arch/powerpc/kernel/kgdb.c

   1 /*
   2  * PowerPC backend to the KGDB stub.
   3  *
   4  * 1998 (c) Michael AK Tesch (tesch@cs.wisc.edu)
   5  * Copyright (C) 2003 Timesys Corporation.
   6  * Copyright (C) 2004-2006 MontaVista Software, Inc.
   7  * PPC64 Mods (C) 2005 Frank Rowand (frowand@mvista.com)
   8  * PPC32 support restored by Vitaly Wool <vwool@ru.mvista.com> and
   9  * Sergei Shtylyov <sshtylyov@ru.mvista.com>
  10  * Copyright (C) 2007-2008 Wind River Systems, Inc.
  11  *
  12  * This file is licensed under the terms of the GNU General Public License
  13  * version 2. This program as licensed "as is" without any warranty of any
  14  * kind, whether express or implied.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/kgdb.h>
  19 #include <linux/smp.h>
  20 #include <linux/signal.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/kdebug.h>
  23 #include <asm/current.h>
  24 #include <asm/processor.h>
  25 #include <asm/machdep.h>
  26 #include <asm/debug.h>
  27 #include <asm/code-patching.h>
  28 #include <linux/slab.h>
  29
  30 /*
  31  * This table contains the mapping between PowerPC hardware trap types, and
  32  * signals, which are primarily what GDB understands.  GDB and the kernel
  33  * don't always agree on values, so we use constants taken from gdb-6.2.
  34  */
  35 static struct hard_trap_info
  36 {
  37         unsigned int tt;                /* Trap type code for powerpc */
  38         unsigned char signo;            /* Signal that we map this trap into */
  39 } hard_trap_info[] = {
  40         { 0x0100, 0x02 /* SIGINT */  },         /* system reset */
  41         { 0x0200, 0x0b /* SIGSEGV */ },         /* machine check */
  42         { 0x0300, 0x0b /* SIGSEGV */ },         /* data access */
  43         { 0x0400, 0x0b /* SIGSEGV */ },         /* instruction access */
  44         { 0x0500, 0x02 /* SIGINT */  },         /* external interrupt */
  45         { 0x0600, 0x0a /* SIGBUS */  },         /* alignment */
  46         { 0x0700, 0x05 /* SIGTRAP */ },         /* program check */
  47         { 0x0800, 0x08 /* SIGFPE */  },         /* fp unavailable */
  48         { 0x0900, 0x0e /* SIGALRM */ },         /* decrementer */
  49         { 0x0c00, 0x14 /* SIGCHLD */ },         /* system call */
  50 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
  51         { 0x2002, 0x05 /* SIGTRAP */ },         /* debug */
  52 #if defined(CONFIG_FSL_BOOKE)
  53         { 0x2010, 0x08 /* SIGFPE */  },         /* spe unavailable */
  54         { 0x2020, 0x08 /* SIGFPE */  },         /* spe unavailable */
  55         { 0x2030, 0x08 /* SIGFPE */  },         /* spe fp data */
  56         { 0x2040, 0x08 /* SIGFPE */  },         /* spe fp data */
  57         { 0x2050, 0x08 /* SIGFPE */  },         /* spe fp round */
  58         { 0x2060, 0x0e /* SIGILL */  },         /* performance monitor */
  59         { 0x2900, 0x08 /* SIGFPE */  },         /* apu unavailable */
  60         { 0x3100, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  61         { 0x3200, 0x02 /* SIGINT */  },         /* watchdog */
  62 #else /* ! CONFIG_FSL_BOOKE */
  63         { 0x1000, 0x0e /* SIGALRM */ },         /* prog interval timer */
  64         { 0x1010, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  65         { 0x1020, 0x02 /* SIGINT */  },         /* watchdog */
  66         { 0x2010, 0x08 /* SIGFPE */  },         /* fp unavailable */
  67         { 0x2020, 0x08 /* SIGFPE */  },         /* ap unavailable */
  68 #endif
  69 #else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
  70         { 0x0d00, 0x05 /* SIGTRAP */ },         /* single-step */
  71 #if defined(CONFIG_PPC_8xx)
  72         { 0x1000, 0x04 /* SIGILL */  },         /* software emulation */
  73 #else /* ! CONFIG_PPC_8xx */
  74         { 0x0f00, 0x04 /* SIGILL */  },         /* performance monitor */
  75         { 0x0f20, 0x08 /* SIGFPE */  },         /* altivec unavailable */
  76         { 0x1300, 0x05 /* SIGTRAP */ },         /* instruction address break */
