linux/arch/powerpc/kernel/kgdb.c
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   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#include <asm/inst.h>
  30
  31/*
  32 * This table contains the mapping between PowerPC hardware trap types, and
  33 * signals, which are primarily what GDB understands.  GDB and the kernel
  34 * don't always agree on values, so we use constants taken from gdb-6.2.
  35 */
  36static struct hard_trap_info
  37{
  38        unsigned int tt;                /* Trap type code for powerpc */
  39        unsigned char signo;            /* Signal that we map this trap into */
  40} hard_trap_info[] = {
  41        { 0x0100, 0x02 /* SIGINT */  },         /* system reset */
  42        { 0x0200, 0x0b /* SIGSEGV */ },         /* machine check */
  43        { 0x0300, 0x0b /* SIGSEGV */ },         /* data access */
  44        { 0x0400, 0x0b /* SIGSEGV */ },         /* instruction access */
  45        { 0x0500, 0x02 /* SIGINT */  },         /* external interrupt */
  46        { 0x0600, 0x0a /* SIGBUS */  },         /* alignment */
  47        { 0x0700, 0x05 /* SIGTRAP */ },         /* program check */
  48        { 0x0800, 0x08 /* SIGFPE */  },         /* fp unavailable */
  49        { 0x0900, 0x0e /* SIGALRM */ },         /* decrementer */
  50        { 0x0c00, 0x14 /* SIGCHLD */ },         /* system call */
  51#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
  52        { 0x2002, 0x05 /* SIGTRAP */ },         /* debug */
  53#if defined(CONFIG_FSL_BOOKE)
  54        { 0x2010, 0x08 /* SIGFPE */  },         /* spe unavailable */
  55        { 0x2020, 0x08 /* SIGFPE */  },         /* spe unavailable */
  56        { 0x2030, 0x08 /* SIGFPE */  },         /* spe fp data */
  57        { 0x2040, 0x08 /* SIGFPE */  },         /* spe fp data */
  58        { 0x2050, 0x08 /* SIGFPE */  },         /* spe fp round */
  59        { 0x2060, 0x0e /* SIGILL */  },         /* performance monitor */
  60        { 0x2900, 0x08 /* SIGFPE */  },         /* apu unavailable */
  61        { 0x3100, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  62        { 0x3200, 0x02 /* SIGINT */  },         /* watchdog */
  63#else /* ! CONFIG_FSL_BOOKE */
  64        { 0x1000, 0x0e /* SIGALRM */ },         /* prog interval timer */
  65        { 0x1010, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  66        { 0x1020, 0x02 /* SIGINT */  },         /* watchdog */
  67        { 0x2010, 0x08 /* SIGFPE */  },         /* fp unavailable */
  68        { 0x2020, 0x08 /* SIGFPE */  },         /* ap unavailable */
  69#endif
  70#else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
  71        { 0x0d00, 0x05 /* SIGTRAP */ },         /* single-step */
  72#if defined(CONFIG_PPC_8xx)
  73        { 0x1000, 0x04 /* SIGILL */  },         /* software emulation */
  74#else /* ! CONFIG_PPC_8xx */
  75        { 0x0f00, 0x04 /* SIGILL */  },         /* performance monitor */
  76        { 0x0f20, 0x08 /* SIGFPE */  },         /* altivec unavailable */
  77        { 0x1300, 0x05 /* SIGTRAP */ },         /* instruction address break */
  78#if defined(CONFIG_PPC64)
  79        { 0x1200, 0x05 /* SIGILL */  },         /* system error */
  80        { 0x1500, 0x04 /* SIGILL */  },         /* soft patch */
  81        { 0x1600, 0x04 /* SIGILL */  },         /* maintenance */
  82        { 0x1700, 0x08 /* SIGFPE */  },         /* altivec assist */
  83        { 0x1800, 0x04 /* SIGILL */  },         /* thermal */
  84#else /* ! CONFIG_PPC64 */
  85        { 0x1400, 0x02 /* SIGINT */  },         /* SMI */
  86        { 0x1600, 0x08 /* SIGFPE */  },         /* altivec assist */
  87        { 0x1700, 0x04 /* SIGILL */  },         /* TAU */
  88        { 0x2000, 0x05 /* SIGTRAP */ },         /* run mode */
  89#endif
  90#endif
  91#endif
  92        { 0x0000, 0x00 }                        /* Must be last */
  93};
  94
  95static int computeSignal(unsigned int tt)
  96{
  97        struct hard_trap_info *ht;
  98
  99        for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
 100                if (ht->tt == tt)
 101                        return ht->signo;
 102
 103        return SIGHUP;          /* default for things we don't know about */
 104}
 105
 106/**
 107 *
 108 *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
 109 *      @exception: Exception vector number
 110 *      @regs: Current &struct pt_regs.
