xref: /illumos-gate/usr/src/uts/i86xpv/os/xpv_panic.c (revision 86ef0a63e1cfa5dc98606efef379365acca98063)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2012 Gary Mills
23  * Copyright 2016 PALO, Richard.
24  *
25  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
26  *
27  * Copyright 2018 Joyent, Inc.
28  */
29 
30 #include <sys/types.h>
31 #include <sys/clock.h>
32 #include <sys/psm.h>
33 #include <sys/archsystm.h>
34 #include <sys/machsystm.h>
35 #include <sys/compress.h>
36 #include <sys/modctl.h>
37 #include <sys/trap.h>
38 #include <sys/panic.h>
39 #include <sys/regset.h>
40 #include <sys/frame.h>
41 #include <sys/kobj.h>
42 #include <sys/apic.h>
43 #include <sys/apic_timer.h>
44 #include <sys/dumphdr.h>
45 #include <sys/mem.h>
46 #include <sys/x86_archext.h>
47 #include <sys/xpv_panic.h>
48 #include <sys/boot_console.h>
49 #include <sys/bootsvcs.h>
50 #include <sys/consdev.h>
51 #include <vm/hat_pte.h>
52 #include <vm/hat_i86.h>
53 
54 /* XXX: need to add a PAE version too, if we ever support both PAE and non */
55 #define	XPV_FILENAME	"/boot/amd64/xen-syms"
56 #define	XPV_MODNAME	"xpv"
57 
58 int xpv_panicking = 0;
59 
60 struct module *xpv_module;
61 struct modctl *xpv_modctl;
62 
63 #define	ALIGN(x, a)	((a) == 0 ? (uintptr_t)(x) : \
64 	(((uintptr_t)(x) + (uintptr_t)(a) - 1l) & ~((uintptr_t)(a) - 1l)))
65 
66 /* Pointer to the xpv_panic_info structure handed to us by Xen.  */
67 static struct panic_info *xpv_panic_info = NULL;
68 
69 /* Timer support */
70 #define	NSEC_SHIFT 5
71 #define	T_XPV_TIMER	0xd1
72 #define	XPV_TIMER_INTERVAL	1000	/* 1000 microseconds */
73 static uint32_t *xpv_apicadr = NULL;
74 static uint_t	nsec_scale;
75 
76 /* IDT support */
77 #pragma	align	16(xpv_panic_idt)
78 static gate_desc_t	xpv_panic_idt[NIDT];	/* interrupt descriptor table */
79 
80 /* Xen pagetables mapped into our HAT's ptable windows */
81 static pfn_t ptable_pfn[MAX_NUM_LEVEL];
82 
83 /* Number of MMU_PAGESIZE pages we're adding to the Solaris dump */
84 static int xpv_dump_pages;
85 
86 /*
87  * There are up to two large swathes of RAM that we don't want to include
88  * in the dump: those that comprise the Xen version of segkpm.  On 32-bit
89  * systems there is no such region of memory.  On 64-bit systems, there
90  * should be just a single contiguous region that corresponds to all of
91  * physical memory.  The tricky bit is that Xen's heap sometimes lives in
92  * the middle of their segkpm, and is mapped using only kpm-like addresses.
93  * In that case, we need to skip the swathes before and after Xen's heap.
94  */
95 uintptr_t kpm1_low = 0;
96 uintptr_t kpm1_high = 0;
97 uintptr_t kpm2_low = 0;
98 uintptr_t kpm2_high = 0;
99 
100 /*
101  * Some commonly used values that we don't want to recompute over and over.
102  */
103 static int xpv_panic_nptes[MAX_NUM_LEVEL];
104 static ulong_t xpv_panic_cr3;
105 static uintptr_t xpv_end;
106 
107 static void xpv_panic_console_print(const char *fmt, ...);
108 static void (*xpv_panic_printf)(const char *, ...) = xpv_panic_console_print;
109 
110 #define	CONSOLE_BUF_SIZE	256
111 static char console_buffer[CONSOLE_BUF_SIZE];
112 static boolean_t use_polledio;
113 
114 /*
115  * Pointers to machine check panic info (if any).
116  */
117 xpv_mca_panic_data_t *xpv_mca_panic_data = NULL;
118 
119 static void
xpv_panic_putc(int m)120 xpv_panic_putc(int m)
121 {
122 	struct cons_polledio *c = cons_polledio;
123 
124 	/* This really shouldn't happen */
125 	if (boot_console_type(NULL) == CONS_HYPERVISOR)
126 		return;
127 
128 	if (use_polledio == B_TRUE)
129 		c->cons_polledio_putchar(c->cons_polledio_argument, m);
130 	else
131 		bcons_putchar(m);
132 }
133 
134 static void
xpv_panic_puts(char * msg)135 xpv_panic_puts(char *msg)
136 {
137 	char *m;
138 
139 	dump_timeleft = dump_timeout;
140 	for (m = msg; *m; m++)
141 		xpv_panic_putc((int)*m);
142 }
143 
144 static void
xpv_panic_console_print(const char * fmt,...)145 xpv_panic_console_print(const char *fmt, ...)
