1 /*-
2 * Copyright (c) 1989, 1990 William F. Jolitz.
3 * Copyright (c) 1990 The Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 4. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: releng/8.0/sys/i386/xen/exception.s 184198 2008-10-23 07:20:43Z kmacy $
31 */
32
33 #include "opt_apic.h"
34 #include "opt_npx.h"
35
36 #include <machine/asmacros.h>
37 #include <machine/psl.h>
38 #include <machine/trap.h>
39
40 #include "assym.s"
41
42 #define SEL_RPL_MASK 0x0002
43 #define __HYPERVISOR_iret 23
44
45 /* Offsets into shared_info_t. */
46
47 #define evtchn_upcall_pending /* 0 */
48 #define evtchn_upcall_mask 1
49
50 #define sizeof_vcpu_shift 6
51
52
53 #ifdef SMP
54 #define GET_VCPU_INFO(reg) movl PCPU(CPUID),reg ; \
55 shl $sizeof_vcpu_shift,reg ; \
56 addl HYPERVISOR_shared_info,reg
57 #else
58 #define GET_VCPU_INFO(reg) movl HYPERVISOR_shared_info,reg
59 #endif
60
61 #define __DISABLE_INTERRUPTS(reg) movb $1,evtchn_upcall_mask(reg)
62 #define __ENABLE_INTERRUPTS(reg) movb $0,evtchn_upcall_mask(reg)
63 #define DISABLE_INTERRUPTS(reg) GET_VCPU_INFO(reg) ; \
64 __DISABLE_INTERRUPTS(reg)
65 #define ENABLE_INTERRUPTS(reg) GET_VCPU_INFO(reg) ; \
66 __ENABLE_INTERRUPTS(reg)
67 #define __TEST_PENDING(reg) testb $0xFF,evtchn_upcall_pending(reg)
68
69 #define POPA \
70 popl %edi; \
71 popl %esi; \
72 popl %ebp; \
73 popl %ebx; \
74 popl %ebx; \
75 popl %edx; \
76 popl %ecx; \
77 popl %eax;
78
79 .text
80
81 /*****************************************************************************/
82 /* Trap handling */
83 /*****************************************************************************/
84 /*
85 * Trap and fault vector routines.
86 *
87 * Most traps are 'trap gates', SDT_SYS386TGT. A trap gate pushes state on
88 * the stack that mostly looks like an interrupt, but does not disable
89 * interrupts. A few of the traps we are use are interrupt gates,
90 * SDT_SYS386IGT, which are nearly the same thing except interrupts are
91 * disabled on entry.
92 *
93 * The cpu will push a certain amount of state onto the kernel stack for
94 * the current process. The amount of state depends on the type of trap
95 * and whether the trap crossed rings or not. See i386/include/frame.h.
96 * At the very least the current EFLAGS (status register, which includes
97 * the interrupt disable state prior to the trap), the code segment register,
98 * and the return instruction pointer are pushed by the cpu. The cpu
99 * will also push an 'error' code for certain traps. We push a dummy
100 * error code for those traps where the cpu doesn't in order to maintain
101 * a consistent frame. We also push a contrived 'trap number'.
102 *
103 * The cpu does not push the general registers, we must do that, and we
104 * must restore them prior to calling 'iret'. The cpu adjusts the %cs and
105 * %ss segment registers, but does not mess with %ds, %es, or %fs. Thus we
106 * must load them with appropriate values for supervisor mode operation.
