arch/hexagon/kernel/traps.c

   1 /*
   2  * Kernel traps/events for Hexagon processor
   3  *
   4  * Copyright (c) 2010-2013, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <linux/init.h>
  22 #include <linux/sched.h>
  23 #include <linux/module.h>
  24 #include <linux/kallsyms.h>
  25 #include <linux/kdebug.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/signal.h>
  28 #include <linux/tracehook.h>
  29 #include <asm/traps.h>
  30 #include <asm/vm_fault.h>
  31 #include <asm/syscall.h>
  32 #include <asm/registers.h>
  33 #include <asm/unistd.h>
  34 #include <asm/sections.h>
  35 #ifdef CONFIG_KGDB
  36 # include <linux/kgdb.h>
  37 #endif
  38
  39 #define TRAP_SYSCALL    1
  40 #define TRAP_DEBUG      0xdb
  41
  42 void __init trap_init(void)
  43 {
  44 }
  45
  46 #ifdef CONFIG_GENERIC_BUG
  47 /* Maybe should resemble arch/sh/kernel/traps.c ?? */
  48 int is_valid_bugaddr(unsigned long addr)
  49 {
  50         return 1;
  51 }
  52 #endif /* CONFIG_GENERIC_BUG */
  53
  54 static const char *ex_name(int ex)
  55 {
  56         switch (ex) {
  57         case HVM_GE_C_XPROT:
  58         case HVM_GE_C_XUSER:
  59                 return "Execute protection fault";
  60         case HVM_GE_C_RPROT:
  61         case HVM_GE_C_RUSER:
  62                 return "Read protection fault";
  63         case HVM_GE_C_WPROT:
  64         case HVM_GE_C_WUSER:
  65                 return "Write protection fault";
  66         case HVM_GE_C_XMAL:
  67                 return "Misaligned instruction";
  68         case HVM_GE_C_WREG:
  69                 return "Multiple writes to same register in packet";
  70         case HVM_GE_C_PCAL:
  71                 return "Program counter values that are not properly aligned";
  72         case HVM_GE_C_RMAL:
  73                 return "Misaligned data load";
  74         case HVM_GE_C_WMAL:
  75                 return "Misaligned data store";
  76         case HVM_GE_C_INVI:
  77         case HVM_GE_C_PRIVI:
  78                 return "Illegal instruction";
  79         case HVM_GE_C_BUS:
  80                 return "Precise bus error";
  81         case HVM_GE_C_CACHE:
  82                 return "Cache error";
  83
  84         case 0xdb:
  85                 return "Debugger trap";
  86
  87         default:
  88                 return "Unrecognized exception";
  89         }
  90 }
  91
  92 static void do_show_stack(struct task_struct *task, unsigned long *fp,
  93                           unsigned long ip)
  94 {
  95         int kstack_depth_to_print = 24;
  96         unsigned long offset, size;
  97         const char *name = NULL;
  98         unsigned long *newfp;
  99         unsigned long low, high;
 100         char tmpstr[128];
 101         char *modname;
 102         int i;
 103
 104         if (task == NULL)
 105                 task = current;
 106
 107         printk(KERN_INFO "CPU#%d, %s/%d, Call Trace:\n",
 108                raw_smp_processor_id(), task->comm,
 109                task_pid_nr(task));
 110
 111         if (fp == NULL) {
 112                 if (task == current) {
 113                         asm("%0 = r30" : "=r" (fp));
 114                 } else {
 115                         fp = (unsigned long *)
 116                              ((struct hexagon_switch_stack *)
 117                              task->thread.switch_sp)->fp;
 118                 }
 119         }
 120
 121         if ((((unsigned long) fp) & 0x3) || ((unsigned long) fp < 0x1000)) {
 122                 printk(KERN_INFO "-- Corrupt frame pointer %p\n", fp);
 123                 return;
 124         }
 125
 126         /* Saved link reg is one word above FP */
 127         if (!ip)
 128                 ip = *(fp+1);
 129
 130         /* Expect kernel stack to be in-bounds */
 131         low = (unsigned long)task_stack_page(task);
 132         high = low + THREAD_SIZE - 8;
 133         low += sizeof(struct thread_info);
 134
 135         for (i = 0; i < kstack_depth_to_print; i++) {
 136
 137                 name = kallsyms_lookup(ip, &size, &offset, &modname, tmpstr);
 138