146 {
147 	va_list ap;
148 
149 	va_start(ap, fmt);
150 	(void) vsnprintf(console_buffer, sizeof (console_buffer), fmt, ap);
151 	va_end(ap);
152 
153 	xpv_panic_puts(console_buffer);
154 }
155 
156 static void
xpv_panic_map(int level,pfn_t pfn)157 xpv_panic_map(int level, pfn_t pfn)
158 {
159 	x86pte_t pte, *pteptr;
160 
161 	/*
162 	 * The provided pfn represents a level 'level' page table.  Map it
163 	 * into the 'level' slot in the list of page table windows.
164 	 */
165 	pteptr = (x86pte_t *)PWIN_PTE_VA(level);
166 	pte = pfn_to_pa(pfn) | PT_VALID;
167 
168 	XPV_ALLOW_PAGETABLE_UPDATES();
169 	if (mmu.pae_hat)
170 		*pteptr = pte;
171 	else
172 		*(x86pte32_t *)pteptr = pte;
173 	XPV_DISALLOW_PAGETABLE_UPDATES();
174 
175 	mmu_flush_tlb_page((uintptr_t)PWIN_VA(level));
176 }
177 
178 /*
179  * Walk the page tables to find the pfn mapped by the given va.
180  */
181 static pfn_t
xpv_va_walk(uintptr_t * vaddr)182 xpv_va_walk(uintptr_t *vaddr)
183 {
184 	int l, idx;
185 	pfn_t pfn;
186 	x86pte_t pte;
187 	x86pte_t *ptep;
188 	uintptr_t va = *vaddr;
189 	uintptr_t scan_va;
190 	caddr_t ptable_window;
191 	static pfn_t toplevel_pfn;
192 	static uintptr_t lastva;
193 
194 	pte = 0;
195 	/*
196 	 * If we do anything other than a simple scan through memory, don't
197 	 * trust the mapped page tables.
198 	 */
199 	if (va != lastva + MMU_PAGESIZE)
200 		for (l = mmu.max_level; l >= 0; l--)
201 			ptable_pfn[l] = PFN_INVALID;
202 
203 	toplevel_pfn = mmu_btop(xpv_panic_cr3);
204 
205 	while (va < xpv_end && va >= *vaddr) {
206 		/* Find the lowest table with any entry for va */
207 		pfn = toplevel_pfn;
208 		for (l = mmu.max_level; l >= 0; l--) {
209 			if (ptable_pfn[l] != pfn) {
210 				xpv_panic_map(l, pfn);
211 				ptable_pfn[l] = pfn;
212 			}
213 
214 			/*
215 			 * Search this pagetable for any mapping to an
216 			 * address >= va.
217 			 */
218 			ptable_window = PWIN_VA(l);
219 			if (l == mmu.max_level && mmu.pae_hat)
220 				ptable_window +=
221 				    (xpv_panic_cr3 & MMU_PAGEOFFSET);
222 
223 			idx = (va >> LEVEL_SHIFT(l)) & (xpv_panic_nptes[l] - 1);
224 			scan_va = va;
225 			while (idx < xpv_panic_nptes[l] && scan_va < xpv_end &&
226 			    scan_va >= *vaddr) {
227 				ptep = (x86pte_t *)(ptable_window +
228 				    (idx << mmu.pte_size_shift));
229 				pte = GET_PTE(ptep);
230 				if (pte & PTE_VALID)
231 					break;
232 				idx++;
233 				scan_va += mmu.level_size[l];
234 			}
235 
236 			/*
237 			 * If there are no valid mappings in this table, we
238 			 * can skip to the end of the VA range it covers.
239 			 */
240 			if (idx == xpv_panic_nptes[l]) {
241 				va = NEXT_ENTRY_VA(va, l + 1);
242 				break;
243 			}
244 
245 			va = scan_va;
246 			/*
247 			 * See if we've hit the end of the range.
248 			 */
249 			if (va >= xpv_end || va < *vaddr)
250 				break;
251 
252 			/*
253 			 * If this mapping is for a pagetable, we drop down
254 			 * to the next level in the hierarchy and look for
255 			 * a mapping in it.
256 			 */
257 			pfn = PTE2MFN(pte, l);
258 			if (!PTE_ISPAGE(pte, l))
259 				continue;
260 
261 			/*
262 			 * The APIC page is magic.  Nothing to see here;
263 			 * move along.
264 			 */
265 			if (((uintptr_t)xpv_apicadr & MMU_PAGEMASK) ==
266 			    (va & MMU_PAGEMASK)) {
267 				va += MMU_PAGESIZE;
268 				break;
269 			}
270 
271 			/*
272 			 * See if the address is within one of the two
273 			 * kpm-like regions we want to skip.
274 			 */
275 			if (va >= kpm1_low && va < kpm1_high) {
276 				va = kpm1_high;
277 				break;
278 			}
279 			if (va >= kpm2_low && va < kpm2_high) {
280 				va = kpm2_high;
281 				break;
282 			}
283 
284 			/*
285 			 * The Xen panic code only handles small pages.  If
286 			 * this mapping is for a large page, we need to
287 			 * identify the consituent page that covers the
288 			 * specific VA we were looking for.
289 			 */
290 			if (l > 0) {
291 				if (l > 1)
292 					panic("Xen panic can't cope with "
293 					    "giant pages.");
294 				idx = (va >> LEVEL_SHIFT(0)) &
295 				    (xpv_panic_nptes[0] - 1);
296 				pfn += idx;
297 			}
298 
299 			*vaddr = va;
300 			lastva = va;
301 			return (pfn | PFN_IS_FOREIGN_MFN);
302 		}
303 	}
304 	return (PFN_INVALID);
305 }
306 
307 /*
308  * Walk through the Xen VA space, finding pages that are mapped in.
