linux-user/qemu.h

   1 #ifndef QEMU_H
   2 #define QEMU_H
   3
   4 #include "hostdep.h"
   5 #include "cpu.h"
   6 #include "exec/exec-all.h"
   7 #include "exec/cpu_ldst.h"
   8
   9 #undef DEBUG_REMAP
  10 #ifdef DEBUG_REMAP
  11 #endif /* DEBUG_REMAP */
  12
  13 #include "exec/user/abitypes.h"
  14
  15 #include "exec/user/thunk.h"
  16 #include "syscall_defs.h"
  17 #include "target_syscall.h"
  18 #include "exec/gdbstub.h"
  19 #include "qemu/queue.h"
  20
  21 /* This is the size of the host kernel's sigset_t, needed where we make
  22  * direct system calls that take a sigset_t pointer and a size.
  23  */
  24 #define SIGSET_T_SIZE (_NSIG / 8)
  25
  26 /* This struct is used to hold certain information about the image.
  27  * Basically, it replicates in user space what would be certain
  28  * task_struct fields in the kernel
  29  */
  30 struct image_info {
  31         abi_ulong       load_bias;
  32         abi_ulong       load_addr;
  33         abi_ulong       start_code;
  34         abi_ulong       end_code;
  35         abi_ulong       start_data;
  36         abi_ulong       end_data;
  37         abi_ulong       start_brk;
  38         abi_ulong       brk;
  39         abi_ulong       start_mmap;
  40         abi_ulong       start_stack;
  41         abi_ulong       stack_limit;
  42         abi_ulong       entry;
  43         abi_ulong       code_offset;
  44         abi_ulong       data_offset;
  45         abi_ulong       saved_auxv;
  46         abi_ulong       auxv_len;
  47         abi_ulong       arg_start;
  48         abi_ulong       arg_end;
  49         abi_ulong       arg_strings;
  50         abi_ulong       env_strings;
  51         abi_ulong       file_string;
  52         uint32_t        elf_flags;
  53         int             personality;
  54
  55         /* The fields below are used in FDPIC mode.  */
  56         abi_ulong       loadmap_addr;
  57         uint16_t        nsegs;
  58         void           *loadsegs;
  59         abi_ulong       pt_dynamic_addr;
  60         struct image_info *other_info;
  61 };
  62
  63 #ifdef TARGET_I386
  64 /* Information about the current linux thread */
  65 struct vm86_saved_state {
  66     uint32_t eax; /* return code */
  67     uint32_t ebx;
  68     uint32_t ecx;
  69     uint32_t edx;
  70     uint32_t esi;
  71     uint32_t edi;
  72     uint32_t ebp;
  73     uint32_t esp;
  74     uint32_t eflags;
  75     uint32_t eip;
  76     uint16_t cs, ss, ds, es, fs, gs;
  77 };
  78 #endif
  79
  80 #if defined(TARGET_ARM) && defined(TARGET_ABI32)
  81 /* FPU emulator */
  82 #include "nwfpe/fpa11.h"
  83 #endif
  84
  85 #define MAX_SIGQUEUE_SIZE 1024
  86
  87 struct emulated_sigtable {
  88     int pending; /* true if signal is pending */
  89     target_siginfo_t info;
  90 };
  91
  92 /* NOTE: we force a big alignment so that the stack stored after is
  93    aligned too */
  94 typedef struct TaskState {
  95     pid_t ts_tid;     /* tid (or pid) of this task */
  96 #ifdef TARGET_ARM
  97 # ifdef TARGET_ABI32
  98     /* FPA state */
  99     FPA11 fpa;
 100 # endif
 101     int swi_errno;
 102 #endif
 103 #if defined(TARGET_I386) && !defined(TARGET_X86_64)
 104     abi_ulong target_v86;
 105     struct vm86_saved_state vm86_saved_regs;
 106     struct target_vm86plus_struct vm86plus;
 107     uint32_t v86flags;
 108     uint32_t v86mask;
 109 #endif
 110     abi_ulong child_tidptr;
 111 #ifdef TARGET_M68K
 112     int sim_syscalls;
 113     abi_ulong tp_value;
 114 #endif
 115 #if defined(TARGET_ARM) || defined(TARGET_M68K)
 116     /* Extra fields for semihosted binaries.  */
 117     abi_ulong heap_base;
 118     abi_ulong heap_limit;
 119 #endif
 120     abi_ulong stack_base;
 121     int used; /* non zero if used */
 122     struct image_info *info;
 123     struct linux_binprm *bprm;
 124
 125     struct emulated_sigtable sync_signal;
 126     struct emulated_sigtable sigtab[TARGET_NSIG];
 127     /* This thread's signal mask, as requested by the guest program.
