db_trace.c revision 290731 
1/*-
2 * Mach Operating System
3 * Copyright (c) 1991,1990 Carnegie Mellon University
4 * All Rights Reserved.
5 *
6 * Permission to use, copy, modify and distribute this software and its
7 * documentation is hereby granted, provided that both the copyright
8 * notice and this permission notice appear in all copies of the
9 * software, derivative works or modified versions, and any portions
10 * thereof, and that both notices appear in supporting documentation.
11 *
12 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
13 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
14 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
15 *
16 * Carnegie Mellon requests users of this software to return to
17 *
18 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
19 *  School of Computer Science
20 *  Carnegie Mellon University
21 *  Pittsburgh PA 15213-3890
22 *
23 * any improvements or extensions that they make and grant Carnegie the
24 * rights to redistribute these changes.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/10/sys/amd64/amd64/db_trace.c 290731 2015-11-12 23:49:47Z jhb $");
29
30#include "opt_compat.h"
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/kdb.h>
35#include <sys/proc.h>
36#include <sys/smp.h>
37#include <sys/stack.h>
38#include <sys/sysent.h>
39
40#include <machine/cpu.h>
41#include <machine/md_var.h>
42#include <machine/pcb.h>
43#include <machine/reg.h>
44#include <machine/stack.h>
45
46#include <vm/vm.h>
47#include <vm/vm_param.h>
48#include <vm/pmap.h>
49
50#include <ddb/ddb.h>
51#include <ddb/db_access.h>
52#include <ddb/db_sym.h>
53#include <ddb/db_variables.h>
54
55static db_varfcn_t db_frame;
56static db_varfcn_t db_frame_seg;
57
58CTASSERT(sizeof(struct dbreg) == sizeof(((struct pcpu *)NULL)->pc_dbreg));
59
60/*
61 * Machine register set.
62 */
63#define	DB_OFFSET(x)	(db_expr_t *)offsetof(struct trapframe, x)
64struct db_variable db_regs[] = {
65	{ "cs",		DB_OFFSET(tf_cs),	db_frame_seg },
66	{ "ds",		DB_OFFSET(tf_ds),	db_frame_seg },
67	{ "es",		DB_OFFSET(tf_es),	db_frame_seg },
68	{ "fs",		DB_OFFSET(tf_fs),	db_frame_seg },
69	{ "gs",		DB_OFFSET(tf_gs),	db_frame_seg },
70	{ "ss",		DB_OFFSET(tf_ss),	db_frame_seg },
71	{ "rax",	DB_OFFSET(tf_rax),	db_frame },
72	{ "rcx",        DB_OFFSET(tf_rcx),	db_frame },
73	{ "rdx",	DB_OFFSET(tf_rdx),	db_frame },
74	{ "rbx",	DB_OFFSET(tf_rbx),	db_frame },
75	{ "rsp",	DB_OFFSET(tf_rsp),	db_frame },
76	{ "rbp",	DB_OFFSET(tf_rbp),	db_frame },
77	{ "rsi",	DB_OFFSET(tf_rsi),	db_frame },
78	{ "rdi",	DB_OFFSET(tf_rdi),	db_frame },
79	{ "r8",		DB_OFFSET(tf_r8),	db_frame },
80	{ "r9",		DB_OFFSET(tf_r9),	db_frame },
81	{ "r10",	DB_OFFSET(tf_r10),	db_frame },
82	{ "r11",	DB_OFFSET(tf_r11),	db_frame },
83	{ "r12",	DB_OFFSET(tf_r12),	db_frame },
84	{ "r13",	DB_OFFSET(tf_r13),	db_frame },
85	{ "r14",	DB_OFFSET(tf_r14),	db_frame },
86	{ "r15",	DB_OFFSET(tf_r15),	db_frame },
87	{ "rip",	DB_OFFSET(tf_rip),	db_frame },
88	{ "rflags",	DB_OFFSET(tf_rflags),	db_frame },
89};
90struct db_variable *db_eregs = db_regs + nitems(db_regs);
91
92static int
93db_frame_seg(struct db_variable *vp, db_expr_t *valuep, int op)
94{
95	uint16_t *reg;
96
97	if (kdb_frame == NULL)
98		return (0);
99
100	reg = (uint16_t *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep);
101	if (op == DB_VAR_GET)
102		*valuep = *reg;
103	else
104		*reg = *valuep;
105	return (1);
106}
107
108static int
109db_frame(struct db_variable *vp, db_expr_t *valuep, int op)
110{
111	long *reg;
112
113	if (kdb_frame == NULL)
114		return (0);
115
116	reg = (long *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep);
117	if (op == DB_VAR_GET)
118		*valuep = *reg;
119	else
