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/8.2/sys/i386/i386/exception.s 215026 2010-11-09 01:57:56Z attilio $
35 */
36
37 #include "opt_apic.h"
38 #include "opt_hwpmc_hooks.h"
39 #include "opt_kdtrace.h"
40 #include "opt_npx.h"
41
42 #include <machine/asmacros.h>
43 #include <machine/psl.h>
44 #include <machine/trap.h>
45
46 #include "assym.s"
47
48 #define SEL_RPL_MASK 0x0003
49 #define GSEL_KPL 0x0020 /* GSEL(GCODE_SEL, SEL_KPL) */
50
51 #ifdef KDTRACE_HOOKS
52 .bss
53 .globl dtrace_invop_jump_addr
54 .align 4
55 .type dtrace_invop_jump_addr, @object
56 .size dtrace_invop_jump_addr, 4
57 dtrace_invop_jump_addr:
58 .zero 4
59 .globl dtrace_invop_calltrap_addr
60 .align 4
61 .type dtrace_invop_calltrap_addr, @object
62 .size dtrace_invop_calltrap_addr, 4
63 dtrace_invop_calltrap_addr:
64 .zero 8
65 #endif
66 .text
67 #ifdef HWPMC_HOOKS
68 ENTRY(start_exceptions)
69 #endif
70 /*****************************************************************************/
71 /* Trap handling */
72 /*****************************************************************************/
73 /*
74 * Trap and fault vector routines.
75 *
76 * Most traps are 'trap gates', SDT_SYS386TGT. A trap gate pushes state on
77 * the stack that mostly looks like an interrupt, but does not disable
78 * interrupts. A few of the traps we are use are interrupt gates,
79 * SDT_SYS386IGT, which are nearly the same thing except interrupts are
80 * disabled on entry.
81 *
82 * The cpu will push a certain amount of state onto the kernel stack for
83 * the current process. The amount of state depends on the type of trap
84 * and whether the trap crossed rings or not. See i386/include/frame.h.
85 * At the very least the current EFLAGS (status register, which includes
86 * the interrupt disable state prior to the trap), the code segment register,
87 * and the return instruction pointer are pushed by the cpu. The cpu
88 * will also push an 'error' code for certain traps. We push a dummy
89 * error code for those traps where the cpu doesn't in order to maintain
90 * a consistent frame. We also push a contrived 'trap number'.
91 *
92 * The cpu does not push the general registers, we must do that, and we
93 * must restore them prior to calling 'iret'. The cpu adjusts the %cs and
94 * %ss segment registers, but does not mess with %ds, %es, or %fs. Thus we
95 * must load them with appropriate values for supervisor mode operation.
96 */
97
98 MCOUNT_LABEL(user)
99 MCOUNT_LABEL(btrap)
100
101 #define TRAP(a) pushl $(a) ; jmp alltraps
102
103 IDTVEC(div)
104 pushl $0; TRAP(T_DIVIDE)
105 IDTVEC(dbg)
106 pushl $0; TRAP(T_TRCTRAP)
107 IDTVEC(nmi)
108 pushl $0; TRAP(T_NMI)
109 IDTVEC(bpt)
110 pushl $0; TRAP(T_BPTFLT)
111 IDTVEC(ofl)
112 pushl $0; TRAP(T_OFLOW)
113 IDTVEC(bnd)
114 pushl $0; TRAP(T_BOUND)
115 #ifndef KDTRACE_HOOKS
116 IDTVEC(ill)
117 pushl $0; TRAP(T_PRIVINFLT)
118 #endif
119 IDTVEC(dna)
120 pushl $0; TRAP(T_DNA)
121 IDTVEC(fpusegm)
122 pushl $0; TRAP(T_FPOPFLT)
123 IDTVEC(tss)
124 TRAP(T_TSSFLT)
125 IDTVEC(missing)
126 TRAP(T_SEGNPFLT)
127 IDTVEC(stk)
128 TRAP(T_STKFLT)
129 IDTVEC(prot)
130 TRAP(T_PROTFLT)
131 IDTVEC(page)
132 TRAP(T_PAGEFLT)
133 IDTVEC(mchk)
134 pushl $0; TRAP(T_MCHK)
135 IDTVEC(rsvd)
136 pushl $0; TRAP(T_RESERVED)
137 IDTVEC(fpu)
138 pushl $0; TRAP(T_ARITHTRAP)
139 IDTVEC(align)
140 TRAP(T_ALIGNFLT)
141 IDTVEC(xmm)
142 pushl $0; TRAP(T_XMMFLT)
143
144 /*
145 * alltraps entry point. Interrupts are enabled if this was a trap
146 * gate (TGT), else disabled if this was an interrupt gate (IGT).