107 */
108
109 MCOUNT_LABEL(user)
110 MCOUNT_LABEL(btrap)
111
112 #define TRAP(a) pushl $(a) ; jmp alltraps
113
114 IDTVEC(div)
115 pushl $0; TRAP(T_DIVIDE)
116 IDTVEC(dbg)
117 pushl $0; TRAP(T_TRCTRAP)
118 IDTVEC(nmi)
119 pushl $0; TRAP(T_NMI)
120 IDTVEC(bpt)
121 pushl $0; TRAP(T_BPTFLT)
122 IDTVEC(ofl)
123 pushl $0; TRAP(T_OFLOW)
124 IDTVEC(bnd)
125 pushl $0; TRAP(T_BOUND)
126 IDTVEC(ill)
127 pushl $0; TRAP(T_PRIVINFLT)
128 IDTVEC(dna)
129 pushl $0; TRAP(T_DNA)
130 IDTVEC(fpusegm)
131 pushl $0; TRAP(T_FPOPFLT)
132 IDTVEC(tss)
133 TRAP(T_TSSFLT)
134 IDTVEC(missing)
135 TRAP(T_SEGNPFLT)
136 IDTVEC(stk)
137 TRAP(T_STKFLT)
138 IDTVEC(prot)
139 TRAP(T_PROTFLT)
140 IDTVEC(page)
141 TRAP(T_PAGEFLT)
142 IDTVEC(mchk)
143 pushl $0; TRAP(T_MCHK)
144 IDTVEC(rsvd)
145 pushl $0; TRAP(T_RESERVED)
146 IDTVEC(fpu)
147 pushl $0; TRAP(T_ARITHTRAP)
148 IDTVEC(align)
149 TRAP(T_ALIGNFLT)
150 IDTVEC(xmm)
151 pushl $0; TRAP(T_XMMFLT)
152
153 IDTVEC(hypervisor_callback)
154 pushl $0;
155 pushl $0;
156 pushal
157 pushl %ds
158 pushl %es
159 pushl %fs
160 upcall_with_regs_pushed:
161 SET_KERNEL_SREGS
162 FAKE_MCOUNT(TF_EIP(%esp))
163 call_evtchn_upcall:
164 movl TF_EIP(%esp),%eax
165 cmpl $scrit,%eax
166 jb 10f
167 cmpl $ecrit,%eax
168 jb critical_region_fixup
169
170 10: pushl %esp
171 call evtchn_do_upcall
172 addl $4,%esp
173
174 /*
175 * Return via doreti to handle ASTs.
176 */
177 MEXITCOUNT
178 jmp doreti
179
180
181 hypervisor_callback_pending:
182 DISABLE_INTERRUPTS(%esi) /* cli */
183 jmp 10b
184 /*
185 * alltraps entry point. Interrupts are enabled if this was a trap
186 * gate (TGT), else disabled if this was an interrupt gate (IGT).
187 * Note that int0x80_syscall is a trap gate. Only page faults
188 * use an interrupt gate.
189 */
190 SUPERALIGN_TEXT
191 .globl alltraps
192 .type alltraps,@function
193 alltraps:
194 pushal
195 pushl %ds
196 pushl %es
197 pushl %fs
198
199 alltraps_with_regs_pushed:
200 SET_KERNEL_SREGS
201 FAKE_MCOUNT(TF_EIP(%esp))
202
203 calltrap:
204 push %esp
205 call trap
206 add $4, %esp
207
208 /*
209 * Return via doreti to handle ASTs.
210 */
211 MEXITCOUNT
212 jmp doreti
213
214 /*
215 * SYSCALL CALL GATE (old entry point for a.out binaries)
216 *
217 * The intersegment call has been set up to specify one dummy parameter.
218 *
219 * This leaves a place to put eflags so that the call frame can be
220 * converted to a trap frame. Note that the eflags is (semi-)bogusly
221 * pushed into (what will be) tf_err and then copied later into the
222 * final spot. It has to be done this way because esp can't be just
223 * temporarily altered for the pushfl - an interrupt might come in
224 * and clobber the saved cs/eip.
225 */
226 SUPERALIGN_TEXT
227 IDTVEC(lcall_syscall)
228 pushfl /* save eflags */
229 popl 8(%esp) /* shuffle into tf_eflags */
230 pushl $7 /* sizeof "lcall 7,0" */
231 subl $4,%esp /* skip over tf_trapno */
232 pushal
233 pushl %ds
234 pushl %es
235 pushl %fs
236 SET_KERNEL_SREGS
237 FAKE_MCOUNT(TF_EIP(%esp))
238 pushl %esp
239 call syscall
240 add $4, %esp
241 MEXITCOUNT
242 jmp doreti
243
244 /*
245 * Call gate entry for FreeBSD ELF and Linux/NetBSD syscall (int 0x80)
246 *
247 * Even though the name says 'int0x80', this is actually a TGT (trap gate)
248 * rather then an IGT (interrupt gate). Thus interrupts are enabled on
249 * entry just as they are for a normal syscall.
