LXR linux/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 <linux/slab.h>
  28
  29/*
  30 * This table contains the mapping between PowerPC hardware trap types, and
  31 * signals, which are primarily what GDB understands.  GDB and the kernel
  32 * don't always agree on values, so we use constants taken from gdb-6.2.
  33 */
  34static struct hard_trap_info
  35{
  36        unsigned int tt;                /* Trap type code for powerpc */
  37        unsigned char signo;            /* Signal that we map this trap into */
  38} hard_trap_info[] = {
  39        { 0x0100, 0x02 /* SIGINT */  },         /* system reset */
  40        { 0x0200, 0x0b /* SIGSEGV */ },         /* machine check */
  41        { 0x0300, 0x0b /* SIGSEGV */ },         /* data access */
  42        { 0x0400, 0x0b /* SIGSEGV */ },         /* instruction access */
  43        { 0x0500, 0x02 /* SIGINT */  },         /* external interrupt */
  44        { 0x0600, 0x0a /* SIGBUS */  },         /* alignment */
  45        { 0x0700, 0x05 /* SIGTRAP */ },         /* program check */
  46        { 0x0800, 0x08 /* SIGFPE */  },         /* fp unavailable */
  47        { 0x0900, 0x0e /* SIGALRM */ },         /* decrementer */
  48        { 0x0c00, 0x14 /* SIGCHLD */ },         /* system call */
  49#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
  50        { 0x2002, 0x05 /* SIGTRAP */ },         /* debug */
  51#if defined(CONFIG_FSL_BOOKE)
  52        { 0x2010, 0x08 /* SIGFPE */  },         /* spe unavailable */
  53        { 0x2020, 0x08 /* SIGFPE */  },         /* spe unavailable */
  54        { 0x2030, 0x08 /* SIGFPE */  },         /* spe fp data */
  55        { 0x2040, 0x08 /* SIGFPE */  },         /* spe fp data */
  56        { 0x2050, 0x08 /* SIGFPE */  },         /* spe fp round */
  57        { 0x2060, 0x0e /* SIGILL */  },         /* performance monitor */
  58        { 0x2900, 0x08 /* SIGFPE */  },         /* apu unavailable */
  59        { 0x3100, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  60        { 0x3200, 0x02 /* SIGINT */  },         /* watchdog */
  61#else /* ! CONFIG_FSL_BOOKE */
  62        { 0x1000, 0x0e /* SIGALRM */ },         /* prog interval timer */
  63        { 0x1010, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  64        { 0x1020, 0x02 /* SIGINT */  },         /* watchdog */
  65        { 0x2010, 0x08 /* SIGFPE */  },         /* fp unavailable */
  66        { 0x2020, 0x08 /* SIGFPE */  },         /* ap unavailable */
  67#endif
  68#else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
  69        { 0x0d00, 0x05 /* SIGTRAP */ },         /* single-step */
  70#if defined(CONFIG_PPC_8xx)
  71        { 0x1000, 0x04 /* SIGILL */  },         /* software emulation */
  72#else /* ! CONFIG_PPC_8xx */
  73        { 0x0f00, 0x04 /* SIGILL */  },         /* performance monitor */
  74        { 0x0f20, 0x08 /* SIGFPE */  },         /* altivec unavailable */
  75        { 0x1300, 0x05 /* SIGTRAP */ },         /* instruction address break */
  76#if defined(CONFIG_PPC64)
  77        { 0x1200, 0x05 /* SIGILL */  },         /* system error */
  78        { 0x1500, 0x04 /* SIGILL */  },         /* soft patch */
  79        { 0x1600, 0x04 /* SIGILL */  },         /* maintenance */
  80        { 0x1700, 0x08 /* SIGFPE */  },         /* altivec assist */
  81        { 0x1800, 0x04 /* SIGILL */  },         /* thermal */
  82#else /* ! CONFIG_PPC64 */
  83        { 0x1400, 0x02 /* SIGINT */  },         /* SMI */
  84        { 0x1600, 0x08 /* SIGFPE */  },         /* altivec assist */
  85        { 0x1700, 0x04 /* SIGILL */  },         /* TAU */
  86        { 0x2000, 0x05 /* SIGTRAP */ },         /* run mode */
  87#endif
  88#endif
  89#endif
  90        { 0x0000, 0x00 }                        /* Must be last */
  91};
  92
  93static int computeSignal(unsigned int tt)
  94{
  95        struct hard_trap_info *ht;
  96
  97        for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
  98                if (ht->tt == tt)
  99                        return ht->signo;
 100
 101        return SIGHUP;          /* default for things we don't know about */
 102}
 103
 104/**
 105 *
 106 *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
 107 *      @exception: Exception vector number
 108 *      @regs: Current &struct pt_regs.