 111 *
 112 *      On some architectures we need to skip a breakpoint exception when
 113 *      it occurs after a breakpoint has been removed.
 114 *
 115 */
 116int kgdb_skipexception(int exception, struct pt_regs *regs)
 117{
 118        return kgdb_isremovedbreak(regs->nip);
 119}
 120
 121static int kgdb_debugger_ipi(struct pt_regs *regs)
 122{
 123        kgdb_nmicallback(raw_smp_processor_id(), regs);
 124        return 0;
 125}
 126
 127#ifdef CONFIG_SMP
 128void kgdb_roundup_cpus(void)
 129{
 130        smp_send_debugger_break();
 131}
 132#endif
 133
 134/* KGDB functions to use existing PowerPC64 hooks. */
 135static int kgdb_debugger(struct pt_regs *regs)
 136{
 137        return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),
 138                                      DIE_OOPS, regs);
 139}
 140
 141static int kgdb_handle_breakpoint(struct pt_regs *regs)
 142{
 143        if (user_mode(regs))
 144                return 0;
 145
 146        if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
 147                return 0;
 148
 149        if (*(u32 *)regs->nip == BREAK_INSTR)
 150                regs->nip += BREAK_INSTR_SIZE;
 151
 152        return 1;
 153}
 154
 155static int kgdb_singlestep(struct pt_regs *regs)
 156{
 157        if (user_mode(regs))
 158                return 0;
 159
 160        kgdb_handle_exception(0, SIGTRAP, 0, regs);
 161
 162        return 1;
 163}
 164
 165static int kgdb_iabr_match(struct pt_regs *regs)
 166{
 167        if (user_mode(regs))
 168                return 0;
 169
 170        if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 171                return 0;
 172        return 1;
 173}
 174
 175static int kgdb_break_match(struct pt_regs *regs)
 176{
 177        if (user_mode(regs))
 178                return 0;
 179
 180        if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 181                return 0;
 182        return 1;
 183}
 184
 185#define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
 186
 187#define PACK32(ptr, src) do {          \
 188        u32 *ptr32;                   \
 189        ptr32 = (u32 *)ptr;           \
 190        *(ptr32++) = (src);           \
 191        ptr = (unsigned long *)ptr32; \
 192        } while (0)
 193
 194void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 195{
 196        struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
 197                                                  STACK_FRAME_OVERHEAD);
 198        unsigned long *ptr = gdb_regs;
 199        int reg;
 200
 201        memset(gdb_regs, 0, NUMREGBYTES);
 202
 203        /* Regs GPR0-2 */
 204        for (reg = 0; reg < 3; reg++)
 205                PACK64(ptr, regs->gpr[reg]);
 206
 207        /* Regs GPR3-13 are caller saved, not in regs->gpr[] */
 208        ptr += 11;
 209
 210        /* Regs GPR14-31 */
 211        for (reg = 14; reg < 32; reg++)
 212                PACK64(ptr, regs->gpr[reg]);
 213
 214#ifdef CONFIG_FSL_BOOKE
 215#ifdef CONFIG_SPE
 216        for (reg = 0; reg < 32; reg++)
 217                PACK64(ptr, p->thread.evr[reg]);
 218#else
 219        ptr += 32;
 220#endif
 221#else
 222        /* fp registers not used by kernel, leave zero */
 223        ptr += 32 * 8 / sizeof(long);
 224#endif
 225
 226        PACK64(ptr, regs->nip);
 227        PACK64(ptr, regs->msr);
 228        PACK32(ptr, regs->ccr);
 229        PACK64(ptr, regs->link);
 230        PACK64(ptr, regs->ctr);
 231        PACK32(ptr, regs->xer);
 232
 233        BUG_ON((unsigned long)ptr >
 234               (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 235}
 236
 237#define GDB_SIZEOF_REG sizeof(unsigned long)
 238#define GDB_SIZEOF_REG_U32 sizeof(u32)
 239
 240#ifdef CONFIG_FSL_BOOKE
 241#define GDB_SIZEOF_FLOAT_REG sizeof(unsigned long)
 242#else
 243#define GDB_SIZEOF_FLOAT_REG sizeof(u64)
 244#endif
 245
 246struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 247{
 248        { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[0]) },
 249        { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[1]) },
 250        { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[2]) },
 251        { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[3]) },
 252        { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[4]) },
 253        { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[5]) },
 254        { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[6]) },
 255        { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[7]) },
 256        { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[8]) },
 257        { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[9]) },
 258        { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[10]) },
 259        { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[11]) },
 260        { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[12]) },
 261        { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[13]) },
 262        { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[14]) },
 263        { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[15]) },
 264        { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[16]) },