 128      * The actual signal mask of this thread may differ:
 129      *  + we don't let SIGSEGV and SIGBUS be blocked while running guest code
 130      *  + sometimes we block all signals to avoid races
 131      */
 132     sigset_t signal_mask;
 133     /* The signal mask imposed by a guest sigsuspend syscall, if we are
 134      * currently in the middle of such a syscall
 135      */
 136     sigset_t sigsuspend_mask;
 137     /* Nonzero if we're leaving a sigsuspend and sigsuspend_mask is valid. */
 138     int in_sigsuspend;
 139
 140     /* Nonzero if process_pending_signals() needs to do something (either
 141      * handle a pending signal or unblock signals).
 142      * This flag is written from a signal handler so should be accessed via
 143      * the atomic_read() and atomic_write() functions. (It is not accessed
 144      * from multiple threads.)
 145      */
 146     int signal_pending;
 147
 148 } __attribute__((aligned(16))) TaskState;
 149
 150 extern char *exec_path;
 151 void init_task_state(TaskState *ts);
 152 void task_settid(TaskState *);
 153 void stop_all_tasks(void);
 154 extern const char *qemu_uname_release;
 155 extern unsigned long mmap_min_addr;
 156
 157 /* ??? See if we can avoid exposing so much of the loader internals.  */
 158
 159 /* Read a good amount of data initially, to hopefully get all the
 160    program headers loaded.  */
 161 #define BPRM_BUF_SIZE  1024
 162
 163 /*
 164  * This structure is used to hold the arguments that are
 165  * used when loading binaries.
 166  */
 167 struct linux_binprm {
 168         char buf[BPRM_BUF_SIZE] __attribute__((aligned));
 169         abi_ulong p;
 170         int fd;
 171         int e_uid, e_gid;
 172         int argc, envc;
 173         char **argv;
 174         char **envp;
 175         char * filename;        /* Name of binary */
 176         int (*core_dump)(int, const CPUArchState *); /* coredump routine */
 177 };
 178
 179 void do_init_thread(struct target_pt_regs *regs, struct image_info *infop);
 180 abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp,
 181                               abi_ulong stringp, int push_ptr);
 182 int loader_exec(int fdexec, const char *filename, char **argv, char **envp,
 183              struct target_pt_regs * regs, struct image_info *infop,
 184              struct linux_binprm *);
 185
 186 uint32_t get_elf_eflags(int fd);
 187 int load_elf_binary(struct linux_binprm *bprm, struct image_info *info);
 188 int load_flt_binary(struct linux_binprm *bprm, struct image_info *info);
 189
 190 abi_long memcpy_to_target(abi_ulong dest, const void *src,
 191                           unsigned long len);
 192 void target_set_brk(abi_ulong new_brk);
 193 abi_long do_brk(abi_ulong new_brk);
 194 void syscall_init(void);
 195 abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
 196                     abi_long arg2, abi_long arg3, abi_long arg4,
 197                     abi_long arg5, abi_long arg6, abi_long arg7,
 198                     abi_long arg8);
 199 void gemu_log(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 200 extern __thread CPUState *thread_cpu;
 201 void cpu_loop(CPUArchState *env);
 202 const char *target_strerror(int err);
 203 int get_osversion(void);
 204 void init_qemu_uname_release(void);
 205 void fork_start(void);
 206 void fork_end(int child);
 207
 208 /* Creates the initial guest address space in the host memory space using
 209  * the given host start address hint and size.  The guest_start parameter
 210  * specifies the start address of the guest space.  guest_base will be the
 211  * difference between the host start address computed by this function and
 212  * guest_start.  If fixed is specified, then the mapped address space must
 213  * start at host_start.  The real start address of the mapped memory space is
 214  * returned or -1 if there was an error.