  77 #if defined(CONFIG_PPC64)
  78         { 0x1200, 0x05 /* SIGILL */  },         /* system error */
  79         { 0x1500, 0x04 /* SIGILL */  },         /* soft patch */
  80         { 0x1600, 0x04 /* SIGILL */  },         /* maintenance */
  81         { 0x1700, 0x08 /* SIGFPE */  },         /* altivec assist */
  82         { 0x1800, 0x04 /* SIGILL */  },         /* thermal */
  83 #else /* ! CONFIG_PPC64 */
  84         { 0x1400, 0x02 /* SIGINT */  },         /* SMI */
  85         { 0x1600, 0x08 /* SIGFPE */  },         /* altivec assist */
  86         { 0x1700, 0x04 /* SIGILL */  },         /* TAU */
  87         { 0x2000, 0x05 /* SIGTRAP */ },         /* run mode */
  88 #endif
  89 #endif
  90 #endif
  91         { 0x0000, 0x00 }                        /* Must be last */
  92 };
  93
  94 static int computeSignal(unsigned int tt)
  95 {
  96         struct hard_trap_info *ht;
  97
  98         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
  99                 if (ht->tt == tt)
 100                         return ht->signo;
 101
 102         return SIGHUP;          /* default for things we don't know about */
 103 }
 104
 105 /**
 106  *
 107  *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
 108  *      @exception: Exception vector number
 109  *      @regs: Current &struct pt_regs.
 110  *
 111  *      On some architectures we need to skip a breakpoint exception when
 112  *      it occurs after a breakpoint has been removed.
 113  *
 114  */
 115 int kgdb_skipexception(int exception, struct pt_regs *regs)
 116 {
 117         return kgdb_isremovedbreak(regs->nip);
 118 }
 119
 120 static int kgdb_debugger_ipi(struct pt_regs *regs)
 121 {
 122         kgdb_nmicallback(raw_smp_processor_id(), regs);
 123         return 0;
 124 }
 125
 126 #ifdef CONFIG_SMP
 127 void kgdb_roundup_cpus(void)
 128 {
 129         smp_send_debugger_break();
 130 }
 131 #endif
 132
 133 /* KGDB functions to use existing PowerPC64 hooks. */
 134 static int kgdb_debugger(struct pt_regs *regs)
 135 {
 136         return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),
 137                                       DIE_OOPS, regs);
 138 }
 139
 140 static int kgdb_handle_breakpoint(struct pt_regs *regs)
 141 {
 142         if (user_mode(regs))
 143                 return 0;
 144
 145         if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
 146                 return 0;
 147
 148         if (*(u32 *)regs->nip == BREAK_INSTR)
 149                 regs->nip += BREAK_INSTR_SIZE;
 150
 151         return 1;
 152 }
 153
 154 static int kgdb_singlestep(struct pt_regs *regs)
 155 {
 156         if (user_mode(regs))
 157                 return 0;
 158
 159         kgdb_handle_exception(0, SIGTRAP, 0, regs);
 160
 161         return 1;
 162 }
 163
 164 static int kgdb_iabr_match(struct pt_regs *regs)
 165 {
 166         if (user_mode(regs))
 167                 return 0;
 168
 169         if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 170                 return 0;
 171         return 1;
 172 }
 173
 174 static int kgdb_break_match(struct pt_regs *regs)
 175 {
 176         if (user_mode(regs))
 177                 return 0;
 178
 179         if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 180                 return 0;
 181         return 1;
 182 }
 183
 184 #define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
 185
 186 #define PACK32(ptr, src) do {          \
 187         u32 *ptr32;                   \
 188         ptr32 = (u32 *)ptr;           \
 189         *(ptr32++) = (src);           \
 190         ptr = (unsigned long *)ptr32; \
 191         } while (0)
 192
 193 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 194 {
 195         struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
 196                                                   STACK_FRAME_OVERHEAD);
 197         unsigned long *ptr = gdb_regs;
 198         int reg;
 199
 200         memset(gdb_regs, 0, NUMREGBYTES);
