1 /*-
2 * Copyright (c) 1989, 1990 William F. Jolitz.
3 * Copyright (c) 1990 The Regents of the University of California.
4 * Copyright (c) 2007 The FreeBSD Foundation
5 * All rights reserved.
6 *
7 * Portions of this software were developed by A. Joseph Koshy under
8 * sponsorship from the FreeBSD Foundation and Google, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * $FreeBSD$
35 */
36
37 #include "opt_apic.h"
38 #include "opt_atpic.h"
39 #include "opt_hwpmc_hooks.h"
40 #include "opt_kdtrace.h"
41 #include "opt_npx.h"
42
43 #include <machine/asmacros.h>
44 #include <machine/psl.h>
45 #include <machine/trap.h>
46
47 #include "assym.s"
48
49 #define SEL_RPL_MASK 0x0003
50 #define GSEL_KPL 0x0020 /* GSEL(GCODE_SEL, SEL_KPL) */
51
52 #ifdef KDTRACE_HOOKS
53 .bss
54 .globl dtrace_invop_jump_addr
55 .align 4
56 .type dtrace_invop_jump_addr, @object
57 .size dtrace_invop_jump_addr, 4
58 dtrace_invop_jump_addr:
59 .zero 4
60 .globl dtrace_invop_calltrap_addr
61 .align 4
62 .type dtrace_invop_calltrap_addr, @object
63 .size dtrace_invop_calltrap_addr, 4
64 dtrace_invop_calltrap_addr:
65 .zero 8
66 #endif
67 .text
68 #ifdef HWPMC_HOOKS
69 ENTRY(start_exceptions)
70 #endif
71 /*****************************************************************************/
72 /* Trap handling */
73 /*****************************************************************************/
74 /*
75 * Trap and fault vector routines.
76 *
77 * Most traps are 'trap gates', SDT_SYS386TGT. A trap gate pushes state on
78 * the stack that mostly looks like an interrupt, but does not disable
79 * interrupts. A few of the traps we are use are interrupt gates,
80 * SDT_SYS386IGT, which are nearly the same thing except interrupts are
81 * disabled on entry.
82 *
83 * The cpu will push a certain amount of state onto the kernel stack for
84 * the current process. The amount of state depends on the type of trap
85 * and whether the trap crossed rings or not. See i386/include/frame.h.
86 * At the very least the current EFLAGS (status register, which includes
87 * the interrupt disable state prior to the trap), the code segment register,
88 * and the return instruction pointer are pushed by the cpu. The cpu
89 * will also push an 'error' code for certain traps. We push a dummy
90 * error code for those traps where the cpu doesn't in order to maintain
91 * a consistent frame. We also push a contrived 'trap number'.
92 *
93 * The cpu does not push the general registers, we must do that, and we
94 * must restore them prior to calling 'iret'. The cpu adjusts the %cs and
95 * %ss segment registers, but does not mess with %ds, %es, or %fs. Thus we
96 * must load them with appropriate values for supervisor mode operation.
