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.h" 22 #include "user-internals.h" 23 #include "elf.h" 24 #include "cpu_loop-common.h" 25 #include "signal-common.h" 26 #include "semihosting/common-semi.h" 27 #include "target/arm/syndrome.h" 28 29 #define get_user_code_u32(x, gaddr, env) \ 30 ({ abi_long __r = get_user_u32((x), (gaddr)); \ 31 if (!__r && bswap_code(arm_sctlr_b(env))) { \ 32 (x) = bswap32(x); \ 33 } \ 34 __r; \ 35 }) 36 37 #define get_user_code_u16(x, gaddr, env) \ 38 ({ abi_long __r = get_user_u16((x), (gaddr)); \ 39 if (!__r && bswap_code(arm_sctlr_b(env))) { \ 40 (x) = bswap16(x); \ 41 } \ 42 __r; \ 43 }) 44 45 #define get_user_data_u32(x, gaddr, env) \ 46 ({ abi_long __r = get_user_u32((x), (gaddr)); \ 47 if (!__r && arm_cpu_bswap_data(env)) { \ 48 (x) = bswap32(x); \ 49 } \ 50 __r; \ 51 }) 52 53 #define get_user_data_u16(x, gaddr, env) \ 54 ({ abi_long __r = get_user_u16((x), (gaddr)); \ 55 if (!__r && arm_cpu_bswap_data(env)) { \ 56 (x) = bswap16(x); \ 57 } \ 58 __r; \ 59 }) 60 61 #define put_user_data_u32(x, gaddr, env) \ 62 ({ typeof(x) __x = (x); \ 63 if (arm_cpu_bswap_data(env)) { \ 64 __x = bswap32(__x); \ 65 } \ 66 put_user_u32(__x, (gaddr)); \ 67 }) 68 69 #define put_user_data_u16(x, gaddr, env) \ 70 ({ typeof(x) __x = (x); \ 71 if (arm_cpu_bswap_data(env)) { \ 72 __x = bswap16(__x); \ 73 } \ 74 put_user_u16(__x, (gaddr)); \ 75 }) 76 77 /* 78 * Similar to code in accel/tcg/user-exec.c, but outside the execution loop. 79 * Must be called with mmap_lock. 80 * We get the PC of the entry address - which is as good as anything, 81 * on a real kernel what you get depends on which mode it uses. 82 */ 83 static void *atomic_mmu_lookup(CPUArchState *env, uint32_t addr, int size) 84 { 85 int need_flags = PAGE_READ | PAGE_WRITE_ORG | PAGE_VALID; 86 int page_flags; 87 88 /* Enforce guest required alignment. */ 89 if (unlikely(addr & (size - 1))) { 90 force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, addr); 91 return NULL; 92 } 93 94 page_flags = page_get_flags(addr); 95 if (unlikely((page_flags & need_flags) != need_flags)) { 96 force_sig_fault(TARGET_SIGSEGV, 97 page_flags & PAGE_VALID ? 98 TARGET_SEGV_ACCERR : TARGET_SEGV_MAPERR, addr); 99 return NULL; 100 } 101 102 return g2h(env_cpu(env), addr); 103 } 104 105 /* 106 * See the Linux kernel's Documentation/arm/kernel_user_helpers.rst 107 * Input: 108 * r0 = oldval 109 * r1 = newval 110 * r2 = pointer to target value 111 * 112 * Output: 113 * r0 = 0 if *ptr was changed, non-0 if no exchange happened 114 * C set if *ptr was changed, clear if no exchange happened 115 */ 116 static void arm_kernel_cmpxchg32_helper(CPUARMState *env) 117 { 118 uint32_t oldval, newval, val, addr, cpsr, *host_addr; 119 120 oldval = env->regs[0]; 121 newval = env->regs[1]; 122 addr = env->regs[2]; 123 124 mmap_lock(); 125 host_addr = atomic_mmu_lookup(env, addr, 4); 126 if (!host_addr) { 127 mmap_unlock(); 128 return; 129 } 130 131 val = qatomic_cmpxchg__nocheck(host_addr, oldval, newval); 132 mmap_unlock(); 133 134 cpsr = (val == oldval) * CPSR_C; 135 cpsr_write(env, cpsr, CPSR_C, CPSRWriteByInstr); 136 env->regs[0] = cpsr ? 