arch/hexagon/kernel/traps.c

   1 /*
   2  * Kernel traps/events for Hexagon processor
   3  *
   4  * Copyright (c) 2010-2014, 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/signal.h>
  23 #include <linux/sched/debug.h>
  24 #include <linux/sched/task_stack.h>
  25 #include <linux/module.h>
  26 #include <linux/kallsyms.h>
  27 #include <linux/kdebug.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/signal.h>
  30 #include <linux/tracehook.h>
  31 #include <asm/traps.h>
  32 #include <asm/vm_fault.h>
  33 #include <asm/syscall.h>
  34 #include <asm/registers.h>
  35 #include <asm/unistd.h>
  36 #include <asm/sections.h>
  37 #ifdef CONFIG_KGDB
  38 # include <linux/kgdb.h>
  39 #endif
  40
  41 #define TRAP_SYSCALL    1
  42 #define TRAP_DEBUG      0xdb
  43
  44 void __init trap_init(void)
  45 {
  46 }
  47
  48 #ifdef CONFIG_GENERIC_BUG
  49 /* Maybe should resemble arch/sh/kernel/traps.c ?? */
  50 int is_valid_bugaddr(unsigned long addr)
  51 {
  52         return 1;
  53 }
  54 #endif /* CONFIG_GENERIC_BUG */
  55
  56 static const char *ex_name(int ex)
  57 {
  58         switch (ex) {
  59         case HVM_GE_C_XPROT:
  60         case HVM_GE_C_XUSER:
  61                 return "Execute protection fault";
  62         case HVM_GE_C_RPROT:
  63         case HVM_GE_C_RUSER:
  64                 return "Read protection fault";
  65         case HVM_GE_C_WPROT:
  66         case HVM_GE_C_WUSER:
  67                 return "Write protection fault";
  68         case HVM_GE_C_XMAL:
  69                 return "Misaligned instruction";
  70         case HVM_GE_C_WREG:
  71                 return "Multiple writes to same register in packet";
  72         case HVM_GE_C_PCAL:
  73                 return "Program counter values that are not properly aligned";
  74         case HVM_GE_C_RMAL:
  75                 return "Misaligned data load";
  76         case HVM_GE_C_WMAL:
  77                 return "Misaligned data store";
  78         case HVM_GE_C_INVI:
  79         case HVM_GE_C_PRIVI:
  80                 return "Illegal instruction";
  81         case HVM_GE_C_BUS:
  82                 return "Precise bus error";
  83         case HVM_GE_C_CACHE:
  84                 return "Cache error";
  85
  86         case 0xdb:
  87                 return "Debugger trap";
  88
  89         default:
  90                 return "Unrecognized exception";
  91         }
  92 }
  93
  94 static void do_show_stack(struct task_struct *task, unsigned long *fp,
  95                           unsigned long ip)
  96 {
  97         int kstack_depth_to_print = 24;
  98         unsigned long offset, size;
  99         const char *name = NULL;
 100         unsigned long *newfp;
 101         unsigned long low, high;
 102         char tmpstr[128];
 103         char *modname;
 104         int i;
 105
 106         if (task == NULL)
 107                 task = current;
 108
 109         printk(KERN_INFO "CPU#%d, %s/%d, Call Trace:\n",
 110                raw_smp_processor_id(), task->comm,
 111                task_pid_nr(task));
 112
 113         if (fp == NULL) {
 114                 if (task == current) {
 115                         asm("%0 = r30" : "=r" (fp));
 116                 } else {
 117                         fp = (unsigned long *)
 118                              ((struct hexagon_switch_stack *)
 119                              task->thread.switch_sp)->fp;
 120                 }
 121         }
 122
 123         if ((((unsigned long) fp) & 0x3) || ((unsigned long) fp < 0x1000)) {
 124                 printk(KERN_INFO "-- Corrupt frame pointer %p\n", fp);
 125                 return;
 126         }
 127
 128         /* Saved link reg is one word above FP */
 129         if (!ip)
 130                 ip = *(fp+1);
 131
 132         /* Expect kernel stack to be in-bounds */
 133         low = (unsigned long)task_stack_page(task);
 134         high = low + THREAD_SIZE - 8;
 135         low += sizeof(struct thread_info);
 136
 137         for (i = 0; i < kstack_depth_to_print; i++) {
 138
 139                 name = kallsyms_lookup(ip, &size, &offset, &modname, tmpstr);
