root/arch/i386/entry.S

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   1 /*
   2  *  linux/arch/i386/entry.S
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * entry.S contains the system-call and fault low-level handling routines.
   9  * This also contains the timer-interrupt handler, as well as all interrupts
  10  * and faults that can result in a task-switch.
  11  *
  12  * NOTE: This code handles signal-recognition, which happens every time
  13  * after a timer-interrupt and after each system call.
  14  *
  15  * I changed all the .align's to 4 (16 byte alignment), as that's faster
  16  * on a 486.
  17  *
  18  * Stack layout in 'ret_from_system_call':
  19  *      ptrace needs to have all regs on the stack.
  20  *      if the order here is changed, it needs to be 
  21  *      updated in fork.c:copy_process, signal.c:do_signal,
  22  *      ptrace.c and ptrace.h
  23  *
  24  *       0(%esp) - %ebx
  25  *       4(%esp) - %ecx
  26  *       8(%esp) - %edx
  27  *       C(%esp) - %esi
  28  *      10(%esp) - %edi
  29  *      14(%esp) - %ebp
  30  *      18(%esp) - %eax
  31  *      1C(%esp) - %ds
  32  *      20(%esp) - %es
  33  *      24(%esp) - %fs
  34  *      28(%esp) - %gs
  35  *      2C(%esp) - orig_eax
  36  *      30(%esp) - %eip
  37  *      34(%esp) - %cs
  38  *      38(%esp) - %eflags
  39  *      3C(%esp) - %oldesp
  40  *      40(%esp) - %oldss
  41  */
  42 
  43 #include <linux/segment.h>
  44 #include <linux/sys.h>
  45 
  46 EBX             = 0x00
  47 ECX             = 0x04
  48 EDX             = 0x08
  49 ESI             = 0x0C
  50 EDI             = 0x10
  51 EBP             = 0x14
  52 EAX             = 0x18
  53 DS              = 0x1C
  54 ES              = 0x20
  55 FS              = 0x24
  56 GS              = 0x28
  57 ORIG_EAX        = 0x2C
  58 EIP             = 0x30
  59 CS              = 0x34
  60 EFLAGS          = 0x38
  61 OLDESP          = 0x3C
  62 OLDSS           = 0x40
  63 
  64 CF_MASK         = 0x00000001
  65 IF_MASK         = 0x00000200
  66 NT_MASK         = 0x00004000
  67 VM_MASK         = 0x00020000
  68 
  69 /*
  70  * these are offsets into the task-struct.
  71  */
  72 state           =  0
  73 counter         =  4
  74 priority        =  8
  75 signal          = 12
  76 blocked         = 16
  77 flags           = 20
  78 errno           = 24
  79 dbgreg6         = 52
  80 dbgreg7         = 56
  81 exec_domain     = 60
  82 
  83 ENOSYS = 38
  84 
  85 .globl _system_call,_lcall7
  86 .globl _device_not_available, _coprocessor_error
  87 .globl _divide_error,_debug,_nmi,_int3,_overflow,_bounds,_invalid_op
  88 .globl _double_fault,_coprocessor_segment_overrun
  89 .globl _invalid_TSS,_segment_not_present,_stack_segment
  90 .globl _general_protection,_reserved
  91 .globl _alignment_check,_page_fault
  92 .globl ret_from_sys_call, _sys_call_table
  93 
  94 #define SAVE_ALL \
  95         cld; \
  96         push %gs; \
  97         push %fs; \
  98         push %es; \
  99         push %ds; \
 100         pushl %eax; \
 101         pushl %ebp; \
 102         pushl %edi; \
 103         pushl %esi; \
 104         pushl %edx; \
 105         pushl %ecx; \
 106         pushl %ebx; \
 107         movl $(KERNEL_DS),%edx; \
 108         mov %dx,%ds; \
 109         mov %dx,%es; \
 110         movl $(USER_DS),%edx; \
 111         mov %dx,%fs;
 112 
 113 #define RESTORE_ALL \
 114         cmpw $(KERNEL_CS),CS(%esp); \
 115         je 1f;   \
 116         movl _current,%eax; \
 117         movl dbgreg7(%eax),%ebx; \
 118         movl %ebx,%db7; \
 119 1:      popl %ebx; \
 120         popl %ecx; \
 121         popl %edx; \
 122         popl %esi; \
 123         popl %edi; \
 124         popl %ebp; \
 125         popl %eax; \
 126         pop %ds; \
 127         pop %es; \
 128         pop %fs; \
 129         pop %gs; \
 130         addl $4,%esp; \
 131         iret
 132 
 133 .align 4
 134 _lcall7:
 135         pushfl                  # We get a different stack layout with call gates,
 136         pushl %eax              # which has to be cleaned up later..
