arch/x86/kernel/kgdb.c

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This source file includes following definitions.
dbg_set_reg
dbg_get_reg
sleeping_thread_to_gdb_regs
kgdb_correct_hw_break
hw_break_reserve_slot
hw_break_release_slot
kgdb_remove_hw_break
kgdb_remove_all_hw_break
kgdb_set_hw_break
kgdb_disable_hw_debug
kgdb_roundup_cpus
kgdb_arch_handle_exception
single_step_cont
kgdb_nmi_handler
__kgdb_notify
kgdb_ll_trap
kgdb_notify
kgdb_arch_init
kgdb_hw_overflow_handler
kgdb_arch_late
kgdb_arch_exit
kgdb_skipexception
kgdb_arch_pc
kgdb_arch_set_pc
kgdb_arch_set_breakpoint
kgdb_arch_remove_breakpoint
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  */
   4 
   5 /*
   6  * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
   7  * Copyright (C) 2000-2001 VERITAS Software Corporation.
   8  * Copyright (C) 2002 Andi Kleen, SuSE Labs
   9  * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
  10  * Copyright (C) 2007 MontaVista Software, Inc.
  11  * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
  12  */
  13 /****************************************************************************
  14  *  Contributor:     Lake Stevens Instrument Division$
  15  *  Written by:      Glenn Engel $
  16  *  Updated by:      Amit Kale<akale@veritas.com>
  17  *  Updated by:      Tom Rini <trini@kernel.crashing.org>
  18  *  Updated by:      Jason Wessel <jason.wessel@windriver.com>
  19  *  Modified for 386 by Jim Kingdon, Cygnus Support.
  20  *  Origianl kgdb, compatibility with 2.1.xx kernel by
  21  *  David Grothe <dave@gcom.com>
  22  *  Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
  23  *  X86_64 changes from Andi Kleen's patch merged by Jim Houston
  24  */
  25 #include <linux/spinlock.h>
  26 #include <linux/kdebug.h>
  27 #include <linux/string.h>
  28 #include <linux/kernel.h>
  29 #include <linux/ptrace.h>
  30 #include <linux/sched.h>
  31 #include <linux/delay.h>
  32 #include <linux/kgdb.h>
  33 #include <linux/smp.h>
  34 #include <linux/nmi.h>
  35 #include <linux/hw_breakpoint.h>
  36 #include <linux/uaccess.h>
  37 #include <linux/memory.h>
  38 
  39 #include <asm/text-patching.h>
  40 #include <asm/debugreg.h>
  41 #include <asm/apicdef.h>
  42 #include <asm/apic.h>
  43 #include <asm/nmi.h>
  44 #include <asm/switch_to.h>
  45 
  46 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
  47 {
  48 #ifdef CONFIG_X86_32
  49         { "ax", 4, offsetof(struct pt_regs, ax) },
  50         { "cx", 4, offsetof(struct pt_regs, cx) },
  51         { "dx", 4, offsetof(struct pt_regs, dx) },
  52         { "bx", 4, offsetof(struct pt_regs, bx) },
  53         { "sp", 4, offsetof(struct pt_regs, sp) },
  54         { "bp", 4, offsetof(struct pt_regs, bp) },
  55         { "si", 4, offsetof(struct pt_regs, si) },
  56         { "di", 4, offsetof(struct pt_regs, di) },
  57         { "ip", 4, offsetof(struct pt_regs, ip) },
  58         { "flags", 4, offsetof(struct pt_regs, flags) },
  59         { "cs", 4, offsetof(struct pt_regs, cs) },
  60         { "ss", 4, offsetof(struct pt_regs, ss) },
  61         { "ds", 4, offsetof(struct pt_regs, ds) },
  62         { "es", 4, offsetof(struct pt_regs, es) },
  63 #else
  64         { "ax", 8, offsetof(struct pt_regs, ax) },
  65         { "bx", 8, offsetof(struct pt_regs, bx) },
  66         { "cx", 8, offsetof(struct pt_regs, cx) },
  67         { "dx", 8, offsetof(struct pt_regs, dx) },
  68         { "si", 8, offsetof(struct pt_regs, si) },
  69         { "di", 8, offsetof(struct pt_regs, di) },
  70         { "bp", 8, offsetof(struct pt_regs, bp) },
  71         { "sp", 8, offsetof(struct pt_regs, sp) },
  72         { "r8", 8, offsetof(struct pt_regs, r8) },
  73         { "r9", 8, offsetof(struct pt_regs, r9) },
