GNU Linux-libre 4.14.290-gnu1
[releases.git] / arch / m32r / kernel / ptrace.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/arch/m32r/kernel/ptrace.c
4  *
5  * Copyright (C) 2002  Hirokazu Takata, Takeo Takahashi
6  * Copyright (C) 2004  Hirokazu Takata, Kei Sakamoto
7  *
8  * Original x86 implementation:
9  *      By Ross Biro 1/23/92
10  *      edited by Linus Torvalds
11  *
12  * Some code taken from sh version:
13  *   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
14  * Some code taken from arm version:
15  *   Copyright (C) 2000 Russell King
16  */
17
18 #include <linux/kernel.h>
19 #include <linux/sched.h>
20 #include <linux/sched/task_stack.h>
21 #include <linux/mm.h>
22 #include <linux/err.h>
23 #include <linux/smp.h>
24 #include <linux/errno.h>
25 #include <linux/ptrace.h>
26 #include <linux/user.h>
27 #include <linux/string.h>
28 #include <linux/signal.h>
29
30 #include <asm/cacheflush.h>
31 #include <asm/io.h>
32 #include <linux/uaccess.h>
33 #include <asm/pgtable.h>
34 #include <asm/processor.h>
35 #include <asm/mmu_context.h>
36
37 /*
38  * This routine will get a word off of the process kernel stack.
39  */
40 static inline unsigned long int
41 get_stack_long(struct task_struct *task, int offset)
42 {
43         unsigned long *stack;
44
45         stack = (unsigned long *)task_pt_regs(task);
46
47         return stack[offset];
48 }
49
50 /*
51  * This routine will put a word on the process kernel stack.
52  */
53 static inline int
54 put_stack_long(struct task_struct *task, int offset, unsigned long data)
55 {
56         unsigned long *stack;
57
58         stack = (unsigned long *)task_pt_regs(task);
59         stack[offset] = data;
60
61         return 0;
62 }
63
64 static int reg_offset[] = {
65         PT_R0, PT_R1, PT_R2, PT_R3, PT_R4, PT_R5, PT_R6, PT_R7,
66         PT_R8, PT_R9, PT_R10, PT_R11, PT_R12, PT_FP, PT_LR, PT_SPU,
67 };
68
69 /*
70  * Read the word at offset "off" into the "struct user".  We
71  * actually access the pt_regs stored on the kernel stack.
72  */
73 static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
74                             unsigned long __user *data)
75 {
76         unsigned long tmp;
77 #ifndef NO_FPU
78         struct user * dummy = NULL;
79 #endif
80
81         if ((off & 3) || off > sizeof(struct user) - 3)
82                 return -EIO;
83
84         off >>= 2;
85         switch (off) {
86         case PT_EVB:
87                 __asm__ __volatile__ (
88                         "mvfc   %0, cr5 \n\t"
89                         : "=r" (tmp)
90                 );
91                 break;
92         case PT_CBR: {
93                         unsigned long psw;
94                         psw = get_stack_long(tsk, PT_PSW);
95                         tmp = ((psw >> 8) & 1);
96                 }
97                 break;
98         case PT_PSW: {
99                         unsigned long psw, bbpsw;
100                         psw = get_stack_long(tsk, PT_PSW);
101                         bbpsw = get_stack_long(tsk, PT_BBPSW);
102                         tmp = ((psw >> 8) & 0xff) | ((bbpsw & 0xff) << 8);
103                 }
104                 break;
105         case PT_PC:
106                 tmp = get_stack_long(tsk, PT_BPC);
107                 break;
108         case PT_BPC:
109                 off = PT_BBPC;
110                 /* fall through */
111         default:
112                 if (off < (sizeof(struct pt_regs) >> 2))
113                         tmp = get_stack_long(tsk, off);
114 #ifndef NO_FPU
115                 else if (off >= (long)(&dummy->fpu >> 2) &&
116                          off < (long)(&dummy->u_fpvalid >> 2)) {
117                         if (!tsk_used_math(tsk)) {
118                                 if (off == (long)(&dummy->fpu.fpscr >> 2))
119                                         tmp = FPSCR_INIT;
120                                 else
121                                         tmp = 0;
122                         } else
123                                 tmp = ((long *)(&tsk->thread.fpu >> 2))
124                                         [off - (long)&dummy->fpu];
125                 } else if (off == (long)(&dummy->u_fpvalid >> 2))
126                         tmp = !!tsk_used_math(tsk);
127 #endif /* not NO_FPU */
128                 else
129                         tmp = 0;
130         }
131
132         return put_user(tmp, data);
133 }
134
135 static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
136                              unsigned long data)
137 {
138         int ret = -EIO;
139 #ifndef NO_FPU
140         struct user * dummy = NULL;
141 #endif
142
143         if ((off & 3) || off > sizeof(struct user) - 3)
144                 return -EIO;
145
146         off >>= 2;
147         switch (off) {
148         case PT_EVB:
149         case PT_BPC:
150         case PT_SPI:
151                 /* We don't allow to modify evb. */
152                 ret = 0;
