the stack frame along the way and save the 65 * offset of the saved RA relative to SP. 66 */ 67 ra_stack_pos = -1; 68 stacksize = 0; 69 for (i = pc; VALID_PC(i); i -= sizeof(insn)) { 70 bcopy((void *)i, &insn, sizeof(insn)); 71 switch (insn.IType.op) { 72 case OP_ADDI: 73 case OP_ADDIU: 74 case OP_DADDI: 75 case OP_DADDIU: 76 if (insn.IType.rs != SP || insn.IType.rt != SP) 77 break; 78 79 /* 80 * Ignore stack fixups in "early" 81 * returns in a function, or if the 82 * call was from an unlikely branch 83 * moved after the end of the normal 84 * return. 85 */ 86 if ((short)insn.IType.imm > 0) 87 break; 88 89 stacksize = -(short)insn.IType.imm; 90 break; 91 92 case OP_SW: 93 case OP_SD: 94 if (insn.IType.rs != SP || insn.IType.rt != RA) 95 break; 96 ra_stack_pos = (short)insn.IType.imm; 97 break; 98 default: 99 break; 100 } 101 102 if (stacksize != 0) 103 break; 104 } 105 106 if (stack_put(st, pc) == -1) 107 break; 108 109 if (ra_stack_pos == -1) 110 break; 111 112 /* 113 * Walk forward from the PC to find the function end 114 * (jr RA). If eret is hit instead, stop unwinding. 115 */ 116 ra_addr = sp + ra_stack_pos; 117 ra = 0; 118 for (i = pc; VALID_PC(i); i += sizeof(insn)) { 119 bcopy((void *)i, &insn, sizeof(insn)); 120 121 switch (insn.IType.op) { 122 case OP_SPECIAL: 123 if (insn.RType.func == OP_JR) { 124 if (insn.RType.rs != RA) 125 break; 126 if (!kstack_contains(td, ra_addr, 127 sizeof(ra))) 128 goto done; 129 ra = *(u_register_t *)ra_addr; 130 if (ra == 0) 131 goto done; 132 ra -= 8; 133 } 134 break; 135 default: 136 break; 137 } 138 139 /* eret */ 140 if (insn.word == 0x42000018) 141 goto done; 142 143 if (ra != 0) 144 break; 145 } 146 147 if (pc == ra && stacksize == 0) 148 break; 149 150 sp += stacksize; 151 pc = ra; 152 } 153 done: 154 return; 155 } 156 157 int 158 stack_save_td(struct stack *st, struct thread *td) 159 { 160 uintptr_t pc, sp; 161 162 THREAD_LOCK_ASSERT(td, MA_OWNED); 163 KASSERT(!TD_IS_SWAPPED(td), 164 ("stack_save_td: thread %p is swapped", td)); 165 166 if (TD_IS_RUNNING(td)) 167 return (EOPNOTSUPP); 168 169 pc = td->td_pcb->pcb_context[PCB_REG_RA]; 170 sp = td->td_pcb->pcb_context[PCB_REG_SP]; 171 stack_capture(st, td, pc, sp); 172 return (0); 173 } 174 175 void 176 stack_save(struct stack *st) 177 { 178 uintptr_t pc, sp; 179 180 pc = (uintptr_t)&&here; 181 sp = (uintptr_t)__builtin_frame_address(0); 182 here: 183 stack_capture(st, curthread, pc, sp); 184 }
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