[PATCH] Uml support: reorganize PTRACE_SYSEMU support
[deliverable/linux.git] / arch / i386 / kernel / entry.S
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) - orig_eax
34 * 28(%esp) - %eip
35 * 2C(%esp) - %cs
36 * 30(%esp) - %eflags
37 * 34(%esp) - %oldesp
38 * 38(%esp) - %oldss
39 *
40 * "current" is in register %ebx during any slow entries.
41 */
42
43 #include <linux/config.h>
44 #include <linux/linkage.h>
45 #include <asm/thread_info.h>
46 #include <asm/errno.h>
47 #include <asm/segment.h>
48 #include <asm/smp.h>
49 #include <asm/page.h>
50 #include <asm/desc.h>
51 #include "irq_vectors.h"
52
53 #define nr_syscalls ((syscall_table_size)/4)
54
55 EBX = 0x00
56 ECX = 0x04
57 EDX = 0x08
58 ESI = 0x0C
59 EDI = 0x10
60 EBP = 0x14
61 EAX = 0x18
62 DS = 0x1C
63 ES = 0x20
64 ORIG_EAX = 0x24
65 EIP = 0x28
66 CS = 0x2C
67 EFLAGS = 0x30
68 OLDESP = 0x34
69 OLDSS = 0x38
70
71 CF_MASK = 0x00000001
72 TF_MASK = 0x00000100
73 IF_MASK = 0x00000200
74 DF_MASK = 0x00000400
75 NT_MASK = 0x00004000
76 VM_MASK = 0x00020000
77
78 #ifdef CONFIG_PREEMPT
79 #define preempt_stop cli
80 #else
81 #define preempt_stop
82 #define resume_kernel restore_nocheck
83 #endif
84
85 #define SAVE_ALL \
86 cld; \
87 pushl %es; \
88 pushl %ds; \
89 pushl %eax; \
90 pushl %ebp; \
91 pushl %edi; \
92 pushl %esi; \
93 pushl %edx; \
94 pushl %ecx; \
95 pushl %ebx; \
96 movl $(__USER_DS), %edx; \
97 movl %edx, %ds; \
98 movl %edx, %es;
99
100 #define RESTORE_INT_REGS \
101 popl %ebx; \
102 popl %ecx; \
103 popl %edx; \
104 popl %esi; \
105 popl %edi; \
106 popl %ebp; \
107 popl %eax
108
109 #define RESTORE_REGS \
110 RESTORE_INT_REGS; \
111 1: popl %ds; \
112 2: popl %es; \
113 .section .fixup,"ax"; \
114 3: movl $0,(%esp); \
115 jmp 1b; \
116 4: movl $0,(%esp); \
117 jmp 2b; \
118 .previous; \
119 .section __ex_table,"a";\
120 .align 4; \
121 .long 1b,3b; \
122 .long 2b,4b; \
123 .previous
124
125
126 ENTRY(ret_from_fork)
127 pushl %eax
128 call schedule_tail
129 GET_THREAD_INFO(%ebp)
130 popl %eax
131 jmp syscall_exit
132
133 /*
134 * Return to user mode is not as complex as all this looks,
135 * but we want the default path for a system call return to
136 * go as quickly as possible which is why some of this is
137 * less clear than it otherwise should be.
138 */
139
140 # userspace resumption stub bypassing syscall exit tracing
141 ALIGN
142 ret_from_exception:
143 preempt_stop
144 ret_from_intr:
145 GET_THREAD_INFO(%ebp)
146 movl EFLAGS(%esp), %eax # mix EFLAGS and CS
147 movb CS(%esp), %al
148 testl $(VM_MASK | 3), %eax
149 jz resume_kernel
150 ENTRY(resume_userspace)
151 cli # make sure we don't miss an interrupt
152 # setting need_resched or sigpending
153 # between sampling and the iret
154 movl TI_flags(%ebp), %ecx
155 andl $_TIF_WORK_MASK, %ecx # is there any work to be done on
156 # int/exception return?
157 jne work_pending
158 jmp restore_all
159
160 #ifdef CONFIG_PREEMPT
161 ENTRY(resume_kernel)
162 cli
163 cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ?
