target-arm/op_helper.c

   1 /*
   2  *  ARM helper routines
   3  *
   4  *  Copyright (c) 2005-2007 CodeSourcery, LLC
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library 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 GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #include "cpu.h"
  20 #include "exec/helper-proto.h"
  21 #include "internals.h"
  22 #include "exec/cpu_ldst.h"
  23
  24 #define SIGNBIT (uint32_t)0x80000000
  25 #define SIGNBIT64 ((uint64_t)1 << 63)
  26
  27 static void raise_exception(CPUARMState *env, int tt)
  28 {
  29     ARMCPU *cpu = arm_env_get_cpu(env);
  30     CPUState *cs = CPU(cpu);
  31
  32     cs->exception_index = tt;
  33     cpu_loop_exit(cs);
  34 }
  35
  36 uint32_t HELPER(neon_tbl)(CPUARMState *env, uint32_t ireg, uint32_t def,
  37                           uint32_t rn, uint32_t maxindex)
  38 {
  39     uint32_t val;
  40     uint32_t tmp;
  41     int index;
  42     int shift;
  43     uint64_t *table;
  44     table = (uint64_t *)&env->vfp.regs[rn];
  45     val = 0;
  46     for (shift = 0; shift < 32; shift += 8) {
  47         index = (ireg >> shift) & 0xff;
  48         if (index < maxindex) {
  49             tmp = (table[index >> 3] >> ((index & 7) << 3)) & 0xff;
  50             val |= tmp << shift;
  51         } else {
  52             val |= def & (0xff << shift);
  53         }
  54     }
  55     return val;
  56 }
  57
  58 #if !defined(CONFIG_USER_ONLY)
  59
  60 /* try to fill the TLB and return an exception if error. If retaddr is
  61  * NULL, it means that the function was called in C code (i.e. not
  62  * from generated code or from helper.c)
  63  */
  64 void tlb_fill(CPUState *cs, target_ulong addr, int is_write, int mmu_idx,
  65               uintptr_t retaddr)
  66 {
  67     int ret;
  68
  69     ret = arm_cpu_handle_mmu_fault(cs, addr, is_write, mmu_idx);
  70     if (unlikely(ret)) {
  71         ARMCPU *cpu = ARM_CPU(cs);
  72         CPUARMState *env = &cpu->env;
  73
  74         if (retaddr) {
  75             /* now we have a real cpu fault */
  76             cpu_restore_state(cs, retaddr);
  77         }
  78         raise_exception(env, cs->exception_index);
  79     }
  80 }
  81 #endif
  82
  83 uint32_t HELPER(add_setq)(CPUARMState *env, uint32_t a, uint32_t b)
  84 {
  85     uint32_t res = a + b;
  86     if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT))
  87         env->QF = 1;
  88     return res;
  89 }
  90
  91 uint32_t HELPER(add_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
  92 {
  93     uint32_t res = a + b;
  94     if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT)) {
  95         env->QF = 1;
  96         res = ~(((int32_t)a >> 31) ^ SIGNBIT);
  97     }
  98     return res;
  99 }
 100
 101 uint32_t HELPER(sub_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
 102 {
 103     uint32_t res = a - b;
 104     if (((res ^ a) & SIGNBIT) && ((a ^ b) & SIGNBIT)) {
 105         env->QF = 1;
 106         res = ~(((int32_t)a >> 31) ^ SIGNBIT);
 107     }
 108     return res;
 109 }
 110
 111 uint32_t HELPER(double_saturate)(CPUARMState *env, int32_t val)
 112 {
 113     uint32_t res;
 114     if (val >= 0x40000000) {
 115         res = ~SIGNBIT;
