arch/powerpc/kernel/kgdb.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * PowerPC backend to the KGDB stub.
   4  *
   5  * 1998 (c) Michael AK Tesch (tesch@cs.wisc.edu)
   6  * Copyright (C) 2003 Timesys Corporation.
   7  * Copyright (C) 2004-2006 MontaVista Software, Inc.
   8  * PPC64 Mods (C) 2005 Frank Rowand (frowand@mvista.com)
   9  * PPC32 support restored by Vitaly Wool <vwool@ru.mvista.com> and
  10  * Sergei Shtylyov <sshtylyov@ru.mvista.com>
  11  * Copyright (C) 2007-2008 Wind River Systems, Inc.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/kgdb.h>
  16 #include <linux/smp.h>
  17 #include <linux/signal.h>
  18 #include <linux/ptrace.h>
  19 #include <linux/kdebug.h>
  20 #include <asm/current.h>
  21 #include <asm/processor.h>
  22 #include <asm/machdep.h>
  23 #include <asm/debug.h>
  24 #include <asm/text-patching.h>
  25 #include <linux/slab.h>
  26 #include <asm/inst.h>
  27
  28 /*
  29  * This table contains the mapping between PowerPC hardware trap types, and
  30  * signals, which are primarily what GDB understands.  GDB and the kernel
  31  * don't always agree on values, so we use constants taken from gdb-6.2.
  32  */
  33 static struct hard_trap_info
  34 {
  35         unsigned int tt;                /* Trap type code for powerpc */
  36         unsigned char signo;            /* Signal that we map this trap into */
  37 } hard_trap_info[] = {
  38         { 0x0100, 0x02 /* SIGINT */  },         /* system reset */
  39         { 0x0200, 0x0b /* SIGSEGV */ },         /* machine check */
  40         { 0x0300, 0x0b /* SIGSEGV */ },         /* data access */
  41         { 0x0400, 0x0b /* SIGSEGV */ },         /* instruction access */
  42         { 0x0500, 0x02 /* SIGINT */  },         /* external interrupt */
  43         { 0x0600, 0x0a /* SIGBUS */  },         /* alignment */
  44         { 0x0700, 0x05 /* SIGTRAP */ },         /* program check */
  45         { 0x0800, 0x08 /* SIGFPE */  },         /* fp unavailable */
  46         { 0x0900, 0x0e /* SIGALRM */ },         /* decrementer */
  47         { 0x0c00, 0x14 /* SIGCHLD */ },         /* system call */
  48 #ifdef CONFIG_BOOKE
  49         { 0x2002, 0x05 /* SIGTRAP */ },         /* debug */
  50 #if defined(CONFIG_PPC_85xx)
  51         { 0x2010, 0x08 /* SIGFPE */  },         /* spe unavailable */
  52         { 0x2020, 0x08 /* SIGFPE */  },         /* spe unavailable */
  53         { 0x2030, 0x08 /* SIGFPE */  },         /* spe fp data */
  54         { 0x2040, 0x08 /* SIGFPE */  },         /* spe fp data */
  55         { 0x2050, 0x08 /* SIGFPE */  },         /* spe fp round */
  56         { 0x2060, 0x0e /* SIGILL */  },         /* performance monitor */
  57         { 0x2900, 0x08 /* SIGFPE */  },         /* apu unavailable */
  58         { 0x3100, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  59         { 0x3200, 0x02 /* SIGINT */  },         /* watchdog */
  60 #else /* ! CONFIG_PPC_85xx */
  61         { 0x1000, 0x0e /* SIGALRM */ },         /* prog interval timer */
  62         { 0x1010, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  63         { 0x1020, 0x02 /* SIGINT */  },         /* watchdog */
  64         { 0x2010, 0x08 /* SIGFPE */  },         /* fp unavailable */
  65         { 0x2020, 0x08 /* SIGFPE */  },         /* ap unavailable */
  66 #endif
  67 #else /* !CONFIG_BOOKE */
  68         { 0x0d00, 0x05 /* SIGTRAP */ },         /* single-step */
  69 #if defined(CONFIG_PPC_8xx)
  70         { 0x1000, 0x04 /* SIGILL */  },         /* software emulation */
  71 #else /* ! CONFIG_PPC_8xx */
  72         { 0x0f00, 0x04 /* SIGILL */  },         /* performance monitor */
  73         { 0x0f20, 0x08 /* SIGFPE */  },         /* altivec unavailable */
  74         { 0x1300, 0x05 /* SIGTRAP */ },         /* instruction address break */
  75 #if defined(CONFIG_PPC64)
  76         { 0x1200, 0x05 /* SIGILL */  },         /* system error */