120		*reg = *valuep;
121	return (1);
122}
123
124#define NORMAL		0
125#define	TRAP		1
126#define	INTERRUPT	2
127#define	SYSCALL		3
128#define	TRAP_INTERRUPT	5
129
130static void db_nextframe(struct amd64_frame **, db_addr_t *, struct thread *);
131static void db_print_stack_entry(const char *, db_addr_t, void *);
132static void decode_syscall(int, struct thread *);
133
134static const char * watchtype_str(int type);
135int  amd64_set_watch(int watchnum, unsigned long watchaddr, int size,
136		    int access, struct dbreg *d);
137int  amd64_clr_watch(int watchnum, struct dbreg *d);
138
139static void
140db_print_stack_entry(const char *name, db_addr_t callpc, void *frame)
141{
142
143	db_printf("%s() at ", name != NULL ? name : "??");
144	db_printsym(callpc, DB_STGY_PROC);
145	if (frame != NULL)
146		db_printf("/frame 0x%lx", (register_t)frame);
147	db_printf("\n");
148}
149
150static void
151decode_syscall(int number, struct thread *td)
152{
153	struct proc *p;
154	c_db_sym_t sym;
155	db_expr_t diff;
156	sy_call_t *f;
157	const char *symname;
158
159	db_printf(" (%d", number);
160	p = (td != NULL) ? td->td_proc : NULL;
161	if (p != NULL && 0 <= number && number < p->p_sysent->sv_size) {
162		f = p->p_sysent->sv_table[number].sy_call;
163		sym = db_search_symbol((db_addr_t)f, DB_STGY_ANY, &diff);
164		if (sym != DB_SYM_NULL && diff == 0) {
165			db_symbol_values(sym, &symname, NULL);
166			db_printf(", %s, %s", p->p_sysent->sv_name, symname);
167		}
168	}
169	db_printf(")");
170}
171
172/*
173 * Figure out the next frame up in the call stack.
174 */
175static void
176db_nextframe(struct amd64_frame **fp, db_addr_t *ip, struct thread *td)
177{
178	struct trapframe *tf;
179	int frame_type;
180	long rip, rsp, rbp;
181	db_expr_t offset;
182	c_db_sym_t sym;
183	const char *name;
184
185	rip = db_get_value((long) &(*fp)->f_retaddr, 8, FALSE);
186	rbp = db_get_value((long) &(*fp)->f_frame, 8, FALSE);
187
188	/*
189	 * Figure out frame type.  We look at the address just before
190	 * the saved instruction pointer as the saved EIP is after the
191	 * call function, and if the function being called is marked as
192	 * dead (such as panic() at the end of dblfault_handler()), then
193	 * the instruction at the saved EIP will be part of a different
194	 * function (syscall() in this example) rather than the one that
195	 * actually made the call.
196	 */
197	frame_type = NORMAL;
198	sym = db_search_symbol(rip - 1, DB_STGY_ANY, &offset);
199	db_symbol_values(sym, &name, NULL);
200	if (name != NULL) {
201		if (strcmp(name, "calltrap") == 0 ||
202		    strcmp(name, "fork_trampoline") == 0 ||
203		    strcmp(name, "nmi_calltrap") == 0 ||
204		    strcmp(name, "Xdblfault") == 0)
205			frame_type = TRAP;
206		else if (strncmp(name, "Xatpic_intr", 11) == 0 ||
207		    strncmp(name, "Xapic_isr", 9) == 0 ||
208		    strcmp(name, "Xtimerint") == 0 ||
209		    strcmp(name, "Xipi_intr_bitmap_handler") == 0 ||
210		    strcmp(name, "Xcpustop") == 0 ||
211		    strcmp(name, "Xcpususpend") == 0 ||
212		    strcmp(name, "Xrendezvous") == 0)
213			frame_type = INTERRUPT;
214		else if (strcmp(name, "Xfast_syscall") == 0)
215			frame_type = SYSCALL;
216#ifdef COMPAT_FREEBSD32
217		else if (strcmp(name, "Xint0x80_syscall") == 0)
218			frame_type = SYSCALL;
219#endif
220		/* XXX: These are interrupts with trap frames. */
221		else if (strcmp(name, "Xtimerint") == 0 ||
222		    strcmp(name, "Xcpustop") == 0 ||
223		    strcmp(name, "Xcpususpend") == 0 ||
224		    strcmp(name, "Xrendezvous") == 0 ||
225		    strcmp(name, "Xipi_intr_bitmap_handler") == 0)
226			frame_type = TRAP_INTERRUPT;
227	}
228
229	/*
230	 * Normal frames need no special processing.