 116         env->QF = 1;
 117     } else if (val <= (int32_t)0xc0000000) {
 118         res = SIGNBIT;
 119         env->QF = 1;
 120     } else {
 121         res = val << 1;
 122     }
 123     return res;
 124 }
 125
 126 uint32_t HELPER(add_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
 127 {
 128     uint32_t res = a + b;
 129     if (res < a) {
 130         env->QF = 1;
 131         res = ~0;
 132     }
 133     return res;
 134 }
 135
 136 uint32_t HELPER(sub_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
 137 {
 138     uint32_t res = a - b;
 139     if (res > a) {
 140         env->QF = 1;
 141         res = 0;
 142     }
 143     return res;
 144 }
 145
 146 /* Signed saturation.  */
 147 static inline uint32_t do_ssat(CPUARMState *env, int32_t val, int shift)
 148 {
 149     int32_t top;
 150     uint32_t mask;
 151
 152     top = val >> shift;
 153     mask = (1u << shift) - 1;
 154     if (top > 0) {
 155         env->QF = 1;
 156         return mask;
 157     } else if (top < -1) {
 158         env->QF = 1;
 159         return ~mask;
 160     }
 161     return val;
 162 }
 163
 164 /* Unsigned saturation.  */
 165 static inline uint32_t do_usat(CPUARMState *env, int32_t val, int shift)
 166 {
 167     uint32_t max;
 168
 169     max = (1u << shift) - 1;
 170     if (val < 0) {
 171         env->QF = 1;
 172         return 0;
 173     } else if (val > max) {
 174         env->QF = 1;
 175         return max;
 176     }
 177     return val;
 178 }
 179
 180 /* Signed saturate.  */
 181 uint32_t HELPER(ssat)(CPUARMState *env, uint32_t x, uint32_t shift)
 182 {
 183     return do_ssat(env, x, shift);
 184 }
 185
 186 /* Dual halfword signed saturate.  */
 187 uint32_t HELPER(ssat16)(CPUARMState *env, uint32_t x, uint32_t shift)
 188 {
 189     uint32_t res;
 190
 191     res = (uint16_t)do_ssat(env, (int16_t)x, shift);
 192     res |= do_ssat(env, ((int32_t)x) >> 16, shift) << 16;
 193     return res;
 194 }
 195
 196 /* Unsigned saturate.  */
 197 uint32_t HELPER(usat)(CPUARMState *env, uint32_t x, uint32_t shift)
 198 {
 199     return do_usat(env, x, shift);
 200 }
 201
 202 /* Dual halfword unsigned saturate.  */
 203 uint32_t HELPER(usat16)(CPUARMState *env, uint32_t x, uint32_t shift)
 204 {
 205     uint32_t res;
 206
 207     res = (uint16_t)do_usat(env, (int16_t)x, shift);
 208     res |= do_usat(env, ((int32_t)x) >> 16, shift) << 16;
 209     return res;
 210 }
 211
 212 void HELPER(wfi)(CPUARMState *env)
 213 {
 214     CPUState *cs = CPU(arm_env_get_cpu(env));
 215
 216     cs->exception_index = EXCP_HLT;
 217     cs->halted = 1;
 218     cpu_loop_exit(cs);
 219 }
 220
 221 void HELPER(wfe)(CPUARMState *env)
 222 {
 223     CPUState *cs = CPU(arm_env_get_cpu(env));
 224
 225     /* Don't actually halt the CPU, just yield back to top
 226      * level loop
 227      */
 228     cs->exception_index = EXCP_YIELD;
 229     cpu_loop_exit(cs);
 230 }
 231
 232 /* Raise an internal-to-QEMU exception. This is limited to only
 233  * those EXCP values which are special cases for QEMU to interrupt
 234  * execution and not to be used for exceptions which are passed to
 235  * the guest (those must all have syndrome information and thus should
 236  * use exception_with_syndrome).