97 */
98
99 MCOUNT_LABEL(user)
100 MCOUNT_LABEL(btrap)
101
102 #define TRAP(a) pushl $(a) ; jmp alltraps
103
104 IDTVEC(div)
105 pushl $0; TRAP(T_DIVIDE)
106 IDTVEC(dbg)
107 pushl $0; TRAP(T_TRCTRAP)
108 IDTVEC(nmi)
109 pushl $0; TRAP(T_NMI)
110 IDTVEC(bpt)
111 pushl $0; TRAP(T_BPTFLT)
112 IDTVEC(dtrace_ret)
113 pushl $0; TRAP(T_DTRACE_RET)
114 IDTVEC(ofl)
115 pushl $0; TRAP(T_OFLOW)
116 IDTVEC(bnd)
117 pushl $0; TRAP(T_BOUND)
118 #ifndef KDTRACE_HOOKS
119 IDTVEC(ill)
120 pushl $0; TRAP(T_PRIVINFLT)
121 #endif
122 IDTVEC(dna)
123 pushl $0; TRAP(T_DNA)
124 IDTVEC(fpusegm)
125 pushl $0; TRAP(T_FPOPFLT)
126 IDTVEC(tss)
127 TRAP(T_TSSFLT)
128 IDTVEC(missing)
129 TRAP(T_SEGNPFLT)
130 IDTVEC(stk)
131 TRAP(T_STKFLT)
132 IDTVEC(prot)
133 TRAP(T_PROTFLT)
134 IDTVEC(page)
135 TRAP(T_PAGEFLT)
136 IDTVEC(mchk)
137 pushl $0; TRAP(T_MCHK)
138 IDTVEC(rsvd)
139 pushl $0; TRAP(T_RESERVED)
140 IDTVEC(fpu)
141 pushl $0; TRAP(T_ARITHTRAP)
142 IDTVEC(align)
143 TRAP(T_ALIGNFLT)
144 IDTVEC(xmm)
145 pushl $0; TRAP(T_XMMFLT)
146
147 /*
148 * All traps except ones for syscalls jump to alltraps. If
149 * interrupts were enabled when the trap occurred, then interrupts
150 * are enabled now if the trap was through a trap gate, else
151 * disabled if the trap was through an interrupt gate. Note that
152 * int0x80_syscall is a trap gate. Interrupt gates are used by
153 * page faults, non-maskable interrupts, debug and breakpoint
154 * exceptions.
155 */
156 SUPERALIGN_TEXT
157 .globl alltraps
158 .type alltraps,@function
159 alltraps:
160 pushal
161 pushl $0
162 movw %ds,(%esp)
163 pushl $0
164 movw %es,(%esp)
165 pushl $0
166 movw %fs,(%esp)
167 alltraps_with_regs_pushed:
168 SET_KERNEL_SREGS
169 cld
170 FAKE_MCOUNT(TF_EIP(%esp))
171 calltrap:
172 pushl %esp
173 call trap
174 add $4, %esp
175
176 /*
177 * Return via doreti to handle ASTs.
178 */
179 MEXITCOUNT
180 jmp doreti
181
182 /*
183 * Privileged instruction fault.
184 */
185 #ifdef KDTRACE_HOOKS
186 SUPERALIGN_TEXT
187 IDTVEC(ill)
188 /* Check if there is no DTrace hook registered. */
189 cmpl $0,dtrace_invop_jump_addr
190 je norm_ill
191
192 /* Check if this is a user fault. */
193 cmpl $GSEL_KPL, 4(%esp) /* Check the code segment. */
194
195 /* If so, just handle it as a normal trap. */
196 jne norm_ill
197
198 /*
199 * This is a kernel instruction fault that might have been caused
200 * by a DTrace provider.
201 */
202 pushal /* Push all registers onto the stack. */
203
204 /*
205 * Set our jump address for the jump back in the event that
206 * the exception wasn't caused by DTrace at all.
207 */
208 movl $norm_ill, dtrace_invop_calltrap_addr
209
210 /* Jump to the code hooked in by DTrace. */
211 jmpl *dtrace_invop_jump_addr
212
213 /*
214 * Process the instruction fault in the normal way.
215 */
216 norm_ill:
217 pushl $0
218 TRAP(T_PRIVINFLT)
219 #endif
220
221 /*
222 * Call gate entry for syscalls (lcall 7,0).
223 * This is used by FreeBSD 1.x a.out executables and "old" NetBSD executables.
224 *
225 * The intersegment call has been set up to specify one dummy parameter.
226 * This leaves a place to put eflags so that the call frame can be
227 * converted to a trap frame. Note that the eflags is (semi-)bogusly
228 * pushed into (what will be) tf_err and then copied later into the
229 * final spot. It has to be done this way because esp can't be just
230 * temporarily altered for the pushfl - an interrupt might come in
231 * and clobber the saved cs/eip.