309  *
310  * These pages all have MFNs rather than PFNs, meaning they may be outside
311  * the physical address space the kernel knows about, or they may collide
312  * with PFNs the kernel is using.
313  *
314  * The obvious trick of just adding the PFN_IS_FOREIGN_MFN bit to the MFNs
315  * to avoid collisions doesn't work.  The pages need to be written to disk
316  * in PFN-order or savecore gets confused.  We can't allocate memory to
317  * contruct a sorted pfn->VA reverse mapping, so we have to write the pages
318  * to disk in VA order.
319  *
320  * To square this circle, we simply make up PFNs for each of Xen's pages.
321  * We assign each mapped page a fake PFN in ascending order.  These fake
322  * PFNs each have the FOREIGN bit set, ensuring that they fall outside the
323  * range of Solaris PFNs written by the kernel.
324  */
325 int
dump_xpv_addr()326 dump_xpv_addr()
327 {
328 	uintptr_t va;
329 	mem_vtop_t mem_vtop;
330 
331 	xpv_dump_pages = 0;
332 	va = xen_virt_start;
333 
334 	while (xpv_va_walk(&va) != PFN_INVALID) {
335 		mem_vtop.m_as = &kas;
336 		mem_vtop.m_va = (void *)va;
337 		mem_vtop.m_pfn = (pfn_t)xpv_dump_pages | PFN_IS_FOREIGN_MFN;
338 
339 		dumpvp_write(&mem_vtop, sizeof (mem_vtop_t));
340 		xpv_dump_pages++;
341 
342 		va += MMU_PAGESIZE;
343 	}
344 
345 	/*
346 	 * Add the shared_info page.  This page actually ends up in the
347 	 * dump twice: once for the Xen va and once for the Solaris va.
348 	 * This isn't ideal, but we don't know the address Xen is using for
349 	 * the page, so we can't share it.
350 	 */
351 	mem_vtop.m_as = &kas;
352 	mem_vtop.m_va = HYPERVISOR_shared_info;
353 	mem_vtop.m_pfn = (pfn_t)xpv_dump_pages | PFN_IS_FOREIGN_MFN;
354 	dumpvp_write(&mem_vtop, sizeof (mem_vtop_t));
355 	xpv_dump_pages++;
356 
357 	return (xpv_dump_pages);
358 }
359 
360 void
dump_xpv_pfn()361 dump_xpv_pfn()
362 {
363 	pfn_t pfn;
364 	int cnt;
365 
366 	for (cnt = 0; cnt < xpv_dump_pages; cnt++) {
367 		pfn = (pfn_t)cnt | PFN_IS_FOREIGN_MFN;
368 		dumpvp_write(&pfn, sizeof (pfn));
369 	}
370 }
371 
372 int
dump_xpv_data(void * dump_cbuf)373 dump_xpv_data(void *dump_cbuf)
374 {
375 	uintptr_t va;
376 	uint32_t csize;
377 	int cnt = 0;
378 
379 	/*
380 	 * XXX: we should probably run this data through a UE check.  The
381 	 * catch is that the UE code relies on on_trap() and getpfnum()
382 	 * working.
383 	 */
384 	va = xen_virt_start;
385 
386 	while (xpv_va_walk(&va) != PFN_INVALID) {
387 		csize = (uint32_t)compress((void *)va, dump_cbuf, PAGESIZE);
388 		dumpvp_write(&csize, sizeof (uint32_t));
389 		dumpvp_write(dump_cbuf, csize);
390 		if (dump_ioerr) {
391 			dumphdr->dump_flags &= ~DF_COMPLETE;
392 			return (cnt);
393 		}
394 		cnt++;
395 		va += MMU_PAGESIZE;
396 	}
397 
398 	/*
399 	 * Finally, dump the shared_info page
400 	 */
401 	csize = (uint32_t)compress((void *)HYPERVISOR_shared_info, dump_cbuf,
402 	    PAGESIZE);
403 	dumpvp_write(&csize, sizeof (uint32_t));
404 	dumpvp_write(dump_cbuf, csize);
405 	if (dump_ioerr)
406 		dumphdr->dump_flags &= ~DF_COMPLETE;
407 	cnt++;
408 
409 	return (cnt);
410 }
411 
412 static void *
showstack(void * fpreg,int xpv_only)413 showstack(void *fpreg, int xpv_only)
414 {
415 	struct frame *fpp;
416 	ulong_t off;
417 	char *sym;
418 	uintptr_t pc, fp, lastfp;
419 	uintptr_t minaddr = min(KERNELBASE, xen_virt_start);
420 
421 	fp = (uintptr_t)fpreg;
422 	if (fp < minaddr) {
423 		xpv_panic_printf("Bad frame ptr: 0x%p\n", fpreg);
424 		return (fpreg);
425 	}
426 
427 	do {
428 		fpp = (struct frame *)fp;
429 		pc = fpp->fr_savpc;
430 
431 		if ((xpv_only != 0) &&
432 		    (fp > xpv_end || fp < xen_virt_start))
433 			break;
434 		if ((sym = kobj_getsymname(pc, &off)) != NULL)
435 			xpv_panic_printf("%08lx %s:%s+%lx\n", fp,
436 			    mod_containing_pc((caddr_t)pc), sym, off);
437 		else if ((pc >= xen_virt_start) && (pc <= xpv_end))
438 			xpv_panic_printf("%08lx 0x%lx (in Xen)\n", fp, pc);
439 		else
440 			xpv_panic_printf("%08lx %lx\n", fp, pc);
441 
442 		lastfp = fp;
443 		fp = fpp->fr_savfp;
444 
445 		/*
446 		 * Xen marks an exception frame by inverting the frame
447 		 * pointer.