 237  */
 238 void HELPER(exception_internal)(CPUARMState *env, uint32_t excp)
 239 {
 240     CPUState *cs = CPU(arm_env_get_cpu(env));
 241
 242     assert(excp_is_internal(excp));
 243     cs->exception_index = excp;
 244     cpu_loop_exit(cs);
 245 }
 246
 247 /* Raise an exception with the specified syndrome register value */
 248 void HELPER(exception_with_syndrome)(CPUARMState *env, uint32_t excp,
 249                                      uint32_t syndrome)
 250 {
 251     CPUState *cs = CPU(arm_env_get_cpu(env));
 252
 253     assert(!excp_is_internal(excp));
 254     cs->exception_index = excp;
 255     env->exception.syndrome = syndrome;
 256     cpu_loop_exit(cs);
 257 }
 258
 259 uint32_t HELPER(cpsr_read)(CPUARMState *env)
 260 {
 261     return cpsr_read(env) & ~(CPSR_EXEC | CPSR_RESERVED);
 262 }
 263
 264 void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)
 265 {
 266     cpsr_write(env, val, mask);
 267 }
 268
 269 /* Access to user mode registers from privileged modes.  */
 270 uint32_t HELPER(get_user_reg)(CPUARMState *env, uint32_t regno)
 271 {
 272     uint32_t val;
 273
 274     if (regno == 13) {
 275         val = env->banked_r13[0];
 276     } else if (regno == 14) {
 277         val = env->banked_r14[0];
 278     } else if (regno >= 8
 279                && (env->uncached_cpsr & 0x1f) == ARM_CPU_MODE_FIQ) {
 280         val = env->usr_regs[regno - 8];
 281     } else {
 282         val = env->regs[regno];
 283     }
 284     return val;
 285 }
 286
 287 void HELPER(set_user_reg)(CPUARMState *env, uint32_t regno, uint32_t val)
 288 {
 289     if (regno == 13) {
 290         env->banked_r13[0] = val;
 291     } else if (regno == 14) {
 292         env->banked_r14[0] = val;
 293     } else if (regno >= 8
 294                && (env->uncached_cpsr & 0x1f) == ARM_CPU_MODE_FIQ) {
 295         env->usr_regs[regno - 8] = val;
 296     } else {
 297         env->regs[regno] = val;
 298     }
 299 }
 300
 301 void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome)
 302 {
 303     const ARMCPRegInfo *ri = rip;
 304
 305     if (arm_feature(env, ARM_FEATURE_XSCALE) && ri->cp < 14
 306         && extract32(env->cp15.c15_cpar, ri->cp, 1) == 0) {
 307         env->exception.syndrome = syndrome;
 308         raise_exception(env, EXCP_UDEF);
 309     }
 310
 311     if (!ri->accessfn) {
 312         return;
 313     }
 314
 315     switch (ri->accessfn(env, ri)) {
 316     case CP_ACCESS_OK:
 317         return;
 318     case CP_ACCESS_TRAP:
 319         env->exception.syndrome = syndrome;
 320         break;
 321     case CP_ACCESS_TRAP_UNCATEGORIZED:
 322         env->exception.syndrome = syn_uncategorized();
 323         break;
 324     default:
 325         g_assert_not_reached();
 326     }
 327     raise_exception(env, EXCP_UDEF);
 328 }
 329
 330 void HELPER(set_cp_reg)(CPUARMState *env, void *rip, uint32_t value)
 331 {
 332     const ARMCPRegInfo *ri = rip;
 333
 334     ri->writefn(env, ri, value);
 335 }
 336
 337 uint32_t HELPER(get_cp_reg)(CPUARMState *env, void *rip)
 338 {
 339     const ARMCPRegInfo *ri = rip;
 340
 341     return ri->readfn(env, ri);
 342 }
 343
 344 void HELPER(set_cp_reg64)(CPUARMState *env, void *rip, uint64_t value)
 345 {
 346     const ARMCPRegInfo *ri = rip;
 347
 348     ri->writefn(env, ri, value);
 349 }
 350
 351 uint64_t HELPER(get_cp_reg64)(CPUARMState *env, void *rip)
 352 {
 353     const ARMCPRegInfo *ri = rip;
 354
 355     return ri->readfn(env, ri);
 356 }
 357
 358 void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op, uint32_t imm)
 359 {
 360     /* MSR_i to update PSTATE. This is OK from EL0 only if UMA is set.
 361      * Note that SPSel is never OK from EL0; we rely on handle_msr_i()
 362      * to catch that case at translate time.
 363      */
 364     if (arm_current_pl(env) == 0 && !(env->cp15.c1_sys & SCTLR_UMA)) {
 365         raise_exception(env, EXCP_UDEF);
 366     }
 367
 368     switch (op) {
 369     case 0x05: /* SPSel */
 370         update_spsel(env, imm);
 371         break;
 372     case 0x1e: /* DAIFSet */
 373         env->daif |= (imm << 6) & PSTATE_DAIF;
 374         break;
 375     case 0x1f: /* DAIFClear */
 376         env->daif &= ~((imm << 6) & PSTATE_DAIF);
 377         break;
 378     default:
 379         g_assert_not_reached();
 380     }
 381 }
 382
 383 void HELPER(clear_pstate_ss)(CPUARMState *env)
 384 {
 385     env->pstate &= ~PSTATE_SS;
 386 }
 387
 388 void HELPER(pre_hvc)(CPUARMState *env)
 389 {
 390     ARMCPU *cpu = arm_env_get_cpu(env);
 391     int cur_el = arm_current_pl(env);
 392     /* FIXME: Use actual secure state.  */
 393     bool secure = false;
 394     bool undef;
 395
 396     if (arm_is_psci_call(cpu, EXCP_HVC)) {
 397         /* If PSCI is enabled and this looks like a valid PSCI call then
 398          * that overrides the architecturally mandated HVC behaviour.