 140
 141                 printk(KERN_INFO "[%p] 0x%lx: %s + 0x%lx", fp, ip, name,
 142                         offset);
 143                 if (((unsigned long) fp < low) || (high < (unsigned long) fp))
 144                         printk(KERN_CONT " (FP out of bounds!)");
 145                 if (modname)
 146                         printk(KERN_CONT " [%s] ", modname);
 147                 printk(KERN_CONT "\n");
 148
 149                 newfp = (unsigned long *) *fp;
 150
 151                 if (((unsigned long) newfp) & 0x3) {
 152                         printk(KERN_INFO "-- Corrupt frame pointer %p\n",
 153                                 newfp);
 154                         break;
 155                 }
 156
 157                 /* Attempt to continue past exception. */
 158                 if (0 == newfp) {
 159                         struct pt_regs *regs = (struct pt_regs *) (((void *)fp)
 160                                                 + 8);
 161
 162                         if (regs->syscall_nr != -1) {
 163                                 printk(KERN_INFO "-- trap0 -- syscall_nr: %ld",
 164                                         regs->syscall_nr);
 165                                 printk(KERN_CONT "  psp: %lx  elr: %lx\n",
 166                                          pt_psp(regs), pt_elr(regs));
 167                                 break;
 168                         } else {
 169                                 /* really want to see more ... */
 170                                 kstack_depth_to_print += 6;
 171                                 printk(KERN_INFO "-- %s (0x%lx)  badva: %lx\n",
 172                                         ex_name(pt_cause(regs)), pt_cause(regs),
 173                                         pt_badva(regs));
 174                         }
 175
 176                         newfp = (unsigned long *) regs->r30;
 177                         ip = pt_elr(regs);
 178                 } else {
 179                         ip = *(newfp + 1);
 180                 }
 181
 182                 /* If link reg is null, we are done. */
 183                 if (ip == 0x0)
 184                         break;
 185
 186                 /* If newfp isn't larger, we're tracing garbage. */
 187                 if (newfp > fp)
 188                         fp = newfp;
 189                 else
 190                         break;
 191         }
 192 }
 193
 194 void show_stack(struct task_struct *task, unsigned long *fp)
 195 {
 196         /* Saved link reg is one word above FP */
 197         do_show_stack(task, fp, 0);
 198 }
 199
 200 int die(const char *str, struct pt_regs *regs, long err)
 201 {
 202         static struct {
 203                 spinlock_t lock;
 204                 int counter;
 205         } die = {
 206                 .lock = __SPIN_LOCK_UNLOCKED(die.lock),
 207                 .counter = 0
 208         };
 209
 210         console_verbose();
 211         oops_enter();
 212
 213         spin_lock_irq(&die.lock);
 214         bust_spinlocks(1);
 215         printk(KERN_EMERG "Oops: %s[#%d]:\n", str, ++die.counter);
 216
 217         if (notify_die(DIE_OOPS, str, regs, err, pt_cause(regs), SIGSEGV) ==
 218             NOTIFY_STOP)
 219                 return 1;
 220
 221         print_modules();
 222         show_regs(regs);
 223         do_show_stack(current, &regs->r30, pt_elr(regs));
 224
 225         bust_spinlocks(0);
 226         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 227
 228         spin_unlock_irq(&die.lock);
 229
 230         if (in_interrupt())
 231                 panic("Fatal exception in interrupt");
 232
 233         if (panic_on_oops)
 234                 panic("Fatal exception");
 235
 236         oops_exit();
 237         do_exit(err);
 238         return 0;
 239 }
 240
 241 int die_if_kernel(char *str, struct pt_regs *regs, long err)
 242 {
 243         if (!user_mode(regs))
 244                 return die(str, regs, err);
 245         else
 246                 return 0;
 247 }
 248
 249 /*
 250  * It's not clear that misaligned fetches are ever recoverable.