448 		 */
449 		if (fp < lastfp) {
450 			if ((~fp > minaddr) && ((~fp) ^ lastfp) < 0xfff)
451 				fp = ~fp;
452 		}
453 	} while (fp > lastfp);
454 	return ((void *)fp);
455 }
456 
457 void *
xpv_traceback(void * fpreg)458 xpv_traceback(void *fpreg)
459 {
460 	return (showstack(fpreg, 1));
461 }
462 
463 static void
xpv_panic_hypercall(ulong_t call)464 xpv_panic_hypercall(ulong_t call)
465 {
466 	panic("Illegally issued hypercall %d during panic!\n", (int)call);
467 }
468 
469 void
xpv_die(struct regs * rp)470 xpv_die(struct regs *rp)
471 {
472 	struct panic_trap_info ti;
473 	struct cregs creg;
474 
475 	ti.trap_regs = rp;
476 	ti.trap_type = rp->r_trapno;
477 
478 	curthread->t_panic_trap = &ti;
479 	if (ti.trap_type == T_PGFLT) {
480 		getcregs(&creg);
481 		ti.trap_addr = (caddr_t)creg.cr_cr2;
482 		panic("Fatal pagefault at 0x%lx.  fault addr=0x%p  rp=0x%p",
483 		    rp->r_pc, (void *)ti.trap_addr, (void *)rp);
484 	} else {
485 		ti.trap_addr = (caddr_t)rp->r_pc;
486 		panic("Fatal trap %ld at 0x%lx.  rp=0x%p", rp->r_trapno,
487 		    rp->r_pc, (void *)rp);
488 	}
489 }
490 
491 /*
492  * Build IDT to handle a Xen panic
493  */
494 static void
switch_to_xpv_panic_idt()495 switch_to_xpv_panic_idt()
496 {
497 	int i;
498 	desctbr_t idtr;
499 	gate_desc_t *idt = xpv_panic_idt;
500 	selector_t cs = get_cs_register();
501 
502 	for (i = 0; i < 32; i++)
503 		set_gatesegd(&idt[i], &xpv_invaltrap, cs, SDT_SYSIGT, TRP_XPL,
504 		    0);
505 
506 	set_gatesegd(&idt[T_ZERODIV], &xpv_div0trap, cs, SDT_SYSIGT, TRP_XPL,
507 	    0);
508 	set_gatesegd(&idt[T_SGLSTP], &xpv_dbgtrap, cs, SDT_SYSIGT, TRP_XPL, 0);
509 	set_gatesegd(&idt[T_NMIFLT], &xpv_nmiint, cs, SDT_SYSIGT, TRP_XPL, 0);
510 	set_gatesegd(&idt[T_BOUNDFLT], &xpv_boundstrap, cs, SDT_SYSIGT,
511 	    TRP_XPL, 0);
512 	set_gatesegd(&idt[T_ILLINST], &xpv_invoptrap, cs, SDT_SYSIGT, TRP_XPL,
513 	    0);
514 	set_gatesegd(&idt[T_NOEXTFLT], &xpv_ndptrap, cs, SDT_SYSIGT, TRP_XPL,
515 	    0);
516 	set_gatesegd(&idt[T_TSSFLT], &xpv_invtsstrap, cs, SDT_SYSIGT, TRP_XPL,
517 	    0);
518 	set_gatesegd(&idt[T_SEGFLT], &xpv_segnptrap, cs, SDT_SYSIGT, TRP_XPL,
519 	    0);
520 	set_gatesegd(&idt[T_STKFLT], &xpv_stktrap, cs, SDT_SYSIGT, TRP_XPL, 0);
521 	set_gatesegd(&idt[T_GPFLT], &xpv_gptrap, cs, SDT_SYSIGT, TRP_XPL, 0);
522 	set_gatesegd(&idt[T_PGFLT], &xpv_pftrap, cs, SDT_SYSIGT, TRP_XPL, 0);
523 	set_gatesegd(&idt[T_EXTERRFLT], &xpv_ndperr, cs, SDT_SYSIGT, TRP_XPL,
524 	    0);
525 	set_gatesegd(&idt[T_ALIGNMENT], &xpv_achktrap, cs, SDT_SYSIGT, TRP_XPL,
526 	    0);
527 	set_gatesegd(&idt[T_MCE], &xpv_mcetrap, cs, SDT_SYSIGT, TRP_XPL, 0);
528 	set_gatesegd(&idt[T_SIMDFPE], &xpv_xmtrap, cs, SDT_SYSIGT, TRP_XPL, 0);
529 
530 	/*
531 	 * We have no double fault handler.  Any single fault represents a
532 	 * catastrophic failure for us, so there is no attempt to handle
533 	 * them cleanly: we just print a message and reboot.  If we
534 	 * encounter a second fault while doing that, there is nothing
535 	 * else we can do.
