linux-user/arm/cpu_loop.c

   1 /*
   2  *  qemu user cpu loop
   3  *
   4  *  Copyright (c) 2003-2008 Fabrice Bellard
   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 as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "qemu/osdep.h"
  21 #include "qemu-common.h"
  22 #include "qemu.h"
  23 #include "elf.h"
  24 #include "cpu_loop-common.h"
  25
  26 #define get_user_code_u32(x, gaddr, env)                \
  27     ({ abi_long __r = get_user_u32((x), (gaddr));       \
  28         if (!__r && bswap_code(arm_sctlr_b(env))) {     \
  29             (x) = bswap32(x);                           \
  30         }                                               \
  31         __r;                                            \
  32     })
  33
  34 #define get_user_code_u16(x, gaddr, env)                \
  35     ({ abi_long __r = get_user_u16((x), (gaddr));       \
  36         if (!__r && bswap_code(arm_sctlr_b(env))) {     \
  37             (x) = bswap16(x);                           \
  38         }                                               \
  39         __r;                                            \
  40     })
  41
  42 #define get_user_data_u32(x, gaddr, env)                \
  43     ({ abi_long __r = get_user_u32((x), (gaddr));       \
  44         if (!__r && arm_cpu_bswap_data(env)) {          \
  45             (x) = bswap32(x);                           \
  46         }                                               \
  47         __r;                                            \
  48     })
  49
  50 #define get_user_data_u16(x, gaddr, env)                \
  51     ({ abi_long __r = get_user_u16((x), (gaddr));       \
  52         if (!__r && arm_cpu_bswap_data(env)) {          \
  53             (x) = bswap16(x);                           \
  54         }                                               \
  55         __r;                                            \
  56     })
  57
  58 #define put_user_data_u32(x, gaddr, env)                \
  59     ({ typeof(x) __x = (x);                             \
  60         if (arm_cpu_bswap_data(env)) {                  \
  61             __x = bswap32(__x);                         \
  62         }                                               \
  63         put_user_u32(__x, (gaddr));                     \
  64     })
  65
  66 #define put_user_data_u16(x, gaddr, env)                \
  67     ({ typeof(x) __x = (x);                             \
  68         if (arm_cpu_bswap_data(env)) {                  \
  69             __x = bswap16(__x);                         \
  70         }                                               \
  71         put_user_u16(__x, (gaddr));                     \
  72     })
  73
  74 /* Commpage handling -- there is no commpage for AArch64 */
  75
  76 /*
  77  * See the Linux kernel's Documentation/arm/kernel_user_helpers.txt
  78  * Input:
  79  * r0 = pointer to oldval
  80  * r1 = pointer to newval
  81  * r2 = pointer to target value
  82  *
  83  * Output:
  84  * r0 = 0 if *ptr was changed, non-0 if no exchange happened
  85  * C set if *ptr was changed, clear if no exchange happened
  86  *
  87  * Note segv's in kernel helpers are a bit tricky, we can set the
  88  * data address sensibly but the PC address is just the entry point.
  89  */
  90 static void arm_kernel_cmpxchg64_helper(CPUARMState *env)
  91 {
  92     uint64_t oldval, newval, val;
  93     uint32_t addr, cpsr;
  94     target_siginfo_t info;
  95
  96     /* Based on the 32 bit code in do_kernel_trap */
  97
  98     /* XXX: This only works between threads, not between processes.