  77         { 0x1500, 0x04 /* SIGILL */  },         /* soft patch */
  78         { 0x1600, 0x04 /* SIGILL */  },         /* maintenance */
  79         { 0x1700, 0x08 /* SIGFPE */  },         /* altivec assist */
  80         { 0x1800, 0x04 /* SIGILL */  },         /* thermal */
  81 #else /* ! CONFIG_PPC64 */
  82         { 0x1400, 0x02 /* SIGINT */  },         /* SMI */
  83         { 0x1600, 0x08 /* SIGFPE */  },         /* altivec assist */
  84         { 0x1700, 0x04 /* SIGILL */  },         /* TAU */
  85         { 0x2000, 0x05 /* SIGTRAP */ },         /* run mode */
  86 #endif
  87 #endif
  88 #endif
  89         { 0x0000, 0x00 }                        /* Must be last */
  90 };
  91
  92 static int computeSignal(unsigned int tt)
  93 {
  94         struct hard_trap_info *ht;
  95
  96         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
  97                 if (ht->tt == tt)
  98                         return ht->signo;
  99
 100         return SIGHUP;          /* default for things we don't know about */
 101 }
 102
 103 /**
 104  *
 105  *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
 106  *      @exception: Exception vector number
 107  *      @regs: Current &struct pt_regs.
 108  *
 109  *      On some architectures we need to skip a breakpoint exception when
 110  *      it occurs after a breakpoint has been removed.
 111  *
 112  */
 113 int kgdb_skipexception(int exception, struct pt_regs *regs)
 114 {
 115         return kgdb_isremovedbreak(regs->nip);
 116 }
 117
 118 static int kgdb_debugger_ipi(struct pt_regs *regs)
 119 {
 120         kgdb_nmicallback(raw_smp_processor_id(), regs);
 121         return 0;
 122 }
 123
 124 #ifdef CONFIG_SMP
 125 void kgdb_roundup_cpus(void)
 126 {
 127         smp_send_debugger_break();
 128 }
 129 #endif
 130
 131 /* KGDB functions to use existing PowerPC64 hooks. */
 132 static int kgdb_debugger(struct pt_regs *regs)
 133 {
 134         return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),
 135                                       DIE_OOPS, regs);
 136 }
 137
 138 static int kgdb_handle_breakpoint(struct pt_regs *regs)
 139 {
 140         if (user_mode(regs))
 141                 return 0;
 142
 143         if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
 144                 return 0;
 145
 146         if (*(u32 *)regs->nip == BREAK_INSTR)
 147                 regs_add_return_ip(regs, BREAK_INSTR_SIZE);
 148
 149         return 1;
 150 }
 151
 152 static int kgdb_singlestep(struct pt_regs *regs)
 153 {
 154         if (user_mode(regs))
 155                 return 0;
 156
 157         kgdb_handle_exception(0, SIGTRAP, 0, regs);
 158
 159         return 1;
 160 }
 161
 162 static int kgdb_iabr_match(struct pt_regs *regs)
 163 {
 164         if (user_mode(regs))
 165                 return 0;
 166
 167         if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 168                 return 0;
 169         return 1;
 170 }
 171
 172 static int kgdb_break_match(struct pt_regs *regs)
 173 {
 174         if (user_mode(regs))
 175                 return 0;
 176
 177         if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 178                 return 0;
 179         return 1;
 180 }
 181
 182 #define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
 183
 184 #define PACK32(ptr, src) do {          \
 185         u32 *ptr32;                   \
 186         ptr32 = (u32 *)ptr;           \
 187         *(ptr32++) = (src);           \
 188         ptr = (unsigned long *)ptr32; \
 189         } while (0)
 190
 191 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 192 {
 193         struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
 194                                                   STACK_INT_FRAME_REGS);
 195         unsigned long *ptr = gdb_regs;
 196         int reg;
 197
 198         memset(gdb_regs, 0, NUMREGBYTES);
 199
 200         /* Regs GPR0-2 */
 201         for (reg = 0; reg < 3; reg++)