  74         { "r10", 8, offsetof(struct pt_regs, r10) },
  75         { "r11", 8, offsetof(struct pt_regs, r11) },
  76         { "r12", 8, offsetof(struct pt_regs, r12) },
  77         { "r13", 8, offsetof(struct pt_regs, r13) },
  78         { "r14", 8, offsetof(struct pt_regs, r14) },
  79         { "r15", 8, offsetof(struct pt_regs, r15) },
  80         { "ip", 8, offsetof(struct pt_regs, ip) },
  81         { "flags", 4, offsetof(struct pt_regs, flags) },
  82         { "cs", 4, offsetof(struct pt_regs, cs) },
  83         { "ss", 4, offsetof(struct pt_regs, ss) },
  84         { "ds", 4, -1 },
  85         { "es", 4, -1 },
  86 #endif
  87         { "fs", 4, -1 },
  88         { "gs", 4, -1 },
  89 };
  90 
  91 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
  92 {
  93         if (
  94 #ifdef CONFIG_X86_32
  95             regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
  96 #endif
  97             regno == GDB_SP || regno == GDB_ORIG_AX)
  98                 return 0;
  99 
 100         if (dbg_reg_def[regno].offset != -1)
 101                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 102                        dbg_reg_def[regno].size);
 103         return 0;
 104 }
 105 
 106 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 107 {
 108         if (regno == GDB_ORIG_AX) {
 109                 memcpy(mem, &regs->orig_ax, sizeof(regs->orig_ax));
 110                 return "orig_ax";
 111         }
 112         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 113                 return NULL;
 114 
 115         if (dbg_reg_def[regno].offset != -1)
 116                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 117                        dbg_reg_def[regno].size);
 118 
 119 #ifdef CONFIG_X86_32
 120         switch (regno) {
 121         case GDB_GS:
 122         case GDB_FS:
 123                 *(unsigned long *)mem = 0xFFFF;
 124                 break;
 125         }
 126 #endif
 127         return dbg_reg_def[regno].name;
 128 }
 129 
 130 /**
 131  *      sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
 132  *      @gdb_regs: A pointer to hold the registers in the order GDB wants.
 133  *      @p: The &struct task_struct of the desired process.
 134  *
 135  *      Convert the register values of the sleeping process in @p to
 136  *      the format that GDB expects.
 137  *      This function is called when kgdb does not have access to the
 138  *      &struct pt_regs and therefore it should fill the gdb registers
 139  *      @gdb_regs with what has been saved in &struct thread_struct
 140  *      thread field during switch_to.
 141  */
 142 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 143 {
 144 #ifndef CONFIG_X86_32
 145         u32 *gdb_regs32 = (u32 *)gdb_regs;
 146 #endif
 147         gdb_regs[GDB_AX]        = 0;
 148         gdb_regs[GDB_BX]        = 0;
 149         gdb_regs[GDB_CX]        = 0;
 150         gdb_regs[GDB_DX]        = 0;
 151         gdb_regs[GDB_SI]        = 0;
 152         gdb_regs[GDB_DI]        = 0;
 153         gdb_regs[GDB_BP]        = ((struct inactive_task_frame *)p->thread.sp)->bp;
 154 #ifdef CONFIG_X86_32
 155         gdb_regs[GDB_DS]        = __KERNEL_DS;
 156         gdb_regs[GDB_ES]        = __KERNEL_DS;
 157         gdb_regs[GDB_PS]        = 0;
 158         gdb_regs[GDB_CS]        = __KERNEL_CS;
 159         gdb_regs[GDB_SS]        = __KERNEL_DS;
 160         gdb_regs[GDB_FS]        = 0xFFFF;
 161         gdb_regs[GDB_GS]        = 0xFFFF;
 162 #else
 163         gdb_regs32[GDB_PS]      = 0;
 164         gdb_regs32[GDB_CS]      = __KERNEL_CS;
 165         gdb_regs32[GDB_SS]      = __KERNEL_DS;
 166         gdb_regs[GDB_R8]        = 0;
 167         gdb_regs[GDB_R9]        = 0;