  99        It's probably possible to implement this with native host
 100        operations. However things like ldrex/strex are much harder so
 101        there's not much point trying.  */
 102     start_exclusive();
 103     cpsr = cpsr_read(env);
 104     addr = env->regs[2];
 105
 106     if (get_user_u64(oldval, env->regs[0])) {
 107         env->exception.vaddress = env->regs[0];
 108         goto segv;
 109     };
 110
 111     if (get_user_u64(newval, env->regs[1])) {
 112         env->exception.vaddress = env->regs[1];
 113         goto segv;
 114     };
 115
 116     if (get_user_u64(val, addr)) {
 117         env->exception.vaddress = addr;
 118         goto segv;
 119     }
 120
 121     if (val == oldval) {
 122         val = newval;
 123
 124         if (put_user_u64(val, addr)) {
 125             env->exception.vaddress = addr;
 126             goto segv;
 127         };
 128
 129         env->regs[0] = 0;
 130         cpsr |= CPSR_C;
 131     } else {
 132         env->regs[0] = -1;
 133         cpsr &= ~CPSR_C;
 134     }
 135     cpsr_write(env, cpsr, CPSR_C, CPSRWriteByInstr);
 136     end_exclusive();
 137     return;
 138
 139 segv:
 140     end_exclusive();
 141     /* We get the PC of the entry address - which is as good as anything,
 142        on a real kernel what you get depends on which mode it uses. */
 143     info.si_signo = TARGET_SIGSEGV;
 144     info.si_errno = 0;
 145     /* XXX: check env->error_code */
 146     info.si_code = TARGET_SEGV_MAPERR;
 147     info._sifields._sigfault._addr = env->exception.vaddress;
 148     queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
 149 }
 150
 151 /* Handle a jump to the kernel code page.  */
 152 static int
 153 do_kernel_trap(CPUARMState *env)
 154 {
 155     uint32_t addr;
 156     uint32_t cpsr;
 157     uint32_t val;
 158
 159     switch (env->regs[15]) {
 160     case 0xffff0fa0: /* __kernel_memory_barrier */
 161         /* ??? No-op. Will need to do better for SMP.  */
 162         break;
 163     case 0xffff0fc0: /* __kernel_cmpxchg */
 164          /* XXX: This only works between threads, not between processes.
 165             It's probably possible to implement this with native host
 166             operations. However things like ldrex/strex are much harder so
 167             there's not much point trying.  */
 168         start_exclusive();
 169         cpsr = cpsr_read(env);
 170         addr = env->regs[2];
 171         /* FIXME: This should SEGV if the access fails.  */
 172         if (get_user_u32(val, addr))
 173             val = ~env->regs[0];
 174         if (val == env->regs[0]) {
 175             val = env->regs[1];
 176             /* FIXME: Check for segfaults.  */
 177             put_user_u32(val, addr);
 178             env->regs[0] = 0;
 179             cpsr |= CPSR_C;
 180         } else {
 181             env->regs[0] = -1;
 182             cpsr &= ~CPSR_C;
 183         }
 184         cpsr_write(env, cpsr, CPSR_C, CPSRWriteByInstr);
 185         end_exclusive();
 186         break;
 187     case 0xffff0fe0: /* __kernel_get_tls */
 188         env->regs[0] = cpu_get_tls(env);
 189         break;
 190     case 0xffff0f60: /* __kernel_cmpxchg64 */
 191         arm_kernel_cmpxchg64_helper(env);
 192         break;
 193
 194     default:
 195         return 1;
 196     }
 197     /* Jump back to the caller.  */
 198     addr = env->regs[14];
 199     if (addr & 1) {
 200         env->thumb = 1;
 201         addr &= ~1;
 202     }
 203     env->regs[15] = addr;
 204
 205     return 0;
 206 }
 207
 208 void cpu_loop(CPUARMState *env)
 209 {
 210     CPUState *cs = env_cpu(env);
 211     int trapnr;
 212     unsigned int n, insn;
 213     target_siginfo_t info;
 214     uint32_t addr;
 215     abi_ulong ret;
 216
 217     for(;;) {
 218         cpu_exec_start(cs);
 219         trapnr = cpu_exec(cs);
 220         cpu_exec_end(cs);
 221         process_queued_cpu_work(cs);
 222
 223         switch(trapnr) {
 224         case EXCP_UDEF:
 225         case EXCP_NOCP:
 226         case EXCP_INVSTATE:
 227             {
 228                 TaskState *ts = cs->opaque;
 229                 uint32_t opcode;
 230                 int rc;
 231
 232                 /* we handle the FPU emulation here, as Linux */
 233                 /* we get the opcode */
 234                 /* FIXME - what to do if get_user() fails? */
 235                 get_user_code_u32(opcode, env->regs[15], env);
 236
 237                 rc = EmulateAll(opcode, &ts->fpa, env);
 238                 if (rc == 0) { /* illegal instruction */
 239                     info.si_signo = TARGET_SIGILL;
 240                     info.si_errno = 0;
 241                     info.si_code = TARGET_ILL_ILLOPN;