0 : -1; 137 } 138 139 /* 140 * See the Linux kernel's Documentation/arm/kernel_user_helpers.rst 141 * Input: 142 * r0 = pointer to oldval 143 * r1 = pointer to newval 144 * r2 = pointer to target value 145 * 146 * Output: 147 * r0 = 0 if *ptr was changed, non-0 if no exchange happened 148 * C set if *ptr was changed, clear if no exchange happened 149 * 150 * Note segv's in kernel helpers are a bit tricky, we can set the 151 * data address sensibly but the PC address is just the entry point. 152 */ 153 static void arm_kernel_cmpxchg64_helper(CPUARMState *env) 154 { 155 uint64_t oldval, newval, val; 156 uint32_t addr, cpsr; 157 uint64_t *host_addr; 158 159 addr = env->regs[0]; 160 if (get_user_u64(oldval, addr)) { 161 goto segv; 162 } 163 164 addr = env->regs[1]; 165 if (get_user_u64(newval, addr)) { 166 goto segv; 167 } 168 169 mmap_lock(); 170 addr = env->regs[2]; 171 host_addr = atomic_mmu_lookup(env, addr, 8); 172 if (!host_addr) { 173 mmap_unlock(); 174 return; 175 } 176 177 #ifdef CONFIG_ATOMIC64 178 val = qatomic_cmpxchg__nocheck(host_addr, oldval, newval); 179 cpsr = (val == oldval) * CPSR_C; 180 #else 181 /* 182 * This only works between threads, not between processes, but since 183 * the host has no 64-bit cmpxchg, it is the best that we can do. 184 */ 185 start_exclusive(); 186 val = *host_addr; 187 if (val == oldval) { 188 *host_addr = newval; 189 cpsr = CPSR_C; 190 } else { 191 cpsr = 0; 192 } 193 end_exclusive(); 194 #endif 195 mmap_unlock(); 196 197 cpsr_write(env, cpsr, CPSR_C, CPSRWriteByInstr); 198 env->regs[0] = cpsr ? 0 : -1; 199 return; 200 201 segv: 202 force_sig_fault(TARGET_SIGSEGV, 203 page_get_flags(addr) & PAGE_VALID ? 204 TARGET_SEGV_ACCERR : TARGET_SEGV_MAPERR, addr); 205 } 206 207 /* Handle a jump to the kernel code page. */ 208 static int 209 do_kernel_trap(CPUARMState *env) 210 { 211 uint32_t addr; 212 213 switch (env->regs[15]) { 214 case 0xffff0fa0: /* __kernel_memory_barrier */ 215 smp_mb(); 216 break; 217 case 0xffff0fc0: /* __kernel_cmpxchg */ 218 arm_kernel_cmpxchg32_helper(env); 219 break; 220 case 0xffff0fe0: /* __kernel_get_tls */ 221 env->regs[0] = cpu_get_tls(env); 222 break; 223 case 0xffff0f60: /* __kernel_cmpxchg64 */ 224 arm_kernel_cmpxchg64_helper(env); 225 break; 226 227 default: 228 return 1; 229 } 230 /* Jump back to the caller. */ 231 addr = env->regs[14]; 232 if (addr & 1) { 233 env->thumb = true; 234 addr &= ~1; 235 } 236 env->regs[15] = addr; 237 238 return 0; 239 } 240 241 static bool insn_is_linux_bkpt(uint32_t opcode, bool is_thumb) 242 { 243 /* 244 * Return true if this insn is one of the three magic UDF insns 245 * which the kernel treats as breakpoint insns. 246 */ 247 if (!is_thumb) { 248 return (opcode & 0x0fffffff) == 0x07f001f0; 249 } else { 250 /* 251 * Note that we get the two halves of the 32-bit T32 insn 252 * in the opposite order to the value the kernel uses in 253 * its undef_hook struct. 254 */ 255 return ((opcode & 0xffff) == 0xde01) || (opcode == 0xa000f7f0); 256 } 257 } 258 259 static bool emulate_arm_fpa11(CPUARMState *env, uint32_t opcode) 260 { 261 TaskState *ts = env_cpu(env)->opaque; 262 int rc = EmulateAll(opcode, &ts->fpa, env); 263 int raise, enabled; 264 265 if (rc == 0) { 266 /* Illegal instruction */ 267 return false; 268 } 269 if (rc > 0) { 270 /* Everything ok. */ 271 env->regs[15] += 4; 272 return true; 273 } 274 275 /* FP exception */ 276 rc = -rc; 277 raise = 0; 278 279 /* Translate softfloat flags to FPSR flags */ 280 if (rc & float_flag_invalid) { 281 raise |= BIT_IOC; 282 } 283 if (rc & float_flag_divbyzero) { 284 raise |= BIT_DZC; 285 } 286 if (rc & float_flag_overflow) { 287 raise |= BIT_OFC; 288 } 289 if (rc & float_flag_underflow) { 290 raise |= BIT_UFC; 291 } 292 if (rc & float_flag_inexact) { 293 raise |= BIT_IXC; 294 } 295 296 /* Accumulate unenabled exceptions */ 297 enabled = ts->fpa.fpsr >> 16; 298 ts->fpa.fpsr |= raise & ~enabled; 299 300 if (raise & enabled) { 301 /* 302 * The kernel's nwfpe emulator does not pass a real si_code. 303 * It merely uses send_sig(SIGFPE, current, 1), which results in 304 * __send_signal() filling out SI_KERNEL with pid and uid 0 (under 305 * the "SEND_SIG_PRIV" case). That's what our force_sig() does. 306 */ 307 force_sig(TARGET_SIGFPE); 308 } else { 309 env->regs[15] += 4; 310 } 311 return true; 312 } 313 314 void cpu_loop(CPUARMState *env) 315 { 316 CPUState *cs = env_cpu(env); 317 int trapnr, si_signo, si_code; 318 unsigned int n, insn; 319 abi_ulong ret; 320 321 for(;;) { 322 cpu_exec_start(cs); 323 trapnr = cpu_exec(cs); 324 cpu_exec_end(cs); 325 process_queued_cpu_work(cs); 326 327 switch(trapnr) { 328 case EXCP_UDEF: 329 case EXCP_NOCP: 330 case EXCP_INVSTATE: 331 { 332 uint32_t opcode; 333 334 /* we handle the FPU emulation here, as Linux */ 335 /* we get the opcode */ 336 /* FIXME - what to do if get_user() fails? */ 337 get_user_code_u32(opcode, env->regs[15], env); 338 339 /* 340 * The Linux kernel treats some UDF patterns specially 341 * to use as breakpoints (instead of the architectural 342 * bkpt insn). These should trigger a SIGTRAP rather 343 * than SIGILL. 344 */ 345 if (insn_is_linux_bkpt(opcode, env->thumb)) { 346 goto excp_debug; 347 } 348 349 if (!env->thumb && emulate_arm_fpa11(env, opcode)) { 350 break; 351 } 352 353 force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN, 354 env->regs[15]); 355 } 356 break; 357 case EXCP_SWI: 358 { 359 env->eabi = 1; 360 /* system call */ 361 if (env->thumb) { 362 /* Thumb is always EABI style with syscall number in r7 */ 363 n = env->regs[7]; 364 } else { 365 /* 366 * Equivalent of kernel CONFIG_OABI_COMPAT: read the 367 * Arm SVC insn to extract the immediate, which is the 368 * syscall number in OABI. 369 */ 370 /* FIXME - what to do if get_user() fails? */ 371 get_user_code_u32(insn, env->regs[15] - 4, env); 372 n = insn & 0xffffff; 373 if (n == 0) { 374 /* zero immediate: EABI, syscall number in r7 */ 375 n = env->regs[7]; 376 } else { 377 /* 378 * This XOR matches the kernel code: an immediate 379 * in the valid range (0x900000 .. 0x9fffff) is 380 * converted into the correct EABI-style syscall 381 * number; invalid immediates end up as values 382 * > 0xfffff and are handled below as out-of-range. 383 */ 384 n ^= ARM_SYSCALL_BASE; 385 env->eabi = 0; 386 } 387 } 388 389 if (n > ARM_NR_BASE) { 390 switch (n) { 391 case ARM_NR_cacheflush: 392 /* nop */ 393 break; 394 case ARM_NR_set_tls: 395 cpu_set_tls(env, env->regs[0]); 396 env->regs[0] = 0; 397 break; 398 case ARM_NR_breakpoint: 399 env->regs[15] -= env->thumb ? 2 : 4; 400 goto excp_debug; 401 case ARM_NR_get_tls: 402 env->regs[0] = cpu_get_tls(env); 403 break; 404 default: 405 if (n < 0xf0800) { 406 /* 407 * Syscalls 0xf0000..0xf07ff (or 0x9f0000.. 408 * 0x9f07ff in OABI numbering) are defined 409 * to return -ENOSYS rather than raising 410 * SIGILL. Note that we have already 411 * removed the 0x900000 prefix. 