 137         SAVE_ALL
 138         movl EIP(%esp),%eax     # due to call gates, this is eflags, not eip..
 139         movl CS(%esp),%edx      # this is eip..
 140         movl EFLAGS(%esp),%ecx  # and this is cs..
 141         movl %eax,EFLAGS(%esp)  #
 142         movl %edx,EIP(%esp)     # Now we move them to their "normal" places
 143         movl %ecx,CS(%esp)      #
 144         movl %esp,%eax
 145         movl _current,%edx
 146         pushl %eax
 147         movl exec_domain(%edx),%edx     # Get the execution domain
 148         movl 4(%edx),%edx       # Get the lcall7 handler for the domain
 149         call *%edx
 150         popl %eax
 151         jmp ret_from_sys_call
 152 
 153 .align 4
 154 handle_bottom_half:
 155         pushfl
 156         incl _intr_count
 157         sti
 158         call _do_bottom_half
 159         popfl
 160         decl _intr_count
 161         jmp 9f
 162 .align 4
 163 reschedule:
 164         pushl $ret_from_sys_call
 165         jmp _schedule
 166 .align 4
 167 _system_call:
 168         pushl %eax                      # save orig_eax
 169         SAVE_ALL
 170         movl $-ENOSYS,EAX(%esp)
 171         cmpl $(NR_syscalls),%eax
 172         jae ret_from_sys_call
 173         movl _sys_call_table(,%eax,4),%eax
 174         testl %eax,%eax
 175         je ret_from_sys_call
 176         movl _current,%ebx
 177         andl $~CF_MASK,EFLAGS(%esp)     # clear carry - assume no errors
 178         movl $0,errno(%ebx)
 179         movl %db6,%edx
 180         movl %edx,dbgreg6(%ebx)  # save current hardware debugging status
 181         testb $0x20,flags(%ebx)         # PF_TRACESYS
 182         jne 1f
 183         call *%eax
 184         movl %eax,EAX(%esp)             # save the return value
 185         movl errno(%ebx),%edx
 186         negl %edx
 187         je ret_from_sys_call
 188         movl %edx,EAX(%esp)
 189         orl $(CF_MASK),EFLAGS(%esp)     # set carry to indicate error
 190         jmp ret_from_sys_call
 191 .align 4
 192 1:      call _syscall_trace
 193         movl ORIG_EAX(%esp),%eax
 194         call _sys_call_table(,%eax,4)
 195         movl %eax,EAX(%esp)             # save the return value
 196         movl _current,%eax
 197         movl errno(%eax),%edx
 198         negl %edx
 199         je 1f
 200         movl %edx,EAX(%esp)
 201         orl $(CF_MASK),EFLAGS(%esp)     # set carry to indicate error
 202 1:      call _syscall_trace
 203 
 204         .align 4,0x90
 205 ret_from_sys_call:
 206         cmpl $0,_intr_count
 207         jne 2f
 208 9:      movl _bh_mask,%eax
 209         andl _bh_active,%eax
 210         jne handle_bottom_half
 211         movl EFLAGS(%esp),%eax          # check VM86 flag: CS/SS are
 212         testl $(VM_MASK),%eax           # different then
 213         jne 1f
 214         cmpw $(KERNEL_CS),CS(%esp)      # was old code segment supervisor ?
 215         je 2f
 216 1:      sti
 217         orl $(IF_MASK),%eax             # these just try to make sure
 218         andl $~NT_MASK,%eax             # the program doesn't do anything
 219         movl %eax,EFLAGS(%esp)          # stupid
 220         cmpl $0,_need_resched
 221         jne reschedule
 222         movl _current,%eax
 223         cmpl _task,%eax                 # task[0] cannot have signals
 224         je 2f
 225         cmpl $0,state(%eax)             # state
 226         jne reschedule
 227         cmpl $0,counter(%eax)           # counter
 228         je reschedule
 229         movl blocked(%eax),%ecx
 230         movl %ecx,%ebx                  # save blocked in %ebx for signal handling
 231         notl %ecx
 232         andl signal(%eax),%ecx
 233         jne signal_return
 234 2:      RESTORE_ALL
 235 .align 4
 236 signal_return:
 237         movl %esp,%ecx
 238         pushl %ecx
 239         testl $(VM_MASK),EFLAGS(%ecx)
 240         jne v86_signal_return
 241         pushl %ebx
 242         call _do_signal
 243         popl %ebx
 244         popl %ebx
 245         RESTORE_ALL
 246 .align 4
 247 v86_signal_return:
 248         call _save_v86_state
 249         movl %eax,%esp
 250         pushl %eax
 251         pushl %ebx
 252         call _do_signal
 253         popl %ebx
 254         popl %ebx
 255         RESTORE_ALL
 256 
 257 .align 4
 258 _divide_error:
 259         pushl $0                # no error code
 260         pushl $_do_divide_error
 261 .align 4,0x90
 262 error_code:
 263         push %fs
 264         push %es
 265         push %ds
 266         pushl %eax
 267         pushl %ebp
 268         pushl %edi
 269         pushl %esi
 270         pushl %edx
 271         pushl %ecx
 272         pushl %ebx
 273         movl $0,%eax
 274         movl %eax,%db7                  # disable hardware debugging...