 242                     info._sifields._sigfault._addr = env->regs[15];
 243                     queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
 244                 } else if (rc < 0) { /* FP exception */
 245                     int arm_fpe=0;
 246
 247                     /* translate softfloat flags to FPSR flags */
 248                     if (-rc & float_flag_invalid)
 249                       arm_fpe |= BIT_IOC;
 250                     if (-rc & float_flag_divbyzero)
 251                       arm_fpe |= BIT_DZC;
 252                     if (-rc & float_flag_overflow)
 253                       arm_fpe |= BIT_OFC;
 254                     if (-rc & float_flag_underflow)
 255                       arm_fpe |= BIT_UFC;
 256                     if (-rc & float_flag_inexact)
 257                       arm_fpe |= BIT_IXC;
 258
 259                     FPSR fpsr = ts->fpa.fpsr;
 260                     //printf("fpsr 0x%x, arm_fpe 0x%x\n",fpsr,arm_fpe);
 261
 262                     if (fpsr & (arm_fpe << 16)) { /* exception enabled? */
 263                       info.si_signo = TARGET_SIGFPE;
 264                       info.si_errno = 0;
 265
 266                       /* ordered by priority, least first */
 267                       if (arm_fpe & BIT_IXC) info.si_code = TARGET_FPE_FLTRES;
 268                       if (arm_fpe & BIT_UFC) info.si_code = TARGET_FPE_FLTUND;
 269                       if (arm_fpe & BIT_OFC) info.si_code = TARGET_FPE_FLTOVF;
 270                       if (arm_fpe & BIT_DZC) info.si_code = TARGET_FPE_FLTDIV;
 271                       if (arm_fpe & BIT_IOC) info.si_code = TARGET_FPE_FLTINV;
 272
 273                       info._sifields._sigfault._addr = env->regs[15];
 274                       queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
 275                     } else {
 276                       env->regs[15] += 4;
 277                     }
 278
 279                     /* accumulate unenabled exceptions */
 280                     if ((!(fpsr & BIT_IXE)) && (arm_fpe & BIT_IXC))
 281                       fpsr |= BIT_IXC;
 282                     if ((!(fpsr & BIT_UFE)) && (arm_fpe & BIT_UFC))
 283                       fpsr |= BIT_UFC;
 284                     if ((!(fpsr & BIT_OFE)) && (arm_fpe & BIT_OFC))
 285                       fpsr |= BIT_OFC;
 286                     if ((!(fpsr & BIT_DZE)) && (arm_fpe & BIT_DZC))
 287                       fpsr |= BIT_DZC;
 288                     if ((!(fpsr & BIT_IOE)) && (arm_fpe & BIT_IOC))
 289                       fpsr |= BIT_IOC;
 290                     ts->fpa.fpsr=fpsr;
 291                 } else { /* everything OK */
 292                     /* increment PC */
 293                     env->regs[15] += 4;
 294                 }
 295             }
 296             break;
 297         case EXCP_SWI:
 298         case EXCP_BKPT:
 299             {
 300                 env->eabi = 1;
 301                 /* system call */
 302                 if (trapnr == EXCP_BKPT) {
 303                     if (env->thumb) {
 304                         /* FIXME - what to do if get_user() fails? */
 305                         get_user_code_u16(insn, env->regs[15], env);
 306                         n = insn & 0xff;
 307                         env->regs[15] += 2;
 308                     } else {
 309                         /* FIXME - what to do if get_user() fails? */
 310                         get_user_code_u32(insn, env->regs[15], env);
 311                         n = (insn & 0xf) | ((insn >> 4) & 0xff0);
 312                         env->regs[15] += 4;
 313                     }
 314                 } else {
 315                     if (env->thumb) {
 316                         /* FIXME - what to do if get_user() fails? */
 317                         get_user_code_u16(insn, env->regs[15] - 2, env);
 318                         n = insn & 0xff;
 319                     } else {
 320                         /* FIXME - what to do if get_user() fails? */
 321                         get_user_code_u32(insn, env->regs[15] - 4, env);
 322                         n = insn & 0xffffff;
 323                     }
 324                 }
 325
 326                 if (n == ARM_NR_cacheflush) {
 327                     /* nop */
 328                 } else if (n == ARM_NR_semihosting
 329                            || n == ARM_NR_thumb_semihosting) {
 330                     env->regs[0] = do_arm_semihosting (env);
 331                 } else if (n == 0 || n >= ARM_SYSCALL_BASE || env->thumb) {
 332                     /* linux syscall */
 333                     if (env->thumb || n == 0) {
 334                         n = env->regs[7];
 335                     } else {
 336                         n -= ARM_SYSCALL_BASE;