232 */
233 SUPERALIGN_TEXT
234 IDTVEC(lcall_syscall)
235 pushfl /* save eflags */
236 popl 8(%esp) /* shuffle into tf_eflags */
237 pushl $7 /* sizeof "lcall 7,0" */
238 pushl $0 /* tf_trapno */
239 pushal
240 pushl $0
241 movw %ds,(%esp)
242 pushl $0
243 movw %es,(%esp)
244 pushl $0
245 movw %fs,(%esp)
246 SET_KERNEL_SREGS
247 cld
248 FAKE_MCOUNT(TF_EIP(%esp))
249 pushl %esp
250 call syscall
251 add $4, %esp
252 MEXITCOUNT
253 jmp doreti
254
255 /*
256 * Trap gate entry for syscalls (int 0x80).
257 * This is used by FreeBSD ELF executables, "new" NetBSD executables, and all
258 * Linux executables.
259 *
260 * Even though the name says 'int0x80', this is actually a trap gate, not an
261 * interrupt gate. Thus interrupts are enabled on entry just as they are for
262 * a normal syscall.
263 */
264 SUPERALIGN_TEXT
265 IDTVEC(int0x80_syscall)
266 pushl $2 /* sizeof "int 0x80" */
267 pushl $0 /* tf_trapno */
268 pushal
269 pushl $0
270 movw %ds,(%esp)
271 pushl $0
272 movw %es,(%esp)
273 pushl $0
274 movw %fs,(%esp)
275 SET_KERNEL_SREGS
276 cld
277 FAKE_MCOUNT(TF_EIP(%esp))
278 pushl %esp
279 call syscall
280 add $4, %esp
281 MEXITCOUNT
282 jmp doreti
283
284 ENTRY(fork_trampoline)
285 pushl %esp /* trapframe pointer */
286 pushl %ebx /* arg1 */
287 pushl %esi /* function */
288 call fork_exit
289 addl $12,%esp
290 /* cut from syscall */
291
292 /*
293 * Return via doreti to handle ASTs.
294 */
295 MEXITCOUNT
296 jmp doreti
297
298
299 /*
300 * To efficiently implement classification of trap and interrupt handlers
301 * for profiling, there must be only trap handlers between the labels btrap
302 * and bintr, and only interrupt handlers between the labels bintr and
303 * eintr. This is implemented (partly) by including files that contain
304 * some of the handlers. Before including the files, set up a normal asm
305 * environment so that the included files doen't need to know that they are
306 * included.
307 */
308
309 .data
310 .p2align 4
311 .text
312 SUPERALIGN_TEXT
313 MCOUNT_LABEL(bintr)
314
315 #ifdef DEV_ATPIC
316 #include <i386/i386/atpic_vector.s>
317 #endif
318
319 #if defined(DEV_APIC) && defined(DEV_ATPIC)
320 .data
321 .p2align 4
322 .text
323 SUPERALIGN_TEXT
324 #endif
325
326 #ifdef DEV_APIC
327 #include <i386/i386/apic_vector.s>
328 #endif
329
330 .data
331 .p2align 4
332 .text
333 SUPERALIGN_TEXT
334 #include <i386/i386/vm86bios.s>
335
336 .text
337 MCOUNT_LABEL(eintr)
338
339 /*
340 * void doreti(struct trapframe)
341 *
342 * Handle return from interrupts, traps and syscalls.
343 */
344 .text
345 SUPERALIGN_TEXT
346 .type doreti,@function
347 doreti:
348 FAKE_MCOUNT($bintr) /* init "from" bintr -> doreti */
349 doreti_next:
350 /*
351 * Check if ASTs can be handled now. ASTs cannot be safely
352 * processed when returning from an NMI.
353 */
354 cmpb $T_NMI,TF_TRAPNO(%esp)
355 #ifdef HWPMC_HOOKS
356 je doreti_nmi
357 #else
358 je doreti_exit
359 #endif
360 /*
361 * PSL_VM must be checked first since segment registers only
362 * have an RPL in non-VM86 mode.
363 * ASTs can not be handled now if we are in a vm86 call.
