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1da177e4 LT |
1 | /* |
2 | * This file is subject to the terms and conditions of the GNU General Public | |
3 | * License. See the file "COPYING" in the main directory of this archive | |
4 | * for more details. | |
5 | * | |
6 | * Copyright (C) 1996, 97, 2000, 2001 by Ralf Baechle | |
7 | * Copyright (C) 2001 MIPS Technologies, Inc. | |
8 | */ | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/signal.h> | |
12 | #include <asm/branch.h> | |
13 | #include <asm/cpu.h> | |
14 | #include <asm/cpu-features.h> | |
1d74f6bc | 15 | #include <asm/fpu.h> |
1da177e4 LT |
16 | #include <asm/inst.h> |
17 | #include <asm/ptrace.h> | |
18 | #include <asm/uaccess.h> | |
19 | ||
20 | /* | |
21 | * Compute the return address and do emulate branch simulation, if required. | |
22 | */ | |
23 | int __compute_return_epc(struct pt_regs *regs) | |
24 | { | |
5e0373b8 AN |
25 | unsigned int __user *addr; |
26 | unsigned int bit, fcr31, dspcontrol; | |
1da177e4 LT |
27 | long epc; |
28 | union mips_instruction insn; | |
29 | ||
30 | epc = regs->cp0_epc; | |
31 | if (epc & 3) | |
32 | goto unaligned; | |
33 | ||
34 | /* | |
35 | * Read the instruction | |
36 | */ | |
5e0373b8 | 37 | addr = (unsigned int __user *) epc; |
1da177e4 LT |
38 | if (__get_user(insn.word, addr)) { |
39 | force_sig(SIGSEGV, current); | |
40 | return -EFAULT; | |
41 | } | |
42 | ||
43 | regs->regs[0] = 0; | |
44 | switch (insn.i_format.opcode) { | |
45 | /* | |
46 | * jr and jalr are in r_format format. | |
47 | */ | |
48 | case spec_op: | |
49 | switch (insn.r_format.func) { | |
50 | case jalr_op: | |
51 | regs->regs[insn.r_format.rd] = epc + 8; | |
52 | /* Fall through */ | |
53 | case jr_op: | |
54 | regs->cp0_epc = regs->regs[insn.r_format.rs]; | |
55 | break; | |
56 | } | |
57 | break; | |
58 | ||
59 | /* | |
60 | * This group contains: | |
61 | * bltz_op, bgez_op, bltzl_op, bgezl_op, | |
62 | * bltzal_op, bgezal_op, bltzall_op, bgezall_op. | |
63 | */ | |
64 | case bcond_op: | |
65 | switch (insn.i_format.rt) { | |
66 | case bltz_op: | |
67 | case bltzl_op: | |
68 | if ((long)regs->regs[insn.i_format.rs] < 0) | |
69 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
70 | else | |
71 | epc += 8; | |
72 | regs->cp0_epc = epc; | |
73 | break; | |
74 | ||
75 | case bgez_op: | |
76 | case bgezl_op: | |
77 | if ((long)regs->regs[insn.i_format.rs] >= 0) | |
78 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
79 | else | |
80 | epc += 8; | |
81 | regs->cp0_epc = epc; | |
82 | break; | |
83 | ||
84 | case bltzal_op: | |
85 | case bltzall_op: | |
86 | regs->regs[31] = epc + 8; | |
87 | if ((long)regs->regs[insn.i_format.rs] < 0) | |
88 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
89 | else | |
90 | epc += 8; | |
91 | regs->cp0_epc = epc; | |
92 | break; | |
93 | ||
94 | case bgezal_op: | |
95 | case bgezall_op: | |
96 | regs->regs[31] = epc + 8; | |
97 | if ((long)regs->regs[insn.i_format.rs] >= 0) | |
98 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
99 | else | |
100 | epc += 8; | |
101 | regs->cp0_epc = epc; | |
102 | break; | |
e50c0a8f RB |
103 | case bposge32_op: |
104 | if (!cpu_has_dsp) | |
105 | goto sigill; | |
106 | ||
107 | dspcontrol = rddsp(0x01); | |
108 | ||