 337                         env->eabi = 0;
 338                     }
 339                     if ( n > ARM_NR_BASE) {
 340                         switch (n) {
 341                         case ARM_NR_cacheflush:
 342                             /* nop */
 343                             break;
 344                         case ARM_NR_set_tls:
 345                             cpu_set_tls(env, env->regs[0]);
 346                             env->regs[0] = 0;
 347                             break;
 348                         case ARM_NR_breakpoint:
 349                             env->regs[15] -= env->thumb ? 2 : 4;
 350                             goto excp_debug;
 351                         case ARM_NR_get_tls:
 352                             env->regs[0] = cpu_get_tls(env);
 353                             break;
 354                         default:
 355                             gemu_log("qemu: Unsupported ARM syscall: 0x%x\n",
 356                                      n);
 357                             env->regs[0] = -TARGET_ENOSYS;
 358                             break;
 359                         }
 360                     } else {
 361                         ret = do_syscall(env,
 362                                          n,
 363                                          env->regs[0],
 364                                          env->regs[1],
 365                                          env->regs[2],
 366                                          env->regs[3],
 367                                          env->regs[4],
 368                                          env->regs[5],
 369                                          0, 0);
 370                         if (ret == -TARGET_ERESTARTSYS) {
 371                             env->regs[15] -= env->thumb ? 2 : 4;
 372                         } else if (ret != -TARGET_QEMU_ESIGRETURN) {
 373                             env->regs[0] = ret;
 374                         }
 375                     }
 376                 } else {
 377                     goto error;
 378                 }
 379             }
 380             break;
 381         case EXCP_SEMIHOST:
 382             env->regs[0] = do_arm_semihosting(env);
 383             break;
 384         case EXCP_INTERRUPT:
 385             /* just indicate that signals should be handled asap */
 386             break;
 387         case EXCP_PREFETCH_ABORT:
 388         case EXCP_DATA_ABORT:
 389             addr = env->exception.vaddress;
 390             {
 391                 info.si_signo = TARGET_SIGSEGV;
 392                 info.si_errno = 0;
 393                 /* XXX: check env->error_code */
 394                 info.si_code = TARGET_SEGV_MAPERR;
 395                 info._sifields._sigfault._addr = addr;
 396                 queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
 397             }
 398             break;
 399         case EXCP_DEBUG:
 400         excp_debug:
 401             info.si_signo = TARGET_SIGTRAP;
 402             info.si_errno = 0;
 403             info.si_code = TARGET_TRAP_BRKPT;
 404             queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
 405             break;
 406         case EXCP_KERNEL_TRAP:
 407             if (do_kernel_trap(env))
 408               goto error;
 409             break;
 410         case EXCP_YIELD:
 411             /* nothing to do here for user-mode, just resume guest code */
 412             break;
 413         case EXCP_ATOMIC:
 414             cpu_exec_step_atomic(cs);
 415             break;
 416         default:
 417         error:
 418             EXCP_DUMP(env, "qemu: unhandled CPU exception 0x%x - aborting\n", trapnr);
 419             abort();
 420         }
 421         process_pending_signals(env);
 422     }
 423 }
 424
 425 void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
 426 {
 427     CPUState *cpu = env_cpu(env);
 428     TaskState *ts = cpu->opaque;
 429     struct image_info *info = ts->info;
 430     int i;
 431
 432     cpsr_write(env, regs->uregs[16], CPSR_USER | CPSR_EXEC,
 433                CPSRWriteByInstr);
 434     for(i = 0; i < 16; i++) {
 435         env->regs[i] = regs->uregs[i];
 436     }
 437 #ifdef TARGET_WORDS_BIGENDIAN
 438     /* Enable BE8.  */
 439     if (EF_ARM_EABI_VERSION(info->elf_flags) >= EF_ARM_EABI_VER4
 440         && (info->elf_flags & EF_ARM_BE8)) {
 441         env->uncached_cpsr |= CPSR_E;
 442         env->cp15.sctlr_el[1] |= SCTLR_E0E;
 443     } else {
 444         env->cp15.sctlr_el[1] |= SCTLR_B;
 445     }
 446 #endif
 447
 448     ts->stack_base = info->start_stack;
 449     ts->heap_base = info->brk;
 450     /* This will be filled in on the first SYS_HEAPINFO call.  */
 451     ts->heap_limit = 0;
 452 }