 139                 printk(KERN_INFO "[%p] 0x%lx: %s + 0x%lx", fp, ip, name,
 140                         offset);
 141                 if (((unsigned long) fp < low) || (high < (unsigned long) fp))
 142                         printk(KERN_CONT " (FP out of bounds!)");
 143                 if (modname)
 144                         printk(KERN_CONT " [%s] ", modname);
 145                 printk(KERN_CONT "\n");
 146
 147                 newfp = (unsigned long *) *fp;
 148
 149                 if (((unsigned long) newfp) & 0x3) {
 150                         printk(KERN_INFO "-- Corrupt frame pointer %p\n",
 151                                 newfp);
 152                         break;
 153                 }
 154
 155                 /* Attempt to continue past exception. */
 156                 if (0 == newfp) {
 157                         struct pt_regs *regs = (struct pt_regs *) (((void *)fp)
 158                                                 + 8);
 159
 160                         if (regs->syscall_nr != -1) {
 161                                 printk(KERN_INFO "-- trap0 -- syscall_nr: %ld",
 162                                         regs->syscall_nr);
 163                                 printk(KERN_CONT "  psp: %lx  elr: %lx\n",
 164                                          pt_psp(regs), pt_elr(regs));
 165                                 break;
 166                         } else {
 167                                 /* really want to see more ... */
 168                                 kstack_depth_to_print += 6;
 169                                 printk(KERN_INFO "-- %s (0x%lx)  badva: %lx\n",
 170                                         ex_name(pt_cause(regs)), pt_cause(regs),
 171                                         pt_badva(regs));
 172                         }
 173
 174                         newfp = (unsigned long *) regs->r30;
 175                         ip = pt_elr(regs);
 176                 } else {
 177                         ip = *(newfp + 1);
 178                 }
 179
 180                 /* If link reg is null, we are done. */
 181                 if (ip == 0x0)
 182                         break;
 183
 184                 /* If newfp isn't larger, we're tracing garbage. */
 185                 if (newfp > fp)
 186                         fp = newfp;
 187                 else
 188                         break;
 189         }
 190 }
 191
 192 void show_stack(struct task_struct *task, unsigned long *fp)
 193 {
 194         /* Saved link reg is one word above FP */
 195         do_show_stack(task, fp, 0);
 196 }
 197
 198 int die(const char *str, struct pt_regs *regs, long err)
 199 {
 200         static struct {
 201                 spinlock_t lock;
 202                 int counter;
 203         } die = {
 204                 .lock = __SPIN_LOCK_UNLOCKED(die.lock),
 205                 .counter = 0
 206         };
 207
 208         console_verbose();
 209         oops_enter();
 210
 211         spin_lock_irq(&die.lock);
 212         bust_spinlocks(1);
 213         printk(KERN_EMERG "Oops: %s[#%d]:\n", str, ++die.counter);
 214
 215         if (notify_die(DIE_OOPS, str, regs, err, pt_cause(regs), SIGSEGV) ==
 216             NOTIFY_STOP)
 217                 return 1;
 218
 219         print_modules();
 220         show_regs(regs);
 221         do_show_stack(current, &regs->r30, pt_elr(regs));
 222
 223         bust_spinlocks(0);
 224         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 225
 226         spin_unlock_irq(&die.lock);
 227
 228         if (in_interrupt())
 229                 panic("Fatal exception in interrupt");
 230
 231         if (panic_on_oops)
 232                 panic("Fatal exception");
 233
 234         oops_exit();
 235         do_exit(err);
 236         return 0;
 237 }
 238
 239 int die_if_kernel(char *str, struct pt_regs *regs, long err)
 240 {
 241         if (!user_mode(regs))
 242                 return die(str, regs, err);
 243         else
 244                 return 0;
 245 }
 246
 247 /*
 248  * It's not clear that misaligned fetches are ever recoverable.