153                 break;
154         case PT_PSW:
155         case PT_CBR: {
156                         /* We allow to modify only cbr in psw */
157                         unsigned long psw;
158                         psw = get_stack_long(tsk, PT_PSW);
159                         psw = (psw & ~0x100) | ((data & 1) << 8);
160                         ret = put_stack_long(tsk, PT_PSW, psw);
161                 }
162                 break;
163         case PT_PC:
164                 off = PT_BPC;
165                 data &= ~1;
166                 /* fall through */
167         default:
168                 if (off < (sizeof(struct pt_regs) >> 2))
169                         ret = put_stack_long(tsk, off, data);
170 #ifndef NO_FPU
171                 else if (off >= (long)(&dummy->fpu >> 2) &&
172                          off < (long)(&dummy->u_fpvalid >> 2)) {
173                         set_stopped_child_used_math(tsk);
174                         ((long *)&tsk->thread.fpu)
175                                 [off - (long)&dummy->fpu] = data;
176                         ret = 0;
177                 } else if (off == (long)(&dummy->u_fpvalid >> 2)) {
178                         conditional_stopped_child_used_math(data, tsk);
179                         ret = 0;
180                 }
181 #endif /* not NO_FPU */
182                 break;
183         }
184
185         return ret;
186 }
187
188 /*
189  * Get all user integer registers.
190  */
191 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
192 {
193         struct pt_regs *regs = task_pt_regs(tsk);
194
195         return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
196 }
197
198 /*
199  * Set all user integer registers.
200  */
201 static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
202 {
203         struct pt_regs newregs;
204         int ret;
205
206         ret = -EFAULT;
207         if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
208                 struct pt_regs *regs = task_pt_regs(tsk);
209                 *regs = newregs;
210                 ret = 0;
211         }
212
213         return ret;
214 }
215
216
217 static inline int
218 check_condition_bit(struct task_struct *child)
219 {
220         return (int)((get_stack_long(child, PT_PSW) >> 8) & 1);
221 }
222
223 static int
224 check_condition_src(unsigned long op, unsigned long regno1,
225                     unsigned long regno2, struct task_struct *child)
226 {
227         unsigned long reg1, reg2;
228
229         reg2 = get_stack_long(child, reg_offset[regno2]);
230
231         switch (op) {
232         case 0x0: /* BEQ */
233                 reg1 = get_stack_long(child, reg_offset[regno1]);
234                 return reg1 == reg2;
235         case 0x1: /* BNE */
236                 reg1 = get_stack_long(child, reg_offset[regno1]);
237                 return reg1 != reg2;
238         case 0x8: /* BEQZ */
239                 return reg2 == 0;
240         case 0x9: /* BNEZ */
241                 return reg2 != 0;
242         case 0xa: /* BLTZ */
243                 return (int)reg2 < 0;
244         case 0xb: /* BGEZ */
245                 return (int)reg2 >= 0;
246         case 0xc: /* BLEZ */
247                 return (int)reg2 <= 0;
248         case 0xd: /* BGTZ */
249                 return (int)reg2 > 0;
250         default:
251                 /* never reached */
252                 return 0;
253         }
254 }
255
256 static void
257 compute_next_pc_for_16bit_insn(unsigned long insn, unsigned long pc,
258                                unsigned long *next_pc,
259                                struct task_struct *child)
260 {
261         unsigned long op, op2, op3;
262         unsigned long disp;
263         unsigned long regno;
264         int parallel = 0;
265
266         if (insn & 0x00008000)
267                 parallel = 1;
268         if (pc & 3)
269                 insn &= 0x7fff; /* right slot */
270         else
271                 insn >>= 16;    /* left slot */
272
273         op = (insn >> 12) & 0xf;
274         op2 = (insn >> 8) & 0xf;
275         op3 = (insn >> 4) & 0xf;
276
277         if (op == 0x7) {
278                 switch (op2) {
279                 case 0xd: /* BNC */
280                 case 0x9: /* BNCL */
281                         if (!check_condition_bit(child)) {
282                                 disp = (long)(insn << 24) >> 22;
283                                 *next_pc = (pc & ~0x3) + disp;
284                                 return;
285                         }
286                         break;
287                 case 0x8: /* BCL */
288                 case 0xc: /* BC */
289                         if (check_condition_bit(child)) {
290                                 disp = (long)(insn << 24) >> 22;
291                                 *next_pc = (pc & ~0x3) + disp;
292                                 return;
293                         }
294                         break;