 201
 202         /* Regs GPR0-2 */
 203         for (reg = 0; reg < 3; reg++)
 204                 PACK64(ptr, regs->gpr[reg]);
 205
 206         /* Regs GPR3-13 are caller saved, not in regs->gpr[] */
 207         ptr += 11;
 208
 209         /* Regs GPR14-31 */
 210         for (reg = 14; reg < 32; reg++)
 211                 PACK64(ptr, regs->gpr[reg]);
 212
 213 #ifdef CONFIG_FSL_BOOKE
 214 #ifdef CONFIG_SPE
 215         for (reg = 0; reg < 32; reg++)
 216                 PACK64(ptr, p->thread.evr[reg]);
 217 #else
 218         ptr += 32;
 219 #endif
 220 #else
 221         /* fp registers not used by kernel, leave zero */
 222         ptr += 32 * 8 / sizeof(long);
 223 #endif
 224
 225         PACK64(ptr, regs->nip);
 226         PACK64(ptr, regs->msr);
 227         PACK32(ptr, regs->ccr);
 228         PACK64(ptr, regs->link);
 229         PACK64(ptr, regs->ctr);
 230         PACK32(ptr, regs->xer);
 231
 232         BUG_ON((unsigned long)ptr >
 233                (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 234 }
 235
 236 #define GDB_SIZEOF_REG sizeof(unsigned long)
 237 #define GDB_SIZEOF_REG_U32 sizeof(u32)
 238
 239 #ifdef CONFIG_FSL_BOOKE
 240 #define GDB_SIZEOF_FLOAT_REG sizeof(unsigned long)
 241 #else
 242 #define GDB_SIZEOF_FLOAT_REG sizeof(u64)
 243 #endif
 244
 245 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 246 {
 247         { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[0]) },
 248         { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[1]) },
 249         { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[2]) },
 250         { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[3]) },
 251         { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[4]) },
 252         { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[5]) },
 253         { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[6]) },
 254         { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[7]) },
 255         { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[8]) },
 256         { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[9]) },
 257         { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[10]) },
 258         { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[11]) },
 259         { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[12]) },
 260         { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[13]) },
 261         { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[14]) },
 262         { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[15]) },
 263         { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[16]) },
 264         { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[17]) },
 265         { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[18]) },
 266         { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[19]) },
 267         { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[20]) },
 268         { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[21]) },
 269         { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[22]) },
 270         { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[23]) },
 271         { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[24]) },
 272         { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[25]) },
 273         { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[26]) },
 274         { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[27]) },
 275         { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[28]) },
 276         { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[29]) },
 277         { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[30]) },
 278         { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[31]) },
 279
 280         { "f0", GDB_SIZEOF_FLOAT_REG, 0 },
 281         { "f1", GDB_SIZEOF_FLOAT_REG, 1 },
 282         { "f2", GDB_SIZEOF_FLOAT_REG, 2 },
 283         { "f3", GDB_SIZEOF_FLOAT_REG, 3 },