 399          */
 400         return;
 401     }
 402
 403     if (!arm_feature(env, ARM_FEATURE_EL2)) {
 404         /* If EL2 doesn't exist, HVC always UNDEFs */
 405         undef = true;
 406     } else if (arm_feature(env, ARM_FEATURE_EL3)) {
 407         /* EL3.HCE has priority over EL2.HCD. */
 408         undef = !(env->cp15.scr_el3 & SCR_HCE);
 409     } else {
 410         undef = env->cp15.hcr_el2 & HCR_HCD;
 411     }
 412
 413     /* In ARMv7 and ARMv8/AArch32, HVC is undef in secure state.
 414      * For ARMv8/AArch64, HVC is allowed in EL3.
 415      * Note that we've already trapped HVC from EL0 at translation
 416      * time.
 417      */
 418     if (secure && (!is_a64(env) || cur_el == 1)) {
 419         undef = true;
 420     }
 421
 422     if (undef) {
 423         env->exception.syndrome = syn_uncategorized();
 424         raise_exception(env, EXCP_UDEF);
 425     }
 426 }
 427
 428 void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
 429 {
 430     ARMCPU *cpu = arm_env_get_cpu(env);
 431     int cur_el = arm_current_pl(env);
 432     /* FIXME: Use real secure state.  */
 433     bool secure = false;
 434     bool smd = env->cp15.scr_el3 & SCR_SMD;
 435     /* On ARMv8 AArch32, SMD only applies to NS state.
 436      * On ARMv7 SMD only applies to NS state and only if EL2 is available.
 437      * For ARMv7 non EL2, we force SMD to zero so we don't need to re-check
 438      * the EL2 condition here.
 439      */
 440     bool undef = is_a64(env) ? smd : (!secure && smd);
 441
 442     if (arm_is_psci_call(cpu, EXCP_SMC)) {
 443         /* If PSCI is enabled and this looks like a valid PSCI call then
 444          * that overrides the architecturally mandated SMC behaviour.
 445          */
 446         return;
 447     }
 448
 449     if (!arm_feature(env, ARM_FEATURE_EL3)) {
 450         /* If we have no EL3 then SMC always UNDEFs */
 451         undef = true;
 452     } else if (!secure && cur_el == 1 && (env->cp15.hcr_el2 & HCR_TSC)) {
 453         /* In NS EL1, HCR controlled routing to EL2 has priority over SMD. */
 454         env->exception.syndrome = syndrome;
 455         raise_exception(env, EXCP_HYP_TRAP);
 456     }
 457
 458     if (undef) {
 459         env->exception.syndrome = syn_uncategorized();
 460         raise_exception(env, EXCP_UDEF);
 461     }
 462 }
 463
 464 void HELPER(exception_return)(CPUARMState *env)
 465 {
 466     int cur_el = arm_current_pl(env);
 467     unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el);
 468     uint32_t spsr = env->banked_spsr[spsr_idx];
 469     int new_el, i;
 470
 471     aarch64_save_sp(env, cur_el);
 472
 473     env->exclusive_addr = -1;
 474
 475     /* We must squash the PSTATE.SS bit to zero unless both of the
 476      * following hold:
 477      *  1. debug exceptions are currently disabled
 478      *  2. singlestep will be active in the EL we return to
 479      * We check 1 here and 2 after we've done the pstate/cpsr write() to
 480      * transition to the EL we're going to.
 481      */
 482     if (arm_generate_debug_exceptions(env)) {
 483         spsr &= ~PSTATE_SS;
 484     }
 485
 486     if (spsr & PSTATE_nRW) {
 487         /* TODO: We currently assume EL1/2/3 are running in AArch64.  */
 488         env->aarch64 = 0;
 489         new_el = 0;
 490         env->uncached_cpsr = 0x10;
 491         cpsr_write(env, spsr, ~0);
 492         if (!arm_singlestep_active(env)) {
 493             env->uncached_cpsr &= ~PSTATE_SS;
 494         }
 495         for (i = 0; i < 15; i++) {
 496             env->regs[i] = env->xregs[i];
 497         }
 498
 499         env->regs[15] = env->elr_el[1] & ~0x1;
 500     } else {
 501         new_el = extract32(spsr, 2, 2);
 502         if (new_el > cur_el
 503             || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) {
 504             /* Disallow return to an EL which is unimplemented or higher
 505              * than the current one.