 109 *
 110 *      On some architectures we need to skip a breakpoint exception when
 111 *      it occurs after a breakpoint has been removed.
 112 *
 113 */
 114int kgdb_skipexception(int exception, struct pt_regs *regs)
 115{
 116        return kgdb_isremovedbreak(regs->nip);
 117}
 118
 119static int kgdb_call_nmi_hook(struct pt_regs *regs)
 120{
 121        kgdb_nmicallback(raw_smp_processor_id(), regs);
 122        return 0;
 123}
 124
 125#ifdef CONFIG_SMP
 126void kgdb_roundup_cpus(unsigned long flags)
 127{
 128        smp_send_debugger_break();
 129}
 130#endif
 131
 132/* KGDB functions to use existing PowerPC64 hooks. */
 133static int kgdb_debugger(struct pt_regs *regs)
 134{
 135        return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),
 136                                      DIE_OOPS, regs);
 137}
 138
 139static int kgdb_handle_breakpoint(struct pt_regs *regs)
 140{
 141        if (user_mode(regs))
 142                return 0;
 143
 144        if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
 145                return 0;
 146
 147        if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
 148                regs->nip += BREAK_INSTR_SIZE;
 149
 150        return 1;
 151}
 152
 153static DEFINE_PER_CPU(struct thread_info, kgdb_thread_info);
 154static int kgdb_singlestep(struct pt_regs *regs)
 155{
 156        struct thread_info *thread_info, *exception_thread_info;
 157        struct thread_info *backup_current_thread_info =
 158                this_cpu_ptr(&kgdb_thread_info);
 159
 160        if (user_mode(regs))
 161                return 0;
 162
 163        /*
 164         * On Book E and perhaps other processors, singlestep is handled on
 165         * the critical exception stack.  This causes current_thread_info()
 166         * to fail, since it it locates the thread_info by masking off
 167         * the low bits of the current stack pointer.  We work around
 168         * this issue by copying the thread_info from the kernel stack
 169         * before calling kgdb_handle_exception, and copying it back
 170         * afterwards.  On most processors the copy is avoided since
 171         * exception_thread_info == thread_info.
 172         */
 173        thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1));
 174        exception_thread_info = current_thread_info();
 175
 176        if (thread_info != exception_thread_info) {
 177                /* Save the original current_thread_info. */
 178                memcpy(backup_current_thread_info, exception_thread_info, sizeof *thread_info);
 179                memcpy(exception_thread_info, thread_info, sizeof *thread_info);
 180        }
 181
 182        kgdb_handle_exception(0, SIGTRAP, 0, regs);
 183
 184        if (thread_info != exception_thread_info)
 185                /* Restore current_thread_info lastly. */
 186                memcpy(exception_thread_info, backup_current_thread_info, sizeof *thread_info);
 187
 188        return 1;
 189}
 190
 191static int kgdb_iabr_match(struct pt_regs *regs)
 192{
 193        if (user_mode(regs))
 194                return 0;
 195
 196        if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 197                return 0;
 198        return 1;
 199}
 200
 201static int kgdb_break_match(struct pt_regs *regs)
 202{
 203        if (user_mode(regs))
 204                return 0;
 205
 206        if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 207                return 0;
 208        return 1;
 209}
 210
 211#define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
 212
 213#define PACK32(ptr, src) do {          \
 214        u32 *ptr32;                   \
 215        ptr32 = (u32 *)ptr;           \
 216        *(ptr32++) = (src);           \
 217        ptr = (unsigned long *)ptr32; \
 218        } while (0)
 219
 220void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 221{
 222        struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
 223                                                  STACK_FRAME_OVERHEAD);
 224        unsigned long *ptr = gdb_regs;
 225        int reg;
 226
 227        memset(gdb_regs, 0, NUMREGBYTES);
 228
 229        /* Regs GPR0-2 */
 230        for (reg = 0; reg < 3; reg++)
 231                PACK64(ptr, regs->gpr[reg]);
 232
 233        /* Regs GPR3-13 are caller saved, not in regs->gpr[] */
 234        ptr += 11;
 235
 236        /* Regs GPR14-31 */
 237        for (reg = 14; reg < 32; reg++)
 238                PACK64(ptr, regs->gpr[reg]);
 239
 240#ifdef CONFIG_FSL_BOOKE