 284         { "f4", GDB_SIZEOF_FLOAT_REG, 4 },
 285         { "f5", GDB_SIZEOF_FLOAT_REG, 5 },
 286         { "f6", GDB_SIZEOF_FLOAT_REG, 6 },
 287         { "f7", GDB_SIZEOF_FLOAT_REG, 7 },
 288         { "f8", GDB_SIZEOF_FLOAT_REG, 8 },
 289         { "f9", GDB_SIZEOF_FLOAT_REG, 9 },
 290         { "f10", GDB_SIZEOF_FLOAT_REG, 10 },
 291         { "f11", GDB_SIZEOF_FLOAT_REG, 11 },
 292         { "f12", GDB_SIZEOF_FLOAT_REG, 12 },
 293         { "f13", GDB_SIZEOF_FLOAT_REG, 13 },
 294         { "f14", GDB_SIZEOF_FLOAT_REG, 14 },
 295         { "f15", GDB_SIZEOF_FLOAT_REG, 15 },
 296         { "f16", GDB_SIZEOF_FLOAT_REG, 16 },
 297         { "f17", GDB_SIZEOF_FLOAT_REG, 17 },
 298         { "f18", GDB_SIZEOF_FLOAT_REG, 18 },
 299         { "f19", GDB_SIZEOF_FLOAT_REG, 19 },
 300         { "f20", GDB_SIZEOF_FLOAT_REG, 20 },
 301         { "f21", GDB_SIZEOF_FLOAT_REG, 21 },
 302         { "f22", GDB_SIZEOF_FLOAT_REG, 22 },
 303         { "f23", GDB_SIZEOF_FLOAT_REG, 23 },
 304         { "f24", GDB_SIZEOF_FLOAT_REG, 24 },
 305         { "f25", GDB_SIZEOF_FLOAT_REG, 25 },
 306         { "f26", GDB_SIZEOF_FLOAT_REG, 26 },
 307         { "f27", GDB_SIZEOF_FLOAT_REG, 27 },
 308         { "f28", GDB_SIZEOF_FLOAT_REG, 28 },
 309         { "f29", GDB_SIZEOF_FLOAT_REG, 29 },
 310         { "f30", GDB_SIZEOF_FLOAT_REG, 30 },
 311         { "f31", GDB_SIZEOF_FLOAT_REG, 31 },
 312
 313         { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, nip) },
 314         { "msr", GDB_SIZEOF_REG, offsetof(struct pt_regs, msr) },
 315         { "cr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ccr) },
 316         { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, link) },
 317         { "ctr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ctr) },
 318         { "xer", GDB_SIZEOF_REG, offsetof(struct pt_regs, xer) },
 319 };
 320
 321 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 322 {
 323         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 324                 return NULL;
 325
 326         if (regno < 32 || regno >= 64)
 327                 /* First 0 -> 31 gpr registers*/
 328                 /* pc, msr, ls... registers 64 -> 69 */
 329                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 330                                 dbg_reg_def[regno].size);
 331
 332         if (regno >= 32 && regno < 64) {
 333                 /* FP registers 32 -> 63 */
 334 #if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
 335                 if (current)
 336                         memcpy(mem, &current->thread.evr[regno-32],
 337                                         dbg_reg_def[regno].size);
 338 #else
 339                 /* fp registers not used by kernel, leave zero */
 340                 memset(mem, 0, dbg_reg_def[regno].size);
 341 #endif
 342         }
 343
 344         return dbg_reg_def[regno].name;
 345 }
 346
 347 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 348 {
 349         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 350                 return -EINVAL;
 351
 352         if (regno < 32 || regno >= 64)
 353                 /* First 0 -> 31 gpr registers*/
 354                 /* pc, msr, ls... registers 64 -> 69 */
 355                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 356                                 dbg_reg_def[regno].size);
 357
 358         if (regno >= 32 && regno < 64) {
 359                 /* FP registers 32 -> 63 */
 360 #if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
 361                 memcpy(&current->thread.evr[regno-32], mem,
 362                                 dbg_reg_def[regno].size);
 363 #else
 364                 /* fp registers not used by kernel, leave zero */
 365                 return 0;
 366 #endif
 367         }
 368
 369         return 0;
 370 }
 371
 372 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 373 {
 374         regs->nip = pc;
 375 }
 376
 377 /*
 378  * This function does PowerPC specific procesing for interfacing to gdb.
