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: releng/10.2/sys/i386/i386/exception.s 251988 2013-06-19 05:05:16Z kib $
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 %ds
162 pushl %es
163 pushl %fs
164 alltraps_with_regs_pushed:
165 SET_KERNEL_SREGS
166 cld
167 FAKE_MCOUNT(TF_EIP(%esp))
168 calltrap:
169 pushl %esp
170 call trap
171 add $4, %esp
172
173 /*
174 * Return via doreti to handle ASTs.
175 */
176 MEXITCOUNT
177 jmp doreti
178
179 /*
180 * Privileged instruction fault.
181 */
182 #ifdef KDTRACE_HOOKS
183 SUPERALIGN_TEXT
184 IDTVEC(ill)
185 /* Check if there is no DTrace hook registered. */
186 cmpl $0,dtrace_invop_jump_addr
187 je norm_ill
188
189 /* Check if this is a user fault. */
190 cmpl $GSEL_KPL, 4(%esp) /* Check the code segment. */
191
192 /* If so, just handle it as a normal trap. */
193 jne norm_ill
194
195 /*
196 * This is a kernel instruction fault that might have been caused
197 * by a DTrace provider.
198 */
199 pushal /* Push all registers onto the stack. */
200
201 /*
202 * Set our jump address for the jump back in the event that
203 * the exception wasn't caused by DTrace at all.
204 */
205 movl $norm_ill, dtrace_invop_calltrap_addr
206
207 /* Jump to the code hooked in by DTrace. */
208 jmpl *dtrace_invop_jump_addr
209
210 /*
211 * Process the instruction fault in the normal way.
212 */
213 norm_ill:
214 pushl $0
215 TRAP(T_PRIVINFLT)
216 #endif
217
218 /*
219 * Call gate entry for syscalls (lcall 7,0).
220 * This is used by FreeBSD 1.x a.out executables and "old" NetBSD executables.
221 *
222 * The intersegment call has been set up to specify one dummy parameter.
223 * This leaves a place to put eflags so that the call frame can be
224 * converted to a trap frame. Note that the eflags is (semi-)bogusly
225 * pushed into (what will be) tf_err and then copied later into the
226 * final spot. It has to be done this way because esp can't be just
227 * temporarily altered for the pushfl - an interrupt might come in
228 * and clobber the saved cs/eip.
229 */
230 SUPERALIGN_TEXT
231 IDTVEC(lcall_syscall)
232 pushfl /* save eflags */
233 popl 8(%esp) /* shuffle into tf_eflags */
234 pushl $7 /* sizeof "lcall 7,0" */
235 subl $4,%esp /* skip over tf_trapno */
236 pushal
237 pushl %ds
238 pushl %es
239 pushl %fs
240 SET_KERNEL_SREGS
241 cld
242 FAKE_MCOUNT(TF_EIP(%esp))
243 pushl %esp
244 call syscall
245 add $4, %esp
246 MEXITCOUNT
247 jmp doreti
248
249 /*
250 * Trap gate entry for syscalls (int 0x80).
251 * This is used by FreeBSD ELF executables, "new" NetBSD executables, and all
252 * Linux executables.
253 *
254 * Even though the name says 'int0x80', this is actually a trap gate, not an
255 * interrupt gate. Thus interrupts are enabled on entry just as they are for
256 * a normal syscall.
257 */
258 SUPERALIGN_TEXT
259 IDTVEC(int0x80_syscall)
260 pushl $2 /* sizeof "int 0x80" */
261 subl $4,%esp /* skip over tf_trapno */
262 pushal
263 pushl %ds
264 pushl %es
265 pushl %fs
266 SET_KERNEL_SREGS
267 cld
268 FAKE_MCOUNT(TF_EIP(%esp))
269 pushl %esp
270 call syscall
271 add $4, %esp
272 MEXITCOUNT
273 jmp doreti
274
275 ENTRY(fork_trampoline)
276 pushl %esp /* trapframe pointer */
277 pushl %ebx /* arg1 */
278 pushl %esi /* function */
279 call fork_exit
280 addl $12,%esp
281 /* cut from syscall */
282
283 /*
284 * Return via doreti to handle ASTs.
285 */
286 MEXITCOUNT
287 jmp doreti
288
289
290 /*
291 * To efficiently implement classification of trap and interrupt handlers
292 * for profiling, there must be only trap handlers between the labels btrap
293 * and bintr, and only interrupt handlers between the labels bintr and
294 * eintr. This is implemented (partly) by including files that contain
295 * some of the handlers. Before including the files, set up a normal asm
296 * environment so that the included files doen't need to know that they are
297 * included.
298 */
299
300 .data
301 .p2align 4
302 .text
303 SUPERALIGN_TEXT
304 MCOUNT_LABEL(bintr)
305
306 #ifdef DEV_ATPIC
307 #include <i386/i386/atpic_vector.s>
308 #endif
309
310 #if defined(DEV_APIC) && defined(DEV_ATPIC)
311 .data
312 .p2align 4
313 .text
314 SUPERALIGN_TEXT
315 #endif
316
317 #ifdef DEV_APIC
318 #include <i386/i386/apic_vector.s>
319 #endif
320
321 .data
322 .p2align 4
323 .text
324 SUPERALIGN_TEXT
325 #include <i386/i386/vm86bios.s>
326
327 .text
328 MCOUNT_LABEL(eintr)
329
330 /*
331 * void doreti(struct trapframe)
332 *
333 * Handle return from interrupts, traps and syscalls.