 275         cld
 276         movl $-1, %eax
 277         xchgl %eax, ORIG_EAX(%esp)      # orig_eax (get the error code. )
 278         xorl %ebx,%ebx                  # zero ebx
 279         mov %gs,%bx                     # get the lower order bits of gs
 280         xchgl %ebx, GS(%esp)            # get the address and save gs.
 281         pushl %eax                      # push the error code
 282         lea 4(%esp),%edx
 283         pushl %edx
 284         movl $(KERNEL_DS),%edx
 285         mov %dx,%ds
 286         mov %dx,%es
 287         movl $(USER_DS),%edx
 288         mov %dx,%fs
 289         pushl %eax
 290         movl _current,%eax
 291         movl %db6,%edx
 292         movl %edx,dbgreg6(%eax)  # save current hardware debugging status
 293         popl %eax
 294         call *%ebx
 295         addl $8,%esp
 296         jmp ret_from_sys_call
 297 
 298 .align 4
 299 _coprocessor_error:
 300         pushl $0
 301         pushl $_do_coprocessor_error
 302         jmp error_code
 303 
 304 .align 4
 305 _device_not_available:
 306         pushl $-1               # mark this as an int
 307         SAVE_ALL
 308         pushl $ret_from_sys_call
 309         movl %cr0,%eax
 310         testl $0x4,%eax                 # EM (math emulation bit)
 311         je _math_state_restore
 312         pushl $0                # temporary storage for ORIG_EIP
 313         call _math_emulate
 314         addl $4,%esp
 315         ret
 316 
 317 .align 4
 318 _debug:
 319         pushl $0
 320         pushl $_do_debug
 321         jmp error_code
 322 
 323 .align 4
 324 _nmi:
 325         pushl $0
 326         pushl $_do_nmi
 327         jmp error_code
 328 
 329 .align 4
 330 _int3:
 331         pushl $0
 332         pushl $_do_int3
 333         jmp error_code
 334 
 335 .align 4
 336 _overflow:
 337         pushl $0
 338         pushl $_do_overflow
 339         jmp error_code
 340 
 341 .align 4
 342 _bounds:
 343         pushl $0
 344         pushl $_do_bounds
 345         jmp error_code
 346 
 347 .align 4
 348 _invalid_op:
 349         pushl $0
 350         pushl $_do_invalid_op
 351         jmp error_code
 352 
 353 .align 4
 354 _coprocessor_segment_overrun:
 355         pushl $0
 356         pushl $_do_coprocessor_segment_overrun
 357         jmp error_code
 358 
 359 .align 4
 360 _reserved:
 361         pushl $0
 362         pushl $_do_reserved
 363         jmp error_code
 364 
 365 .align 4
 366 _double_fault:
 367         pushl $_do_double_fault
 368         jmp error_code
 369 
 370 .align 4
 371 _invalid_TSS:
 372         pushl $_do_invalid_TSS
 373         jmp error_code
 374 
 375 .align 4
 376 _segment_not_present:
 377         pushl $_do_segment_not_present
 378         jmp error_code
 379 
 380 .align 4
 381 _stack_segment:
 382         pushl $_do_stack_segment
 383         jmp error_code
 384 
 385 .align 4
 386 _general_protection:
 387         pushl $_do_general_protection
 388         jmp error_code
 389 
 390 .align 4
 391 _alignment_check:
 392         pushl $_do_alignment_check
 393         jmp error_code
 394 
 395 .align 4
 396 _page_fault:
 397         pushl $_do_page_fault
 398         jmp error_code
 399 
 400 .data
 401 .align 4
 402 _sys_call_table:
 403         .long _sys_setup                /* 0 */
 404         .long _sys_exit
 405         .long _sys_fork
 406         .long _sys_read
 407         .long _sys_write
 408         .long _sys_open                 /* 5 */
 409         .long _sys_close
 410         .long _sys_waitpid
 411         .long _sys_creat
 412         .long _sys_link
 413         .long _sys_unlink               /* 10 */
 414         .long _sys_execve
 415         .long _sys_chdir
 416         .long _sys_time
 417         .long _sys_mknod
 418         .long _sys_chmod                /* 15 */
 419         .long _sys_chown
 420         .long _sys_break
 421         .long _sys_stat
 422         .long _sys_lseek
 423         .long _sys_getpid               /* 20 */
 424         .long _sys_mount
 425         .long _sys_umount
 426         .long _sys_setuid
 427         .long _sys_getuid
 428         .long _sys_stime                /* 25 */
 429         .long _sys_ptrace
 430         .long _sys_alarm
 431         .long _sys_fstat