 379  */
 380 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 381                                char *remcom_in_buffer, char *remcom_out_buffer,
 382                                struct pt_regs *linux_regs)
 383 {
 384         char *ptr = &remcom_in_buffer[1];
 385         unsigned long addr;
 386
 387         switch (remcom_in_buffer[0]) {
 388                 /*
 389                  * sAA..AA   Step one instruction from AA..AA
 390                  * This will return an error to gdb ..
 391                  */
 392         case 's':
 393         case 'c':
 394                 /* handle the optional parameter */
 395                 if (kgdb_hex2long(&ptr, &addr))
 396                         linux_regs->nip = addr;
 397
 398                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 399                 /* set the trace bit if we're stepping */
 400                 if (remcom_in_buffer[0] == 's') {
 401 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 402                         mtspr(SPRN_DBCR0,
 403                               mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
 404                         linux_regs->msr |= MSR_DE;
 405 #else
 406                         linux_regs->msr |= MSR_SE;
 407 #endif
 408                         atomic_set(&kgdb_cpu_doing_single_step,
 409                                    raw_smp_processor_id());
 410                 }
 411                 return 0;
 412         }
 413
 414         return -1;
 415 }
 416
 417 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 418 {
 419         int err;
 420         unsigned int instr;
 421         unsigned int *addr = (unsigned int *)bpt->bpt_addr;
 422
 423         err = probe_kernel_address(addr, instr);
 424         if (err)
 425                 return err;
 426
 427         err = patch_instruction(addr, BREAK_INSTR);
 428         if (err)
 429                 return -EFAULT;
 430
 431         *(unsigned int *)bpt->saved_instr = instr;
 432
 433         return 0;
 434 }
 435
 436 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 437 {
 438         int err;
 439         unsigned int instr = *(unsigned int *)bpt->saved_instr;
 440         unsigned int *addr = (unsigned int *)bpt->bpt_addr;
 441
 442         err = patch_instruction(addr, instr);
 443         if (err)
 444                 return -EFAULT;
 445
 446         return 0;
 447 }
 448
 449 /*
 450  * Global data
 451  */
 452 const struct kgdb_arch arch_kgdb_ops;
 453
 454 static int kgdb_not_implemented(struct pt_regs *regs)
 455 {
 456         return 0;
 457 }
 458
 459 static void *old__debugger_ipi;
 460 static void *old__debugger;
 461 static void *old__debugger_bpt;
 462 static void *old__debugger_sstep;
 463 static void *old__debugger_iabr_match;
 464 static void *old__debugger_break_match;
 465 static void *old__debugger_fault_handler;
 466
 467 int kgdb_arch_init(void)
 468 {
 469         old__debugger_ipi = __debugger_ipi;
 470         old__debugger = __debugger;
 471         old__debugger_bpt = __debugger_bpt;
 472         old__debugger_sstep = __debugger_sstep;
 473         old__debugger_iabr_match = __debugger_iabr_match;
 474         old__debugger_break_match = __debugger_break_match;
 475         old__debugger_fault_handler = __debugger_fault_handler;
 476
 477         __debugger_ipi = kgdb_debugger_ipi;
 478         __debugger = kgdb_debugger;
 479         __debugger_bpt = kgdb_handle_breakpoint;
 480         __debugger_sstep = kgdb_singlestep;
 481         __debugger_iabr_match = kgdb_iabr_match;
 482         __debugger_break_match = kgdb_break_match;
 483         __debugger_fault_handler = kgdb_not_implemented;
 484
 485         return 0;
 486 }
 487
 488 void kgdb_arch_exit(void)
 489 {
 490         __debugger_ipi = old__debugger_ipi;
 491         __debugger = old__debugger;
 492         __debugger_bpt = old__debugger_bpt;
 493         __debugger_sstep = old__debugger_sstep;
 494         __debugger_iabr_match = old__debugger_iabr_match;
 495         __debugger_break_match = old__debugger_break_match;
 496         __debugger_fault_handler = old__debugger_fault_handler;
 497 }