295                 case 0xe: /* BL */
296                 case 0xf: /* BRA */
297                         disp = (long)(insn << 24) >> 22;
298                         *next_pc = (pc & ~0x3) + disp;
299                         return;
300                         break;
301                 }
302         } else if (op == 0x1) {
303                 switch (op2) {
304                 case 0x0:
305                         if (op3 == 0xf) { /* TRAP */
306 #if 1
307                                 /* pass through */
308 #else
309                                 /* kernel space is not allowed as next_pc */
310                                 unsigned long evb;
311                                 unsigned long trapno;
312                                 trapno = insn & 0xf;
313                                 __asm__ __volatile__ (
314                                         "mvfc %0, cr5\n"
315                                         :"=r"(evb)
316                                         :
317                                 );
318                                 *next_pc = evb + (trapno << 2);
319                                 return;
320 #endif
321                         } else if (op3 == 0xd) { /* RTE */
322                                 *next_pc = get_stack_long(child, PT_BPC);
323                                 return;
324                         }
325                         break;
326                 case 0xc: /* JC */
327                         if (op3 == 0xc && check_condition_bit(child)) {
328                                 regno = insn & 0xf;
329                                 *next_pc = get_stack_long(child,
330                                                           reg_offset[regno]);
331                                 return;
332                         }
333                         break;
334                 case 0xd: /* JNC */
335                         if (op3 == 0xc && !check_condition_bit(child)) {
336                                 regno = insn & 0xf;
337                                 *next_pc = get_stack_long(child,
338                                                           reg_offset[regno]);
339                                 return;
340                         }
341                         break;
342                 case 0xe: /* JL */
343                 case 0xf: /* JMP */
344                         if (op3 == 0xc) { /* JMP */
345                                 regno = insn & 0xf;
346                                 *next_pc = get_stack_long(child,
347                                                           reg_offset[regno]);
348                                 return;
349                         }
350                         break;
351                 }
352         }
353         if (parallel)
354                 *next_pc = pc + 4;
355         else
356                 *next_pc = pc + 2;
357 }
358
359 static void
360 compute_next_pc_for_32bit_insn(unsigned long insn, unsigned long pc,
361                                unsigned long *next_pc,
362                                struct task_struct *child)
363 {
364         unsigned long op;
365         unsigned long op2;
366         unsigned long disp;
367         unsigned long regno1, regno2;
368
369         op = (insn >> 28) & 0xf;
370         if (op == 0xf) {        /* branch 24-bit relative */
371                 op2 = (insn >> 24) & 0xf;
372                 switch (op2) {
373                 case 0xd:       /* BNC */
374                 case 0x9:       /* BNCL */
375                         if (!check_condition_bit(child)) {
376                                 disp = (long)(insn << 8) >> 6;
377                                 *next_pc = (pc & ~0x3) + disp;
378                                 return;
379                         }
380                         break;
381                 case 0x8:       /* BCL */
382                 case 0xc:       /* BC */
383                         if (check_condition_bit(child)) {
384                                 disp = (long)(insn << 8) >> 6;
385                                 *next_pc = (pc & ~0x3) + disp;
386                                 return;
387                         }
388                         break;
389                 case 0xe:       /* BL */
390                 case 0xf:       /* BRA */
391                         disp = (long)(insn << 8) >> 6;
392                         *next_pc = (pc & ~0x3) + disp;
393                         return;
394                 }
395         } else if (op == 0xb) { /* branch 16-bit relative */
396                 op2 = (insn >> 20) & 0xf;
397                 switch (op2) {
398                 case 0x0: /* BEQ */
399                 case 0x1: /* BNE */
400                 case 0x8: /* BEQZ */
401                 case 0x9: /* BNEZ */
402                 case 0xa: /* BLTZ */
403                 case 0xb: /* BGEZ */
404                 case 0xc: /* BLEZ */
405                 case 0xd: /* BGTZ */