231	 */
232	if (frame_type == NORMAL) {
233		*ip = (db_addr_t) rip;
234		*fp = (struct amd64_frame *) rbp;
235		return;
236	}
237
238	db_print_stack_entry(name, rip, &(*fp)->f_frame);
239
240	/*
241	 * Point to base of trapframe which is just above the
242	 * current frame.
243	 */
244	tf = (struct trapframe *)((long)*fp + 16);
245
246	if (INKERNEL((long) tf)) {
247		rsp = tf->tf_rsp;
248		rip = tf->tf_rip;
249		rbp = tf->tf_rbp;
250		switch (frame_type) {
251		case TRAP:
252			db_printf("--- trap %#r", tf->tf_trapno);
253			break;
254		case SYSCALL:
255			db_printf("--- syscall");
256			decode_syscall(tf->tf_rax, td);
257			break;
258		case TRAP_INTERRUPT:
259		case INTERRUPT:
260			db_printf("--- interrupt");
261			break;
262		default:
263			panic("The moon has moved again.");
264		}
265		db_printf(", rip = %#lr, rsp = %#lr, rbp = %#lr ---\n", rip,
266		    rsp, rbp);
267	}
268
269	*ip = (db_addr_t) rip;
270	*fp = (struct amd64_frame *) rbp;
271}
272
273static int
274db_backtrace(struct thread *td, struct trapframe *tf, struct amd64_frame *frame,
275    db_addr_t pc, register_t sp, int count)
276{
277	struct amd64_frame *actframe;
278	const char *name;
279	db_expr_t offset;
280	c_db_sym_t sym;
281	boolean_t first;
282
283	if (count == -1)
284		count = 1024;
285
286	first = TRUE;
287	while (count-- && !db_pager_quit) {
288		sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
289		db_symbol_values(sym, &name, NULL);
290
291		/*
292		 * Attempt to determine a (possibly fake) frame that gives
293		 * the caller's pc.  It may differ from `frame' if the
294		 * current function never sets up a standard frame or hasn't
295		 * set one up yet or has just discarded one.  The last two
296		 * cases can be guessed fairly reliably for code generated
297		 * by gcc.  The first case is too much trouble to handle in
298		 * general because the amount of junk on the stack depends
299		 * on the pc (the special handling of "calltrap", etc. in
300		 * db_nextframe() works because the `next' pc is special).
301		 */
302		actframe = frame;
303		if (first) {
304			first = FALSE;
305			if (sym == C_DB_SYM_NULL && sp != 0) {
306				/*
307				 * If a symbol couldn't be found, we've probably
308				 * jumped to a bogus location, so try and use
309				 * the return address to find our caller.
310				 */
311				db_print_stack_entry(name, pc, NULL);
312				pc = db_get_value(sp, 8, FALSE);
313				if (db_search_symbol(pc, DB_STGY_PROC,
314				    &offset) == C_DB_SYM_NULL)
315					break;
316				continue;
317			} else if (tf != NULL) {
318				int instr;
319
320				instr = db_get_value(pc, 4, FALSE);
321				if ((instr & 0xffffffff) == 0xe5894855) {
322					/* pushq %rbp; movq %rsp, %rbp */
323					actframe = (void *)(tf->tf_rsp - 8);
324				} else if ((instr & 0xffffff) == 0xe58948) {
325					/* movq %rsp, %rbp */
326					actframe = (void *)tf->tf_rsp;
327					if (tf->tf_rbp == 0) {
328						/* Fake frame better. */
329						frame = actframe;
330					}
331				} else if ((instr & 0xff) == 0xc3) {
332					/* ret */
333					actframe = (void *)(tf->tf_rsp - 8);
334				} else if (offset == 0) {
335					/* Probably an assembler symbol. */
336					actframe = (void *)(tf->tf_rsp - 8);
337				}
338			} else if (strcmp(name, "fork_trampoline") == 0) {
339				/*
340				 * Don't try to walk back on a stack for a
341				 * process that hasn't actually been run yet.
