1/*-
2 * Copyright (c) 2005 Antoine Brodin
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <sys/types.h>
31#include <sys/systm.h>
32#include <sys/param.h>
33#include <sys/proc.h>
34#include <sys/stack.h>
35
36#include <machine/mips_opcode.h>
37
38#include <machine/param.h>
39#include <machine/pcb.h>
40#include <machine/regnum.h>
41
42static u_register_t
43stack_register_fetch(u_register_t sp, u_register_t stack_pos)
44{
45	u_register_t * stack =
46	    ((u_register_t *)(intptr_t)sp + (size_t)stack_pos/sizeof(u_register_t));
47
48	return *stack;
49}
50
51static void
52stack_capture(struct stack *st, u_register_t pc, u_register_t sp)
53{
54	u_register_t  ra = 0, i, stacksize;
55	short ra_stack_pos = 0;
56	InstFmt insn;
57
58	stack_zero(st);
59
60	for (;;) {
61		stacksize = 0;
62		if (pc <= (u_register_t)(intptr_t)btext)
63			break;
64		for (i = pc; i >= (u_register_t)(intptr_t)btext; i -= sizeof (insn)) {
65			bcopy((void *)(intptr_t)i, &insn, sizeof insn);
66			switch (insn.IType.op) {
67			case OP_ADDI:
68			case OP_ADDIU:
69			case OP_DADDI:
70			case OP_DADDIU:
71				if (insn.IType.rs != SP || insn.IType.rt != SP)
72					break;
73				stacksize = -(short)insn.IType.imm;
74				break;
75
76			case OP_SW:
77			case OP_SD:
78				if (insn.IType.rs != SP || insn.IType.rt != RA)
79					break;
80				ra_stack_pos = (short)insn.IType.imm;
81				break;
82			default:
83				break;
84			}
85
86			if (stacksize)
87				break;
88		}
89
90		if (stack_put(st, pc) == -1)
91			break;
92
93		for (i = pc; !ra; i += sizeof (insn)) {
94			bcopy((void *)(intptr_t)i, &insn, sizeof insn);
95
96			switch (insn.IType.op) {
97			case OP_SPECIAL:
98				if((insn.RType.func == OP_JR))
99				{
100					if (ra >= (u_register_t)(intptr_t)btext)
101						break;
102					if (insn.RType.rs != RA)
103						break;
104					ra = stack_register_fetch(sp,
105					    ra_stack_pos);
106					if (!ra)
107						goto done;
108					ra -= 8;
109				}
110				break;
111			default:
112				break;
113			}
114			/* eret */
115			if (insn.word == 0x42000018)
116				goto done;
117		}
118
119		if (pc == ra && stacksize == 0)
120			break;
121
122		sp += stacksize;
123		pc = ra;
124		ra = 0;
125	}
126done:
127	return;
128}
129
130void
131stack_save_td(struct stack *st, struct thread *td)
132{
133	u_register_t pc, sp;
134
135	if (TD_IS_SWAPPED(td))
136		panic("stack_save_td: swapped");
137	if (TD_IS_RUNNING(td))
138		panic("stack_save_td: running");
139
140	pc = td->td_pcb->pcb_regs.pc;
141	sp = td->td_pcb->pcb_regs.sp;
142	stack_capture(st, pc, sp);
143}
144
145void
146stack_save(struct stack *st)
147{
148	u_register_t pc, sp;
149
150	if (curthread == NULL)
151		panic("stack_save: curthread == NULL");
152
153	pc = curthread->td_pcb->pcb_regs.pc;
154	sp = curthread->td_pcb->pcb_regs.sp;
155	stack_capture(st, pc, sp);
156}
157