 215  */
 216 unsigned long init_guest_space(unsigned long host_start,
 217                                unsigned long host_size,
 218                                unsigned long guest_start,
 219                                bool fixed);
 220
 221 #include "qemu/log.h"
 222
 223 /* safe_syscall.S */
 224
 225 /**
 226  * safe_syscall:
 227  * @int number: number of system call to make
 228  * ...: arguments to the system call
 229  *
 230  * Call a system call if guest signal not pending.
 231  * This has the same API as the libc syscall() function, except that it
 232  * may return -1 with errno == TARGET_ERESTARTSYS if a signal was pending.
 233  *
 234  * Returns: the system call result, or -1 with an error code in errno
 235  * (Errnos are host errnos; we rely on TARGET_ERESTARTSYS not clashing
 236  * with any of the host errno values.)
 237  */
 238
 239 /* A guide to using safe_syscall() to handle interactions between guest
 240  * syscalls and guest signals:
 241  *
 242  * Guest syscalls come in two flavours:
 243  *
 244  * (1) Non-interruptible syscalls
 245  *
 246  * These are guest syscalls that never get interrupted by signals and
 247  * so never return EINTR. They can be implemented straightforwardly in
 248  * QEMU: just make sure that if the implementation code has to make any
 249  * blocking calls that those calls are retried if they return EINTR.
 250  * It's also OK to implement these with safe_syscall, though it will be
 251  * a little less efficient if a signal is delivered at the 'wrong' moment.
 252  *
 253  * Some non-interruptible syscalls need to be handled using block_signals()
 254  * to block signals for the duration of the syscall. This mainly applies
 255  * to code which needs to modify the data structures used by the
 256  * host_signal_handler() function and the functions it calls, including
 257  * all syscalls which change the thread's signal mask.
 258  *
 259  * (2) Interruptible syscalls
 260  *
 261  * These are guest syscalls that can be interrupted by signals and
 262  * for which we need to either return EINTR or arrange for the guest
 263  * syscall to be restarted. This category includes both syscalls which
 264  * always restart (and in the kernel return -ERESTARTNOINTR), ones
 265  * which only restart if there is no handler (kernel returns -ERESTARTNOHAND
 266  * or -ERESTART_RESTARTBLOCK), and the most common kind which restart
 267  * if the handler was registered with SA_RESTART (kernel returns
 268  * -ERESTARTSYS). System calls which are only interruptible in some
 269  * situations (like 'open') also need to be handled this way.
 270  *
 271  * Here it is important that the host syscall is made
 272  * via this safe_syscall() function, and *not* via the host libc.
 273  * If the host libc is used then the implementation will appear to work
 274  * most of the time, but there will be a race condition where a
 275  * signal could arrive just before we make the host syscall inside libc,
 276  * and then then guest syscall will not correctly be interrupted.
 277  * Instead the implementation of the guest syscall can use the safe_syscall
 278  * function but otherwise just return the result or errno in the usual
 279  * way; the main loop code will take care of restarting the syscall
 280  * if appropriate.
 281  *
 282  * (If the implementation needs to make multiple host syscalls this is
 283  * OK; any which might really block must be via safe_syscall(); for those
 284  * which are only technically blocking (ie which we know in practice won't
 285  * stay in the host kernel indefinitely) it's OK to use libc if necessary.
 286  * You must be able to cope with backing out correctly if some safe_syscall
 287  * you make in the implementation returns either -TARGET_ERESTARTSYS or
 288  * EINTR though.)