334 */
335 .text
336 SUPERALIGN_TEXT
337 .type doreti,@function
338 doreti:
339 FAKE_MCOUNT($bintr) /* init "from" bintr -> doreti */
340 doreti_next:
341 /*
342 * Check if ASTs can be handled now. ASTs cannot be safely
343 * processed when returning from an NMI.
344 */
345 cmpb $T_NMI,TF_TRAPNO(%esp)
346 #ifdef HWPMC_HOOKS
347 je doreti_nmi
348 #else
349 je doreti_exit
350 #endif
351 /*
352 * PSL_VM must be checked first since segment registers only
353 * have an RPL in non-VM86 mode.
354 * ASTs can not be handled now if we are in a vm86 call.
355 */
356 testl $PSL_VM,TF_EFLAGS(%esp)
357 jz doreti_notvm86
358 movl PCPU(CURPCB),%ecx
359 testl $PCB_VM86CALL,PCB_FLAGS(%ecx)
360 jz doreti_ast
361 jmp doreti_exit
362
363 doreti_notvm86:
364 testb $SEL_RPL_MASK,TF_CS(%esp) /* are we returning to user mode? */
365 jz doreti_exit /* can't handle ASTs now if not */
366
367 doreti_ast:
368 /*
369 * Check for ASTs atomically with returning. Disabling CPU
370 * interrupts provides sufficient locking even in the SMP case,
371 * since we will be informed of any new ASTs by an IPI.
372 */
373 cli
374 movl PCPU(CURTHREAD),%eax
375 testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%eax)
376 je doreti_exit
377 sti
378 pushl %esp /* pass a pointer to the trapframe */
379 call ast
380 add $4,%esp
381 jmp doreti_ast
382
383 /*
384 * doreti_exit: pop registers, iret.
385 *
386 * The segment register pop is a special case, since it may
387 * fault if (for example) a sigreturn specifies bad segment
388 * registers. The fault is handled in trap.c.
389 */
390 doreti_exit:
391 MEXITCOUNT
392
393 .globl doreti_popl_fs
394 doreti_popl_fs:
395 popl %fs
396 .globl doreti_popl_es
397 doreti_popl_es:
398 popl %es
399 .globl doreti_popl_ds
400 doreti_popl_ds:
401 popl %ds
402 popal
403 addl $8,%esp
404 .globl doreti_iret
405 doreti_iret:
406 iret
407
408 /*
409 * doreti_iret_fault and friends. Alternative return code for
410 * the case where we get a fault in the doreti_exit code
411 * above. trap() (i386/i386/trap.c) catches this specific
412 * case, sends the process a signal and continues in the
413 * corresponding place in the code below.
414 */
415 ALIGN_TEXT
416 .globl doreti_iret_fault
417 doreti_iret_fault:
418 subl $8,%esp
419 pushal
420 pushl %ds
421 .globl doreti_popl_ds_fault
422 doreti_popl_ds_fault:
423 pushl %es
424 .globl doreti_popl_es_fault
425 doreti_popl_es_fault:
426 pushl %fs
427 .globl doreti_popl_fs_fault
428 doreti_popl_fs_fault:
429 sti
430 movl $0,TF_ERR(%esp) /* XXX should be the error code */
431 movl $T_PROTFLT,TF_TRAPNO(%esp)
432 jmp alltraps_with_regs_pushed
433 #ifdef HWPMC_HOOKS
434 doreti_nmi:
435 /*
436 * Since we are returning from an NMI, check if the current trap
437 * was from user mode and if so whether the current thread
438 * needs a user call chain capture.
439 */
440 testb $SEL_RPL_MASK,TF_CS(%esp)
441 jz doreti_exit
442 movl PCPU(CURTHREAD),%eax /* curthread present? */
443 orl %eax,%eax
444 jz doreti_exit
445 testl $TDP_CALLCHAIN,TD_PFLAGS(%eax) /* flagged for capture? */
446 jz doreti_exit
447 /*
448 * Take the processor out of NMI mode by executing a fake "iret".
449 */
450 pushfl
451 pushl %cs
452 pushl $outofnmi
453 iret
454 outofnmi:
455 /*
456 * Call the callchain capture hook after turning interrupts back on.
457 */
458 movl pmc_hook,%ecx
459 orl %ecx,%ecx
460 jz doreti_exit
461 pushl %esp /* frame pointer */
462 pushl $PMC_FN_USER_CALLCHAIN /* command */
463 movl PCPU(CURTHREAD),%eax
464 pushl %eax /* curthread */
465 sti
466 call *%ecx
467 addl $12,%esp
468 jmp doreti_ast
469 ENTRY(end_exceptions)
470 #endif
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