 251  */
 252 static void misaligned_instruction(struct pt_regs *regs)
 253 {
 254         die_if_kernel("Misaligned Instruction", regs, 0);
 255         force_sig(SIGBUS, current);
 256 }
 257
 258 /*
 259  * Misaligned loads and stores, on the other hand, can be
 260  * emulated, and probably should be, some day.  But for now
 261  * they will be considered fatal.
 262  */
 263 static void misaligned_data_load(struct pt_regs *regs)
 264 {
 265         die_if_kernel("Misaligned Data Load", regs, 0);
 266         force_sig(SIGBUS, current);
 267 }
 268
 269 static void misaligned_data_store(struct pt_regs *regs)
 270 {
 271         die_if_kernel("Misaligned Data Store", regs, 0);
 272         force_sig(SIGBUS, current);
 273 }
 274
 275 static void illegal_instruction(struct pt_regs *regs)
 276 {
 277         die_if_kernel("Illegal Instruction", regs, 0);
 278         force_sig(SIGILL, current);
 279 }
 280
 281 /*
 282  * Precise bus errors may be recoverable with a a retry,
 283  * but for now, treat them as irrecoverable.
 284  */
 285 static void precise_bus_error(struct pt_regs *regs)
 286 {
 287         die_if_kernel("Precise Bus Error", regs, 0);
 288         force_sig(SIGBUS, current);
 289 }
 290
 291 /*
 292  * If anything is to be done here other than panic,
 293  * it will probably be complex and migrate to another
 294  * source module.  For now, just die.
 295  */
 296 static void cache_error(struct pt_regs *regs)
 297 {
 298         die("Cache Error", regs, 0);
 299 }
 300
 301 /*
 302  * General exception handler
 303  */
 304 void do_genex(struct pt_regs *regs)
 305 {
 306         /*
 307          * Decode Cause and Dispatch
 308          */
 309         switch (pt_cause(regs)) {
 310         case HVM_GE_C_XPROT:
 311         case HVM_GE_C_XUSER:
 312                 execute_protection_fault(regs);
 313                 break;
 314         case HVM_GE_C_RPROT:
 315         case HVM_GE_C_RUSER:
 316                 read_protection_fault(regs);
 317                 break;
 318         case HVM_GE_C_WPROT:
 319         case HVM_GE_C_WUSER:
 320                 write_protection_fault(regs);
 321                 break;
 322         case HVM_GE_C_XMAL:
 323                 misaligned_instruction(regs);
 324                 break;
 325         case HVM_GE_C_WREG:
 326                 illegal_instruction(regs);
 327                 break;
 328         case HVM_GE_C_PCAL:
 329                 misaligned_instruction(regs);
 330                 break;
 331         case HVM_GE_C_RMAL:
 332                 misaligned_data_load(regs);
 333                 break;
 334         case HVM_GE_C_WMAL:
 335                 misaligned_data_store(regs);
 336                 break;
 337         case HVM_GE_C_INVI:
 338         case HVM_GE_C_PRIVI:
 339                 illegal_instruction(regs);
 340                 break;
 341         case HVM_GE_C_BUS:
 342                 precise_bus_error(regs);
 343                 break;
 344         case HVM_GE_C_CACHE:
 345                 cache_error(regs);
 346                 break;
 347         default:
 348                 /* Halt and catch fire */
 349                 panic("Unrecognized exception 0x%lx\n", pt_cause(regs));
 350                 break;
 351         }
 352 }
 353
 354 /* Indirect system call dispatch */
 355 long sys_syscall(void)
 356 {
 357         printk(KERN_ERR "sys_syscall invoked!\n");
 358         return -ENOSYS;
 359 }
 360
 361 void do_trap0(struct pt_regs *regs)
 362 {
 363         syscall_fn syscall;
 364
 365         switch (pt_cause(regs)) {
 366         case TRAP_SYSCALL:
 367                 /* System call is trap0 #1 */
 368
 369                 /* allow strace to catch syscall args  */
 370                 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE) &&
 371                         tracehook_report_syscall_entry(regs)))
 372                         return;  /*  return -ENOSYS somewhere?  */
 373
 374                 /* Interrupts should be re-enabled for syscall processing */
 375                 __vmsetie(VM_INT_ENABLE);
 376
 377                 /*
 378                  * System call number is in r6, arguments in r0..r5.