536 	 */
537 
538 	/*
539 	 * Be prepared to absorb any stray device interrupts received
540 	 * while writing the core to disk.
541 	 */
542 	for (i = 33; i < NIDT; i++)
543 		set_gatesegd(&idt[i], &xpv_surprise_intr, cs, SDT_SYSIGT,
544 		    TRP_XPL, 0);
545 
546 	/* The one interrupt we expect to get is from the APIC timer.  */
547 	set_gatesegd(&idt[T_XPV_TIMER], &xpv_timer_trap, cs, SDT_SYSIGT,
548 	    TRP_XPL, 0);
549 
550 	idtr.dtr_base = (uintptr_t)xpv_panic_idt;
551 	idtr.dtr_limit = sizeof (xpv_panic_idt) - 1;
552 	wr_idtr(&idtr);
553 
554 	/* Catch any hypercalls. */
555 	wrmsr(MSR_AMD_LSTAR, (uintptr_t)xpv_panic_hypercall);
556 	wrmsr(MSR_AMD_CSTAR, (uintptr_t)xpv_panic_hypercall);
557 }
558 
559 static void
xpv_apic_clkinit()560 xpv_apic_clkinit()
561 {
562 	uint_t		apic_ticks = 0;
563 
564 	/*
565 	 * Measure how many APIC ticks there are within a fixed time
566 	 * period.  We're going to be fairly coarse here.  This timer is
567 	 * just being used to detect a stalled panic, so as long as we have
568 	 * the right order of magnitude, everything should be fine.
569 	 */
570 	xpv_apicadr[APIC_SPUR_INT_REG] = AV_UNIT_ENABLE | APIC_SPUR_INTR;
571 	xpv_apicadr[APIC_LOCAL_TIMER] = AV_MASK;
572 	xpv_apicadr[APIC_INT_VECT0] = AV_MASK;	/* local intr reg 0 */
573 
574 	xpv_apicadr[APIC_DIVIDE_REG] = 0;
575 	xpv_apicadr[APIC_INIT_COUNT] = APIC_MAXVAL;
576 	drv_usecwait(XPV_TIMER_INTERVAL);
577 	apic_ticks = APIC_MAXVAL - xpv_apicadr[APIC_CURR_COUNT];
578 
579 	/*
580 	 * apic_ticks now represents roughly how many apic ticks comprise
581 	 * one timeout interval.  Program the timer to send us an interrupt
582 	 * every time that interval expires.
583 	 */
584 	xpv_apicadr[APIC_LOCAL_TIMER] = T_XPV_TIMER | AV_PERIODIC;
585 	xpv_apicadr[APIC_INIT_COUNT] = apic_ticks;
586 	xpv_apicadr[APIC_EOI_REG] = 0;
587 }
588 
589 void
xpv_timer_tick(void)590 xpv_timer_tick(void)
591 {
592 	static int ticks = 0;
593 
594 	if (ticks++ >= MICROSEC / XPV_TIMER_INTERVAL) {
595 		ticks = 0;
596 		if (dump_timeleft && (--dump_timeleft == 0))
597 			panic("Xen panic timeout\n");
598 	}
599 	xpv_apicadr[APIC_EOI_REG] = 0;
600 }
601 
602 void
xpv_interrupt(void)603 xpv_interrupt(void)
604 {
605 #ifdef	DEBUG
606 	static int cnt = 0;
607 
608 	if (cnt++ < 10)
609 		xpv_panic_printf("Unexpected interrupt received.\n");
610 	if ((cnt < 1000) && ((cnt % 100) == 0))
611 		xpv_panic_printf("%d unexpected interrupts received.\n", cnt);
612 #endif
613 
614 	xpv_apicadr[APIC_EOI_REG] = 0;
615 }
616 
617 /*
618  * Managing time in panic context is trivial.  We only have a single CPU,
619  * we never get rescheduled, we never get suspended.  We just need to
620  * convert clock ticks into nanoseconds.
621  */
622 static hrtime_t
xpv_panic_gethrtime(void)623 xpv_panic_gethrtime(void)
624 {
625 	hrtime_t tsc, hrt;
626 	unsigned int *l = (unsigned int *)&(tsc);
627 
628 	tsc = __rdtsc_insn();
629 	hrt = (mul32(l[1], nsec_scale) << NSEC_SHIFT) +
630 	    (mul32(l[0], nsec_scale) >> (32 - NSEC_SHIFT));
631 
632 	return (hrt);
633 }
634 
635 static void
xpv_panic_time_init()636 xpv_panic_time_init()
637 {
638 	nsec_scale =
639 	    CPU->cpu_m.mcpu_vcpu_info->time.tsc_to_system_mul >> NSEC_SHIFT;
640 
641 	gethrtimef = xpv_panic_gethrtime;
642 }
643 
644 static void
xpv_panicsys(struct regs * rp,char * fmt,...)645 xpv_panicsys(struct regs *rp, char *fmt, ...)
