xref: /freebsd/sys/arm64/arm64/trap.c (revision 85732ac8) 
1 /*-
2  * Copyright (c) 2014 Andrew Turner
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
34 #include <sys/lock.h>
35 #include <sys/mutex.h>
36 #include <sys/pioctl.h>
37 #include <sys/proc.h>
38 #include <sys/ptrace.h>
39 #include <sys/syscall.h>
40 #include <sys/sysent.h>
41 #ifdef KDB
42 #include <sys/kdb.h>
43 #endif
44 
45 #include <vm/vm.h>
46 #include <vm/pmap.h>
47 #include <vm/vm_kern.h>
48 #include <vm/vm_map.h>
49 #include <vm/vm_param.h>
50 #include <vm/vm_extern.h>
51 
52 #include <machine/frame.h>
53 #include <machine/pcb.h>
54 #include <machine/pcpu.h>
55 #include <machine/undefined.h>
56 
57 #ifdef KDTRACE_HOOKS
58 #include <sys/dtrace_bsd.h>
59 #endif
60 
61 #ifdef VFP
62 #include <machine/vfp.h>
63 #endif
64 
65 #ifdef KDB
66 #include <machine/db_machdep.h>
67 #endif
68 
69 #ifdef DDB
70 #include <ddb/db_output.h>
71 #endif
72 
73 extern register_t fsu_intr_fault;
74 
75 /* Called from exception.S */
76 void do_el1h_sync(struct thread *, struct trapframe *);
77 void do_el0_sync(struct thread *, struct trapframe *);
78 void do_el0_error(struct trapframe *);
79 void do_serror(struct trapframe *);
80 void unhandled_exception(struct trapframe *);
81 
82 static void print_registers(struct trapframe *frame);
83 
84 int (*dtrace_invop_jump_addr)(struct trapframe *);
85 
86 static __inline void
87 call_trapsignal(struct thread *td, int sig, int code, void *addr)
88 {
89 	ksiginfo_t ksi;
90 
91 	ksiginfo_init_trap(&ksi);
92 	ksi.ksi_signo = sig;
93 	ksi.ksi_code = code;
94 	ksi.ksi_addr = addr;
95 	trapsignal(td, &ksi);
96 }
97 
98 int
99 cpu_fetch_syscall_args(struct thread *td)
100 {
101 	struct proc *p;
102 	register_t *ap;
103 	struct syscall_args *sa;
104 	int nap;
105 
106 	nap = 8;
107 	p = td->td_proc;
108 	ap = td->td_frame->tf_x;
109 	sa = &td->td_sa;
110 
111 	sa->code = td->td_frame->tf_x[8];
112 
113 	if (sa->code == SYS_syscall || sa->code == SYS___syscall) {
114 		sa->code = *ap++;
115 		nap--;
116 	}
117 
118 	if (p->p_sysent->sv_mask)
119 		sa->code &= p->p_sysent->sv_mask;
120 	if (sa->code >= p->p_sysent->sv_size)
121 		sa->callp = &p->p_sysent->sv_table[0];
122 	else
123 		sa->callp = &p->p_sysent->sv_table[sa->code];
124 
125 	sa->narg = sa->callp->sy_narg;
126 	memcpy(sa->args, ap, nap * sizeof(register_t));
127 	if (sa->narg > nap)
128 		panic("ARM64TODO: Could we have more than 8 args?");
129 
130 	td->td_retval[0] = 0;
131 	td->td_retval[1] = 0;
132 
133 	return (0);
134 }
135 
136 #include "../../kern/subr_syscall.c"
137 
138 static void
139 svc_handler(struct thread *td, struct trapframe *frame)
140 {
141 	int error;
142 
143 	if ((frame->tf_esr & ESR_ELx_ISS_MASK) == 0) {
144 		error = syscallenter(td);
145 		syscallret(td, error);
146 	} else {
147 		call_trapsignal(td, SIGILL, ILL_ILLOPN, (void *)frame->tf_elr);
148 		userret(td, frame);
149 	}
150 }
151 
152 static void
153 data_abort(struct thread *td, struct trapframe *frame, uint64_t esr,
154     uint64_t far, int lower)
155 {
156 	struct vm_map *map;
157 	struct proc *p;
158 	struct pcb *pcb;
159 	vm_prot_t ftype;
160 	vm_offset_t va;
161 	int error, sig, ucode;
162 #ifdef KDB
163 	bool handled;
164 #endif
165 
166 	/*
167 	 * According to the ARMv8-A rev. A.g, B2.10.5 "Load-Exclusive
168 	 * and Store-Exclusive instruction usage restrictions", state
169 	 * of the exclusive monitors after data abort exception is unknown.
170 	 */
171 	clrex();
172 
173 #ifdef KDB
174 	if (kdb_active) {
175 		kdb_reenter();
176 		return;
177 	}
178 #endif
179 
180 	pcb = td->td_pcb;
181 	p = td->td_proc;
182 	if (lower)
183 		map = &p->p_vmspace->vm_map;
184 	else {
185 		/* The top bit tells us which range to use */
186 		if (far >= VM_MAXUSER_ADDRESS) {
187 			map = kernel_map;
188 		} else {
189 			map = &p->p_vmspace->vm_map;
190 			if (map == NULL)
191 				map = kernel_map;
192 		}
193 	}
194 
195 	/*
196 	 * The call to pmap_fault can be dangerous when coming from the
197 	 * kernel as it may be not be able to lock the pmap to check if
198 	 * the address is now valid. Because of this we filter the cases
199 	 * when we are not going to see superpage activity.
