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/init.h>
  19 #include <linux/kgdb.h>
  20 #include <linux/smp.h>
  21 #include <linux/signal.h>
  22 #include <linux/ptrace.h>
  23 #include <asm/current.h>
  24 #include <asm/processor.h>
  25 #include <asm/machdep.h>
  26
  27 /*
  28  * This table contains the mapping between PowerPC hardware trap types, and
  29  * signals, which are primarily what GDB understands.  GDB and the kernel
  30  * don't always agree on values, so we use constants taken from gdb-6.2.
  31  */
  32 static struct hard_trap_info
  33 {
  34         unsigned int tt;                /* Trap type code for powerpc */
  35         unsigned char signo;            /* Signal that we map this trap into */
  36 } hard_trap_info[] = {
  37         { 0x0100, 0x02 /* SIGINT */  },         /* system reset */
  38         { 0x0200, 0x0b /* SIGSEGV */ },         /* machine check */
  39         { 0x0300, 0x0b /* SIGSEGV */ },         /* data access */
  40         { 0x0400, 0x0b /* SIGSEGV */ },         /* instruction access */
  41         { 0x0500, 0x02 /* SIGINT */  },         /* external interrupt */
  42         { 0x0600, 0x0a /* SIGBUS */  },         /* alignment */
  43         { 0x0700, 0x05 /* SIGTRAP */ },         /* program check */
  44         { 0x0800, 0x08 /* SIGFPE */  },         /* fp unavailable */
  45         { 0x0900, 0x0e /* SIGALRM */ },         /* decrementer */
  46         { 0x0c00, 0x14 /* SIGCHLD */ },         /* system call */
  47 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
  48         { 0x2002, 0x05 /* SIGTRAP */ },         /* debug */
  49 #if defined(CONFIG_FSL_BOOKE)
  50         { 0x2010, 0x08 /* SIGFPE */  },         /* spe unavailable */
  51         { 0x2020, 0x08 /* SIGFPE */  },         /* spe unavailable */
  52         { 0x2030, 0x08 /* SIGFPE */  },         /* spe fp data */
  53         { 0x2040, 0x08 /* SIGFPE */  },         /* spe fp data */
  54         { 0x2050, 0x08 /* SIGFPE */  },         /* spe fp round */
  55         { 0x2060, 0x0e /* SIGILL */  },         /* performance monitor */
  56         { 0x2900, 0x08 /* SIGFPE */  },         /* apu unavailable */
  57         { 0x3100, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  58         { 0x3200, 0x02 /* SIGINT */  },         /* watchdog */
  59 #else /* ! CONFIG_FSL_BOOKE */
  60         { 0x1000, 0x0e /* SIGALRM */ },         /* prog interval timer */
  61         { 0x1010, 0x0e /* SIGALRM */ },         /* fixed interval timer */
  62         { 0x1020, 0x02 /* SIGINT */  },         /* watchdog */
  63         { 0x2010, 0x08 /* SIGFPE */  },         /* fp unavailable */
  64         { 0x2020, 0x08 /* SIGFPE */  },         /* ap unavailable */
  65 #endif
  66 #else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
  67         { 0x0d00, 0x05 /* SIGTRAP */ },         /* single-step */
  68 #if defined(CONFIG_8xx)
  69         { 0x1000, 0x04 /* SIGILL */  },         /* software emulation */
  70 #else /* ! CONFIG_8xx */
  71         { 0x0f00, 0x04 /* SIGILL */  },         /* performance monitor */
  72         { 0x0f20, 0x08 /* SIGFPE */  },         /* altivec unavailable */
  73         { 0x1300, 0x05 /* SIGTRAP */ },         /* instruction address break */
  74 #if defined(CONFIG_PPC64)
  75         { 0x1200, 0x05 /* SIGILL */  },         /* system error */
  76         { 0x1500, 0x04 /* SIGILL */  },         /* soft patch */
  77         { 0x1600, 0x04 /* SIGILL */  },         /* maintenance */
  78         { 0x1700, 0x08 /* SIGFPE */  },         /* altivec assist */
  79         { 0x1800, 0x04 /* SIGILL */  },         /* thermal */
  80 #else /* ! CONFIG_PPC64 */
  81         { 0x1400, 0x02 /* SIGINT */  },         /* SMI */
  82         { 0x1600, 0x08 /* SIGFPE */  },         /* altivec assist */
  83         { 0x1700, 0x04 /* SIGILL */  },         /* TAU */
  84         { 0x2000, 0x05 /* SIGTRAP */ },         /* run mode */
  85 #endif
  86 #endif
  87 #endif
  88         { 0x0000, 0x00 }                        /* Must be last */
  89 };
  90
  91 static int computeSignal(unsigned int tt)
  92 {
  93         struct hard_trap_info *ht;
  94
  95         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
  96                 if (ht->tt == tt)
  97                         return ht->signo;
  98
  99         return SIGHUP;          /* default for things we don't know about */
 100 }
 101
 102 static int kgdb_call_nmi_hook(struct pt_regs *regs)
 103 {
 104         kgdb_nmicallback(raw_smp_processor_id(), regs);
 105         return 0;
 106 }
 107
 108 #ifdef CONFIG_SMP
 109 void kgdb_roundup_cpus(unsigned long flags)
 110 {
 111         smp_send_debugger_break(MSG_ALL_BUT_SELF);
 112 }
 113 #endif
 114
 115 /* KGDB functions to use existing PowerPC64 hooks. */
 116 static int kgdb_debugger(struct pt_regs *regs)
 117 {
 118         return kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs);
 119 }
 120
 121 static int kgdb_handle_breakpoint(struct pt_regs *regs)
 122 {
 123         if (user_mode(regs))
 124                 return 0;
 125
 126         if (kgdb_handle_exception(0, SIGTRAP, 0, regs) != 0)
 127                 return 0;
 128
 129         if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
 130                 regs->nip += 4;
 131
 132         return 1;
 133 }
 134
 135 static int kgdb_singlestep(struct pt_regs *regs)
 136 {
 137         struct thread_info *thread_info, *exception_thread_info;
 138
 139         if (user_mode(regs))
 140                 return 0;
 141
 142         /*
 143          * On Book E and perhaps other processsors, singlestep is handled on
 144          * the critical exception stack.  This causes current_thread_info()
 145          * to fail, since it it locates the thread_info by masking off
 146          * the low bits of the current stack pointer.  We work around
 147          * this issue by copying the thread_info from the kernel stack
 148          * before calling kgdb_handle_exception, and copying it back
 149          * afterwards.  On most processors the copy is avoided since
 150          * exception_thread_info == thread_info.