646 {
647 	extern void panicsys(const char *, va_list, struct regs *, int);
648 	va_list alist;
649 
650 	va_start(alist, fmt);
651 	panicsys(fmt, alist, rp, 1);
652 	va_end(alist);
653 }
654 
655 void
xpv_do_panic(void * arg)656 xpv_do_panic(void *arg)
657 {
658 	struct panic_info *pip = (struct panic_info *)arg;
659 	int l;
660 	struct cregs creg;
661 	extern uintptr_t postbootkernelbase;
662 
663 	if (xpv_panicking++ > 0)
664 		panic("multiple calls to xpv_do_panic()");
665 
666 	/*
667 	 * Indicate to the underlying panic framework that a panic has been
668 	 * initiated.  This is ordinarily done as part of vpanic().  Since
669 	 * we already have all the register state saved by the hypervisor,
670 	 * we skip that and jump straight into the panic processing code.
671 	 *
672 	 * XXX If another thread grabs and wins the panic_quiesce trigger
673 	 * then we'll have two threads in panicsys believing they are in
674 	 * charge of the panic attempt!
675 	 */
676 	(void) panic_trigger(&panic_quiesce);
677 
678 	/*
679 	 * bzero() and bcopy() get unhappy when asked to operate on
680 	 * addresses outside of the kernel.  At this point Xen is really a
681 	 * part of the kernel, so we update the routines' notion of where
682 	 * the kernel starts.
683 	 */
684 	postbootkernelbase = xen_virt_start;
685 
686 #if defined(HYPERVISOR_VIRT_END)
687 	xpv_end = HYPERVISOR_VIRT_END;
688 #else
689 	xpv_end = (uintptr_t)UINTPTR_MAX - sizeof (uintptr_t);
690 #endif
691 
692 	/*
693 	 * If we were redirecting console output to the hypervisor, we have
694 	 * to stop.
695 	 */
696 	use_polledio = B_FALSE;
697 	if (boot_console_type(NULL) == CONS_HYPERVISOR) {
698 		bcons_device_change(CONS_HYPERVISOR);
699 	} else if (cons_polledio != NULL &&
700 	    cons_polledio->cons_polledio_putchar != NULL)  {
701 		if (cons_polledio->cons_polledio_enter != NULL)
702 			cons_polledio->cons_polledio_enter(
703 			    cons_polledio->cons_polledio_argument);
704 		use_polledio = 1;
705 	}
706 
707 	/* Make sure we handle all console output from here on. */
708 	sysp->bsvc_putchar = xpv_panic_putc;
709 
710 	/*
711 	 * If we find an unsupported panic_info structure, there's not much
712 	 * we can do other than complain, plow on, and hope for the best.
713 	 */
714 	if (pip->pi_version != PANIC_INFO_VERSION)
715 		xpv_panic_printf("Warning: Xen is using an unsupported "
716 		    "version of the panic_info structure.\n");
717 
718 	xpv_panic_info = pip;
719 
720 	kpm1_low = (uintptr_t)xpv_panic_info->pi_ram_start;
721 	if (xpv_panic_info->pi_xen_start == NULL) {
722 		kpm1_high = (uintptr_t)xpv_panic_info->pi_ram_end;
723 	} else {
724 		kpm1_high = (uintptr_t)xpv_panic_info->pi_xen_start;
725 		kpm2_low = (uintptr_t)xpv_panic_info->pi_xen_end;
726 		kpm2_high = (uintptr_t)xpv_panic_info->pi_ram_end;
727 	}
728 
729 	/*
730 	 * Make sure we are running on the Solaris %gs.  The Xen panic code
731 	 * should already have set up the GDT properly.
732 	 */
733 	xpv_panic_resetgs();
734 	wrmsr(MSR_AMD_GSBASE, (uint64_t)&cpus[0]);
735 
736 	xpv_panic_time_init();
737 
738 	/*
739 	 * Switch to our own IDT, avoiding any accidental returns to Xen
740 	 * world.
741 	 */
742 	switch_to_xpv_panic_idt();
743 
744 	/*
745 	 * Initialize the APIC timer, which is used to detect a hung dump
746 	 * attempt.
747 	 */
748 	xpv_apicadr = pip->pi_apic;
749 	xpv_apic_clkinit();
750 
751 	/*
752 	 * Set up a few values that we'll need repeatedly.
753 	 */
754 	getcregs(&creg);
755 	xpv_panic_cr3 = creg.cr_cr3;
756 	for (l = mmu.max_level; l >= 0; l--)
757 		xpv_panic_nptes[l] = mmu.ptes_per_table;
758 
759 	/* Add the fake Xen module to the module list */
760 	if (xpv_module != NULL) {
761 		extern int last_module_id;
762 
763 		xpv_modctl->mod_id = last_module_id++;
764 		xpv_modctl->mod_next = &modules;
765 		xpv_modctl->mod_prev = modules.mod_prev;
766 		modules.mod_prev->mod_next = xpv_modctl;
767 		modules.mod_prev = xpv_modctl;
768 	}
769 
770 	if (pip->pi_mca.mpd_magic == MCA_PANICDATA_MAGIC)
771 		xpv_mca_panic_data = &pip->pi_mca;
772 
773 	xpv_panic_printf = printf;
774 	xpv_panicsys((struct regs *)pip->pi_regs, pip->pi_panicstr);
775 	xpv_panic_printf("Failed to reboot following panic.\n");
776 	for (;;)
777 		;
778 }
779 
780 /*
781  * Set up the necessary data structures to pretend that the Xen hypervisor
782  * is a loadable module, allowing mdb to find the Xen symbols in a crash
783  * dump.  Since these symbols all map to VA space Solaris doesn't normally
784  * have access to, we don't link these structures into the kernel's lists
785  * until/unless we hit a Xen panic.