 506              */
 507             goto illegal_return;
 508         }
 509         if (extract32(spsr, 1, 1)) {
 510             /* Return with reserved M[1] bit set */
 511             goto illegal_return;
 512         }
 513         if (new_el == 0 && (spsr & PSTATE_SP)) {
 514             /* Return to EL0 with M[0] bit set */
 515             goto illegal_return;
 516         }
 517         env->aarch64 = 1;
 518         pstate_write(env, spsr);
 519         if (!arm_singlestep_active(env)) {
 520             env->pstate &= ~PSTATE_SS;
 521         }
 522         aarch64_restore_sp(env, new_el);
 523         env->pc = env->elr_el[cur_el];
 524     }
 525
 526     return;
 527
 528 illegal_return:
 529     /* Illegal return events of various kinds have architecturally
 530      * mandated behaviour:
 531      * restore NZCV and DAIF from SPSR_ELx
 532      * set PSTATE.IL
 533      * restore PC from ELR_ELx
 534      * no change to exception level, execution state or stack pointer
 535      */
 536     env->pstate |= PSTATE_IL;
 537     env->pc = env->elr_el[cur_el];
 538     spsr &= PSTATE_NZCV | PSTATE_DAIF;
 539     spsr |= pstate_read(env) & ~(PSTATE_NZCV | PSTATE_DAIF);
 540     pstate_write(env, spsr);
 541     if (!arm_singlestep_active(env)) {
 542         env->pstate &= ~PSTATE_SS;
 543     }
 544 }
 545
 546 /* Return true if the linked breakpoint entry lbn passes its checks */
 547 static bool linked_bp_matches(ARMCPU *cpu, int lbn)
 548 {
 549     CPUARMState *env = &cpu->env;
 550     uint64_t bcr = env->cp15.dbgbcr[lbn];
 551     int brps = extract32(cpu->dbgdidr, 24, 4);
 552     int ctx_cmps = extract32(cpu->dbgdidr, 20, 4);
 553     int bt;
 554     uint32_t contextidr;
 555
 556     /* Links to unimplemented or non-context aware breakpoints are
 557      * CONSTRAINED UNPREDICTABLE: either behave as if disabled, or
 558      * as if linked to an UNKNOWN context-aware breakpoint (in which
 559      * case DBGWCR<n>_EL1.LBN must indicate that breakpoint).
 560      * We choose the former.
 561      */
 562     if (lbn > brps || lbn < (brps - ctx_cmps)) {
 563         return false;
 564     }
 565
 566     bcr = env->cp15.dbgbcr[lbn];
 567
 568     if (extract64(bcr, 0, 1) == 0) {
 569         /* Linked breakpoint disabled : generate no events */
 570         return false;
 571     }
 572
 573     bt = extract64(bcr, 20, 4);
 574
 575     /* We match the whole register even if this is AArch32 using the
 576      * short descriptor format (in which case it holds both PROCID and ASID),
 577      * since we don't implement the optional v7 context ID masking.
 578      */
 579     contextidr = extract64(env->cp15.contextidr_el1, 0, 32);
 580
 581     switch (bt) {
 582     case 3: /* linked context ID match */
 583         if (arm_current_pl(env) > 1) {
 584             /* Context matches never fire in EL2 or (AArch64) EL3 */
 585             return false;
 586         }
 587         return (contextidr == extract64(env->cp15.dbgbvr[lbn], 0, 32));
 588     case 5: /* linked address mismatch (reserved in AArch64) */
 589     case 9: /* linked VMID match (reserved if no EL2) */
 590     case 11: /* linked context ID and VMID match (reserved if no EL2) */
 591     default:
 592         /* Links to Unlinked context breakpoints must generate no
 593          * events; we choose to do the same for reserved values too.