147 * Note that int0x80_syscall is a trap gate. Interrupt gates are
148 * used by page faults, non-maskable interrupts, debug and breakpoint
149 * exceptions.
150 */
151
152 SUPERALIGN_TEXT
153 .globl alltraps
154 .type alltraps,@function
155 alltraps:
156 pushal
157 pushl %ds
158 pushl %es
159 pushl %fs
160 alltraps_with_regs_pushed:
161 SET_KERNEL_SREGS
162 cld
163 FAKE_MCOUNT(TF_EIP(%esp))
164 calltrap:
165 pushl %esp
166 call trap
167 add $4, %esp
168
169 /*
170 * Return via doreti to handle ASTs.
171 */
172 MEXITCOUNT
173 jmp doreti
174
175 /*
176 * Privileged instruction fault.
177 */
178 #ifdef KDTRACE_HOOKS
179 SUPERALIGN_TEXT
180 IDTVEC(ill)
181 /* Check if there is no DTrace hook registered. */
182 cmpl $0,dtrace_invop_jump_addr
183 je norm_ill
184
185 /* Check if this is a user fault. */
186 cmpl $GSEL_KPL, 4(%esp) /* Check the code segment. */
187
188 /* If so, just handle it as a normal trap. */
189 jne norm_ill
190
191 /*
192 * This is a kernel instruction fault that might have been caused
193 * by a DTrace provider.
194 */
195 pushal /* Push all registers onto the stack. */
196
197 /*
198 * Set our jump address for the jump back in the event that
199 * the exception wasn't caused by DTrace at all.
200 */
201 movl $norm_ill, dtrace_invop_calltrap_addr
202
203 /* Jump to the code hooked in by DTrace. */
204 jmpl *dtrace_invop_jump_addr
205
206 /*
207 * Process the instruction fault in the normal way.
208 */
209 norm_ill:
210 pushl $0
211 TRAP(T_PRIVINFLT)
212 #endif
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 cld
238 FAKE_MCOUNT(TF_EIP(%esp))
239 pushl %esp
240 call syscall
241 add $4, %esp
242 MEXITCOUNT
243 jmp doreti
244
245 /*
246 * Call gate entry for FreeBSD ELF and Linux/NetBSD syscall (int 0x80)
247 *
248 * Even though the name says 'int0x80', this is actually a TGT (trap gate)
249 * rather then an IGT (interrupt gate). Thus interrupts are enabled on
250 * entry just as they are for a normal syscall.
251 */
252 SUPERALIGN_TEXT
253 IDTVEC(int0x80_syscall)
254 pushl $2 /* sizeof "int 0x80" */
255 subl $4,%esp /* skip over tf_trapno */
256 pushal
257 pushl %ds
258 pushl %es
259 pushl %fs
260 SET_KERNEL_SREGS
261 cld
262 FAKE_MCOUNT(TF_EIP(%esp))
263 pushl %esp
264 call syscall
265 add $4, %esp
266 MEXITCOUNT
267 jmp doreti
268
269 ENTRY(fork_trampoline)
270 pushl %esp /* trapframe pointer */
271 pushl %ebx /* arg1 */
272 pushl %esi /* function */
273 call fork_exit
274 addl $12,%esp
275 /* cut from syscall */
276
277 /*
278 * Return via doreti to handle ASTs.
279 */
280 MEXITCOUNT
281 jmp doreti
282
283
284 /*
285 * To efficiently implement classification of trap and interrupt handlers
286 * for profiling, there must be only trap handlers between the labels btrap
287 * and bintr, and only interrupt handlers between the labels bintr and
288 * eintr. This is implemented (partly) by including files that contain
289 * some of the handlers. Before including the files, set up a normal asm
290 * environment so that the included files doen't need to know that they are
291 * included.
292 */
293
294 .data
295 .p2align 4
296 .text
297 SUPERALIGN_TEXT
298 MCOUNT_LABEL(bintr)
299
300 #include <i386/i386/atpic_vector.s>
301
302 #ifdef DEV_APIC
303 .data
304 .p2align 4
305 .text
306 SUPERALIGN_TEXT
307
308 #include <i386/i386/apic_vector.s>
309 #endif
310
311 .data
312 .p2align 4
313 .text
314 SUPERALIGN_TEXT
315 #include <i386/i386/vm86bios.s>
316
317 .text
318 MCOUNT_LABEL(eintr)
319
320 /*
321 * void doreti(struct trapframe)
322 *
323 * Handle return from interrupts, traps and syscalls.