164 jnz restore_nocheck
165 need_resched:
166 movl TI_flags(%ebp), %ecx # need_resched set ?
167 testb $_TIF_NEED_RESCHED, %cl
168 jz restore_all
169 testl $IF_MASK,EFLAGS(%esp) # interrupts off (exception path) ?
170 jz restore_all
171 call preempt_schedule_irq
172 jmp need_resched
173 #endif
174
175 /* SYSENTER_RETURN points to after the "sysenter" instruction in
176 the vsyscall page. See vsyscall-sysentry.S, which defines the symbol. */
177
178 # sysenter call handler stub
179 ENTRY(sysenter_entry)
180 movl TSS_sysenter_esp0(%esp),%esp
181 sysenter_past_esp:
182 sti
183 pushl $(__USER_DS)
184 pushl %ebp
185 pushfl
186 pushl $(__USER_CS)
187 pushl $SYSENTER_RETURN
188
189 /*
190 * Load the potential sixth argument from user stack.
191 * Careful about security.
192 */
193 cmpl $__PAGE_OFFSET-3,%ebp
194 jae syscall_fault
195 1: movl (%ebp),%ebp
196 .section __ex_table,"a"
197 .align 4
198 .long 1b,syscall_fault
199 .previous
200
201 pushl %eax
202 SAVE_ALL
203 GET_THREAD_INFO(%ebp)
204
205 /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
206 testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
207 jnz syscall_trace_entry
208 cmpl $(nr_syscalls), %eax
209 jae syscall_badsys
210 call *sys_call_table(,%eax,4)
211 movl %eax,EAX(%esp)
212 cli
213 movl TI_flags(%ebp), %ecx
214 testw $_TIF_ALLWORK_MASK, %cx
215 jne syscall_exit_work
216 /* if something modifies registers it must also disable sysexit */
217 movl EIP(%esp), %edx
218 movl OLDESP(%esp), %ecx
219 xorl %ebp,%ebp
220 sti
221 sysexit
222
223
224 # system call handler stub
225 ENTRY(system_call)
226 pushl %eax # save orig_eax
227 SAVE_ALL
228 GET_THREAD_INFO(%ebp)
229 # system call tracing in operation / emulation
230 /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
231 testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
232 jnz syscall_trace_entry
233 cmpl $(nr_syscalls), %eax
234 jae syscall_badsys
235 syscall_call:
236 call *sys_call_table(,%eax,4)
237 movl %eax,EAX(%esp) # store the return value
238 syscall_exit:
239 cli # make sure we don't miss an interrupt
240 # setting need_resched or sigpending
241 # between sampling and the iret
242 movl TI_flags(%ebp), %ecx
243 testw $_TIF_ALLWORK_MASK, %cx # current->work
244 jne syscall_exit_work
245
246 restore_all:
247 movl EFLAGS(%esp), %eax # mix EFLAGS, SS and CS
248 # Warning: OLDSS(%esp) contains the wrong/random values if we
249 # are returning to the kernel.
250 # See comments in process.c:copy_thread() for details.
251 movb OLDSS(%esp), %ah
252 movb CS(%esp), %al
253 andl $(VM_MASK | (4 << 8) | 3), %eax
254 cmpl $((4 << 8) | 3), %eax
255 je ldt_ss # returning to user-space with LDT SS
256 restore_nocheck:
257 RESTORE_REGS
258 addl $4, %esp
259 1: iret
260 .section .fixup,"ax"
261 iret_exc:
262 sti
263 pushl $0 # no error code
264 pushl $do_iret_error
265 jmp error_code
266 .previous
267 .section __ex_table,"a"
268 .align 4
269 .long 1b,iret_exc
270 .previous
271
272 ldt_ss:
273 larl OLDSS(%esp), %eax
274 jnz restore_nocheck
275 testl $0x00400000, %eax # returning to 32bit stack?
276 jnz restore_nocheck # allright, normal return
277 /* If returning to userspace with 16bit stack,
278 * try to fix the higher word of ESP, as the CPU
279 * won't restore it.