250 */
251 SUPERALIGN_TEXT
252 IDTVEC(int0x80_syscall)
253 pushl $2 /* sizeof "int 0x80" */
254 pushl $0xBEEF /* for debug */
255 pushal
256 pushl %ds
257 pushl %es
258 pushl %fs
259 SET_KERNEL_SREGS
260 FAKE_MCOUNT(TF_EIP(%esp))
261 pushl %esp
262 call syscall
263 add $4, %esp
264 MEXITCOUNT
265 jmp doreti
266
267 ENTRY(fork_trampoline)
268 pushl %esp /* trapframe pointer */
269 pushl %ebx /* arg1 */
270 pushl %esi /* function */
271 call fork_exit
272 addl $12,%esp
273 /* cut from syscall */
274
275 /*
276 * Return via doreti to handle ASTs.
277 */
278 MEXITCOUNT
279 jmp doreti
280
281
282 /*
283 * To efficiently implement classification of trap and interrupt handlers
284 * for profiling, there must be only trap handlers between the labels btrap
285 * and bintr, and only interrupt handlers between the labels bintr and
286 * eintr. This is implemented (partly) by including files that contain
287 * some of the handlers. Before including the files, set up a normal asm
288 * environment so that the included files doen't need to know that they are
289 * included.
290 */
291
292 .data
293 .p2align 4
294 .text
295 SUPERALIGN_TEXT
296 MCOUNT_LABEL(bintr)
297
298 #ifdef DEV_ATPIC
299 #include <i386/isa/atpic_vector.s>
300 #endif
301
302 #ifdef DEV_APIC
303 .data
304 .p2align 4
305 .text
306 SUPERALIGN_TEXT
307
308 #include <i386/i386/apic_vector.s>
309 #endif
310
311 .data
312 .p2align 4
313 .text
314 SUPERALIGN_TEXT
315 #include <i386/i386/vm86bios.s>
316
317 .text
318 MCOUNT_LABEL(eintr)
319
320 /*
321 * void doreti(struct trapframe)
322 *
323 * Handle return from interrupts, traps and syscalls.
324 */
325 .text
326 SUPERALIGN_TEXT
327 .type doreti,@function
328 doreti:
329 FAKE_MCOUNT($bintr) /* init "from" bintr -> doreti */
330 doreti_next:
331 #ifdef notyet
332 /*
333 * Check if ASTs can be handled now. PSL_VM must be checked first
334 * since segment registers only have an RPL in non-VM86 mode.
335 */
336 testl $PSL_VM,TF_EFLAGS(%esp) /* are we in vm86 mode? */
337 jz doreti_notvm86
338 movl PCPU(CURPCB),%ecx
339 testl $PCB_VM86CALL,PCB_FLAGS(%ecx) /* are we in a vm86 call? */
340 jz doreti_ast /* can handle ASTS now if not */
341 jmp doreti_exit
342
343 doreti_notvm86:
344 #endif
345 testb $SEL_RPL_MASK,TF_CS(%esp) /* are we returning to user mode? */
346 jz doreti_exit /* can't handle ASTs now if not */
347
348 doreti_ast:
349 /*
350 * Check for ASTs atomically with returning. Disabling CPU
351 * interrupts provides sufficient locking even in the SMP case,
352 * since we will be informed of any new ASTs by an IPI.
353 */
354 DISABLE_INTERRUPTS(%esi) /* cli */
355 movl PCPU(CURTHREAD),%eax
356 testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%eax)
357 je doreti_exit
358 ENABLE_INTERRUPTS(%esi) /* sti */
359 pushl %esp /* pass a pointer to the trapframe */
360 call ast
361 add $4,%esp
362 jmp doreti_ast
363
364 /*
365 * doreti_exit: pop registers, iret.
366 *
367 * The segment register pop is a special case, since it may
368 * fault if (for example) a sigreturn specifies bad segment
369 * registers. The fault is handled in trap.c.
370 */
371 doreti_exit:
372 ENABLE_INTERRUPTS(%esi) # reenable event callbacks (sti)
373
374 .globl scrit
375 scrit:
376 __TEST_PENDING(%esi)
377 jnz hypervisor_callback_pending /* More to go */
378
379 MEXITCOUNT
380
381 .globl doreti_popl_fs
382 doreti_popl_fs:
383 popl %fs
384 .globl doreti_popl_es
385 doreti_popl_es:
386 popl %es
387 .globl doreti_popl_ds
388 doreti_popl_ds:
389 popl %ds
390
391 /*
392 * This is important: as nothing is atomic over here (we can get
393 * interrupted any time), we use the critical_region_fixup() in
394 * order to figure out where out stack is. Therefore, do NOT use
395 * 'popal' here without fixing up the table!