 289  *
 290  * block_signals() cannot be used for interruptible syscalls.
 291  *
 292  *
 293  * How and why the safe_syscall implementation works:
 294  *
 295  * The basic setup is that we make the host syscall via a known
 296  * section of host native assembly. If a signal occurs, our signal
 297  * handler checks the interrupted host PC against the addresse of that
 298  * known section. If the PC is before or at the address of the syscall
 299  * instruction then we change the PC to point at a "return
 300  * -TARGET_ERESTARTSYS" code path instead, and then exit the signal handler
 301  * (causing the safe_syscall() call to immediately return that value).
 302  * Then in the main.c loop if we see this magic return value we adjust
 303  * the guest PC to wind it back to before the system call, and invoke
 304  * the guest signal handler as usual.
 305  *
 306  * This winding-back will happen in two cases:
 307  * (1) signal came in just before we took the host syscall (a race);
 308  *   in this case we'll take the guest signal and have another go
 309  *   at the syscall afterwards, and this is indistinguishable for the
 310  *   guest from the timing having been different such that the guest
 311  *   signal really did win the race
 312  * (2) signal came in while the host syscall was blocking, and the
 313  *   host kernel decided the syscall should be restarted;
 314  *   in this case we want to restart the guest syscall also, and so
 315  *   rewinding is the right thing. (Note that "restart" semantics mean
 316  *   "first call the signal handler, then reattempt the syscall".)
 317  * The other situation to consider is when a signal came in while the
 318  * host syscall was blocking, and the host kernel decided that the syscall
 319  * should not be restarted; in this case QEMU's host signal handler will
 320  * be invoked with the PC pointing just after the syscall instruction,
 321  * with registers indicating an EINTR return; the special code in the
 322  * handler will not kick in, and we will return EINTR to the guest as
 323  * we should.
 324  *
 325  * Notice that we can leave the host kernel to make the decision for
 326  * us about whether to do a restart of the syscall or not; we do not
 327  * need to check SA_RESTART flags in QEMU or distinguish the various
 328  * kinds of restartability.
 329  */
 330 #ifdef HAVE_SAFE_SYSCALL
 331 /* The core part of this function is implemented in assembly */
 332 extern long safe_syscall_base(int *pending, long number, ...);
 333
 334 #define safe_syscall(...)                                               \
 335     ({                                                                  \
 336         long ret_;                                                      \
 337         int *psp_ = &((TaskState *)thread_cpu->opaque)->signal_pending; \
 338         ret_ = safe_syscall_base(psp_, __VA_ARGS__);                    \
 339         if (is_error(ret_)) {                                           \
 340             errno = -ret_;                                              \
 341             ret_ = -1;                                                  \
 342         }                                                               \
 343         ret_;                                                           \
 344     })
 345
 346 #else
 347
 348 /* Fallback for architectures which don't yet provide a safe-syscall assembly
 349  * fragment; note that this is racy!
 350  * This should go away when all host architectures have been updated.
 351  */
 352 #define safe_syscall syscall
 353
 354 #endif
 355
 356 /* syscall.c */
 357 int host_to_target_waitstatus(int status);
 358
 359 /* strace.c */
 360 void print_syscall(int num,
 361                    abi_long arg1, abi_long arg2, abi_long arg3,
 362                    abi_long arg4, abi_long arg5, abi_long arg6);
 363 void print_syscall_ret(int num, abi_long arg1);
 364 /**
 365  * print_taken_signal:
 366  * @target_signum: target signal being taken
 367  * @tinfo: target_siginfo_t which will be passed to the guest for the signal
 368  *
 369  * Print strace output indicating that this signal is being taken by the guest,
 370  * in a format similar to:
 371  * --- SIGSEGV {si_signo=SIGSEGV, si_code=SI_KERNEL, si_addr=0} ---
 372  */
 373 void print_taken_signal(int target_signum, const target_siginfo_t *tinfo);
 374 extern int do_strace;
 375
 376 /* signal.c */
 377 void process_pending_signals(CPUArchState *cpu_env);
 378 void signal_init(void);
 379 int queue_signal(CPUArchState *env, int sig, int si_type,
 380                  target_siginfo_t *info);
 381 void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info);
 382 void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo);
 383 int target_to_host_signal(int sig);
 384 int host_to_target_signal(int sig);
 385 long do_sigreturn(CPUArchState *env);
 386 long do_rt_sigreturn(CPUArchState *env);
 387 abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp);
 388 int do_sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
 389 /**
 390  * block_signals: block all signals while handling this guest syscall
 391  *
 392  * Block all signals, and arrange that the signal mask is returned to
 393  * its correct value for the guest before we resume execution of guest code.