 432         .long _sys_pause
 433         .long _sys_utime                /* 30 */
 434         .long _sys_stty
 435         .long _sys_gtty
 436         .long _sys_access
 437         .long _sys_nice
 438         .long _sys_ftime                /* 35 */
 439         .long _sys_sync
 440         .long _sys_kill
 441         .long _sys_rename
 442         .long _sys_mkdir
 443         .long _sys_rmdir                /* 40 */
 444         .long _sys_dup
 445         .long _sys_pipe
 446         .long _sys_times
 447         .long _sys_prof
 448         .long _sys_brk                  /* 45 */
 449         .long _sys_setgid
 450         .long _sys_getgid
 451         .long _sys_signal
 452         .long _sys_geteuid
 453         .long _sys_getegid              /* 50 */
 454         .long _sys_acct
 455         .long _sys_phys
 456         .long _sys_lock
 457         .long _sys_ioctl
 458         .long _sys_fcntl                /* 55 */
 459         .long _sys_mpx
 460         .long _sys_setpgid
 461         .long _sys_ulimit
 462         .long _sys_olduname
 463         .long _sys_umask                /* 60 */
 464         .long _sys_chroot
 465         .long _sys_ustat
 466         .long _sys_dup2
 467         .long _sys_getppid
 468         .long _sys_getpgrp              /* 65 */
 469         .long _sys_setsid
 470         .long _sys_sigaction
 471         .long _sys_sgetmask
 472         .long _sys_ssetmask
 473         .long _sys_setreuid             /* 70 */
 474         .long _sys_setregid
 475         .long _sys_sigsuspend
 476         .long _sys_sigpending
 477         .long _sys_sethostname
 478         .long _sys_setrlimit            /* 75 */
 479         .long _sys_getrlimit
 480         .long _sys_getrusage
 481         .long _sys_gettimeofday
 482         .long _sys_settimeofday
 483         .long _sys_getgroups            /* 80 */
 484         .long _sys_setgroups
 485         .long _sys_select
 486         .long _sys_symlink
 487         .long _sys_lstat
 488         .long _sys_readlink             /* 85 */
 489         .long _sys_uselib
 490         .long _sys_swapon
 491         .long _sys_reboot
 492         .long _sys_readdir
 493         .long _sys_mmap                 /* 90 */
 494         .long _sys_munmap
 495         .long _sys_truncate
 496         .long _sys_ftruncate
 497         .long _sys_fchmod
 498         .long _sys_fchown               /* 95 */
 499         .long _sys_getpriority
 500         .long _sys_setpriority
 501         .long _sys_profil
 502         .long _sys_statfs
 503         .long _sys_fstatfs              /* 100 */
 504         .long _sys_ioperm
 505         .long _sys_socketcall
 506         .long _sys_syslog
 507         .long _sys_setitimer
 508         .long _sys_getitimer            /* 105 */
 509         .long _sys_newstat
 510         .long _sys_newlstat
 511         .long _sys_newfstat
 512         .long _sys_uname
 513         .long _sys_iopl                 /* 110 */
 514         .long _sys_vhangup
 515         .long _sys_idle
 516         .long _sys_vm86
 517         .long _sys_wait4
 518         .long _sys_swapoff              /* 115 */
 519         .long _sys_sysinfo
 520         .long _sys_ipc
 521         .long _sys_fsync
 522         .long _sys_sigreturn
 523         .long _sys_clone                /* 120 */
 524         .long _sys_setdomainname
 525         .long _sys_newuname
 526         .long _sys_modify_ldt
 527         .long _sys_adjtimex
 528         .long _sys_mprotect             /* 125 */
 529         .long _sys_sigprocmask
 530         .long _sys_create_module
 531         .long _sys_init_module
 532         .long _sys_delete_module
 533         .long _sys_get_kernel_syms      /* 130 */
 534         .long _sys_quotactl
 535         .long _sys_getpgid
 536         .long _sys_fchdir
 537         .long _sys_bdflush
 538         .long _sys_sysfs                /* 135 */
 539         .long _sys_personality
 540         .long 0                         /* for afs_syscall */
 541         .long _sys_setfsuid
 542         .long _sys_setfsgid
 543         .long _sys_llseek               /* 140 */
 544         .space (NR_syscalls-140)*4

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