396 */
397 POPA
398 addl $8,%esp
399 .globl doreti_iret
400 doreti_iret:
401 jmp hypercall_page + (__HYPERVISOR_iret * 32)
402 .globl ecrit
403 ecrit:
404 /*
405 * doreti_iret_fault and friends. Alternative return code for
406 * the case where we get a fault in the doreti_exit code
407 * above. trap() (i386/i386/trap.c) catches this specific
408 * case, sends the process a signal and continues in the
409 * corresponding place in the code below.
410 */
411 ALIGN_TEXT
412 .globl doreti_iret_fault
413 doreti_iret_fault:
414 subl $8,%esp
415 pushal
416 pushl %ds
417 .globl doreti_popl_ds_fault
418 doreti_popl_ds_fault:
419 pushl %es
420 .globl doreti_popl_es_fault
421 doreti_popl_es_fault:
422 pushl %fs
423 .globl doreti_popl_fs_fault
424 doreti_popl_fs_fault:
425 movl $0,TF_ERR(%esp) /* XXX should be the error code */
426 movl $T_PROTFLT,TF_TRAPNO(%esp)
427 jmp alltraps_with_regs_pushed
428
429 /*
430 # [How we do the fixup]. We want to merge the current stack frame with the
431 # just-interrupted frame. How we do this depends on where in the critical
432 # region the interrupted handler was executing, and so how many saved
433 # registers are in each frame. We do this quickly using the lookup table
434 # 'critical_fixup_table'. For each byte offset in the critical region, it
435 # provides the number of bytes which have already been popped from the
436 # interrupted stack frame.
437 */
438
439 .globl critical_region_fixup
440 critical_region_fixup:
441 addl $critical_fixup_table-scrit,%eax
442 movzbl (%eax),%eax # %eax contains num bytes popped
443 movl %esp,%esi
444 add %eax,%esi # %esi points at end of src region
445 movl %esp,%edi
446 add $0x40,%edi # %edi points at end of dst region
447 movl %eax,%ecx
448 shr $2,%ecx # convert bytes to words
449 je 16f # skip loop if nothing to copy
450 15: subl $4,%esi # pre-decrementing copy loop
451 subl $4,%edi
452 movl (%esi),%eax
453 movl %eax,(%edi)
454 loop 15b
455 16: movl %edi,%esp # final %edi is top of merged stack
456 jmp hypervisor_callback_pending
457
458
459 critical_fixup_table:
460 .byte 0x0,0x0,0x0 #testb $0x1,(%esi)
461 .byte 0x0,0x0,0x0,0x0,0x0,0x0 #jne ea
462 .byte 0x0,0x0 #pop %fs
463 .byte 0x04 #pop %es
464 .byte 0x08 #pop %ds
465 .byte 0x0c #pop %edi
466 .byte 0x10 #pop %esi
467 .byte 0x14 #pop %ebp
468 .byte 0x18 #pop %ebx
469 .byte 0x1c #pop %ebx
470 .byte 0x20 #pop %edx
471 .byte 0x24 #pop %ecx
472 .byte 0x28 #pop %eax
473 .byte 0x2c,0x2c,0x2c #add $0x8,%esp
474 #if 0
475 .byte 0x34 #iret
476 #endif
477 .byte 0x34,0x34,0x34,0x34,0x34 #HYPERVISOR_iret
478
479
480 /* # Hypervisor uses this for application faults while it executes.*/
481 ENTRY(failsafe_callback)
482 pushal
483 call xen_failsafe_handler
484 /*# call install_safe_pf_handler */
485 movl 28(%esp),%ebx
486 1: movl %ebx,%ds
487 movl 32(%esp),%ebx
488 2: movl %ebx,%es
489 movl 36(%esp),%ebx
490 3: movl %ebx,%fs
491 movl 40(%esp),%ebx
492 4: movl %ebx,%gs
493 /*# call install_normal_pf_handler */
494 popal
495 addl $12,%esp
496 iret
497
498
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