 394  * If this function returns non-zero, then the caller should immediately
 395  * return -TARGET_ERESTARTSYS to the main loop, which will take the pending
 396  * signal and restart execution of the syscall.
 397  * If block_signals() returns zero, then the caller can continue with
 398  * emulation of the system call knowing that no signals can be taken
 399  * (and therefore that no race conditions will result).
 400  * This should only be called once, because if it is called a second time
 401  * it will always return non-zero. (Think of it like a mutex that can't
 402  * be recursively locked.)
 403  * Signals will be unblocked again by process_pending_signals().
 404  *
 405  * Return value: non-zero if there was a pending signal, zero if not.
 406  */
 407 int block_signals(void); /* Returns non zero if signal pending */
 408
 409 #ifdef TARGET_I386
 410 /* vm86.c */
 411 void save_v86_state(CPUX86State *env);
 412 void handle_vm86_trap(CPUX86State *env, int trapno);
 413 void handle_vm86_fault(CPUX86State *env);
 414 int do_vm86(CPUX86State *env, long subfunction, abi_ulong v86_addr);
 415 #elif defined(TARGET_SPARC64)
 416 void sparc64_set_context(CPUSPARCState *env);
 417 void sparc64_get_context(CPUSPARCState *env);
 418 #endif
 419
 420 /* mmap.c */
 421 int target_mprotect(abi_ulong start, abi_ulong len, int prot);
 422 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
 423                      int flags, int fd, abi_ulong offset);
 424 int target_munmap(abi_ulong start, abi_ulong len);
 425 abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
 426                        abi_ulong new_size, unsigned long flags,
 427                        abi_ulong new_addr);
 428 extern unsigned long last_brk;
 429 extern abi_ulong mmap_next_start;
 430 abi_ulong mmap_find_vma(abi_ulong, abi_ulong);
 431 void mmap_fork_start(void);
 432 void mmap_fork_end(int child);
 433
 434 /* main.c */
 435 extern unsigned long guest_stack_size;
 436
 437 /* user access */
 438
 439 #define VERIFY_READ 0
 440 #define VERIFY_WRITE 1 /* implies read access */
 441
 442 static inline int access_ok(int type, abi_ulong addr, abi_ulong size)
 443 {
 444     return page_check_range((target_ulong)addr, size,
 445                             (type == VERIFY_READ) ? PAGE_READ : (PAGE_READ | PAGE_WRITE)) == 0;
 446 }
 447
 448 /* NOTE __get_user and __put_user use host pointers and don't check access.
 449    These are usually used to access struct data members once the struct has
 450    been locked - usually with lock_user_struct.  */
 451
 452 /* Tricky points:
 453    - Use __builtin_choose_expr to avoid type promotion from ?:,
 454    - Invalid sizes result in a compile time error stemming from
 455      the fact that abort has no parameters.