 151          */
 152         thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1));
 153         exception_thread_info = current_thread_info();
 154
 155         if (thread_info != exception_thread_info)
 156                 memcpy(exception_thread_info, thread_info, sizeof *thread_info);
 157
 158         kgdb_handle_exception(0, SIGTRAP, 0, regs);
 159
 160         if (thread_info != exception_thread_info)
 161                 memcpy(thread_info, exception_thread_info, sizeof *thread_info);
 162
 163         return 1;
 164 }
 165
 166 static int kgdb_iabr_match(struct pt_regs *regs)
 167 {
 168         if (user_mode(regs))
 169                 return 0;
 170
 171         if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 172                 return 0;
 173         return 1;
 174 }
 175
 176 static int kgdb_dabr_match(struct pt_regs *regs)
 177 {
 178         if (user_mode(regs))
 179                 return 0;
 180
 181         if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
 182                 return 0;
 183         return 1;
 184 }
 185
 186 #define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
 187
 188 #define PACK32(ptr, src) do {          \
 189         u32 *ptr32;                   \
 190         ptr32 = (u32 *)ptr;           \
 191         *(ptr32++) = (src);           \
 192         ptr = (unsigned long *)ptr32; \
 193         } while (0)
 194
 195
 196 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 197 {
 198         unsigned long *ptr = gdb_regs;
 199         int reg;
 200
 201         memset(gdb_regs, 0, NUMREGBYTES);
 202
 203         for (reg = 0; reg < 32; reg++)
 204                 PACK64(ptr, regs->gpr[reg]);
 205
 206 #ifdef CONFIG_FSL_BOOKE
 207 #ifdef CONFIG_SPE
 208         for (reg = 0; reg < 32; reg++)
 209                 PACK64(ptr, current->thread.evr[reg]);
 210 #else
 211         ptr += 32;
 212 #endif
 213 #else
 214         /* fp registers not used by kernel, leave zero */
 215         ptr += 32 * 8 / sizeof(long);
 216 #endif
 217
 218         PACK64(ptr, regs->nip);
 219         PACK64(ptr, regs->msr);
 220         PACK32(ptr, regs->ccr);
 221         PACK64(ptr, regs->link);
 222         PACK64(ptr, regs->ctr);
 223         PACK32(ptr, regs->xer);
 224
 225         BUG_ON((unsigned long)ptr >
 226                (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 227 }
 228
 229 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 230 {
 231         struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
 232                                                   STACK_FRAME_OVERHEAD);
 233         unsigned long *ptr = gdb_regs;
 234         int reg;
 235
 236         memset(gdb_regs, 0, NUMREGBYTES);
 237
 238         /* Regs GPR0-2 */
 239         for (reg = 0; reg < 3; reg++)
 240                 PACK64(ptr, regs->gpr[reg]);
 241
 242         /* Regs GPR3-13 are caller saved, not in regs->gpr[] */
 243         ptr += 11;
 244
 245         /* Regs GPR14-31 */
 246         for (reg = 14; reg < 32; reg++)
 247                 PACK64(ptr, regs->gpr[reg]);
 248
 249 #ifdef CONFIG_FSL_BOOKE
 250 #ifdef CONFIG_SPE
 251         for (reg = 0; reg < 32; reg++)
 252                 PACK64(ptr, p->thread.evr[reg]);
 253 #else
 254         ptr += 32;
 255 #endif
 256 #else
 257         /* fp registers not used by kernel, leave zero */
 258         ptr += 32 * 8 / sizeof(long);
 259 #endif
 260
 261         PACK64(ptr, regs->nip);
 262         PACK64(ptr, regs->msr);
 263         PACK32(ptr, regs->ccr);
 264         PACK64(ptr, regs->link);
 265         PACK64(ptr, regs->ctr);
 266         PACK32(ptr, regs->xer);
 267
 268         BUG_ON((unsigned long)ptr >
 269                (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 270 }
 271
 272 #define UNPACK64(dest, ptr) do { dest = *(ptr++); } while (0)
 273
 274 #define UNPACK32(dest, ptr) do {       \
 275         u32 *ptr32;                   \
 276         ptr32 = (u32 *)ptr;           \
 277         dest = *(ptr32++);            \
 278         ptr = (unsigned long *)ptr32; \
 279         } while (0)
 280
 281 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 282 {
 283         unsigned long *ptr = gdb_regs;
 284         int reg;
 285