 202                 PACK64(ptr, regs->gpr[reg]);
 203
 204         /* Regs GPR3-13 are caller saved, not in regs->gpr[] */
 205         ptr += 11;
 206
 207         /* Regs GPR14-31 */
 208         for (reg = 14; reg < 32; reg++)
 209                 PACK64(ptr, regs->gpr[reg]);
 210
 211 #ifdef CONFIG_PPC_85xx
 212 #ifdef CONFIG_SPE
 213         for (reg = 0; reg < 32; reg++)
 214                 PACK64(ptr, p->thread.evr[reg]);
 215 #else
 216         ptr += 32;
 217 #endif
 218 #else
 219         /* fp registers not used by kernel, leave zero */
 220         ptr += 32 * 8 / sizeof(long);
 221 #endif
 222
 223         PACK64(ptr, regs->nip);
 224         PACK64(ptr, regs->msr);
 225         PACK32(ptr, regs->ccr);
 226         PACK64(ptr, regs->link);
 227         PACK64(ptr, regs->ctr);
 228         PACK32(ptr, regs->xer);
 229
 230         BUG_ON((unsigned long)ptr >
 231                (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 232 }
 233
 234 #define GDB_SIZEOF_REG sizeof(unsigned long)
 235 #define GDB_SIZEOF_REG_U32 sizeof(u32)
 236
 237 #ifdef CONFIG_PPC_85xx
 238 #define GDB_SIZEOF_FLOAT_REG sizeof(unsigned long)
 239 #else
 240 #define GDB_SIZEOF_FLOAT_REG sizeof(u64)
 241 #endif
 242
 243 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 244 {
 245         { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[0]) },
 246         { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[1]) },
 247         { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[2]) },
 248         { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[3]) },
 249         { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[4]) },
 250         { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[5]) },
 251         { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[6]) },
 252         { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[7]) },
 253         { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[8]) },
 254         { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[9]) },
 255         { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[10]) },
 256         { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[11]) },
 257         { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[12]) },
 258         { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[13]) },
 259         { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[14]) },
 260         { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[15]) },
 261         { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[16]) },
 262         { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[17]) },
 263         { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[18]) },
 264         { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[19]) },
 265         { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[20]) },
 266         { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[21]) },
 267         { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[22]) },
 268         { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[23]) },
 269         { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[24]) },
 270         { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[25]) },
 271         { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[26]) },
 272         { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[27]) },
 273         { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[28]) },
 274         { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[29]) },
 275         { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[30]) },
 276         { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[31]) },
 277
 278         { "f0", GDB_SIZEOF_FLOAT_REG, 0 },
 279         { "f1", GDB_SIZEOF_FLOAT_REG, 1 },
 280         { "f2", GDB_SIZEOF_FLOAT_REG, 2 },
 281         { "f3", GDB_SIZEOF_FLOAT_REG, 3 },
 282         { "f4", GDB_SIZEOF_FLOAT_REG, 4 },
