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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> | |
d8d4e3ae | 12 | #include <linux/module.h> |
1da177e4 LT |
13 | #include <asm/branch.h> |
14 | #include <asm/cpu.h> | |
15 | #include <asm/cpu-features.h> | |
1d74f6bc | 16 | #include <asm/fpu.h> |
fb6883e5 | 17 | #include <asm/fpu_emulator.h> |
1da177e4 LT |
18 | #include <asm/inst.h> |
19 | #include <asm/ptrace.h> | |
20 | #include <asm/uaccess.h> | |
21 | ||
fb6883e5 | 22 | /* |
8508488f SH |
23 | * Calculate and return exception PC in case of branch delay slot |
24 | * for microMIPS and MIPS16e. It does not clear the ISA mode bit. | |
fb6883e5 LY |
25 | */ |
26 | int __isa_exception_epc(struct pt_regs *regs) | |
27 | { | |
fb6883e5 | 28 | unsigned short inst; |
8508488f | 29 | long epc = regs->cp0_epc; |
fb6883e5 LY |
30 | |
31 | /* Calculate exception PC in branch delay slot. */ | |
32 | if (__get_user(inst, (u16 __user *) msk_isa16_mode(epc))) { | |
33 | /* This should never happen because delay slot was checked. */ | |
34 | force_sig(SIGSEGV, current); | |
35 | return epc; | |
36 | } | |
8508488f SH |
37 | if (cpu_has_mips16) { |
38 | if (((union mips16e_instruction)inst).ri.opcode | |
39 | == MIPS16e_jal_op) | |
40 | epc += 4; | |
41 | else | |
42 | epc += 2; | |
43 | } else if (mm_insn_16bit(inst)) | |
fb6883e5 LY |
44 | epc += 2; |
45 | else | |
46 | epc += 4; | |
47 | ||
48 | return epc; | |
49 | } | |
50 | ||
51 | /* | |
52 | * Compute return address and emulate branch in microMIPS mode after an | |
53 | * exception only. It does not handle compact branches/jumps and cannot | |
54 | * be used in interrupt context. (Compact branches/jumps do not cause | |
55 | * exceptions.) | |
56 | */ | |
57 | int __microMIPS_compute_return_epc(struct pt_regs *regs) | |
58 | { | |
59 | u16 __user *pc16; | |
60 | u16 halfword; | |
61 | unsigned int word; | |
62 | unsigned long contpc; | |
63 | struct mm_decoded_insn mminsn = { 0 }; | |
64 | ||
65 | mminsn.micro_mips_mode = 1; | |
66 | ||
67 | /* This load never faults. */ | |
68 | pc16 = (unsigned short __user *)msk_isa16_mode(regs->cp0_epc); | |
69 | __get_user(halfword, pc16); | |
70 | pc16++; | |
71 | contpc = regs->cp0_epc + 2; | |
72 | word = ((unsigned int)halfword << 16); | |
73 | mminsn.pc_inc = 2; | |
74 | ||
75 | if (!mm_insn_16bit(halfword)) { | |
76 | __get_user(halfword, pc16); | |
77 | pc16++; | |
78 | contpc = regs->cp0_epc + 4; | |
79 | mminsn.pc_inc = 4; | |
80 | word |= halfword; | |
81 | } | |
82 | mminsn.insn = word; | |
83 | ||
84 | if (get_user(halfword, pc16)) | |
85 | goto sigsegv; | |
86 | mminsn.next_pc_inc = 2; | |
87 | word = ((unsigned int)halfword << 16); | |
88 | ||
89 | if (!mm_insn_16bit(halfword)) { | |
90 | pc16++; | |
91 | if (get_user(halfword, pc16)) | |
92 | goto sigsegv; | |
93 | mminsn.next_pc_inc = 4; | |
94 | word |= halfword; | |
95 | } | |
96 | mminsn.next_insn = word; | |
97 | ||
98 | mm_isBranchInstr(regs, mminsn, &contpc); | |