 456    - It's easier to use the endian-specific unaligned load/store
 457      functions than host-endian unaligned load/store plus tswapN.  */
 458
 459 #define __put_user_e(x, hptr, e)                                        \
 460   (__builtin_choose_expr(sizeof(*(hptr)) == 1, stb_p,                   \
 461    __builtin_choose_expr(sizeof(*(hptr)) == 2, stw_##e##_p,             \
 462    __builtin_choose_expr(sizeof(*(hptr)) == 4, stl_##e##_p,             \
 463    __builtin_choose_expr(sizeof(*(hptr)) == 8, stq_##e##_p, abort))))   \
 464      ((hptr), (x)), (void)0)
 465
 466 #define __get_user_e(x, hptr, e)                                        \
 467   ((x) = (typeof(*hptr))(                                               \
 468    __builtin_choose_expr(sizeof(*(hptr)) == 1, ldub_p,                  \
 469    __builtin_choose_expr(sizeof(*(hptr)) == 2, lduw_##e##_p,            \
 470    __builtin_choose_expr(sizeof(*(hptr)) == 4, ldl_##e##_p,             \
 471    __builtin_choose_expr(sizeof(*(hptr)) == 8, ldq_##e##_p, abort))))   \
 472      (hptr)), (void)0)
 473
 474 #ifdef TARGET_WORDS_BIGENDIAN
 475 # define __put_user(x, hptr)  __put_user_e(x, hptr, be)
 476 # define __get_user(x, hptr)  __get_user_e(x, hptr, be)
 477 #else
 478 # define __put_user(x, hptr)  __put_user_e(x, hptr, le)
 479 # define __get_user(x, hptr)  __get_user_e(x, hptr, le)
 480 #endif
 481
 482 /* put_user()/get_user() take a guest address and check access */
 483 /* These are usually used to access an atomic data type, such as an int,
 484  * that has been passed by address.  These internally perform locking
 485  * and unlocking on the data type.
 486  */
 487 #define put_user(x, gaddr, target_type)                                 \
 488 ({                                                                      \
 489     abi_ulong __gaddr = (gaddr);                                        \
 490     target_type *__hptr;                                                \
 491     abi_long __ret = 0;                                                 \
 492     if ((__hptr = lock_user(VERIFY_WRITE, __gaddr, sizeof(target_type), 0))) { \
 493         __put_user((x), __hptr);                                \
 494         unlock_user(__hptr, __gaddr, sizeof(target_type));              \
 495     } else                                                              \
 496         __ret = -TARGET_EFAULT;                                         \
 497     __ret;                                                              \
 498 })
 499
 500 #define get_user(x, gaddr, target_type)                                 \
 501 ({                                                                      \
 502     abi_ulong __gaddr = (gaddr);                                        \
 503     target_type *__hptr;                                                \
 504     abi_long __ret = 0;                                                 \
 505     if ((__hptr = lock_user(VERIFY_READ, __gaddr, sizeof(target_type), 1))) { \
 506         __get_user((x), __hptr);                                \
 507         unlock_user(__hptr, __gaddr, 0);                                \
 508     } else {                                                            \
 509         /* avoid warning */                                             \
 510         (x) = 0;                                                        \
 511         __ret = -TARGET_EFAULT;                                         \
 512     }                                                                   \
 513     __ret;                                                              \
 514 })
 515
 516 #define put_user_ual(x, gaddr) put_user((x), (gaddr), abi_ulong)
 517 #define put_user_sal(x, gaddr) put_user((x), (gaddr), abi_long)
 518 #define put_user_u64(x, gaddr) put_user((x), (gaddr), uint64_t)
 519 #define put_user_s64(x, gaddr) put_user((x), (gaddr), int64_t)
 520 #define put_user_u32(x, gaddr) put_user((x), (gaddr), uint32_t)
 521 #define put_user_s32(x, gaddr) put_user((x), (gaddr), int32_t)
 522 #define put_user_u16(x, gaddr) put_user((x), (gaddr), uint16_t)
 523 #define put_user_s16(x, gaddr) put_user((x), (gaddr), int16_t)
 524 #define put_user_u8(x, gaddr)  put_user((x), (gaddr), uint8_t)
 525 #define put_user_s8(x, gaddr)  put_user((x), (gaddr), int8_t)
 526
 527 #define get_user_ual(x, gaddr) get_user((x), (gaddr), abi_ulong)
 528 #define get_user_sal(x, gaddr) get_user((x), (gaddr), abi_long)
 529 #define get_user_u64(x, gaddr) get_user((x), (gaddr), uint64_t)
 530 #define get_user_s64(x, gaddr) get_user((x), (gaddr), int64_t)
 531 #define get_user_u32(x, gaddr) get_user((x), (gaddr), uint32_t)
 532 #define get_user_s32(x, gaddr) get_user((x), (gaddr), int32_t)
 533 #define get_user_u16(x, gaddr) get_user((x), (gaddr), uint16_t)
 534 #define get_user_s16(x, gaddr) get_user((x), (gaddr), int16_t)
 535 #define get_user_u8(x, gaddr)  get_user((x), (gaddr), uint8_t)
 536 #define get_user_s8(x, gaddr)  get_user((x), (gaddr), int8_t)
 537
 538 /* copy_from_user() and copy_to_user() are usually used to copy data
 539  * buffers between the target and host.  These internally perform
 540  * locking/unlocking of the memory.