 249  */
 250 static void misaligned_instruction(struct pt_regs *regs)
 251 {
 252         die_if_kernel("Misaligned Instruction", regs, 0);
 253         force_sig(SIGBUS, current);
 254 }
 255
 256 /*
 257  * Misaligned loads and stores, on the other hand, can be
 258  * emulated, and probably should be, some day.  But for now
 259  * they will be considered fatal.
 260  */
 261 static void misaligned_data_load(struct pt_regs *regs)
 262 {
 263         die_if_kernel("Misaligned Data Load", regs, 0);
 264         force_sig(SIGBUS, current);
 265 }
 266
 267 static void misaligned_data_store(struct pt_regs *regs)
 268 {
 269         die_if_kernel("Misaligned Data Store", regs, 0);
 270         force_sig(SIGBUS, current);
 271 }
 272
 273 static void illegal_instruction(struct pt_regs *regs)
 274 {
 275         die_if_kernel("Illegal Instruction", regs, 0);
 276         force_sig(SIGILL, current);
 277 }
 278
 279 /*
 280  * Precise bus errors may be recoverable with a a retry,
 281  * but for now, treat them as irrecoverable.
 282  */
 283 static void precise_bus_error(struct pt_regs *regs)
 284 {
 285         die_if_kernel("Precise Bus Error", regs, 0);
 286         force_sig(SIGBUS, current);
 287 }
 288
 289 /*
 290  * If anything is to be done here other than panic,
 291  * it will probably be complex and migrate to another
 292  * source module.  For now, just die.
 293  */
 294 static void cache_error(struct pt_regs *regs)
 295 {
 296         die("Cache Error", regs, 0);
 297 }
 298
 299 /*
 300  * General exception handler
 301  */
 302 void do_genex(struct pt_regs *regs)
 303 {
 304         /*
 305          * Decode Cause and Dispatch
 306          */
 307         switch (pt_cause(regs)) {
 308         case HVM_GE_C_XPROT:
 309         case HVM_GE_C_XUSER:
 310                 execute_protection_fault(regs);
 311                 break;
 312         case HVM_GE_C_RPROT:
 313         case HVM_GE_C_RUSER:
 314                 read_protection_fault(regs);
 315                 break;
 316         case HVM_GE_C_WPROT:
 317         case HVM_GE_C_WUSER:
 318                 write_protection_fault(regs);
 319                 break;
 320         case HVM_GE_C_XMAL:
 321                 misaligned_instruction(regs);
 322                 break;
 323         case HVM_GE_C_WREG:
 324                 illegal_instruction(regs);
 325                 break;
 326         case HVM_GE_C_PCAL:
 327                 misaligned_instruction(regs);
 328                 break;
 329         case HVM_GE_C_RMAL:
 330                 misaligned_data_load(regs);
 331                 break;
 332         case HVM_GE_C_WMAL:
 333                 misaligned_data_store(regs);
 334                 break;
 335         case HVM_GE_C_INVI:
 336         case HVM_GE_C_PRIVI:
 337                 illegal_instruction(regs);
 338                 break;
 339         case HVM_GE_C_BUS:
 340                 precise_bus_error(regs);
 341                 break;
 342         case HVM_GE_C_CACHE:
 343                 cache_error(regs);
 344                 break;
 345         default:
 346                 /* Halt and catch fire */
 347                 panic("Unrecognized exception 0x%lx\n", pt_cause(regs));
 348                 break;
 349         }
 350 }
 351
 352 /* Indirect system call dispatch */
 353 long sys_syscall(void)
 354 {
 355         printk(KERN_ERR "sys_syscall invoked!\n");
 356         return -ENOSYS;
 357 }
 358
 359 void do_trap0(struct pt_regs *regs)
 360 {
 361         syscall_fn syscall;
 362
 363         switch (pt_cause(regs)) {
 364         case TRAP_SYSCALL:
 365                 /* System call is trap0 #1 */
 366
 367                 /* allow strace to catch syscall args  */
 368                 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE) &&
 369                         tracehook_report_syscall_entry(regs)))
 370                         return;  /*  return -ENOSYS somewhere?  */
 371
 372                 /* Interrupts should be re-enabled for syscall processing */
 373                 __vmsetie(VM_INT_ENABLE);
 374
 375                 /*
 376                  * System call number is in r6, arguments in r0..r5.