280 * This is an "official" bug of all the x86-compatible
281 * CPUs, which we can try to work around to make
282 * dosemu and wine happy. */
283 subl $8, %esp # reserve space for switch16 pointer
284 cli
285 movl %esp, %eax
286 /* Set up the 16bit stack frame with switch32 pointer on top,
287 * and a switch16 pointer on top of the current frame. */
288 call setup_x86_bogus_stack
289 RESTORE_REGS
290 lss 20+4(%esp), %esp # switch to 16bit stack
291 1: iret
292 .section __ex_table,"a"
293 .align 4
294 .long 1b,iret_exc
295 .previous
296
297 # perform work that needs to be done immediately before resumption
298 ALIGN
299 work_pending:
300 testb $_TIF_NEED_RESCHED, %cl
301 jz work_notifysig
302 work_resched:
303 call schedule
304 cli # make sure we don't miss an interrupt
305 # setting need_resched or sigpending
306 # between sampling and the iret
307 movl TI_flags(%ebp), %ecx
308 andl $_TIF_WORK_MASK, %ecx # is there any work to be done other
309 # than syscall tracing?
310 jz restore_all
311 testb $_TIF_NEED_RESCHED, %cl
312 jnz work_resched
313
314 work_notifysig: # deal with pending signals and
315 # notify-resume requests
316 testl $VM_MASK, EFLAGS(%esp)
317 movl %esp, %eax
318 jne work_notifysig_v86 # returning to kernel-space or
319 # vm86-space
320 xorl %edx, %edx
321 call do_notify_resume
322 jmp restore_all
323
324 ALIGN
325 work_notifysig_v86:
326 pushl %ecx # save ti_flags for do_notify_resume
327 call save_v86_state # %eax contains pt_regs pointer
328 popl %ecx
329 movl %eax, %esp
330 xorl %edx, %edx
331 call do_notify_resume
332 jmp restore_all
333
334 # perform syscall exit tracing
335 ALIGN
336 syscall_trace_entry:
337 movl $-ENOSYS,EAX(%esp)
338 movl %esp, %eax
339 xorl %edx,%edx
340 call do_syscall_trace
341 cmpl $0, %eax
342 jne syscall_skip # ret != 0 -> running under PTRACE_SYSEMU,
343 # so must skip actual syscall
344 movl ORIG_EAX(%esp), %eax
345 cmpl $(nr_syscalls), %eax
346 jnae syscall_call
347 jmp syscall_exit
348 syscall_skip:
349 cli # make sure we don't miss an interrupt
350 # setting need_resched or sigpending
351 # between sampling and the iret
352 movl TI_flags(%ebp), %ecx
353 jmp work_pending
354
355 # perform syscall exit tracing
356 ALIGN
357 syscall_exit_work:
358 testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP), %cl
359 jz work_pending
360 sti # could let do_syscall_trace() call
361 # schedule() instead
362 movl %esp, %eax
363 movl $1, %edx
364 call do_syscall_trace
365 jmp resume_userspace
366
367 ALIGN
368 syscall_fault:
369 pushl %eax # save orig_eax
370 SAVE_ALL
371 GET_THREAD_INFO(%ebp)
372 movl $-EFAULT,EAX(%esp)
373 jmp resume_userspace
374
375 ALIGN
376 syscall_badsys:
377 movl $-ENOSYS,EAX(%esp)
378 jmp resume_userspace
379
380 #define FIXUP_ESPFIX_STACK \
381 movl %esp, %eax; \
382 /* switch to 32bit stack using the pointer on top of 16bit stack */ \
383 lss %ss:CPU_16BIT_STACK_SIZE-8, %esp; \
384 /* copy data from 16bit stack to 32bit stack */ \
385 call fixup_x86_bogus_stack; \
386 /* put ESP to the proper location */ \
387 movl %eax, %esp;
388 #define UNWIND_ESPFIX_STACK \
389 pushl %eax; \
390 movl %ss, %eax; \
391 /* see if on 16bit stack */ \
392 cmpw $__ESPFIX_SS, %ax; \
393 jne 28f; \
394 movl $__KERNEL_DS, %edx; \
395 movl %edx, %ds; \
396 movl %edx, %es; \
397 /* switch to 32bit stack */ \
398 FIXUP_ESPFIX_STACK \
399 28: popl %eax;
400
401 /*
402 * Build the entry stubs and pointer table with
403 * some assembler magic.