786  *
787  * The observant reader will note a striking amount of overlap between this
788  * code and that found in krtld.  While it would be handy if we could just
789  * ask krtld to do this work for us, it's not that simple.  Among the
790  * complications: we're not actually loading the text here (grub did it at
791  * boot), the .text section is writable, there are no relocations to do,
792  * none of the module text/data is in readable memory, etc.  Training krtld
793  * to deal with this weird module is as complicated, and more risky, than
794  * reimplementing the necessary subset of it here.
795  */
796 static void
init_xen_module()797 init_xen_module()
798 {
799 	struct _buf *file = NULL;
800 	struct module *mp;
801 	struct modctl *mcp;
802 	int i, shn;
803 	Shdr *shp, *ctf_shp;
804 	char *names = NULL;
805 	size_t n, namesize, text_align, data_align;
806 	const char machine = EM_AMD64;
807 
808 	/* Allocate and init the module structure */
809 	mp = kmem_zalloc(sizeof (*mp), KM_SLEEP);
810 	mp->filename = kobj_zalloc(strlen(XPV_FILENAME) + 1, KM_SLEEP);
811 	(void) strcpy(mp->filename, XPV_FILENAME);
812 
813 	/* Allocate and init the modctl structure */
814 	mcp = kmem_zalloc(sizeof (*mcp), KM_SLEEP);
815 	mcp->mod_modname = kobj_zalloc(strlen(XPV_MODNAME) + 1, KM_SLEEP);
816 	(void) strcpy(mcp->mod_modname, XPV_MODNAME);
817 	mcp->mod_filename = kobj_zalloc(strlen(XPV_FILENAME) + 1, KM_SLEEP);
818 	(void) strcpy(mcp->mod_filename, XPV_FILENAME);
819 	mcp->mod_inprogress_thread = (kthread_id_t)-1;
820 	mcp->mod_ref = 1;
821 	mcp->mod_loaded = 1;
822 	mcp->mod_loadcnt = 1;
823 	mcp->mod_mp = mp;
824 
825 	/*
826 	 * Try to open a Xen image that hasn't had its symbol and CTF
827 	 * information stripped off.
828 	 */
829 	file = kobj_open_file(XPV_FILENAME);
830 	if (file == (struct _buf *)-1) {
831 		file = NULL;
832 		goto err;
833 	}
834 
835 	/*
836 	 * Read the header and ensure that this is an ELF file for the
837 	 * proper ISA.  If it's not, somebody has done something very
838 	 * stupid.  Why bother?  See Mencken.
839 	 */
840 	if (kobj_read_file(file, (char *)&mp->hdr, sizeof (mp->hdr), 0) < 0)
841 		goto err;
842 	for (i = 0; i < SELFMAG; i++)
843 		if (mp->hdr.e_ident[i] != ELFMAG[i])
844 			goto err;
845 	if ((mp->hdr.e_ident[EI_DATA] != ELFDATA2LSB) ||
846 	    (mp->hdr.e_machine != machine))
847 		goto err;
848 
849 	/* Read in the section headers */
850 	n = mp->hdr.e_shentsize * mp->hdr.e_shnum;
851 	mp->shdrs = kmem_zalloc(n, KM_SLEEP);
852 	if (kobj_read_file(file, mp->shdrs, n, mp->hdr.e_shoff) < 0)
853 		goto err;
854 
855 	/* Read the section names */
856 	shp = (Shdr *)(mp->shdrs + mp->hdr.e_shstrndx * mp->hdr.e_shentsize);
857 	namesize = shp->sh_size;
858 	names = kmem_zalloc(shp->sh_size, KM_SLEEP);
859 	if (kobj_read_file(file, names, shp->sh_size, shp->sh_offset) < 0)
860 		goto err;
861 
862 	/*
863 	 * Fill in the text and data size fields.
864 	 */
865 	ctf_shp = NULL;
866 	text_align = data_align = 0;
867 	for (shn = 1; shn < mp->hdr.e_shnum; shn++) {
868 		shp = (Shdr *)(mp->shdrs + shn * mp->hdr.e_shentsize);
869 
870 		/* Sanity check the offset of the section name */
871 		if (shp->sh_name >= namesize)
872 			continue;
873 
874 		/* If we find the symtab section, remember it for later. */
875 		if (shp->sh_type == SHT_SYMTAB) {
876 			mp->symtbl_section = shn;
877 			mp->symhdr = shp;
878 			continue;
879 		}
880 
881 		/* If we find the CTF section, remember it for later. */
882 		if ((shp->sh_size != 0) &&
883 		    (strcmp(names + shp->sh_name, ".SUNW_ctf") == 0)) {
884 			ctf_shp = shp;
885 			continue;
886 		}
887 
888 		if (!(shp->sh_flags & SHF_ALLOC))
889 			continue;
890 
891 		/*
892 		 * Xen marks its text section as writable, so we need to
893 		 * look for the name - not just the flag.