 377                  * Fortunately, no Linux syscall has more than 6 arguments,
 378                  * and Hexagon ABI passes first 6 arguments in registers.
 379                  * 64-bit arguments are passed in odd/even register pairs.
 380                  * Fortunately, we have no system calls that take more
 381                  * than three arguments with more than one 64-bit value.
 382                  * Should that change, we'd need to redesign to copy
 383                  * between user and kernel stacks.
 384                  */
 385                 regs->syscall_nr = regs->r06;
 386
 387                 /*
 388                  * GPR R0 carries the first parameter, and is also used
 389                  * to report the return value.  We need a backup of
 390                  * the user's value in case we need to do a late restart
 391                  * of the system call.
 392                  */
 393                 regs->restart_r0 = regs->r00;
 394
 395                 if ((unsigned long) regs->syscall_nr >= __NR_syscalls) {
 396                         regs->r00 = -1;
 397                 } else {
 398                         syscall = (syscall_fn)
 399                                   (sys_call_table[regs->syscall_nr]);
 400                         regs->r00 = syscall(regs->r00, regs->r01,
 401                                    regs->r02, regs->r03,
 402                                    regs->r04, regs->r05);
 403                 }
 404
 405                 /* allow strace to get the syscall return state  */
 406                 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE)))
 407                         tracehook_report_syscall_exit(regs, 0);
 408
 409                 break;
 410         case TRAP_DEBUG:
 411                 /* Trap0 0xdb is debug breakpoint */
 412                 if (user_mode(regs)) {
 413                         struct siginfo info;
 414
 415                         info.si_signo = SIGTRAP;
 416                         info.si_errno = 0;
 417                         /*
 418                          * Some architecures add some per-thread state
 419                          * to distinguish between breakpoint traps and
 420                          * trace traps.  We may want to do that, and
 421                          * set the si_code value appropriately, or we
 422                          * may want to use a different trap0 flavor.
 423                          */
 424                         info.si_code = TRAP_BRKPT;
 425                         info.si_addr = (void __user *) pt_elr(regs);
 426                         send_sig_info(SIGTRAP, &info, current);
 427                 } else {
 428 #ifdef CONFIG_KGDB
 429                         kgdb_handle_exception(pt_cause(regs), SIGTRAP,
 430                                               TRAP_BRKPT, regs);
 431 #endif
 432                 }
 433                 break;
 434         }
 435         /* Ignore other trap0 codes for now, especially 0 (Angel calls) */
 436 }
 437
 438 /*
 439  * Machine check exception handler
 440  */
 441 void do_machcheck(struct pt_regs *regs)
 442 {
 443         /* Halt and catch fire */
 444         __vmstop();
 445 }
 446
 447 /*
 448  * Treat this like the old 0xdb trap.
 449  */
 450
 451 void do_debug_exception(struct pt_regs *regs)
 452 {
 453         regs->hvmer.vmest &= ~HVM_VMEST_CAUSE_MSK;
 454         regs->hvmer.vmest |= (TRAP_DEBUG << HVM_VMEST_CAUSE_SFT);
 455         do_trap0(regs);
 456 }