99 | ||
100 | regs->cp0_epc = contpc; | |
101 | ||
102 | return 0; | |
103 | ||
104 | sigsegv: | |
105 | force_sig(SIGSEGV, current); | |
106 | return -EFAULT; | |
107 | } | |
108 | ||
8508488f SH |
109 | /* |
110 | * Compute return address and emulate branch in MIPS16e mode after an | |
111 | * exception only. It does not handle compact branches/jumps and cannot | |
112 | * be used in interrupt context. (Compact branches/jumps do not cause | |
113 | * exceptions.) | |
114 | */ | |
115 | int __MIPS16e_compute_return_epc(struct pt_regs *regs) | |
116 | { | |
117 | u16 __user *addr; | |
118 | union mips16e_instruction inst; | |
119 | u16 inst2; | |
120 | u32 fullinst; | |
121 | long epc; | |
122 | ||
123 | epc = regs->cp0_epc; | |
124 | ||
125 | /* Read the instruction. */ | |
126 | addr = (u16 __user *)msk_isa16_mode(epc); | |
127 | if (__get_user(inst.full, addr)) { | |
128 | force_sig(SIGSEGV, current); | |
129 | return -EFAULT; | |
130 | } | |
131 | ||
132 | switch (inst.ri.opcode) { | |
133 | case MIPS16e_extend_op: | |
134 | regs->cp0_epc += 4; | |
135 | return 0; | |
136 | ||
137 | /* | |
138 | * JAL and JALX in MIPS16e mode | |
139 | */ | |
140 | case MIPS16e_jal_op: | |
141 | addr += 1; | |
142 | if (__get_user(inst2, addr)) { | |
143 | force_sig(SIGSEGV, current); | |
144 | return -EFAULT; | |
145 | } | |
146 | fullinst = ((unsigned)inst.full << 16) | inst2; | |
147 | regs->regs[31] = epc + 6; | |
148 | epc += 4; | |
149 | epc >>= 28; | |
150 | epc <<= 28; | |
151 | /* | |
152 | * JAL:5 X:1 TARGET[20-16]:5 TARGET[25:21]:5 TARGET[15:0]:16 | |
153 | * | |
154 | * ......TARGET[15:0].................TARGET[20:16]........... | |
155 | * ......TARGET[25:21] | |
156 | */ | |
157 | epc |= | |
158 | ((fullinst & 0xffff) << 2) | ((fullinst & 0x3e00000) >> 3) | | |
159 | ((fullinst & 0x1f0000) << 7); | |
160 | if (!inst.jal.x) | |
161 | set_isa16_mode(epc); /* Set ISA mode bit. */ | |
162 | regs->cp0_epc = epc; | |
163 | return 0; | |
164 | ||
165 | /* | |
166 | * J(AL)R(C) | |
167 | */ | |
168 | case MIPS16e_rr_op: | |
169 | if (inst.rr.func == MIPS16e_jr_func) { | |
170 | ||
171 | if (inst.rr.ra) | |
172 | regs->cp0_epc = regs->regs[31]; | |
173 | else | |
174 | regs->cp0_epc = | |
175 | regs->regs[reg16to32[inst.rr.rx]]; | |
176 | ||
177 | if (inst.rr.l) { | |
178 | if (inst.rr.nd) | |
179 | regs->regs[31] = epc + 2; | |
180 | else | |
181 | regs->regs[31] = epc + 4; | |
182 | } | |
183 | return 0; | |
184 | } | |
185 | break; | |
186 | } | |
187 | ||
188 | /* | |
189 | * All other cases have no branch delay slot and are 16-bits. | |
190 | * Branches do not cause an exception. | |
191 | */ | |
192 | regs->cp0_epc += 2; | |
193 | ||
194 | return 0; | |
195 | } | |
196 | ||
d8d4e3ae MS |
197 | /** |
198 | * __compute_return_epc_for_insn - Computes the return address and do emulate | |
199 | * branch simulation, if required. | |
200 | * | |
201 | * @regs: Pointer to pt_regs | |
202 | * @insn: branch instruction to decode | |