 168         gdb_regs[GDB_R10]       = 0;
 169         gdb_regs[GDB_R11]       = 0;
 170         gdb_regs[GDB_R12]       = 0;
 171         gdb_regs[GDB_R13]       = 0;
 172         gdb_regs[GDB_R14]       = 0;
 173         gdb_regs[GDB_R15]       = 0;
 174 #endif
 175         gdb_regs[GDB_PC]        = 0;
 176         gdb_regs[GDB_SP]        = p->thread.sp;
 177 }
 178 
 179 static struct hw_breakpoint {
 180         unsigned                enabled;
 181         unsigned long           addr;
 182         int                     len;
 183         int                     type;
 184         struct perf_event       * __percpu *pev;
 185 } breakinfo[HBP_NUM];
 186 
 187 static unsigned long early_dr7;
 188 
 189 static void kgdb_correct_hw_break(void)
 190 {
 191         int breakno;
 192 
 193         for (breakno = 0; breakno < HBP_NUM; breakno++) {
 194                 struct perf_event *bp;
 195                 struct arch_hw_breakpoint *info;
 196                 int val;
 197                 int cpu = raw_smp_processor_id();
 198                 if (!breakinfo[breakno].enabled)
 199                         continue;
 200                 if (dbg_is_early) {
 201                         set_debugreg(breakinfo[breakno].addr, breakno);
 202                         early_dr7 |= encode_dr7(breakno,
 203                                                 breakinfo[breakno].len,
 204                                                 breakinfo[breakno].type);
 205                         set_debugreg(early_dr7, 7);
 206                         continue;
 207                 }
 208                 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
 209                 info = counter_arch_bp(bp);
 210                 if (bp->attr.disabled != 1)
 211                         continue;
 212                 bp->attr.bp_addr = breakinfo[breakno].addr;
 213                 bp->attr.bp_len = breakinfo[breakno].len;
 214                 bp->attr.bp_type = breakinfo[breakno].type;
 215                 info->address = breakinfo[breakno].addr;
 216                 info->len = breakinfo[breakno].len;
 217                 info->type = breakinfo[breakno].type;
 218                 val = arch_install_hw_breakpoint(bp);
 219                 if (!val)
 220                         bp->attr.disabled = 0;
 221         }
 222         if (!dbg_is_early)
 223                 hw_breakpoint_restore();
 224 }
 225 
 226 static int hw_break_reserve_slot(int breakno)
 227 {
 228         int cpu;
 229         int cnt = 0;
 230         struct perf_event **pevent;
 231 
 232         if (dbg_is_early)
 233                 return 0;
 234 
 235         for_each_online_cpu(cpu) {
 236                 cnt++;
 237                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
 238                 if (dbg_reserve_bp_slot(*pevent))
 239                         goto fail;
 240         }
 241 
 242         return 0;
 243 
 244 fail:
 245         for_each_online_cpu(cpu) {
 246                 cnt--;
 247                 if (!cnt)
 248                         break;
 249                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
 250                 dbg_release_bp_slot(*pevent);
 251         }
 252         return -1;
 253 }
 254 
 255 static int hw_break_release_slot(int breakno)
 256 {
 257         struct perf_event **pevent;
 258         int cpu;
 259 
 260         if (dbg_is_early)
 261                 return 0;
 262 
 263         for_each_online_cpu(cpu) {
 264                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
 265                 if (dbg_release_bp_slot(*pevent))
 266                         /*
 267                          * The debugger is responsible for handing the retry on
 268                          * remove failure.