 265        { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[17]) },
 266        { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[18]) },
 267        { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[19]) },
 268        { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[20]) },
 269        { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[21]) },
 270        { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[22]) },
 271        { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[23]) },
 272        { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[24]) },
 273        { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[25]) },
 274        { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[26]) },
 275        { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[27]) },
 276        { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[28]) },
 277        { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[29]) },
 278        { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[30]) },
 279        { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[31]) },
 280
 281        { "f0", GDB_SIZEOF_FLOAT_REG, 0 },
 282        { "f1", GDB_SIZEOF_FLOAT_REG, 1 },
 283        { "f2", GDB_SIZEOF_FLOAT_REG, 2 },
 284        { "f3", GDB_SIZEOF_FLOAT_REG, 3 },
 285        { "f4", GDB_SIZEOF_FLOAT_REG, 4 },
 286        { "f5", GDB_SIZEOF_FLOAT_REG, 5 },
 287        { "f6", GDB_SIZEOF_FLOAT_REG, 6 },
 288        { "f7", GDB_SIZEOF_FLOAT_REG, 7 },
 289        { "f8", GDB_SIZEOF_FLOAT_REG, 8 },
 290        { "f9", GDB_SIZEOF_FLOAT_REG, 9 },
 291        { "f10", GDB_SIZEOF_FLOAT_REG, 10 },
 292        { "f11", GDB_SIZEOF_FLOAT_REG, 11 },
 293        { "f12", GDB_SIZEOF_FLOAT_REG, 12 },
 294        { "f13", GDB_SIZEOF_FLOAT_REG, 13 },
 295        { "f14", GDB_SIZEOF_FLOAT_REG, 14 },
 296        { "f15", GDB_SIZEOF_FLOAT_REG, 15 },
 297        { "f16", GDB_SIZEOF_FLOAT_REG, 16 },
 298        { "f17", GDB_SIZEOF_FLOAT_REG, 17 },
 299        { "f18", GDB_SIZEOF_FLOAT_REG, 18 },
 300        { "f19", GDB_SIZEOF_FLOAT_REG, 19 },
 301        { "f20", GDB_SIZEOF_FLOAT_REG, 20 },
 302        { "f21", GDB_SIZEOF_FLOAT_REG, 21 },
 303        { "f22", GDB_SIZEOF_FLOAT_REG, 22 },
 304        { "f23", GDB_SIZEOF_FLOAT_REG, 23 },
 305        { "f24", GDB_SIZEOF_FLOAT_REG, 24 },
 306        { "f25", GDB_SIZEOF_FLOAT_REG, 25 },
 307        { "f26", GDB_SIZEOF_FLOAT_REG, 26 },
 308        { "f27", GDB_SIZEOF_FLOAT_REG, 27 },
 309        { "f28", GDB_SIZEOF_FLOAT_REG, 28 },
 310        { "f29", GDB_SIZEOF_FLOAT_REG, 29 },
 311        { "f30", GDB_SIZEOF_FLOAT_REG, 30 },
 312        { "f31", GDB_SIZEOF_FLOAT_REG, 31 },
 313
 314        { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, nip) },
 315        { "msr", GDB_SIZEOF_REG, offsetof(struct pt_regs, msr) },
 316        { "cr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ccr) },
 317        { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, link) },
 318        { "ctr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ctr) },
 319        { "xer", GDB_SIZEOF_REG, offsetof(struct pt_regs, xer) },
 320};
 321
 322char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 323{
 324        if (regno >= DBG_MAX_REG_NUM || regno < 0)
 325                return NULL;
 326
 327        if (regno < 32 || regno >= 64)
 328                /* First 0 -> 31 gpr registers*/
 329                /* pc, msr, ls... registers 64 -> 69 */
 330                memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 331                                dbg_reg_def[regno].size);
 332
 333        if (regno >= 32 && regno < 64) {
 334                /* FP registers 32 -> 63 */
 335#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
 336                if (current)
 337                        memcpy(mem, &current->thread.evr[regno-32],
 338                                        dbg_reg_def[regno].size);
 339#else
 340                /* fp registers not used by kernel, leave zero */
 341                memset(mem, 0, dbg_reg_def[regno].size);
 342#endif
 343        }
 344
 345        return dbg_reg_def[regno].name;
 346}
 347
 348int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 349{
 350        if (regno >= DBG_MAX_REG_NUM || regno < 0)
 351                return -EINVAL;
 352
 353        if (regno < 32 || regno >= 64)
 354                /* First 0 -> 31 gpr registers*/
 355                /* pc, msr, ls... registers 64 -> 69 */
 356                memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 357                                dbg_reg_def[regno].size);
 358
 359        if (regno >= 32 && regno < 64) {
 360                /* FP registers 32 -> 63 */
 361#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
 362                memcpy(&current->thread.evr[regno-32], mem,
 363                                dbg_reg_def[regno].size);
 364#else
 365                /* fp registers not used by kernel, leave zero */
 366                return 0;
 367#endif
 368        }
 369
 370        return 0;
 371}
 372
 373void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 374{
 375        regs->nip = pc;
 376}
 377
 378/*
 379 * This function does PowerPC specific procesing for interfacing to gdb.