342				 */
343				db_print_stack_entry(name, pc, actframe);
344				break;
345			}
346		}
347
348		db_print_stack_entry(name, pc, actframe);
349
350		if (actframe != frame) {
351			/* `frame' belongs to caller. */
352			pc = (db_addr_t)
353			    db_get_value((long)&actframe->f_retaddr, 8, FALSE);
354			continue;
355		}
356
357		db_nextframe(&frame, &pc, td);
358
359		if (INKERNEL((long)pc) && !INKERNEL((long)frame)) {
360			sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
361			db_symbol_values(sym, &name, NULL);
362			db_print_stack_entry(name, pc, frame);
363			break;
364		}
365		if (!INKERNEL((long) frame)) {
366			break;
367		}
368	}
369
370	return (0);
371}
372
373void
374db_trace_self(void)
375{
376	struct amd64_frame *frame;
377	db_addr_t callpc;
378	register_t rbp;
379
380	__asm __volatile("movq %%rbp,%0" : "=r" (rbp));
381	frame = (struct amd64_frame *)rbp;
382	callpc = (db_addr_t)db_get_value((long)&frame->f_retaddr, 8, FALSE);
383	frame = frame->f_frame;
384	db_backtrace(curthread, NULL, frame, callpc, 0, -1);
385}
386
387int
388db_trace_thread(struct thread *thr, int count)
389{
390	struct pcb *ctx;
391	struct trapframe *tf;
392
393	ctx = kdb_thr_ctx(thr);
394	tf = thr == kdb_thread ? kdb_frame : NULL;
395	return (db_backtrace(thr, tf, (struct amd64_frame *)ctx->pcb_rbp,
396	    ctx->pcb_rip, ctx->pcb_rsp, count));
397}
398
399int
400amd64_set_watch(watchnum, watchaddr, size, access, d)
401	int watchnum;
402	unsigned long watchaddr;
403	int size;
404	int access;
405	struct dbreg *d;
406{
407	int i, len;
408
409	if (watchnum == -1) {
410		for (i = 0; i < 4; i++)
411			if (!DBREG_DR7_ENABLED(d->dr[7], i))
412				break;
413		if (i < 4)
414			watchnum = i;
415		else
416			return (-1);
417	}
418
419	switch (access) {
420	case DBREG_DR7_EXEC:
421		size = 1; /* size must be 1 for an execution breakpoint */
422		/* fall through */
423	case DBREG_DR7_WRONLY:
424	case DBREG_DR7_RDWR:
425		break;
426	default:
427		return (-1);
428	}
429
430	/*
431	 * we can watch a 1, 2, 4, or 8 byte sized location
432	 */
433	switch (size) {
434	case 1:
435		len = DBREG_DR7_LEN_1;
436		break;
437	case 2:
438		len = DBREG_DR7_LEN_2;
439		break;
440	case 4:
441		len = DBREG_DR7_LEN_4;
442		break;
443	case 8:
444		len = DBREG_DR7_LEN_8;
445		break;
446	default:
447		return (-1);
448	}
449
450	/* clear the bits we are about to affect */
451	d->dr[7] &= ~DBREG_DR7_MASK(watchnum);
452
453	/* set drN register to the address, N=watchnum */
454	DBREG_DRX(d, watchnum) = watchaddr;
455
456	/* enable the watchpoint */
457	d->dr[7] |= DBREG_DR7_SET(watchnum, len, access,
458	    DBREG_DR7_GLOBAL_ENABLE);
459
460	return (watchnum);
461}
462
463
464int
465amd64_clr_watch(watchnum, d)
466	int watchnum;
467	struct dbreg *d;
468{
469
470	if (watchnum < 0 || watchnum >= 4)
471		return (-1);
472
473	d->dr[7] &= ~DBREG_DR7_MASK(watchnum);
474	DBREG_DRX(d, watchnum) = 0;
475
476	return (0);
477}
478
479
480int
481db_md_set_watchpoint(addr, size)
482	db_expr_t addr;
483	db_expr_t size;
484{
485	struct dbreg *d;
486	struct pcpu *pc;
487	int avail, c, cpu, i, wsize;
488