 269                          */
 270                         return -1;
 271         }
 272         return 0;
 273 }
 274 
 275 static int
 276 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 277 {
 278         int i;
 279 
 280         for (i = 0; i < HBP_NUM; i++)
 281                 if (breakinfo[i].addr == addr && breakinfo[i].enabled)
 282                         break;
 283         if (i == HBP_NUM)
 284                 return -1;
 285 
 286         if (hw_break_release_slot(i)) {
 287                 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
 288                 return -1;
 289         }
 290         breakinfo[i].enabled = 0;
 291 
 292         return 0;
 293 }
 294 
 295 static void kgdb_remove_all_hw_break(void)
 296 {
 297         int i;
 298         int cpu = raw_smp_processor_id();
 299         struct perf_event *bp;
 300 
 301         for (i = 0; i < HBP_NUM; i++) {
 302                 if (!breakinfo[i].enabled)
 303                         continue;
 304                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
 305                 if (!bp->attr.disabled) {
 306                         arch_uninstall_hw_breakpoint(bp);
 307                         bp->attr.disabled = 1;
 308                         continue;
 309                 }
 310                 if (dbg_is_early)
 311                         early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
 312                                                  breakinfo[i].type);
 313                 else if (hw_break_release_slot(i))
 314                         printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
 315                                breakinfo[i].addr);
 316                 breakinfo[i].enabled = 0;
 317         }
 318 }
 319 
 320 static int
 321 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 322 {
 323         int i;
 324 
 325         for (i = 0; i < HBP_NUM; i++)
 326                 if (!breakinfo[i].enabled)
 327                         break;
 328         if (i == HBP_NUM)
 329                 return -1;
 330 
 331         switch (bptype) {
 332         case BP_HARDWARE_BREAKPOINT:
 333                 len = 1;
 334                 breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
 335                 break;
 336         case BP_WRITE_WATCHPOINT:
 337                 breakinfo[i].type = X86_BREAKPOINT_WRITE;
 338                 break;
 339         case BP_ACCESS_WATCHPOINT:
 340                 breakinfo[i].type = X86_BREAKPOINT_RW;
 341                 break;
 342         default:
 343                 return -1;
 344         }
 345         switch (len) {
 346         case 1:
 347                 breakinfo[i].len = X86_BREAKPOINT_LEN_1;
 348                 break;
 349         case 2:
 350                 breakinfo[i].len = X86_BREAKPOINT_LEN_2;
 351                 break;
 352         case 4:
 353                 breakinfo[i].len = X86_BREAKPOINT_LEN_4;
 354                 break;
 355 #ifdef CONFIG_X86_64
 356         case 8:
 357                 breakinfo[i].len = X86_BREAKPOINT_LEN_8;
 358                 break;
 359 #endif
 360         default:
 361                 return -1;
 362         }
 363         breakinfo[i].addr = addr;
 364         if (hw_break_reserve_slot(i)) {
 365                 breakinfo[i].addr = 0;
 366                 return -1;
 367         }
 368         breakinfo[i].enabled = 1;
 369 
 370         return 0;
 371 }
 372 
 373 /**
 374  *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
 375  *      @regs: Current &struct pt_regs.
 376  *
 377  *      This function will be called if the particular architecture must
 378  *      disable hardware debugging while it is processing gdb packets or
 379  *      handling exception.
 380  */
 381 static void kgdb_disable_hw_debug(struct pt_regs *regs)
 382 {
 383         int i;
 384         int cpu = raw_smp_processor_id();
 385         struct perf_event *bp;
 386 
 387         /* Disable hardware debugging while we are in kgdb: */
 388         set_debugreg(0UL, 7);
 389         for (i = 0; i < HBP_NUM; i++) {
 390                 if (!breakinfo[i].enabled)
 391                         continue;
 392                 if (dbg_is_early) {
 393                         early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
 394                                                  breakinfo[i].type);
 395                         continue;
 396                 }
 397                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
 398                 if (bp->attr.disabled == 1)
 399                         continue;
 400                 arch_uninstall_hw_breakpoint(bp);
 401                 bp->attr.disabled = 1;
 402         }
 403 }
 404 
 405 #ifdef CONFIG_SMP
 406 /**
 407  *      kgdb_roundup_cpus - Get other CPUs into a holding pattern
 408  *
 409  *      On SMP systems, we need to get the attention of the other CPUs
 410  *      and get them be in a known state.  This should do what is needed
 411  *      to get the other CPUs to call kgdb_wait(). Note that on some arches,
 412  *      the NMI approach is not used for rounding up all the CPUs. For example,
 413  *      in case of MIPS, smp_call_function() is used to roundup CPUs.