203 | * @returns: -EFAULT on error and forces SIGBUS, and on success | |
204 | * returns 0 or BRANCH_LIKELY_TAKEN as appropriate after | |
205 | * evaluating the branch. | |
1da177e4 | 206 | */ |
d8d4e3ae MS |
207 | int __compute_return_epc_for_insn(struct pt_regs *regs, |
208 | union mips_instruction insn) | |
1da177e4 | 209 | { |
5e0373b8 | 210 | unsigned int bit, fcr31, dspcontrol; |
d8d4e3ae MS |
211 | long epc = regs->cp0_epc; |
212 | int ret = 0; | |
1da177e4 | 213 | |
1da177e4 LT |
214 | switch (insn.i_format.opcode) { |
215 | /* | |
216 | * jr and jalr are in r_format format. | |
217 | */ | |
218 | case spec_op: | |
219 | switch (insn.r_format.func) { | |
220 | case jalr_op: | |
221 | regs->regs[insn.r_format.rd] = epc + 8; | |
222 | /* Fall through */ | |
223 | case jr_op: | |
224 | regs->cp0_epc = regs->regs[insn.r_format.rs]; | |
225 | break; | |
226 | } | |
227 | break; | |
228 | ||
229 | /* | |
230 | * This group contains: | |
231 | * bltz_op, bgez_op, bltzl_op, bgezl_op, | |
232 | * bltzal_op, bgezal_op, bltzall_op, bgezall_op. | |
233 | */ | |
234 | case bcond_op: | |
235 | switch (insn.i_format.rt) { | |
70342287 | 236 | case bltz_op: |
1da177e4 | 237 | case bltzl_op: |
d8d4e3ae | 238 | if ((long)regs->regs[insn.i_format.rs] < 0) { |
1da177e4 | 239 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
240 | if (insn.i_format.rt == bltzl_op) |
241 | ret = BRANCH_LIKELY_TAKEN; | |
242 | } else | |
1da177e4 LT |
243 | epc += 8; |
244 | regs->cp0_epc = epc; | |
245 | break; | |
246 | ||
247 | case bgez_op: | |
248 | case bgezl_op: | |
d8d4e3ae | 249 | if ((long)regs->regs[insn.i_format.rs] >= 0) { |
1da177e4 | 250 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
251 | if (insn.i_format.rt == bgezl_op) |
252 | ret = BRANCH_LIKELY_TAKEN; | |
253 | } else | |
1da177e4 LT |
254 | epc += 8; |
255 | regs->cp0_epc = epc; | |
256 | break; | |
257 | ||
258 | case bltzal_op: | |
259 | case bltzall_op: | |
260 | regs->regs[31] = epc + 8; | |
d8d4e3ae | 261 | if ((long)regs->regs[insn.i_format.rs] < 0) { |
1da177e4 | 262 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
263 | if (insn.i_format.rt == bltzall_op) |
264 | ret = BRANCH_LIKELY_TAKEN; | |
265 | } else | |
1da177e4 LT |
266 | epc += 8; |
267 | regs->cp0_epc = epc; | |
268 | break; | |
269 | ||
270 | case bgezal_op: | |
271 | case bgezall_op: | |
272 | regs->regs[31] = epc + 8; | |
d8d4e3ae | 273 | if ((long)regs->regs[insn.i_format.rs] >= 0) { |
1da177e4 | 274 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
275 | if (insn.i_format.rt == bgezall_op) |
276 | ret = BRANCH_LIKELY_TAKEN; | |
277 | } else | |
1da177e4 LT |
278 | epc += 8; |
279 | regs->cp0_epc = epc; | |
280 | break; | |
d8d4e3ae | 281 | |
e50c0a8f RB |
282 | case bposge32_op: |
283 | if (!cpu_has_dsp) | |
284 | goto sigill; | |
285 | ||
286 | dspcontrol = rddsp(0x01); | |
287 | ||
288 | if (dspcontrol >= 32) { | |
289 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