404 */
405 .data
406 ENTRY(interrupt)
407 .text
408
409 vector=0
410 ENTRY(irq_entries_start)
411 .rept NR_IRQS
412 ALIGN
413 1: pushl $vector-256
414 jmp common_interrupt
415 .data
416 .long 1b
417 .text
418 vector=vector+1
419 .endr
420
421 ALIGN
422 common_interrupt:
423 SAVE_ALL
424 movl %esp,%eax
425 call do_IRQ
426 jmp ret_from_intr
427
428 #define BUILD_INTERRUPT(name, nr) \
429 ENTRY(name) \
430 pushl $nr-256; \
431 SAVE_ALL \
432 movl %esp,%eax; \
433 call smp_/**/name; \
434 jmp ret_from_intr;
435
436 /* The include is where all of the SMP etc. interrupts come from */
437 #include "entry_arch.h"
438
439 ENTRY(divide_error)
440 pushl $0 # no error code
441 pushl $do_divide_error
442 ALIGN
443 error_code:
444 pushl %ds
445 pushl %eax
446 xorl %eax, %eax
447 pushl %ebp
448 pushl %edi
449 pushl %esi
450 pushl %edx
451 decl %eax # eax = -1
452 pushl %ecx
453 pushl %ebx
454 cld
455 pushl %es
456 UNWIND_ESPFIX_STACK
457 popl %ecx
458 movl ES(%esp), %edi # get the function address
459 movl ORIG_EAX(%esp), %edx # get the error code
460 movl %eax, ORIG_EAX(%esp)
461 movl %ecx, ES(%esp)
462 movl $(__USER_DS), %ecx
463 movl %ecx, %ds
464 movl %ecx, %es
465 movl %esp,%eax # pt_regs pointer
466 call *%edi
467 jmp ret_from_exception
468
469 ENTRY(coprocessor_error)
470 pushl $0
471 pushl $do_coprocessor_error
472 jmp error_code
473
474 ENTRY(simd_coprocessor_error)
475 pushl $0
476 pushl $do_simd_coprocessor_error
477 jmp error_code
478
479 ENTRY(device_not_available)
480 pushl $-1 # mark this as an int
481 SAVE_ALL
482 movl %cr0, %eax
483 testl $0x4, %eax # EM (math emulation bit)
484 jne device_not_available_emulate
485 preempt_stop
486 call math_state_restore
487 jmp ret_from_exception
488 device_not_available_emulate:
489 pushl $0 # temporary storage for ORIG_EIP
490 call math_emulate
491 addl $4, %esp
492 jmp ret_from_exception
493
494 /*
495 * Debug traps and NMI can happen at the one SYSENTER instruction
496 * that sets up the real kernel stack. Check here, since we can't
497 * allow the wrong stack to be used.
498 *
499 * "TSS_sysenter_esp0+12" is because the NMI/debug handler will have
500 * already pushed 3 words if it hits on the sysenter instruction:
501 * eflags, cs and eip.
502 *
503 * We just load the right stack, and push the three (known) values
504 * by hand onto the new stack - while updating the return eip past
505 * the instruction that would have done it for sysenter.
506 */
507 #define FIX_STACK(offset, ok, label) \
508 cmpw $__KERNEL_CS,4(%esp); \
509 jne ok; \
510 label: \
511 movl TSS_sysenter_esp0+offset(%esp),%esp; \
512 pushfl; \
513 pushl $__KERNEL_CS; \
514 pushl $sysenter_past_esp
515
516 ENTRY(debug)
517 cmpl $sysenter_entry,(%esp)
518 jne debug_stack_correct
519 FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
520 debug_stack_correct:
521 pushl $-1 # mark this as an int
522 SAVE_ALL
523 xorl %edx,%edx # error code 0
524 movl %esp,%eax # pt_regs pointer
525 call do_debug
526 jmp ret_from_exception
527
528 /*
529 * NMI is doubly nasty. It can happen _while_ we're handling
530 * a debug fault, and the debug fault hasn't yet been able to
531 * clear up the stack. So we first check whether we got an
532 * NMI on the sysenter entry path, but after that we need to
533 * check whether we got an NMI on the debug path where the debug
534 * fault happened on the sysenter path.