 414  *
 415  *      On non-SMP systems, this is not called.
 416  */
 417 void kgdb_roundup_cpus(void)
 418 {
 419         apic_send_IPI_allbutself(NMI_VECTOR);
 420 }
 421 #endif
 422 
 423 /**
 424  *      kgdb_arch_handle_exception - Handle architecture specific GDB packets.
 425  *      @e_vector: The error vector of the exception that happened.
 426  *      @signo: The signal number of the exception that happened.
 427  *      @err_code: The error code of the exception that happened.
 428  *      @remcomInBuffer: The buffer of the packet we have read.
 429  *      @remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into.
 430  *      @linux_regs: The &struct pt_regs of the current process.
 431  *
 432  *      This function MUST handle the 'c' and 's' command packets,
 433  *      as well packets to set / remove a hardware breakpoint, if used.
 434  *      If there are additional packets which the hardware needs to handle,
 435  *      they are handled here.  The code should return -1 if it wants to
 436  *      process more packets, and a %0 or %1 if it wants to exit from the
 437  *      kgdb callback.
 438  */
 439 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
 440                                char *remcomInBuffer, char *remcomOutBuffer,
 441                                struct pt_regs *linux_regs)
 442 {
 443         unsigned long addr;
 444         char *ptr;
 445 
 446         switch (remcomInBuffer[0]) {
 447         case 'c':
 448         case 's':
 449                 /* try to read optional parameter, pc unchanged if no parm */
 450                 ptr = &remcomInBuffer[1];
 451                 if (kgdb_hex2long(&ptr, &addr))
 452                         linux_regs->ip = addr;
 453                 /* fall through */
 454         case 'D':
 455         case 'k':
 456                 /* clear the trace bit */
 457                 linux_regs->flags &= ~X86_EFLAGS_TF;
 458                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 459 
 460                 /* set the trace bit if we're stepping */
 461                 if (remcomInBuffer[0] == 's') {
 462                         linux_regs->flags |= X86_EFLAGS_TF;
 463                         atomic_set(&kgdb_cpu_doing_single_step,
 464                                    raw_smp_processor_id());
 465                 }
 466 
 467                 return 0;
 468         }
 469 
 470         /* this means that we do not want to exit from the handler: */
 471         return -1;
 472 }
 473 
 474 static inline int
 475 single_step_cont(struct pt_regs *regs, struct die_args *args)
 476 {
 477         /*
 478          * Single step exception from kernel space to user space so
 479          * eat the exception and continue the process:
 480          */
 481         printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
 482                         "resuming...\n");
 483         kgdb_arch_handle_exception(args->trapnr, args->signr,
 484                                    args->err, "c", "", regs);
 485         /*
 486          * Reset the BS bit in dr6 (pointed by args->err) to
 487          * denote completion of processing
 488          */
 489         (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
 490 
 491         return NOTIFY_STOP;
 492 }
 493 
 494 static DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS);
 495 
 496 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
 497 {
 498         int cpu;
 499 
 500         switch (cmd) {
 501         case NMI_LOCAL:
 502                 if (atomic_read(&kgdb_active) != -1) {
 503                         /* KGDB CPU roundup */
 504                         cpu = raw_smp_processor_id();
 505                         kgdb_nmicallback(cpu, regs);
 506                         set_bit(cpu, was_in_debug_nmi);
 507                         touch_nmi_watchdog();
 508 
 509                         return NMI_HANDLED;
 510                 }
 511                 break;
 512 
 513         case NMI_UNKNOWN:
 514                 cpu = raw_smp_processor_id();
 515 
 516                 if (__test_and_clear_bit(cpu, was_in_debug_nmi))
 517                         return NMI_HANDLED;
 518 
 519                 break;
 520         default:
 521                 /* do nothing */
 522                 break;
 523         }
 524         return NMI_DONE;
 525 }
 526 
 527 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 528 {
 529         struct pt_regs *regs = args->regs;
 530 
 531         switch (cmd) {
 532         case DIE_DEBUG:
 533                 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
 534                         if (user_mode(regs))
 535                                 return single_step_cont(regs, args);
 536                         break;
 537                 } else if (test_thread_flag(TIF_SINGLESTEP))
 538                         /* This means a user thread is single stepping