 380 */
 381int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 382                               char *remcom_in_buffer, char *remcom_out_buffer,
 383                               struct pt_regs *linux_regs)
 384{
 385        char *ptr = &remcom_in_buffer[1];
 386        unsigned long addr;
 387
 388        switch (remcom_in_buffer[0]) {
 389                /*
 390                 * sAA..AA   Step one instruction from AA..AA
 391                 * This will return an error to gdb ..
 392                 */
 393        case 's':
 394        case 'c':
 395                /* handle the optional parameter */
 396                if (kgdb_hex2long(&ptr, &addr))
 397                        linux_regs->nip = addr;
 398
 399                atomic_set(&kgdb_cpu_doing_single_step, -1);
 400                /* set the trace bit if we're stepping */
 401                if (remcom_in_buffer[0] == 's') {
 402#ifdef CONFIG_PPC_ADV_DEBUG_REGS
 403                        mtspr(SPRN_DBCR0,
 404                              mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
 405                        linux_regs->msr |= MSR_DE;
 406#else
 407                        linux_regs->msr |= MSR_SE;
 408#endif
 409                        atomic_set(&kgdb_cpu_doing_single_step,
 410                                   raw_smp_processor_id());
 411                }
 412                return 0;
 413        }
 414
 415        return -1;
 416}
 417
 418int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 419{
 420        int err;
 421        unsigned int instr;
 422        struct ppc_inst *addr = (struct ppc_inst *)bpt->bpt_addr;
 423
 424        err = get_kernel_nofault(instr, (unsigned *) addr);
 425        if (err)
 426                return err;
 427
 428        err = patch_instruction(addr, ppc_inst(BREAK_INSTR));
 429        if (err)
 430                return -EFAULT;
 431
 432        *(unsigned int *)bpt->saved_instr = instr;
 433
 434        return 0;
 435}
 436
 437int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 438{
 439        int err;
 440        unsigned int instr = *(unsigned int *)bpt->saved_instr;
 441        struct ppc_inst *addr = (struct ppc_inst *)bpt->bpt_addr;
 442
 443        err = patch_instruction(addr, ppc_inst(instr));
 444        if (err)
 445                return -EFAULT;
 446
 447        return 0;
 448}
 449
 450/*
 451 * Global data
 452 */
 453const struct kgdb_arch arch_kgdb_ops;
 454
 455static int kgdb_not_implemented(struct pt_regs *regs)
 456{
 457        return 0;
 458}
 459
 460static void *old__debugger_ipi;
 461static void *old__debugger;
 462static void *old__debugger_bpt;
 463static void *old__debugger_sstep;
 464static void *old__debugger_iabr_match;
 465static void *old__debugger_break_match;
 466static void *old__debugger_fault_handler;
 467
 468int kgdb_arch_init(void)
 469{
 470        old__debugger_ipi = __debugger_ipi;
 471        old__debugger = __debugger;
 472        old__debugger_bpt = __debugger_bpt;
 473        old__debugger_sstep = __debugger_sstep;
 474        old__debugger_iabr_match = __debugger_iabr_match;
 475        old__debugger_break_match = __debugger_break_match;
 476        old__debugger_fault_handler = __debugger_fault_handler;
 477
 478        __debugger_ipi = kgdb_debugger_ipi;
 479        __debugger = kgdb_debugger;
 480        __debugger_bpt = kgdb_handle_breakpoint;
 481        __debugger_sstep = kgdb_singlestep;
 482        __debugger_iabr_match = kgdb_iabr_match;
 483        __debugger_break_match = kgdb_break_match;
 484        __debugger_fault_handler = kgdb_not_implemented;
 485
 486        return 0;
 487}
 488
 489void kgdb_arch_exit(void)
 490{
 491        __debugger_ipi = old__debugger_ipi;
 492        __debugger = old__debugger;
 493        __debugger_bpt = old__debugger_bpt;
 494        __debugger_sstep = old__debugger_sstep;
 495        __debugger_iabr_match = old__debugger_iabr_match;
 496        __debugger_break_match = old__debugger_break_match;
 497        __debugger_fault_handler = old__debugger_fault_handler;
 498}
 499
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