 379                  * Fortunately, no Linux syscall has more than 6 arguments,
 380                  * and Hexagon ABI passes first 6 arguments in registers.
 381                  * 64-bit arguments are passed in odd/even register pairs.
 382                  * Fortunately, we have no system calls that take more
 383                  * than three arguments with more than one 64-bit value.
 384                  * Should that change, we'd need to redesign to copy
 385                  * between user and kernel stacks.
 386                  */
 387                 regs->syscall_nr = regs->r06;
 388
 389                 /*
 390                  * GPR R0 carries the first parameter, and is also used
 391                  * to report the return value.  We need a backup of
 392                  * the user's value in case we need to do a late restart
 393                  * of the system call.
 394                  */
 395                 regs->restart_r0 = regs->r00;
 396
 397                 if ((unsigned long) regs->syscall_nr >= __NR_syscalls) {
 398                         regs->r00 = -1;
 399                 } else {
 400                         syscall = (syscall_fn)
 401                                   (sys_call_table[regs->syscall_nr]);
 402                         regs->r00 = syscall(regs->r00, regs->r01,
 403                                    regs->r02, regs->r03,
 404                                    regs->r04, regs->r05);
 405                 }
 406
 407                 /* allow strace to get the syscall return state  */
 408                 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE)))
 409                         tracehook_report_syscall_exit(regs, 0);
 410
 411                 break;
 412         case TRAP_DEBUG:
 413                 /* Trap0 0xdb is debug breakpoint */
 414                 if (user_mode(regs)) {
 415                         /*
 416                          * Some architecures add some per-thread state
 417                          * to distinguish between breakpoint traps and
 418                          * trace traps.  We may want to do that, and
 419                          * set the si_code value appropriately, or we
 420                          * may want to use a different trap0 flavor.
 421                          */
 422                         force_sig_fault(SIGTRAP, TRAP_BRKPT,
 423                                         (void __user *) pt_elr(regs), current);
 424                 } else {
 425 #ifdef CONFIG_KGDB
 426                         kgdb_handle_exception(pt_cause(regs), SIGTRAP,
 427                                               TRAP_BRKPT, regs);
 428 #endif
 429                 }
 430                 break;
 431         }
 432         /* Ignore other trap0 codes for now, especially 0 (Angel calls) */
 433 }
 434
 435 /*
 436  * Machine check exception handler
 437  */
 438 void do_machcheck(struct pt_regs *regs)
 439 {
 440         /* Halt and catch fire */
 441         __vmstop();
 442 }
 443
 444 /*
 445  * Treat this like the old 0xdb trap.
 446  */
 447
 448 void do_debug_exception(struct pt_regs *regs)
 449 {
 450         regs->hvmer.vmest &= ~HVM_VMEST_CAUSE_MSK;
 451         regs->hvmer.vmest |= (TRAP_DEBUG << HVM_VMEST_CAUSE_SFT);
 452         do_trap0(regs);
 453 }