 594          */
 595         return false;
 596     }
 597
 598     return false;
 599 }
 600
 601 static bool bp_wp_matches(ARMCPU *cpu, int n, bool is_wp)
 602 {
 603     CPUARMState *env = &cpu->env;
 604     uint64_t cr;
 605     int pac, hmc, ssc, wt, lbn;
 606     /* TODO: check against CPU security state when we implement TrustZone */
 607     bool is_secure = false;
 608
 609     if (is_wp) {
 610         if (!env->cpu_watchpoint[n]
 611             || !(env->cpu_watchpoint[n]->flags & BP_WATCHPOINT_HIT)) {
 612             return false;
 613         }
 614         cr = env->cp15.dbgwcr[n];
 615     } else {
 616         uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
 617
 618         if (!env->cpu_breakpoint[n] || env->cpu_breakpoint[n]->pc != pc) {
 619             return false;
 620         }
 621         cr = env->cp15.dbgbcr[n];
 622     }
 623     /* The WATCHPOINT_HIT flag guarantees us that the watchpoint is
 624      * enabled and that the address and access type match; for breakpoints
 625      * we know the address matched; check the remaining fields, including
 626      * linked breakpoints. We rely on WCR and BCR having the same layout
 627      * for the LBN, SSC, HMC, PAC/PMC and is-linked fields.
 628      * Note that some combinations of {PAC, HMC, SSC} are reserved and
 629      * must act either like some valid combination or as if the watchpoint
 630      * were disabled. We choose the former, and use this together with
 631      * the fact that EL3 must always be Secure and EL2 must always be
 632      * Non-Secure to simplify the code slightly compared to the full
 633      * table in the ARM ARM.
 634      */
 635     pac = extract64(cr, 1, 2);
 636     hmc = extract64(cr, 13, 1);
 637     ssc = extract64(cr, 14, 2);
 638
 639     switch (ssc) {
 640     case 0:
 641         break;
 642     case 1:
 643     case 3:
 644         if (is_secure) {
 645             return false;
 646         }
 647         break;
 648     case 2:
 649         if (!is_secure) {
 650             return false;
 651         }
 652         break;
 653     }
 654
 655     /* TODO: this is not strictly correct because the LDRT/STRT/LDT/STT
 656      * "unprivileged access" instructions should match watchpoints as if
 657      * they were accesses done at EL0, even if the CPU is at EL1 or higher.
 658      * Implementing this would require reworking the core watchpoint code
 659      * to plumb the mmu_idx through to this point. Luckily Linux does not
 660      * rely on this behaviour currently.
 661      * For breakpoints we do want to use the current CPU state.
 662      */
 663     switch (arm_current_pl(env)) {
 664     case 3:
 665     case 2:
 666         if (!hmc) {
 667             return false;
 668         }
 669         break;
 670     case 1:
 671         if (extract32(pac, 0, 1) == 0) {
 672             return false;
 673         }
 674         break;
 675     case 0:
 676         if (extract32(pac, 1, 1) == 0) {
 677             return false;
 678         }
 679         break;
 680     default:
 681         g_assert_not_reached();
 682     }
 683
 684     wt = extract64(cr, 20, 1);
 685     lbn = extract64(cr, 16, 4);
 686
 687     if (wt && !linked_bp_matches(cpu, lbn)) {
 688         return false;
 689     }
 690
 691     return true;
 692 }
 693
 694 static bool check_watchpoints(ARMCPU *cpu)
 695 {
 696     CPUARMState *env = &cpu->env;
 697     int n;
 698
 699     /* If watchpoints are disabled globally or we can't take debug
 700      * exceptions here then watchpoint firings are ignored.
 701      */
 702     if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
 703         || !arm_generate_debug_exceptions(env)) {
 704         return false;
 705     }
 706
 707     for (n = 0; n < ARRAY_SIZE(env->cpu_watchpoint); n++) {
 708         if (bp_wp_matches(cpu, n, true)) {
 709             return true;
 710         }
 711     }
 712     return false;
 713 }
 714
 715 static bool check_breakpoints(ARMCPU *cpu)
 716 {
 717     CPUARMState *env = &cpu->env;
 718     int n;
 719
 720     /* If breakpoints are disabled globally or we can't take debug
 721      * exceptions here then breakpoint firings are ignored.
 722      */
 723     if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
 724         || !arm_generate_debug_exceptions(env)) {
 725         return false;
 726     }
 727
 728     for (n = 0; n < ARRAY_SIZE(env->cpu_breakpoint); n++) {
 729         if (bp_wp_matches(cpu, n, false)) {
 730             return true;
 731         }
 732     }
 733     return false;
 734 }
 735
 736 void arm_debug_excp_handler(CPUState *cs)
 737 {
 738     /* Called by core code when a watchpoint or breakpoint fires;
 739      * need to check which one and raise the appropriate exception.