535 */
536 ENTRY(nmi)
537 pushl %eax
538 movl %ss, %eax
539 cmpw $__ESPFIX_SS, %ax
540 popl %eax
541 je nmi_16bit_stack
542 cmpl $sysenter_entry,(%esp)
543 je nmi_stack_fixup
544 pushl %eax
545 movl %esp,%eax
546 /* Do not access memory above the end of our stack page,
547 * it might not exist.
548 */
549 andl $(THREAD_SIZE-1),%eax
550 cmpl $(THREAD_SIZE-20),%eax
551 popl %eax
552 jae nmi_stack_correct
553 cmpl $sysenter_entry,12(%esp)
554 je nmi_debug_stack_check
555 nmi_stack_correct:
556 pushl %eax
557 SAVE_ALL
558 xorl %edx,%edx # zero error code
559 movl %esp,%eax # pt_regs pointer
560 call do_nmi
561 jmp restore_all
562
563 nmi_stack_fixup:
564 FIX_STACK(12,nmi_stack_correct, 1)
565 jmp nmi_stack_correct
566 nmi_debug_stack_check:
567 cmpw $__KERNEL_CS,16(%esp)
568 jne nmi_stack_correct
569 cmpl $debug - 1,(%esp)
570 jle nmi_stack_correct
571 cmpl $debug_esp_fix_insn,(%esp)
572 jle nmi_debug_stack_fixup
573 nmi_debug_stack_fixup:
574 FIX_STACK(24,nmi_stack_correct, 1)
575 jmp nmi_stack_correct
576
577 nmi_16bit_stack:
578 /* create the pointer to lss back */
579 pushl %ss
580 pushl %esp
581 movzwl %sp, %esp
582 addw $4, (%esp)
583 /* copy the iret frame of 12 bytes */
584 .rept 3
585 pushl 16(%esp)
586 .endr
587 pushl %eax
588 SAVE_ALL
589 FIXUP_ESPFIX_STACK # %eax == %esp
590 xorl %edx,%edx # zero error code
591 call do_nmi
592 RESTORE_REGS
593 lss 12+4(%esp), %esp # back to 16bit stack
594 1: iret
595 .section __ex_table,"a"
596 .align 4
597 .long 1b,iret_exc
598 .previous
599
600 ENTRY(int3)
601 pushl $-1 # mark this as an int
602 SAVE_ALL
603 xorl %edx,%edx # zero error code
604 movl %esp,%eax # pt_regs pointer
605 call do_int3
606 jmp ret_from_exception
607
608 ENTRY(overflow)
609 pushl $0
610 pushl $do_overflow
611 jmp error_code
612
613 ENTRY(bounds)
614 pushl $0
615 pushl $do_bounds
616 jmp error_code
617
618 ENTRY(invalid_op)
619 pushl $0
620 pushl $do_invalid_op
621 jmp error_code
622
623 ENTRY(coprocessor_segment_overrun)
624 pushl $0
625 pushl $do_coprocessor_segment_overrun
626 jmp error_code
627
628 ENTRY(invalid_TSS)
629 pushl $do_invalid_TSS
630 jmp error_code
631
632 ENTRY(segment_not_present)
633 pushl $do_segment_not_present
634 jmp error_code
635
636 ENTRY(stack_segment)
637 pushl $do_stack_segment
638 jmp error_code
639
640 ENTRY(general_protection)
641 pushl $do_general_protection
642 jmp error_code
643
644 ENTRY(alignment_check)
645 pushl $do_alignment_check
646 jmp error_code
647
648 ENTRY(page_fault)
649 pushl $do_page_fault
650 jmp error_code
651
652 #ifdef CONFIG_X86_MCE
653 ENTRY(machine_check)
654 pushl $0
655 pushl machine_check_vector
656 jmp error_code
657 #endif
658
659 ENTRY(spurious_interrupt_bug)
660 pushl $0
661 pushl $do_spurious_interrupt_bug
662 jmp error_code
663
664 #include "syscall_table.S"
665
666 syscall_table_size=(.-sys_call_table)
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