 541  */
 542 abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len);
 543 abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len);
 544
 545 /* Functions for accessing guest memory.  The tget and tput functions
 546    read/write single values, byteswapping as necessary.  The lock_user function
 547    gets a pointer to a contiguous area of guest memory, but does not perform
 548    any byteswapping.  lock_user may return either a pointer to the guest
 549    memory, or a temporary buffer.  */
 550
 551 /* Lock an area of guest memory into the host.  If copy is true then the
 552    host area will have the same contents as the guest.  */
 553 static inline void *lock_user(int type, abi_ulong guest_addr, long len, int copy)
 554 {
 555     if (!access_ok(type, guest_addr, len))
 556         return NULL;
 557 #ifdef DEBUG_REMAP
 558     {
 559         void *addr;
 560         addr = g_malloc(len);
 561         if (copy)
 562             memcpy(addr, g2h(guest_addr), len);
 563         else
 564             memset(addr, 0, len);
 565         return addr;
 566     }
 567 #else
 568     return g2h(guest_addr);
 569 #endif
 570 }
 571
 572 /* Unlock an area of guest memory.  The first LEN bytes must be
 573    flushed back to guest memory. host_ptr = NULL is explicitly
 574    allowed and does nothing. */
 575 static inline void unlock_user(void *host_ptr, abi_ulong guest_addr,
 576                                long len)
 577 {
 578
 579 #ifdef DEBUG_REMAP
 580     if (!host_ptr)
 581         return;
 582     if (host_ptr == g2h(guest_addr))
 583         return;
 584     if (len > 0)
 585         memcpy(g2h(guest_addr), host_ptr, len);
 586     g_free(host_ptr);
 587 #endif
 588 }
 589
 590 /* Return the length of a string in target memory or -TARGET_EFAULT if
 591    access error. */
 592 abi_long target_strlen(abi_ulong gaddr);
 593
 594 /* Like lock_user but for null terminated strings.  */
 595 static inline void *lock_user_string(abi_ulong guest_addr)
 596 {
 597     abi_long len;
 598     len = target_strlen(guest_addr);
 599     if (len < 0)
 600         return NULL;
 601     return lock_user(VERIFY_READ, guest_addr, (long)(len + 1), 1);
 602 }
 603
 604 /* Helper macros for locking/unlocking a target struct.  */
 605 #define lock_user_struct(type, host_ptr, guest_addr, copy)      \
 606     (host_ptr = lock_user(type, guest_addr, sizeof(*host_ptr), copy))
 607 #define unlock_user_struct(host_ptr, guest_addr, copy)          \
 608     unlock_user(host_ptr, guest_addr, (copy) ? sizeof(*host_ptr) : 0)
 609
 610 #include <pthread.h>
 611
 612 /* Include target-specific struct and function definitions;
 613  * they may need access to the target-independent structures
 614  * above, so include them last.
 615  */
 616 #include "target_cpu.h"
 617 #include "target_signal.h"
 618 #include "target_structs.h"
 619
 620 #endif /* QEMU_H */