 740      */
 741     ARMCPU *cpu = ARM_CPU(cs);
 742     CPUARMState *env = &cpu->env;
 743     CPUWatchpoint *wp_hit = cs->watchpoint_hit;
 744
 745     if (wp_hit) {
 746         if (wp_hit->flags & BP_CPU) {
 747             cs->watchpoint_hit = NULL;
 748             if (check_watchpoints(cpu)) {
 749                 bool wnr = (wp_hit->flags & BP_WATCHPOINT_HIT_WRITE) != 0;
 750                 bool same_el = arm_debug_target_el(env) == arm_current_pl(env);
 751
 752                 env->exception.syndrome = syn_watchpoint(same_el, 0, wnr);
 753                 if (extended_addresses_enabled(env)) {
 754                     env->exception.fsr = (1 << 9) | 0x22;
 755                 } else {
 756                     env->exception.fsr = 0x2;
 757                 }
 758                 env->exception.vaddress = wp_hit->hitaddr;
 759                 raise_exception(env, EXCP_DATA_ABORT);
 760             } else {
 761                 cpu_resume_from_signal(cs, NULL);
 762             }
 763         }
 764     } else {
 765         if (check_breakpoints(cpu)) {
 766             bool same_el = (arm_debug_target_el(env) == arm_current_pl(env));
 767             env->exception.syndrome = syn_breakpoint(same_el);
 768             if (extended_addresses_enabled(env)) {
 769                 env->exception.fsr = (1 << 9) | 0x22;
 770             } else {
 771                 env->exception.fsr = 0x2;
 772             }
 773             /* FAR is UNKNOWN, so doesn't need setting */
 774             raise_exception(env, EXCP_PREFETCH_ABORT);
 775         }
 776     }
 777 }
 778
 779 /* ??? Flag setting arithmetic is awkward because we need to do comparisons.
 780    The only way to do that in TCG is a conditional branch, which clobbers
 781    all our temporaries.  For now implement these as helper functions.  */
 782
 783 /* Similarly for variable shift instructions.  */
 784
 785 uint32_t HELPER(shl_cc)(CPUARMState *env, uint32_t x, uint32_t i)
 786 {
 787     int shift = i & 0xff;
 788     if (shift >= 32) {
 789         if (shift == 32)
 790             env->CF = x & 1;
 791         else
 792             env->CF = 0;
 793         return 0;
 794     } else if (shift != 0) {
 795         env->CF = (x >> (32 - shift)) & 1;
 796         return x << shift;
 797     }
 798     return x;
 799 }
 800
 801 uint32_t HELPER(shr_cc)(CPUARMState *env, uint32_t x, uint32_t i)
 802 {
 803     int shift = i & 0xff;
 804     if (shift >= 32) {
 805         if (shift == 32)
 806             env->CF = (x >> 31) & 1;
 807         else
 808             env->CF = 0;
 809         return 0;
 810     } else if (shift != 0) {
 811         env->CF = (x >> (shift - 1)) & 1;
 812         return x >> shift;
 813     }
 814     return x;
 815 }
 816
 817 uint32_t HELPER(sar_cc)(CPUARMState *env, uint32_t x, uint32_t i)
 818 {
 819     int shift = i & 0xff;
 820     if (shift >= 32) {
 821         env->CF = (x >> 31) & 1;
 822         return (int32_t)x >> 31;
 823     } else if (shift != 0) {
 824         env->CF = (x >> (shift - 1)) & 1;
 825         return (int32_t)x >> shift;
 826     }
 827     return x;
 828 }
 829
 830 uint32_t HELPER(ror_cc)(CPUARMState *env, uint32_t x, uint32_t i)
 831 {
 832     int shift1, shift;
 833     shift1 = i & 0xff;
 834     shift = shift1 & 0x1f;
 835     if (shift == 0) {
 836         if (shift1 != 0)
 837             env->CF = (x >> 31) & 1;
 838         return x;
 839     } else {
 840         env->CF = (x >> (shift - 1)) & 1;
 841         return ((uint32_t)x >> shift) | (x << (32 - shift));
 842     }
 843 }