 539                          * a system call which should be ignored
 540                          */
 541                         return NOTIFY_DONE;
 542                 /* fall through */
 543         default:
 544                 if (user_mode(regs))
 545                         return NOTIFY_DONE;
 546         }
 547 
 548         if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
 549                 return NOTIFY_DONE;
 550 
 551         /* Must touch watchdog before return to normal operation */
 552         touch_nmi_watchdog();
 553         return NOTIFY_STOP;
 554 }
 555 
 556 int kgdb_ll_trap(int cmd, const char *str,
 557                  struct pt_regs *regs, long err, int trap, int sig)
 558 {
 559         struct die_args args = {
 560                 .regs   = regs,
 561                 .str    = str,
 562                 .err    = err,
 563                 .trapnr = trap,
 564                 .signr  = sig,
 565 
 566         };
 567 
 568         if (!kgdb_io_module_registered)
 569                 return NOTIFY_DONE;
 570 
 571         return __kgdb_notify(&args, cmd);
 572 }
 573 
 574 static int
 575 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 576 {
 577         unsigned long flags;
 578         int ret;
 579 
 580         local_irq_save(flags);
 581         ret = __kgdb_notify(ptr, cmd);
 582         local_irq_restore(flags);
 583 
 584         return ret;
 585 }
 586 
 587 static struct notifier_block kgdb_notifier = {
 588         .notifier_call  = kgdb_notify,
 589 };
 590 
 591 /**
 592  *      kgdb_arch_init - Perform any architecture specific initialization.
 593  *
 594  *      This function will handle the initialization of any architecture
 595  *      specific callbacks.
 596  */
 597 int kgdb_arch_init(void)
 598 {
 599         int retval;
 600 
 601         retval = register_die_notifier(&kgdb_notifier);
 602         if (retval)
 603                 goto out;
 604 
 605         retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
 606                                         0, "kgdb");
 607         if (retval)
 608                 goto out1;
 609 
 610         retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
 611                                         0, "kgdb");
 612 
 613         if (retval)
 614                 goto out2;
 615 
 616         return retval;
 617 
 618 out2:
 619         unregister_nmi_handler(NMI_LOCAL, "kgdb");
 620 out1:
 621         unregister_die_notifier(&kgdb_notifier);
 622 out:
 623         return retval;
 624 }
 625 
 626 static void kgdb_hw_overflow_handler(struct perf_event *event,
 627                 struct perf_sample_data *data, struct pt_regs *regs)
 628 {
 629         struct task_struct *tsk = current;
 630         int i;
 631 
 632         for (i = 0; i < 4; i++)
 633                 if (breakinfo[i].enabled)
 634                         tsk->thread.debugreg6 |= (DR_TRAP0 << i);
 635 }
 636 
 637 void kgdb_arch_late(void)
 638 {
 639         int i, cpu;
 640         struct perf_event_attr attr;
 641         struct perf_event **pevent;
 642 
 643         /*
 644          * Pre-allocate the hw breakpoint structions in the non-atomic
 645          * portion of kgdb because this operation requires mutexs to
 646          * complete.
 647          */
 648         hw_breakpoint_init(&attr);
 649         attr.bp_addr = (unsigned long)kgdb_arch_init;
 650         attr.bp_len = HW_BREAKPOINT_LEN_1;
 651         attr.bp_type = HW_BREAKPOINT_W;
 652         attr.disabled = 1;
 653         for (i = 0; i < HBP_NUM; i++) {
 654                 if (breakinfo[i].pev)
 655                         continue;
 656                 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
 657                 if (IS_ERR((void * __force)breakinfo[i].pev)) {
 658                         printk(KERN_ERR "kgdb: Could not allocate hw"
 659                                "breakpoints\nDisabling the kernel debugger\n");
 660                         breakinfo[i].pev = NULL;
 661                         kgdb_arch_exit();
 662                         return;
 663                 }
 664                 for_each_online_cpu(cpu) {
 665                         pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
 666                         pevent[0]->hw.sample_period = 1;
 667                         pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
 668                         if (pevent[0]->destroy != NULL) {
 669                                 pevent[0]->destroy = NULL;
 670                                 release_bp_slot(*pevent);
 671                         }
 672                 }
 673         }
 674 }
 675 
 676 /**
 677  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
 678  *
 679  *      This function will handle the uninitalization of any architecture
 680  *      specific callbacks, for dynamic registration and unregistration.