109 | if (dspcontrol >= 32) { | |
110 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
111 | } else | |
112 | epc += 8; | |
113 | regs->cp0_epc = epc; | |
114 | break; | |
1da177e4 LT |
115 | } |
116 | break; | |
117 | ||
118 | /* | |
119 | * These are unconditional and in j_format. | |
120 | */ | |
121 | case jal_op: | |
122 | regs->regs[31] = regs->cp0_epc + 8; | |
123 | case j_op: | |
124 | epc += 4; | |
125 | epc >>= 28; | |
126 | epc <<= 28; | |
127 | epc |= (insn.j_format.target << 2); | |
128 | regs->cp0_epc = epc; | |
129 | break; | |
130 | ||
131 | /* | |
132 | * These are conditional and in i_format. | |
133 | */ | |
134 | case beq_op: | |
135 | case beql_op: | |
136 | if (regs->regs[insn.i_format.rs] == | |
137 | regs->regs[insn.i_format.rt]) | |
138 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
139 | else | |
140 | epc += 8; | |
141 | regs->cp0_epc = epc; | |
142 | break; | |
143 | ||
144 | case bne_op: | |
145 | case bnel_op: | |
146 | if (regs->regs[insn.i_format.rs] != | |
147 | regs->regs[insn.i_format.rt]) | |
148 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
149 | else | |
150 | epc += 8; | |
151 | regs->cp0_epc = epc; | |
152 | break; | |
153 | ||
154 | case blez_op: /* not really i_format */ | |
155 | case blezl_op: | |
156 | /* rt field assumed to be zero */ | |
157 | if ((long)regs->regs[insn.i_format.rs] <= 0) | |
158 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
159 | else | |
160 | epc += 8; | |
161 | regs->cp0_epc = epc; | |
162 | break; | |
163 | ||
164 | case bgtz_op: | |
165 | case bgtzl_op: | |
166 | /* rt field assumed to be zero */ | |
167 | if ((long)regs->regs[insn.i_format.rs] > 0) | |
168 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
169 | else | |
170 | epc += 8; | |
171 | regs->cp0_epc = epc; | |
172 | break; | |
173 | ||
174 | /* | |
175 | * And now the FPA/cp1 branch instructions. | |
176 | */ | |
177 | case cop1_op: | |
1d74f6bc RB |
178 | preempt_disable(); |
179 | if (is_fpu_owner()) | |
1da177e4 | 180 | asm volatile("cfc1\t%0,$31" : "=r" (fcr31)); |
1d74f6bc | 181 | else |
eae89076 | 182 | fcr31 = current->thread.fpu.fcr31; |
1d74f6bc RB |
183 | preempt_enable(); |
184 | ||
1da177e4 LT |
185 | bit = (insn.i_format.rt >> 2); |
186 | bit += (bit != 0); | |
187 | bit += 23; | |
ee1cca1b | 188 | switch (insn.i_format.rt & 3) { |
1da177e4 LT |
189 | case 0: /* bc1f */ |
190 | case 2: /* bc1fl */ | |
191 | if (~fcr31 & (1 << bit)) | |
192 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
193 | else | |
194 | epc += 8; | |
195 | regs->cp0_epc = epc; | |
196 | break; | |
197 | ||
198 | case 1: /* bc1t */ | |
199 | case 3: /* bc1tl */ | |
200 | if (fcr31 & (1 << bit)) | |
201 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
202 | else | |
203 | epc += 8; | |
204 | regs->cp0_epc = epc; | |
205 | break; | |
206 | } | |
207 | break; | |
208 | } | |
209 | ||
210 | return 0; | |
211 | ||
212 | unaligned: | |
213 | printk("%s: unaligned epc - sending SIGBUS.\n", current->comm); | |
214 | force_sig(SIGBUS, current); | |
215 | return -EFAULT; | |
e50c0a8f RB |
216 | |
217 | sigill: | |
218 | printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm); | |
219 | force_sig(SIGBUS, current); | |
220 | return -EFAULT; | |
1da177e4 | 221 | } |