 241#ifdef CONFIG_SPE
 242        for (reg = 0; reg < 32; reg++)
 243                PACK64(ptr, p->thread.evr[reg]);
 244#else
 245        ptr += 32;
 246#endif
 247#else
 248        /* fp registers not used by kernel, leave zero */
 249        ptr += 32 * 8 / sizeof(long);
 250#endif
 251
 252        PACK64(ptr, regs->nip);
 253        PACK64(ptr, regs->msr);
 254        PACK32(ptr, regs->ccr);
 255        PACK64(ptr, regs->link);
 256        PACK64(ptr, regs->ctr);
 257        PACK32(ptr, regs->xer);
 258
 259        BUG_ON((unsigned long)ptr >
 260               (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 261}
 262
 263#define GDB_SIZEOF_REG sizeof(unsigned long)
 264#define GDB_SIZEOF_REG_U32 sizeof(u32)
 265
 266#ifdef CONFIG_FSL_BOOKE
 267#define GDB_SIZEOF_FLOAT_REG sizeof(unsigned long)
 268#else
 269#define GDB_SIZEOF_FLOAT_REG sizeof(u64)
 270#endif
 271
 272struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 273{
 274        { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[0]) },
 275        { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[1]) },
 276        { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[2]) },
 277        { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[3]) },
 278        { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[4]) },
 279        { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[5]) },
 280        { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[6]) },
 281        { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[7]) },
 282        { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[8]) },
 283        { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[9]) },
 284        { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[10]) },
 285        { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[11]) },
 286        { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[12]) },
 287        { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[13]) },
 288        { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[14]) },
 289        { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[15]) },
 290        { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[16]) },
 291        { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[17]) },
 292        { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[18]) },
 293        { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[19]) },
 294        { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[20]) },
 295        { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[21]) },
 296        { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[22]) },
 297        { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[23]) },
 298        { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[24]) },
 299        { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[25]) },
 300        { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[26]) },
 301        { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[27]) },
 302        { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[28]) },
 303        { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[29]) },
 304        { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[30]) },
 305        { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[31]) },
 306
 307        { "f0", GDB_SIZEOF_FLOAT_REG, 0 },
 308        { "f1", GDB_SIZEOF_FLOAT_REG, 1 },
 309        { "f2", GDB_SIZEOF_FLOAT_REG, 2 },
 310        { "f3", GDB_SIZEOF_FLOAT_REG, 3 },
 311        { "f4", GDB_SIZEOF_FLOAT_REG, 4 },
 312        { "f5", GDB_SIZEOF_FLOAT_REG, 5 },
 313        { "f6", GDB_SIZEOF_FLOAT_REG, 6 },
 314        { "f7", GDB_SIZEOF_FLOAT_REG, 7 },
 315        { "f8", GDB_SIZEOF_FLOAT_REG, 8 },
 316        { "f9", GDB_SIZEOF_FLOAT_REG, 9 },
 317        { "f10", GDB_SIZEOF_FLOAT_REG, 10 },
 318        { "f11", GDB_SIZEOF_FLOAT_REG, 11 },
 319        { "f12", GDB_SIZEOF_FLOAT_REG, 12 },
 320        { "f13", GDB_SIZEOF_FLOAT_REG, 13 },
 321        { "f14", GDB_SIZEOF_FLOAT_REG, 14 },
 322        { "f15", GDB_SIZEOF_FLOAT_REG, 15 },
 323        { "f16", GDB_SIZEOF_FLOAT_REG, 16 },
 324        { "f17", GDB_SIZEOF_FLOAT_REG, 17 },
 325        { "f18", GDB_SIZEOF_FLOAT_REG, 18 },
 326        { "f19", GDB_SIZEOF_FLOAT_REG, 19 },
 327        { "f20", GDB_SIZEOF_FLOAT_REG, 20 },
 328        { "f21", GDB_SIZEOF_FLOAT_REG, 21 },
 329        { "f22", GDB_SIZEOF_FLOAT_REG, 22 },
 330        { "f23", GDB_SIZEOF_FLOAT_REG, 23 },
 331        { "f24", GDB_SIZEOF_FLOAT_REG, 24 },