290 | } else | |
291 | epc += 8; | |
292 | regs->cp0_epc = epc; | |
293 | break; | |
1da177e4 LT |
294 | } |
295 | break; | |
296 | ||
297 | /* | |
298 | * These are unconditional and in j_format. | |
299 | */ | |
300 | case jal_op: | |
301 | regs->regs[31] = regs->cp0_epc + 8; | |
302 | case j_op: | |
303 | epc += 4; | |
304 | epc >>= 28; | |
305 | epc <<= 28; | |
306 | epc |= (insn.j_format.target << 2); | |
307 | regs->cp0_epc = epc; | |
fb6883e5 LY |
308 | if (insn.i_format.opcode == jalx_op) |
309 | set_isa16_mode(regs->cp0_epc); | |
1da177e4 LT |
310 | break; |
311 | ||
312 | /* | |
313 | * These are conditional and in i_format. | |
314 | */ | |
315 | case beq_op: | |
316 | case beql_op: | |
317 | if (regs->regs[insn.i_format.rs] == | |
d8d4e3ae | 318 | regs->regs[insn.i_format.rt]) { |
1da177e4 | 319 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
320 | if (insn.i_format.rt == beql_op) |
321 | ret = BRANCH_LIKELY_TAKEN; | |
322 | } else | |
1da177e4 LT |
323 | epc += 8; |
324 | regs->cp0_epc = epc; | |
325 | break; | |
326 | ||
327 | case bne_op: | |
328 | case bnel_op: | |
329 | if (regs->regs[insn.i_format.rs] != | |
d8d4e3ae | 330 | regs->regs[insn.i_format.rt]) { |
1da177e4 | 331 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
332 | if (insn.i_format.rt == bnel_op) |
333 | ret = BRANCH_LIKELY_TAKEN; | |
334 | } else | |
1da177e4 LT |
335 | epc += 8; |
336 | regs->cp0_epc = epc; | |
337 | break; | |
338 | ||
339 | case blez_op: /* not really i_format */ | |
340 | case blezl_op: | |
341 | /* rt field assumed to be zero */ | |
d8d4e3ae | 342 | if ((long)regs->regs[insn.i_format.rs] <= 0) { |
1da177e4 | 343 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
344 | if (insn.i_format.rt == bnel_op) |
345 | ret = BRANCH_LIKELY_TAKEN; | |
346 | } else | |
1da177e4 LT |
347 | epc += 8; |
348 | regs->cp0_epc = epc; | |
349 | break; | |
350 | ||
351 | case bgtz_op: | |
352 | case bgtzl_op: | |
353 | /* rt field assumed to be zero */ | |
d8d4e3ae | 354 | if ((long)regs->regs[insn.i_format.rs] > 0) { |
1da177e4 | 355 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
356 | if (insn.i_format.rt == bnel_op) |
357 | ret = BRANCH_LIKELY_TAKEN; | |
358 | } else | |
1da177e4 LT |
359 | epc += 8; |
360 | regs->cp0_epc = epc; | |
361 | break; | |
362 | ||
363 | /* | |
364 | * And now the FPA/cp1 branch instructions. | |
365 | */ | |
366 | case cop1_op: | |
1d74f6bc RB |
367 | preempt_disable(); |
368 | if (is_fpu_owner()) | |
1da177e4 | 369 | asm volatile("cfc1\t%0,$31" : "=r" (fcr31)); |
1d74f6bc | 370 | else |
eae89076 | 371 | fcr31 = current->thread.fpu.fcr31; |
1d74f6bc RB |
372 | preempt_enable(); |
373 | ||
1da177e4 LT |
374 | bit = (insn.i_format.rt >> 2); |
375 | bit += (bit != 0); | |
376 | bit += 23; | |
ee1cca1b | 377 | switch (insn.i_format.rt & 3) { |
70342287 RB |
378 | case 0: /* bc1f */ |
379 | case 2: /* bc1fl */ | |
d8d4e3ae | 380 | if (~fcr31 & (1 << bit)) { |