 283         { "f5", GDB_SIZEOF_FLOAT_REG, 5 },
 284         { "f6", GDB_SIZEOF_FLOAT_REG, 6 },
 285         { "f7", GDB_SIZEOF_FLOAT_REG, 7 },
 286         { "f8", GDB_SIZEOF_FLOAT_REG, 8 },
 287         { "f9", GDB_SIZEOF_FLOAT_REG, 9 },
 288         { "f10", GDB_SIZEOF_FLOAT_REG, 10 },
 289         { "f11", GDB_SIZEOF_FLOAT_REG, 11 },
 290         { "f12", GDB_SIZEOF_FLOAT_REG, 12 },
 291         { "f13", GDB_SIZEOF_FLOAT_REG, 13 },
 292         { "f14", GDB_SIZEOF_FLOAT_REG, 14 },
 293         { "f15", GDB_SIZEOF_FLOAT_REG, 15 },
 294         { "f16", GDB_SIZEOF_FLOAT_REG, 16 },
 295         { "f17", GDB_SIZEOF_FLOAT_REG, 17 },
 296         { "f18", GDB_SIZEOF_FLOAT_REG, 18 },
 297         { "f19", GDB_SIZEOF_FLOAT_REG, 19 },
 298         { "f20", GDB_SIZEOF_FLOAT_REG, 20 },
 299         { "f21", GDB_SIZEOF_FLOAT_REG, 21 },
 300         { "f22", GDB_SIZEOF_FLOAT_REG, 22 },
 301         { "f23", GDB_SIZEOF_FLOAT_REG, 23 },
 302         { "f24", GDB_SIZEOF_FLOAT_REG, 24 },
 303         { "f25", GDB_SIZEOF_FLOAT_REG, 25 },
 304         { "f26", GDB_SIZEOF_FLOAT_REG, 26 },
 305         { "f27", GDB_SIZEOF_FLOAT_REG, 27 },
 306         { "f28", GDB_SIZEOF_FLOAT_REG, 28 },
 307         { "f29", GDB_SIZEOF_FLOAT_REG, 29 },
 308         { "f30", GDB_SIZEOF_FLOAT_REG, 30 },
 309         { "f31", GDB_SIZEOF_FLOAT_REG, 31 },
 310
 311         { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, nip) },
 312         { "msr", GDB_SIZEOF_REG, offsetof(struct pt_regs, msr) },
 313         { "cr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ccr) },
 314         { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, link) },
 315         { "ctr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ctr) },
 316         { "xer", GDB_SIZEOF_REG, offsetof(struct pt_regs, xer) },
 317 };
 318
 319 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 320 {
 321         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 322                 return NULL;
 323
 324         if (regno < 32 || regno >= 64)
 325                 /* First 0 -> 31 gpr registers*/
 326                 /* pc, msr, ls... registers 64 -> 69 */
 327                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 328                                 dbg_reg_def[regno].size);
 329
 330         if (regno >= 32 && regno < 64) {
 331                 /* FP registers 32 -> 63 */
 332 #if defined(CONFIG_PPC_85xx) && defined(CONFIG_SPE)
 333                 if (current)
 334                         memcpy(mem, &current->thread.evr[regno-32],
 335                                         dbg_reg_def[regno].size);
 336 #else
 337                 /* fp registers not used by kernel, leave zero */
 338                 memset(mem, 0, dbg_reg_def[regno].size);
 339 #endif
 340         }
 341
 342         return dbg_reg_def[regno].name;
 343 }
 344
 345 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 346 {
 347         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 348                 return -EINVAL;
 349
 350         if (regno < 32 || regno >= 64)
 351                 /* First 0 -> 31 gpr registers*/
 352                 /* pc, msr, ls... registers 64 -> 69 */
 353                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 354                                 dbg_reg_def[regno].size);
 355
 356         if (regno >= 32 && regno < 64) {
 357                 /* FP registers 32 -> 63 */
 358 #if defined(CONFIG_PPC_85xx) && defined(CONFIG_SPE)
 359                 memcpy(&current->thread.evr[regno-32], mem,
 360                                 dbg_reg_def[regno].size);
 361 #else
 362                 /* fp registers not used by kernel, leave zero */
 363                 return 0;
 364 #endif
 365         }
 366
 367         return 0;
 368 }
 369
 370 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 371 {
 372         regs_set_return_ip(regs, pc);
 373 }
 374
 375 /*
 376  * This function does PowerPC specific processing for interfacing to gdb.