406                         regno1 = ((insn >> 24) & 0xf);
407                         regno2 = ((insn >> 16) & 0xf);
408                         if (check_condition_src(op2, regno1, regno2, child)) {
409                                 disp = (long)(insn << 16) >> 14;
410                                 *next_pc = (pc & ~0x3) + disp;
411                                 return;
412                         }
413                         break;
414                 }
415         }
416         *next_pc = pc + 4;
417 }
418
419 static inline void
420 compute_next_pc(unsigned long insn, unsigned long pc,
421                 unsigned long *next_pc, struct task_struct *child)
422 {
423         if (insn & 0x80000000)
424                 compute_next_pc_for_32bit_insn(insn, pc, next_pc, child);
425         else
426                 compute_next_pc_for_16bit_insn(insn, pc, next_pc, child);
427 }
428
429 static int
430 register_debug_trap(struct task_struct *child, unsigned long next_pc,
431         unsigned long next_insn, unsigned long *code)
432 {
433         struct debug_trap *p = &child->thread.debug_trap;
434         unsigned long addr = next_pc & ~3;
435
436         if (p->nr_trap == MAX_TRAPS) {
437                 printk("kernel BUG at %s %d: p->nr_trap = %d\n",
438                                         __FILE__, __LINE__, p->nr_trap);
439                 return -1;
440         }
441         p->addr[p->nr_trap] = addr;
442         p->insn[p->nr_trap] = next_insn;
443         p->nr_trap++;
444         if (next_pc & 3) {
445                 *code = (next_insn & 0xffff0000) | 0x10f1;
446                 /* xxx --> TRAP1 */
447         } else {
448                 if ((next_insn & 0x80000000) || (next_insn & 0x8000)) {
449                         *code = 0x10f17000;
450                         /* TRAP1 --> NOP */
451                 } else {
452                         *code = (next_insn & 0xffff) | 0x10f10000;
453                         /* TRAP1 --> xxx */
454                 }
455         }
456         return 0;
457 }
458
459 static int
460 unregister_debug_trap(struct task_struct *child, unsigned long addr,
461                       unsigned long *code)
462 {
463         struct debug_trap *p = &child->thread.debug_trap;
464         int i;
465
466         /* Search debug trap entry. */
467         for (i = 0; i < p->nr_trap; i++) {
468                 if (p->addr[i] == addr)
469                         break;
470         }
471         if (i >= p->nr_trap) {
472                 /* The trap may be requested from debugger.
473                  * ptrace should do nothing in this case.
474                  */
475                 return 0;
476         }
477
478         /* Recover original instruction code. */
479         *code = p->insn[i];
480
481         /* Shift debug trap entries. */
482         while (i < p->nr_trap - 1) {
483                 p->insn[i] = p->insn[i + 1];
484                 p->addr[i] = p->addr[i + 1];
485                 i++;
486         }
487         p->nr_trap--;
488         return 1;
489 }
490
491 static void
492 unregister_all_debug_traps(struct task_struct *child)
493 {
494         struct debug_trap *p = &child->thread.debug_trap;
495         int i;
496
497         for (i = 0; i < p->nr_trap; i++)
498                 access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]),
499                                 FOLL_FORCE | FOLL_WRITE);
500         p->nr_trap = 0;
501 }
502
503 static inline void
504 invalidate_cache(void)
505 {
506 #if defined(CONFIG_CHIP_M32700) || defined(CONFIG_CHIP_OPSP)
507
508         _flush_cache_copyback_all();
509
510 #else   /* ! CONFIG_CHIP_M32700 */
511
512         /* Invalidate cache */
513         __asm__ __volatile__ (
514                 "ldi    r0, #-1                                 \n\t"
515                 "ldi    r1, #0                                  \n\t"
516                 "stb    r1, @r0         ; cache off             \n\t"
517                 ";                                              \n\t"
518                 "ldi    r0, #-2                                 \n\t"
519                 "ldi    r1, #1                                  \n\t"
520                 "stb    r1, @r0         ; cache invalidate      \n\t"
521                 ".fillinsn                                      \n"
522                 "0:                                             \n\t"
523                 "ldb    r1, @r0         ; invalidate check      \n\t"
524                 "bnez   r1, 0b                                  \n\t"
525                 ";                                              \n\t"
526                 "ldi    r0, #-1                                 \n\t"
527                 "ldi    r1, #1                                  \n\t"
528                 "stb    r1, @r0         ; cache on              \n\t"
529                 : : : "r0", "r1", "memory"
530         );
531         /* FIXME: copying-back d-cache and invalidating i-cache are needed.