 286         for (reg = 0; reg < 32; reg++)
 287                 UNPACK64(regs->gpr[reg], ptr);
 288
 289 #ifdef CONFIG_FSL_BOOKE
 290 #ifdef CONFIG_SPE
 291         for (reg = 0; reg < 32; reg++)
 292                 UNPACK64(current->thread.evr[reg], ptr);
 293 #else
 294         ptr += 32;
 295 #endif
 296 #else
 297         /* fp registers not used by kernel, leave zero */
 298         ptr += 32 * 8 / sizeof(int);
 299 #endif
 300
 301         UNPACK64(regs->nip, ptr);
 302         UNPACK64(regs->msr, ptr);
 303         UNPACK32(regs->ccr, ptr);
 304         UNPACK64(regs->link, ptr);
 305         UNPACK64(regs->ctr, ptr);
 306         UNPACK32(regs->xer, ptr);
 307
 308         BUG_ON((unsigned long)ptr >
 309                (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 310 }
 311
 312 /*
 313  * This function does PowerPC specific procesing for interfacing to gdb.
 314  */
 315 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 316                                char *remcom_in_buffer, char *remcom_out_buffer,
 317                                struct pt_regs *linux_regs)
 318 {
 319         char *ptr = &remcom_in_buffer[1];
 320         unsigned long addr;
 321
 322         switch (remcom_in_buffer[0]) {
 323                 /*
 324                  * sAA..AA   Step one instruction from AA..AA
 325                  * This will return an error to gdb ..
 326                  */
 327         case 's':
 328         case 'c':
 329                 /* handle the optional parameter */
 330                 if (kgdb_hex2long(&ptr, &addr))
 331                         linux_regs->nip = addr;
 332
 333                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 334                 /* set the trace bit if we're stepping */
 335                 if (remcom_in_buffer[0] == 's') {
 336 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
 337                         mtspr(SPRN_DBCR0,
 338                               mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
 339                         linux_regs->msr |= MSR_DE;
 340 #else
 341                         linux_regs->msr |= MSR_SE;
 342 #endif
 343                         kgdb_single_step = 1;
 344                         atomic_set(&kgdb_cpu_doing_single_step,
 345                                    raw_smp_processor_id());
 346                 }
 347                 return 0;
 348         }
 349
 350         return -1;
 351 }
 352
 353 /*
 354  * Global data
 355  */
 356 struct kgdb_arch arch_kgdb_ops = {
 357         .gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
 358 };
 359
 360 static int kgdb_not_implemented(struct pt_regs *regs)
 361 {
 362         return 0;
 363 }
 364
 365 static void *old__debugger_ipi;
 366 static void *old__debugger;
 367 static void *old__debugger_bpt;
 368 static void *old__debugger_sstep;
 369 static void *old__debugger_iabr_match;
 370 static void *old__debugger_dabr_match;
 371 static void *old__debugger_fault_handler;
 372
 373 int kgdb_arch_init(void)
 374 {
 375         old__debugger_ipi = __debugger_ipi;
 376         old__debugger = __debugger;
 377         old__debugger_bpt = __debugger_bpt;
 378         old__debugger_sstep = __debugger_sstep;
 379         old__debugger_iabr_match = __debugger_iabr_match;
 380         old__debugger_dabr_match = __debugger_dabr_match;
 381         old__debugger_fault_handler = __debugger_fault_handler;
 382
 383         __debugger_ipi = kgdb_call_nmi_hook;
 384         __debugger = kgdb_debugger;
 385         __debugger_bpt = kgdb_handle_breakpoint;
 386         __debugger_sstep = kgdb_singlestep;
 387         __debugger_iabr_match = kgdb_iabr_match;
 388         __debugger_dabr_match = kgdb_dabr_match;
 389         __debugger_fault_handler = kgdb_not_implemented;
 390
 391         return 0;
 392 }
 393
 394 void kgdb_arch_exit(void)
 395 {
 396         __debugger_ipi = old__debugger_ipi;
 397         __debugger = old__debugger;
 398         __debugger_bpt = old__debugger_bpt;
 399         __debugger_sstep = old__debugger_sstep;
 400         __debugger_iabr_match = old__debugger_iabr_match;
 401         __debugger_dabr_match = old__debugger_dabr_match;
 402         __debugger_fault_handler = old__debugger_fault_handler;
 403 }