364 */
365 testl $PSL_VM,TF_EFLAGS(%esp)
366 jz doreti_notvm86
367 movl PCPU(CURPCB),%ecx
368 testl $PCB_VM86CALL,PCB_FLAGS(%ecx)
369 jz doreti_ast
370 jmp doreti_exit
371
372 doreti_notvm86:
373 testb $SEL_RPL_MASK,TF_CS(%esp) /* are we returning to user mode? */
374 jz doreti_exit /* can't handle ASTs now if not */
375
376 doreti_ast:
377 /*
378 * Check for ASTs atomically with returning. Disabling CPU
379 * interrupts provides sufficient locking even in the SMP case,
380 * since we will be informed of any new ASTs by an IPI.
381 */
382 cli
383 movl PCPU(CURTHREAD),%eax
384 testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%eax)
385 je doreti_exit
386 sti
387 pushl %esp /* pass a pointer to the trapframe */
388 call ast
389 add $4,%esp
390 jmp doreti_ast
391
392 /*
393 * doreti_exit: pop registers, iret.
394 *
395 * The segment register pop is a special case, since it may
396 * fault if (for example) a sigreturn specifies bad segment
397 * registers. The fault is handled in trap.c.
398 */
399 doreti_exit:
400 MEXITCOUNT
401
402 .globl doreti_popl_fs
403 doreti_popl_fs:
404 popl %fs
405 .globl doreti_popl_es
406 doreti_popl_es:
407 popl %es
408 .globl doreti_popl_ds
409 doreti_popl_ds:
410 popl %ds
411 popal
412 addl $8,%esp
413 .globl doreti_iret
414 doreti_iret:
415 iret
416
417 /*
418 * doreti_iret_fault and friends. Alternative return code for
419 * the case where we get a fault in the doreti_exit code
420 * above. trap() (i386/i386/trap.c) catches this specific
421 * case, sends the process a signal and continues in the
422 * corresponding place in the code below.
423 */
424 ALIGN_TEXT
425 .globl doreti_iret_fault
426 doreti_iret_fault:
427 subl $8,%esp
428 pushal
429 pushl $0
430 movw %ds,(%esp)
431 .globl doreti_popl_ds_fault
432 doreti_popl_ds_fault:
433 pushl $0
434 movw %es,(%esp)
435 .globl doreti_popl_es_fault
436 doreti_popl_es_fault:
437 pushl $0
438 movw %fs,(%esp)
439 .globl doreti_popl_fs_fault
440 doreti_popl_fs_fault:
441 sti
442 movl $0,TF_ERR(%esp) /* XXX should be the error code */
443 movl $T_PROTFLT,TF_TRAPNO(%esp)
444 jmp alltraps_with_regs_pushed
445 #ifdef HWPMC_HOOKS
446 doreti_nmi:
447 /*
448 * Since we are returning from an NMI, check if the current trap
449 * was from user mode and if so whether the current thread
450 * needs a user call chain capture.
451 */
452 testb $SEL_RPL_MASK,TF_CS(%esp)
453 jz doreti_exit
454 movl PCPU(CURTHREAD),%eax /* curthread present? */
455 orl %eax,%eax
456 jz doreti_exit
457 testl $TDP_CALLCHAIN,TD_PFLAGS(%eax) /* flagged for capture? */
458 jz doreti_exit
459 /*
460 * Take the processor out of NMI mode by executing a fake "iret".
461 */
462 pushfl
463 pushl %cs
464 pushl $outofnmi
465 iret
466 outofnmi:
467 /*
468 * Call the callchain capture hook after turning interrupts back on.
469 */
470 movl pmc_hook,%ecx
471 orl %ecx,%ecx
472 jz doreti_exit
473 pushl %esp /* frame pointer */
474 pushl $PMC_FN_USER_CALLCHAIN /* command */
475 movl PCPU(CURTHREAD),%eax
476 pushl %eax /* curthread */
477 sti
478 call *%ecx
479 addl $12,%esp
480 jmp doreti_ast
481 ENTRY(end_exceptions)
482 #endif
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