 681  */
 682 void kgdb_arch_exit(void)
 683 {
 684         int i;
 685         for (i = 0; i < 4; i++) {
 686                 if (breakinfo[i].pev) {
 687                         unregister_wide_hw_breakpoint(breakinfo[i].pev);
 688                         breakinfo[i].pev = NULL;
 689                 }
 690         }
 691         unregister_nmi_handler(NMI_UNKNOWN, "kgdb");
 692         unregister_nmi_handler(NMI_LOCAL, "kgdb");
 693         unregister_die_notifier(&kgdb_notifier);
 694 }
 695 
 696 /**
 697  *
 698  *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
 699  *      @exception: Exception vector number
 700  *      @regs: Current &struct pt_regs.
 701  *
 702  *      On some architectures we need to skip a breakpoint exception when
 703  *      it occurs after a breakpoint has been removed.
 704  *
 705  * Skip an int3 exception when it occurs after a breakpoint has been
 706  * removed. Backtrack eip by 1 since the int3 would have caused it to
 707  * increment by 1.
 708  */
 709 int kgdb_skipexception(int exception, struct pt_regs *regs)
 710 {
 711         if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
 712                 regs->ip -= 1;
 713                 return 1;
 714         }
 715         return 0;
 716 }
 717 
 718 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
 719 {
 720         if (exception == 3)
 721                 return instruction_pointer(regs) - 1;
 722         return instruction_pointer(regs);
 723 }
 724 
 725 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 726 {
 727         regs->ip = ip;
 728 }
 729 
 730 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 731 {
 732         int err;
 733 
 734         bpt->type = BP_BREAKPOINT;
 735         err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
 736                                 BREAK_INSTR_SIZE);
 737         if (err)
 738                 return err;
 739         err = probe_kernel_write((char *)bpt->bpt_addr,
 740                                  arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
 741         if (!err)
 742                 return err;
 743         /*
 744          * It is safe to call text_poke_kgdb() because normal kernel execution
 745          * is stopped on all cores, so long as the text_mutex is not locked.
 746          */
 747         if (mutex_is_locked(&text_mutex))
 748                 return -EBUSY;
 749         text_poke_kgdb((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
 750                        BREAK_INSTR_SIZE);
 751         bpt->type = BP_POKE_BREAKPOINT;
 752 
 753         return 0;
 754 }
 755 
 756 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 757 {
 758         if (bpt->type != BP_POKE_BREAKPOINT)
 759                 goto knl_write;
 760         /*
 761          * It is safe to call text_poke_kgdb() because normal kernel execution
 762          * is stopped on all cores, so long as the text_mutex is not locked.
 763          */
 764         if (mutex_is_locked(&text_mutex))
 765                 goto knl_write;
 766         text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr,
 767                        BREAK_INSTR_SIZE);
 768         return 0;
 769 
 770 knl_write:
 771         return probe_kernel_write((char *)bpt->bpt_addr,
 772                                   (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
 773 }
 774 
 775 const struct kgdb_arch arch_kgdb_ops = {
 776         /* Breakpoint instruction: */
 777         .gdb_bpt_instr          = { 0xcc },
 778         .flags                  = KGDB_HW_BREAKPOINT,
 779         .set_hw_breakpoint      = kgdb_set_hw_break,
 780         .remove_hw_breakpoint   = kgdb_remove_hw_break,
 781         .disable_hw_break       = kgdb_disable_hw_debug,
 782         .remove_all_hw_break    = kgdb_remove_all_hw_break,
 783         .correct_hw_break       = kgdb_correct_hw_break,
 784 };
/* [<][>][^][v][top][bottom][index][help] */
root/arch/x86/kernel/kgdb.c

DEFINITIONS