1da177e4 | 381 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
382 | if (insn.i_format.rt == 2) |
383 | ret = BRANCH_LIKELY_TAKEN; | |
384 | } else | |
1da177e4 LT |
385 | epc += 8; |
386 | regs->cp0_epc = epc; | |
387 | break; | |
388 | ||
70342287 RB |
389 | case 1: /* bc1t */ |
390 | case 3: /* bc1tl */ | |
d8d4e3ae | 391 | if (fcr31 & (1 << bit)) { |
1da177e4 | 392 | epc = epc + 4 + (insn.i_format.simmediate << 2); |
d8d4e3ae MS |
393 | if (insn.i_format.rt == 3) |
394 | ret = BRANCH_LIKELY_TAKEN; | |
395 | } else | |
1da177e4 LT |
396 | epc += 8; |
397 | regs->cp0_epc = epc; | |
398 | break; | |
399 | } | |
400 | break; | |
126336f0 DD |
401 | #ifdef CONFIG_CPU_CAVIUM_OCTEON |
402 | case lwc2_op: /* This is bbit0 on Octeon */ | |
403 | if ((regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt)) | |
404 | == 0) | |
405 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
406 | else | |
407 | epc += 8; | |
408 | regs->cp0_epc = epc; | |
409 | break; | |
410 | case ldc2_op: /* This is bbit032 on Octeon */ | |
411 | if ((regs->regs[insn.i_format.rs] & | |
412 | (1ull<<(insn.i_format.rt+32))) == 0) | |
413 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
414 | else | |
415 | epc += 8; | |
416 | regs->cp0_epc = epc; | |
417 | break; | |
418 | case swc2_op: /* This is bbit1 on Octeon */ | |
419 | if (regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt)) | |
420 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
421 | else | |
422 | epc += 8; | |
423 | regs->cp0_epc = epc; | |
424 | break; | |
425 | case sdc2_op: /* This is bbit132 on Octeon */ | |
426 | if (regs->regs[insn.i_format.rs] & | |
427 | (1ull<<(insn.i_format.rt+32))) | |
428 | epc = epc + 4 + (insn.i_format.simmediate << 2); | |
429 | else | |
430 | epc += 8; | |
431 | regs->cp0_epc = epc; | |
432 | break; | |
433 | #endif | |
1da177e4 LT |
434 | } |
435 | ||
d8d4e3ae | 436 | return ret; |
1da177e4 | 437 | |
d8d4e3ae MS |
438 | sigill: |
439 | printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm); | |
1da177e4 LT |
440 | force_sig(SIGBUS, current); |
441 | return -EFAULT; | |
d8d4e3ae MS |
442 | } |
443 | EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn); | |
e50c0a8f | 444 | |
d8d4e3ae MS |
445 | int __compute_return_epc(struct pt_regs *regs) |
446 | { | |
447 | unsigned int __user *addr; | |
448 | long epc; | |
449 | union mips_instruction insn; | |
450 | ||
451 | epc = regs->cp0_epc; | |
452 | if (epc & 3) | |
453 | goto unaligned; | |
454 | ||
455 | /* | |
456 | * Read the instruction | |
457 | */ | |
458 | addr = (unsigned int __user *) epc; | |
459 | if (__get_user(insn.word, addr)) { | |
460 | force_sig(SIGSEGV, current); | |
461 | return -EFAULT; | |
462 | } | |
463 | ||
464 | return __compute_return_epc_for_insn(regs, insn); | |
465 | ||
466 | unaligned: | |
467 | printk("%s: unaligned epc - sending SIGBUS.\n", current->comm); | |
e50c0a8f RB |
468 | force_sig(SIGBUS, current); |
469 | return -EFAULT; | |
1da177e4 | 470 | } |