 377  */
 378 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 379                                char *remcom_in_buffer, char *remcom_out_buffer,
 380                                struct pt_regs *linux_regs)
 381 {
 382         char *ptr = &remcom_in_buffer[1];
 383         unsigned long addr;
 384
 385         switch (remcom_in_buffer[0]) {
 386                 /*
 387                  * sAA..AA   Step one instruction from AA..AA
 388                  * This will return an error to gdb ..
 389                  */
 390         case 's':
 391         case 'c':
 392                 /* handle the optional parameter */
 393                 if (kgdb_hex2long(&ptr, &addr))
 394                         regs_set_return_ip(linux_regs, addr);
 395
 396                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 397                 /* set the trace bit if we're stepping */
 398                 if (remcom_in_buffer[0] == 's') {
 399 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 400                         mtspr(SPRN_DBCR0,
 401                               mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
 402                         regs_set_return_msr(linux_regs, linux_regs->msr | MSR_DE);
 403 #else
 404                         regs_set_return_msr(linux_regs, linux_regs->msr | MSR_SE);
 405 #endif
 406                         atomic_set(&kgdb_cpu_doing_single_step,
 407                                    raw_smp_processor_id());
 408                 }
 409                 return 0;
 410         }
 411
 412         return -1;
 413 }
 414
 415 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 416 {
 417         u32 instr, *addr = (u32 *)bpt->bpt_addr;
 418         int err;
 419
 420         err = get_kernel_nofault(instr, addr);
 421         if (err)
 422                 return err;
 423
 424         err = patch_instruction(addr, ppc_inst(BREAK_INSTR));
 425         if (err)
 426                 return -EFAULT;
 427
 428         *(u32 *)bpt->saved_instr = instr;
 429
 430         return 0;
 431 }
 432
 433 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 434 {
 435         int err;
 436         unsigned int instr = *(unsigned int *)bpt->saved_instr;
 437         u32 *addr = (u32 *)bpt->bpt_addr;
 438
 439         err = patch_instruction(addr, ppc_inst(instr));
 440         if (err)
 441                 return -EFAULT;
 442
 443         return 0;
 444 }
 445
 446 /*
 447  * Global data
 448  */
 449 const struct kgdb_arch arch_kgdb_ops;
 450
 451 static int kgdb_not_implemented(struct pt_regs *regs)
 452 {
 453         return 0;
 454 }
 455
 456 static void *old__debugger_ipi;
 457 static void *old__debugger;
 458 static void *old__debugger_bpt;
 459 static void *old__debugger_sstep;
 460 static void *old__debugger_iabr_match;
 461 static void *old__debugger_break_match;
 462 static void *old__debugger_fault_handler;
 463
 464 int kgdb_arch_init(void)
 465 {
 466         old__debugger_ipi = __debugger_ipi;
 467         old__debugger = __debugger;
 468         old__debugger_bpt = __debugger_bpt;
 469         old__debugger_sstep = __debugger_sstep;
 470         old__debugger_iabr_match = __debugger_iabr_match;
 471         old__debugger_break_match = __debugger_break_match;
 472         old__debugger_fault_handler = __debugger_fault_handler;
 473
 474         __debugger_ipi = kgdb_debugger_ipi;
 475         __debugger = kgdb_debugger;
 476         __debugger_bpt = kgdb_handle_breakpoint;
 477         __debugger_sstep = kgdb_singlestep;
 478         __debugger_iabr_match = kgdb_iabr_match;
 479         __debugger_break_match = kgdb_break_match;
 480         __debugger_fault_handler = kgdb_not_implemented;
 481
 482         return 0;
 483 }
 484
 485 void kgdb_arch_exit(void)
 486 {
 487         __debugger_ipi = old__debugger_ipi;
 488         __debugger = old__debugger;
 489         __debugger_bpt = old__debugger_bpt;
 490         __debugger_sstep = old__debugger_sstep;
 491         __debugger_iabr_match = old__debugger_iabr_match;
 492         __debugger_break_match = old__debugger_break_match;
 493         __debugger_fault_handler = old__debugger_fault_handler;
 494 }