 332        { "f25", GDB_SIZEOF_FLOAT_REG, 25 },
 333        { "f26", GDB_SIZEOF_FLOAT_REG, 26 },
 334        { "f27", GDB_SIZEOF_FLOAT_REG, 27 },
 335        { "f28", GDB_SIZEOF_FLOAT_REG, 28 },
 336        { "f29", GDB_SIZEOF_FLOAT_REG, 29 },
 337        { "f30", GDB_SIZEOF_FLOAT_REG, 30 },
 338        { "f31", GDB_SIZEOF_FLOAT_REG, 31 },
 339
 340        { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, nip) },
 341        { "msr", GDB_SIZEOF_REG, offsetof(struct pt_regs, msr) },
 342        { "cr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ccr) },
 343        { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, link) },
 344        { "ctr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ctr) },
 345        { "xer", GDB_SIZEOF_REG, offsetof(struct pt_regs, xer) },
 346};
 347
 348char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 349{
 350        if (regno >= DBG_MAX_REG_NUM || regno < 0)
 351                return NULL;
 352
 353        if (regno < 32 || regno >= 64)
 354                /* First 0 -> 31 gpr registers*/
 355                /* pc, msr, ls... registers 64 -> 69 */
 356                memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 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                if (current)
 363                        memcpy(mem, &current->thread.evr[regno-32],
 364                                        dbg_reg_def[regno].size);
 365#else
 366                /* fp registers not used by kernel, leave zero */
 367                memset(mem, 0, dbg_reg_def[regno].size);
 368#endif
 369        }
 370
 371        return dbg_reg_def[regno].name;
 372}
 373
 374int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 375{
 376        if (regno >= DBG_MAX_REG_NUM || regno < 0)
 377                return -EINVAL;
 378
 379        if (regno < 32 || regno >= 64)
 380                /* First 0 -> 31 gpr registers*/
 381                /* pc, msr, ls... registers 64 -> 69 */
 382                memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 383                                dbg_reg_def[regno].size);
 384
 385        if (regno >= 32 && regno < 64) {
 386                /* FP registers 32 -> 63 */
 387#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
 388                memcpy(&current->thread.evr[regno-32], mem,
 389                                dbg_reg_def[regno].size);
 390#else
 391                /* fp registers not used by kernel, leave zero */
 392                return 0;
 393#endif
 394        }
 395
 396        return 0;
 397}
 398
 399void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 400{
 401        regs->nip = pc;
 402}
 403
 404/*
 405 * This function does PowerPC specific procesing for interfacing to gdb.
 406 */
 407int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 408                               char *remcom_in_buffer, char *remcom_out_buffer,
 409                               struct pt_regs *linux_regs)
 410{
 411        char *ptr = &remcom_in_buffer[1];
 412        unsigned long addr;
 413
 414        switch (remcom_in_buffer[0]) {
 415                /*
 416                 * sAA..AA   Step one instruction from AA..AA
 417                 * This will return an error to gdb ..
 418                 */
 419        case 's':
 420        case 'c':
 421                /* handle the optional parameter */
 422                if (kgdb_hex2long(&ptr, &addr))
 423                        linux_regs->nip = addr;
 424
 425                atomic_set(&kgdb_cpu_doing_single_step, -1);
 426                /* set the trace bit if we're stepping */
 427                if (remcom_in_buffer[0] == 's') {
 428#ifdef CONFIG_PPC_ADV_DEBUG_REGS
 429                        mtspr(SPRN_DBCR0,
 430                              mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
 431                        linux_regs->msr |= MSR_DE;
 432#else
 433                        linux_regs->msr |= MSR_SE;
 434#endif
 435                        atomic_set(&kgdb_cpu_doing_single_step,
 436                                   raw_smp_processor_id());
 437                }
 438                return 0;
 439        }
 440
 441        return -1;
 442}
 443
 444/*
 445 * Global data
 446 */
 447struct kgdb_arch arch_kgdb_ops = {
 448#ifdef __LITTLE_ENDIAN__
 449        .gdb_bpt_instr = {0x08, 0x10, 0x82, 0x7d},
 450#else
 451        .gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
 452#endif
 453};
 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_call_nmi_hook;
 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