489	d = (struct dbreg *)PCPU_PTR(dbreg);
490	cpu = PCPU_GET(cpuid);
491	fill_dbregs(NULL, d);
492
493	avail = 0;
494	for (i = 0; i < 4; i++) {
495		if (!DBREG_DR7_ENABLED(d->dr[7], i))
496			avail++;
497	}
498
499	if (avail * 8 < size)
500		return (-1);
501
502	for (i = 0; i < 4 && size > 0; i++) {
503		if (!DBREG_DR7_ENABLED(d->dr[7], i)) {
504			if (size >= 8 || (avail == 1 && size > 4))
505				wsize = 8;
506			else if (size > 2)
507				wsize = 4;
508			else
509				wsize = size;
510			amd64_set_watch(i, addr, wsize, DBREG_DR7_WRONLY, d);
511			addr += wsize;
512			size -= wsize;
513			avail--;
514		}
515	}
516
517	set_dbregs(NULL, d);
518	CPU_FOREACH(c) {
519		if (c == cpu)
520			continue;
521		pc = pcpu_find(c);
522		memcpy(pc->pc_dbreg, d, sizeof(*d));
523		pc->pc_dbreg_cmd = PC_DBREG_CMD_LOAD;
524	}
525
526	return (0);
527}
528
529int
530db_md_clr_watchpoint(addr, size)
531	db_expr_t addr;
532	db_expr_t size;
533{
534	struct dbreg *d;
535	struct pcpu *pc;
536	int i, c, cpu;
537
538	d = (struct dbreg *)PCPU_PTR(dbreg);
539	cpu = PCPU_GET(cpuid);
540	fill_dbregs(NULL, d);
541
542	for (i = 0; i < 4; i++) {
543		if (DBREG_DR7_ENABLED(d->dr[7], i)) {
544			if (DBREG_DRX((d), i) >= addr &&
545			    DBREG_DRX((d), i) < addr + size)
546				amd64_clr_watch(i, d);
547
548		}
549	}
550
551	set_dbregs(NULL, d);
552	CPU_FOREACH(c) {
553		if (c == cpu)
554			continue;
555		pc = pcpu_find(c);
556		memcpy(pc->pc_dbreg, d, sizeof(*d));
557		pc->pc_dbreg_cmd = PC_DBREG_CMD_LOAD;
558	}
559
560	return (0);
561}
562
563
564static const char *
565watchtype_str(type)
566	int type;
567{
568	switch (type) {
569		case DBREG_DR7_EXEC   : return "execute";    break;
570		case DBREG_DR7_RDWR   : return "read/write"; break;
571		case DBREG_DR7_WRONLY : return "write";	     break;
572		default		      : return "invalid";    break;
573	}
574}
575
576
577void
578db_md_list_watchpoints()
579{
580	struct dbreg d;
581	int i, len, type;
582
583	fill_dbregs(NULL, &d);
584
585	db_printf("\nhardware watchpoints:\n");
586	db_printf("  watch    status        type  len             address\n");
587	db_printf("  -----  --------  ----------  ---  ------------------\n");
588	for (i = 0; i < 4; i++) {
589		if (DBREG_DR7_ENABLED(d.dr[7], i)) {
590			type = DBREG_DR7_ACCESS(d.dr[7], i);
591			len = DBREG_DR7_LEN(d.dr[7], i);
592			if (len == DBREG_DR7_LEN_8)
593				len = 8;
594			else
595				len++;
596			db_printf("  %-5d  %-8s  %10s  %3d  ",
597			    i, "enabled", watchtype_str(type), len);
598			db_printsym((db_addr_t)DBREG_DRX((&d), i), DB_STGY_ANY);
599			db_printf("\n");
600		} else {
601			db_printf("  %-5d  disabled\n", i);
602		}
603	}
604
605	db_printf("\ndebug register values:\n");
606	for (i = 0; i < 8; i++) {
607		db_printf("  dr%d 0x%016lx\n", i, DBREG_DRX((&d), i));
608	}
609	db_printf("\n");
610}
611
612void
613amd64_db_resume_dbreg(void)
614{
615	struct dbreg *d;
616
617	switch (PCPU_GET(dbreg_cmd)) {
618	case PC_DBREG_CMD_LOAD:
619		d = (struct dbreg *)PCPU_PTR(dbreg);
620		set_dbregs(NULL, d);
621		PCPU_SET(dbreg_cmd, PC_DBREG_CMD_NONE);
622		break;
623	}
624}
625