324 */
325 .text
326 SUPERALIGN_TEXT
327 .type doreti,@function
328 doreti:
329 FAKE_MCOUNT($bintr) /* init "from" bintr -> doreti */
330 doreti_next:
331 /*
332 * Check if ASTs can be handled now. ASTs cannot be safely
333 * processed when returning from an NMI.
334 */
335 cmpb $T_NMI,TF_TRAPNO(%esp)
336 #ifdef HWPMC_HOOKS
337 je doreti_nmi
338 #else
339 je doreti_exit
340 #endif
341 /*
342 * PSL_VM must be checked first since segment registers only
343 * have an RPL in non-VM86 mode.
344 */
345 testl $PSL_VM,TF_EFLAGS(%esp) /* are we in vm86 mode? */
346 jz doreti_notvm86
347 movl PCPU(CURPCB),%ecx
348 testl $PCB_VM86CALL,PCB_FLAGS(%ecx) /* are we in a vm86 call? */
349 jz doreti_ast /* can handle ASTS now if not */
350 jmp doreti_exit
351
352 doreti_notvm86:
353 testb $SEL_RPL_MASK,TF_CS(%esp) /* are we returning to user mode? */
354 jz doreti_exit /* can't handle ASTs now if not */
355
356 doreti_ast:
357 /*
358 * Check for ASTs atomically with returning. Disabling CPU
359 * interrupts provides sufficient locking even in the SMP case,
360 * since we will be informed of any new ASTs by an IPI.
361 */
362 cli
363 movl PCPU(CURTHREAD),%eax
364 testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%eax)
365 je doreti_exit
366 sti
367 pushl %esp /* pass a pointer to the trapframe */
368 call ast
369 add $4,%esp
370 jmp doreti_ast
371
372 /*
373 * doreti_exit: pop registers, iret.
374 *
375 * The segment register pop is a special case, since it may
376 * fault if (for example) a sigreturn specifies bad segment
377 * registers. The fault is handled in trap.c.
378 */
379 doreti_exit:
380 MEXITCOUNT
381
382 .globl doreti_popl_fs
383 doreti_popl_fs:
384 popl %fs
385 .globl doreti_popl_es
386 doreti_popl_es:
387 popl %es
388 .globl doreti_popl_ds
389 doreti_popl_ds:
390 popl %ds
391 popal
392 addl $8,%esp
393 .globl doreti_iret
394 doreti_iret:
395 iret
396
397 /*
398 * doreti_iret_fault and friends. Alternative return code for
399 * the case where we get a fault in the doreti_exit code
400 * above. trap() (i386/i386/trap.c) catches this specific
401 * case, sends the process a signal and continues in the
402 * corresponding place in the code below.
403 */
404 ALIGN_TEXT
405 .globl doreti_iret_fault
406 doreti_iret_fault:
407 subl $8,%esp
408 pushal
409 pushl %ds
410 .globl doreti_popl_ds_fault
411 doreti_popl_ds_fault:
412 pushl %es
413 .globl doreti_popl_es_fault
414 doreti_popl_es_fault:
415 pushl %fs
416 .globl doreti_popl_fs_fault
417 doreti_popl_fs_fault:
418 movl $0,TF_ERR(%esp) /* XXX should be the error code */
419 movl $T_PROTFLT,TF_TRAPNO(%esp)
420 jmp alltraps_with_regs_pushed
421 #ifdef HWPMC_HOOKS
422 doreti_nmi:
423 /*
424 * Since we are returning from an NMI, check if the current trap
425 * was from user mode and if so whether the current thread
426 * needs a user call chain capture.
427 */
428 testb $SEL_RPL_MASK,TF_CS(%esp)
429 jz doreti_exit
430 movl PCPU(CURTHREAD),%eax /* curthread present? */
431 orl %eax,%eax
432 jz doreti_exit
433 testl $TDP_CALLCHAIN,TD_PFLAGS(%eax) /* flagged for capture? */
434 jz doreti_exit
435 /*
436 * Take the processor out of NMI mode by executing a fake "iret".
437 */
438 pushfl
439 pushl %cs
440 pushl $outofnmi
441 iret
442 outofnmi:
443 /*
444 * Call the callchain capture hook after turning interrupts back on.
445 */
446 movl pmc_hook,%ecx
447 orl %ecx,%ecx
448 jz doreti_exit
449 pushl %esp /* frame pointer */
450 pushl $PMC_FN_USER_CALLCHAIN /* command */
451 movl PCPU(CURTHREAD),%eax
452 pushl %eax /* curthread */
453 sti
454 call *%ecx
455 addl $12,%esp
456 jmp doreti_ast
457 ENTRY(end_exceptions)
458 #endif
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