894 		 */
895 		if ((strcmp(&names[shp->sh_name], ".text") != 0) &&
896 		    (shp->sh_flags & SHF_WRITE) != 0) {
897 			if (shp->sh_addralign > data_align)
898 				data_align = shp->sh_addralign;
899 			mp->data_size = ALIGN(mp->data_size, data_align);
900 			mp->data_size += ALIGN(shp->sh_size, 8);
901 			if (mp->data == NULL || mp->data > (char *)shp->sh_addr)
902 				mp->data = (char *)shp->sh_addr;
903 		} else {
904 			if (shp->sh_addralign > text_align)
905 				text_align = shp->sh_addralign;
906 			mp->text_size = ALIGN(mp->text_size, text_align);
907 			mp->text_size += ALIGN(shp->sh_size, 8);
908 			if (mp->text == NULL || mp->text > (char *)shp->sh_addr)
909 				mp->text = (char *)shp->sh_addr;
910 		}
911 	}
912 	kmem_free(names, namesize);
913 	names = NULL;
914 	shp = NULL;
915 	mcp->mod_text = mp->text;
916 	mcp->mod_text_size = mp->text_size;
917 
918 	/*
919 	 * If we have symbol table and string table sections, read them in
920 	 * now.  If we don't, we just plow on.  We'll still get a valid
921 	 * core dump, but finding anything useful will be just a bit
922 	 * harder.
923 	 *
924 	 * Note: we don't bother with a hash table.  We'll never do a
925 	 * symbol lookup unless we crash, and then mdb creates its own.  We
926 	 * also don't try to perform any relocations.  Xen should be loaded
927 	 * exactly where the ELF file indicates, and the symbol information
928 	 * in the file should be complete and correct already.  Static
929 	 * linking ain't all bad.
930 	 */
931 	if ((mp->symhdr != NULL) && (mp->symhdr->sh_link < mp->hdr.e_shnum)) {
932 		mp->strhdr = (Shdr *)
933 		    (mp->shdrs + mp->symhdr->sh_link * mp->hdr.e_shentsize);
934 		mp->nsyms = mp->symhdr->sh_size / mp->symhdr->sh_entsize;
935 
936 		/* Allocate space for the symbol table and strings.  */
937 		mp->symsize = mp->symhdr->sh_size +
938 		    mp->nsyms * sizeof (symid_t) + mp->strhdr->sh_size;
939 		mp->symspace = kmem_zalloc(mp->symsize, KM_SLEEP);
940 		mp->symtbl = mp->symspace;
941 		mp->strings = (char *)(mp->symtbl + mp->symhdr->sh_size);
942 
943 		if ((kobj_read_file(file, mp->symtbl,
944 		    mp->symhdr->sh_size, mp->symhdr->sh_offset) < 0) ||
945 		    (kobj_read_file(file, mp->strings,
946 		    mp->strhdr->sh_size, mp->strhdr->sh_offset) < 0))
947 			goto err;
948 	}
949 
950 	/*
951 	 * Read in the CTF section
952 	 */
953 	if ((ctf_shp != NULL) && ((moddebug & MODDEBUG_NOCTF) == 0)) {
954 		mp->ctfdata = kmem_zalloc(ctf_shp->sh_size, KM_SLEEP);
955 		mp->ctfsize = ctf_shp->sh_size;
956 		if (kobj_read_file(file, mp->ctfdata, mp->ctfsize,
957 		    ctf_shp->sh_offset) < 0)
958 			goto err;
959 	}
960 
961 	kobj_close_file(file);
962 
963 	xpv_module = mp;
964 	xpv_modctl = mcp;
965 	return;
966 
967 err:
968 	cmn_err(CE_WARN, "Failed to initialize xpv module.");
969 	if (file != NULL)
970 		kobj_close_file(file);
971 
972 	kmem_free(mp->filename, strlen(XPV_FILENAME) + 1);
973 	if (mp->shdrs != NULL)
974 		kmem_free(mp->shdrs, mp->hdr.e_shentsize * mp->hdr.e_shnum);
975 	if (mp->symspace != NULL)
976 		kmem_free(mp->symspace, mp->symsize);
977 	if (mp->ctfdata != NULL)
978 		kmem_free(mp->ctfdata, mp->ctfsize);
979 	kmem_free(mp, sizeof (*mp));
980 	kmem_free(mcp->mod_filename, strlen(XPV_FILENAME) + 1);
981 	kmem_free(mcp->mod_modname, strlen(XPV_MODNAME) + 1);
982 	kmem_free(mcp, sizeof (*mcp));
983 	if (names != NULL)
984 		kmem_free(names, namesize);
985 }
986 
987 void
xpv_panic_init()988 xpv_panic_init()
989 {
990 	xen_platform_op_t op;
991 	int i;
992 
993 	ASSERT(DOMAIN_IS_INITDOMAIN(xen_info));
994 
995 	for (i = 0; i < mmu.num_level; i++)
996 		ptable_pfn[i] = PFN_INVALID;
997 
998 	/* Let Xen know where to jump if/when it panics. */
999 	op.cmd = XENPF_panic_init;
1000 	op.interface_version = XENPF_INTERFACE_VERSION;
1001 	op.u.panic_init.panic_addr = (unsigned long)xpv_panic_hdlr;
1002 
1003 	(void) HYPERVISOR_platform_op(&op);
1004 
1005 	init_xen_module();
1006 }
1007