412 */ 413 qemu_log_mask(LOG_UNIMP, 414 "qemu: Unsupported ARM syscall: 0x%x\n", 415 n); 416 env->regs[0] = -TARGET_ENOSYS; 417 } else { 418 /* 419 * Otherwise SIGILL. This includes any SWI with 420 * immediate not originally 0x9fxxxx, because 421 * of the earlier XOR. 422 * Like the real kernel, we report the addr of the 423 * SWI in the siginfo si_addr but leave the PC 424 * pointing at the insn after the SWI. 425 */ 426 abi_ulong faultaddr = env->regs[15]; 427 faultaddr -= env->thumb ? 2 : 4; 428 force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLTRP, 429 faultaddr); 430 } 431 break; 432 } 433 } else { 434 ret = do_syscall(env, 435 n, 436 env->regs[0], 437 env->regs[1], 438 env->regs[2], 439 env->regs[3], 440 env->regs[4], 441 env->regs[5], 442 0, 0); 443 if (ret == -QEMU_ERESTARTSYS) { 444 env->regs[15] -= env->thumb ? 2 : 4; 445 } else if (ret != -QEMU_ESIGRETURN) { 446 env->regs[0] = ret; 447 } 448 } 449 } 450 break; 451 case EXCP_SEMIHOST: 452 do_common_semihosting(cs); 453 env->regs[15] += env->thumb ? 2 : 4; 454 break; 455 case EXCP_INTERRUPT: 456 /* just indicate that signals should be handled asap */ 457 break; 458 case EXCP_PREFETCH_ABORT: 459 case EXCP_DATA_ABORT: 460 /* For user-only we don't set TTBCR_EAE, so look at the FSR. */ 461 switch (env->exception.fsr & 0x1f) { 462 case 0x1: /* Alignment */ 463 si_signo = TARGET_SIGBUS; 464 si_code = TARGET_BUS_ADRALN; 465 break; 466 case 0x3: /* Access flag fault, level 1 */ 467 case 0x6: /* Access flag fault, level 2 */ 468 case 0x9: /* Domain fault, level 1 */ 469 case 0xb: /* Domain fault, level 2 */ 470 case 0xd: /* Permission fault, level 1 */ 471 case 0xf: /* Permission fault, level 2 */ 472 si_signo = TARGET_SIGSEGV; 473 si_code = TARGET_SEGV_ACCERR; 474 break; 475 case 0x5: /* Translation fault, level 1 */ 476 case 0x7: /* Translation fault, level 2 */ 477 si_signo = TARGET_SIGSEGV; 478 si_code = TARGET_SEGV_MAPERR; 479 break; 480 default: 481 g_assert_not_reached(); 482 } 483 force_sig_fault(si_signo, si_code, env->exception.vaddress); 484 break; 485 case EXCP_DEBUG: 486 case EXCP_BKPT: 487 excp_debug: 488 force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_BRKPT, env->regs[15]); 489 break; 490 case EXCP_KERNEL_TRAP: 491 if (do_kernel_trap(env)) 492 goto error; 493 break; 494 case EXCP_YIELD: 495 /* nothing to do here for user-mode, just resume guest code */ 496 break; 497 case EXCP_ATOMIC: 498 cpu_exec_step_atomic(cs); 499 break; 500 default: 501 error: 502 EXCP_DUMP(env, "qemu: unhandled CPU exception 0x%x - aborting\n", trapnr); 503 abort(); 504 } 505 process_pending_signals(env); 506 } 507 } 508 509 void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs) 510 { 511 CPUState *cpu = env_cpu(env); 512 TaskState *ts = cpu->opaque; 513 struct image_info *info = ts->info; 514 int i; 515 516 cpsr_write(env, regs->uregs[16], CPSR_USER | CPSR_EXEC, 517 CPSRWriteByInstr); 518 for(i = 0; i < 16; i++) { 519 env->regs[i] = regs->uregs[i]; 520 } 521 #if TARGET_BIG_ENDIAN 522 /* Enable BE8. */ 523 if (EF_ARM_EABI_VERSION(info->elf_flags) >= EF_ARM_EABI_VER4 524 && (info->elf_flags & EF_ARM_BE8)) { 525 env->uncached_cpsr |= CPSR_E; 526 env->cp15.sctlr_el[1] |= SCTLR_E0E; 527 } else { 528 env->cp15.sctlr_el[1] |= SCTLR_B; 529 } 530 arm_rebuild_hflags(env); 531 #endif 532 533 ts->stack_base = info->start_stack; 534 ts->heap_base = info->brk; 535 /* This will be filled in on the first SYS_HEAPINFO call. */ 536 ts->heap_limit = 0; 537 } 538