532          */
533 #endif  /* CONFIG_CHIP_M32700 */
534 }
535
536 /* Embed a debug trap (TRAP1) code */
537 static int
538 embed_debug_trap(struct task_struct *child, unsigned long next_pc)
539 {
540         unsigned long next_insn, code;
541         unsigned long addr = next_pc & ~3;
542
543         if (access_process_vm(child, addr, &next_insn, sizeof(next_insn),
544                         FOLL_FORCE)
545             != sizeof(next_insn)) {
546                 return -1; /* error */
547         }
548
549         /* Set a trap code. */
550         if (register_debug_trap(child, next_pc, next_insn, &code)) {
551                 return -1; /* error */
552         }
553         if (access_process_vm(child, addr, &code, sizeof(code),
554                         FOLL_FORCE | FOLL_WRITE)
555             != sizeof(code)) {
556                 return -1; /* error */
557         }
558         return 0; /* success */
559 }
560
561 void
562 withdraw_debug_trap(struct pt_regs *regs)
563 {
564         unsigned long addr;
565         unsigned long code;
566
567         addr = (regs->bpc - 2) & ~3;
568         regs->bpc -= 2;
569         if (unregister_debug_trap(current, addr, &code)) {
570             access_process_vm(current, addr, &code, sizeof(code),
571                     FOLL_FORCE | FOLL_WRITE);
572             invalidate_cache();
573         }
574 }
575
576 void
577 init_debug_traps(struct task_struct *child)
578 {
579         struct debug_trap *p = &child->thread.debug_trap;
580         int i;
581         p->nr_trap = 0;
582         for (i = 0; i < MAX_TRAPS; i++) {
583                 p->addr[i] = 0;
584                 p->insn[i] = 0;
585         }
586 }
587
588 void user_enable_single_step(struct task_struct *child)
589 {
590         unsigned long next_pc;
591         unsigned long pc, insn;
592
593         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
594
595         /* Compute next pc.  */
596         pc = get_stack_long(child, PT_BPC);
597
598         if (access_process_vm(child, pc&~3, &insn, sizeof(insn),
599                         FOLL_FORCE)
600             != sizeof(insn))
601                 return;
602
603         compute_next_pc(insn, pc, &next_pc, child);
604         if (next_pc & 0x80000000)
605                 return;
606
607         if (embed_debug_trap(child, next_pc))
608                 return;
609
610         invalidate_cache();
611 }
612
613 void user_disable_single_step(struct task_struct *child)
614 {
615         unregister_all_debug_traps(child);
616         invalidate_cache();
617 }
618
619 /*
620  * Called by kernel/ptrace.c when detaching..
621  *
622  * Make sure single step bits etc are not set.
623  */
624 void ptrace_disable(struct task_struct *child)
625 {
626         /* nothing to do.. */
627 }
628
629 long
630 arch_ptrace(struct task_struct *child, long request,
631             unsigned long addr, unsigned long data)
632 {
633         int ret;
634         unsigned long __user *datap = (unsigned long __user *) data;
635
636         switch (request) {
637         /*
638          * read word at location "addr" in the child process.
639          */
640         case PTRACE_PEEKTEXT:
641         case PTRACE_PEEKDATA:
642                 ret = generic_ptrace_peekdata(child, addr, data);
643                 break;
644
645         /*
646          * read the word at location addr in the USER area.
647          */
648         case PTRACE_PEEKUSR:
649                 ret = ptrace_read_user(child, addr, datap);
650                 break;
651
652         /*
653          * write the word at location addr.
654          */
655         case PTRACE_POKETEXT:
656         case PTRACE_POKEDATA:
657                 ret = generic_ptrace_pokedata(child, addr, data);
658                 if (ret == 0 && request == PTRACE_POKETEXT)
659                         invalidate_cache();
660                 break;
661
662         /*
663          * write the word at location addr in the USER area.
664          */
665         case PTRACE_POKEUSR:
666                 ret = ptrace_write_user(child, addr, data);
667                 break;
668
669         case PTRACE_GETREGS:
670                 ret = ptrace_getregs(child, datap);
671                 break;
672
673         case PTRACE_SETREGS:
674                 ret = ptrace_setregs(child, datap);
675                 break;
676
677         default:
678                 ret = ptrace_request(child, request, addr, data);
679                 break;
680         }
681
682         return ret;
683 }
684
685 /* notification of system call entry/exit
686  * - triggered by current->work.syscall_trace
687  */
688 void do_syscall_trace(void)
689 {
690         if (!test_thread_flag(TIF_SYSCALL_TRACE))
691                 return;
692         if (!(current->ptrace & PT_PTRACED))
693                 return;
694         /* the 0x80 provides a way for the tracing parent to distinguish
695            between a syscall stop and SIGTRAP delivery */
696         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
697                                  ? 0x80 : 0));
698
699         /*
700          * this isn't the same as continuing with a signal, but it will do
701          * for normal use.  strace only continues with a signal if the
702          * stopping signal is not SIGTRAP.  -brl
703          */
704         if (current->exit_code) {
705                 send_sig(current->exit_code, current, 1);
706                 current->exit_code = 0;
707         }
708 }