200 	 */
201 	if (!lower) {
202 		/*
203 		 * We may fault in a DMAP region due to a superpage being
204 		 * unmapped when the access took place.
205 		 */
206 		if (map == kernel_map && !VIRT_IN_DMAP(far))
207 			goto no_pmap_fault;
208 		/*
209 		 * We can also fault in the userspace handling functions,
210 		 * e.g. copyin. In these cases we will have set a fault
211 		 * handler so we can check if this is set before calling
212 		 * pmap_fault.
213 		 */
214 		if (map != kernel_map && pcb->pcb_onfault == 0)
215 			goto no_pmap_fault;
216 	}
217 
218 	if (pmap_fault(map->pmap, esr, far) == KERN_SUCCESS)
219 		return;
220 
221 no_pmap_fault:
222 	KASSERT(td->td_md.md_spinlock_count == 0,
223 	    ("data abort with spinlock held"));
224 	if (td->td_critnest != 0 || WITNESS_CHECK(WARN_SLEEPOK |
225 	    WARN_GIANTOK, NULL, "Kernel page fault") != 0) {
226 		print_registers(frame);
227 		printf(" far: %16lx\n", far);
228 		printf(" esr:         %.8lx\n", esr);
229 		panic("data abort in critical section or under mutex");
230 	}
231 
232 	va = trunc_page(far);
233 	ftype = ((esr >> 6) & 1) ? VM_PROT_READ | VM_PROT_WRITE : VM_PROT_READ;
234 
235 	/* Fault in the page. */
236 	error = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
237 	if (error != KERN_SUCCESS) {
238 		if (lower) {
239 			sig = SIGSEGV;
240 			if (error == KERN_PROTECTION_FAILURE)
241 				ucode = SEGV_ACCERR;
242 			else
243 				ucode = SEGV_MAPERR;
244 			call_trapsignal(td, sig, ucode, (void *)far);
245 		} else {
246 			if (td->td_intr_nesting_level == 0 &&
247 			    pcb->pcb_onfault != 0) {
248 				frame->tf_x[0] = error;
249 				frame->tf_elr = pcb->pcb_onfault;
250 				return;
251 			}
252 
253 			printf("Fatal data abort:\n");
254 			print_registers(frame);
255 			printf(" far: %16lx\n", far);
256 			printf(" esr:         %.8lx\n", esr);
257 
258 #ifdef KDB
259 			if (debugger_on_trap) {
260 				kdb_why = KDB_WHY_TRAP;
261 				handled = kdb_trap(ESR_ELx_EXCEPTION(esr), 0,
262 				    frame);
263 				kdb_why = KDB_WHY_UNSET;
264 				if (handled)
265 					return;
266 			}
267 #endif
268 			panic("vm_fault failed: %lx", frame->tf_elr);
269 		}
270 	}
271 
272 	if (lower)
273 		userret(td, frame);
274 }
275 
276 static void
277 print_registers(struct trapframe *frame)
278 {
279 	u_int reg;
280 
281 	for (reg = 0; reg < nitems(frame->tf_x); reg++) {
282 		printf(" %sx%d: %16lx\n", (reg < 10) ? " " : "", reg,
283 		    frame->tf_x[reg]);
284 	}
285 	printf("  sp: %16lx\n", frame->tf_sp);
286 	printf("  lr: %16lx\n", frame->tf_lr);
287 	printf(" elr: %16lx\n", frame->tf_elr);
288 	printf("spsr:         %8x\n", frame->tf_spsr);
289 }
290 
291 void
292 do_el1h_sync(struct thread *td, struct trapframe *frame)
293 {
294 	struct trapframe *oframe;
295 	uint32_t exception;
296 	uint64_t esr, far;
297 
298 	/* Read the esr register to get the exception details */
299 	esr = frame->tf_esr;
300 	exception = ESR_ELx_EXCEPTION(esr);
301 
302 #ifdef KDTRACE_HOOKS
303 	if (dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, exception))
304 		return;
305 #endif
306 
307 	CTR4(KTR_TRAP,
308 	    "do_el1_sync: curthread: %p, esr %lx, elr: %lx, frame: %p", td,
309 	    esr, frame->tf_elr, frame);
310 
311 	oframe = td->td_frame;
312 
313 	switch (exception) {
314 	case EXCP_BRK:
315 	case EXCP_WATCHPT_EL1:
316 	case EXCP_SOFTSTP_EL1:
317 		break;
318 	default:
319 		td->td_frame = frame;
320 		break;
321 	}
322 
323 	switch(exception) {
324 	case EXCP_FP_SIMD:
325 	case EXCP_TRAP_FP:
326 #ifdef VFP
327 		if ((td->td_pcb->pcb_fpflags & PCB_FP_KERN) != 0) {
328 			vfp_restore_state();
329 		} else
330 #endif
331 		{
332 			print_registers(frame);
333 			printf(" esr:         %.8lx\n", esr);
334 			panic("VFP exception in the kernel");
335 		}
336 		break;
337 	case EXCP_INSN_ABORT:
338 	case EXCP_DATA_ABORT:
339 		far = READ_SPECIALREG(far_el1);
340 		intr_enable();
341 		data_abort(td, frame, esr, far, 0);
342 		break;
343 	case EXCP_BRK:
344 #ifdef KDTRACE_HOOKS
345 		if ((esr & ESR_ELx_ISS_MASK) == 0x40d && \
346 		    dtrace_invop_jump_addr != 0) {
347 			dtrace_invop_jump_addr(frame);
348 			break;
349 		}
350 #endif
351 #ifdef KDB
352 		kdb_trap(exception, 0,
353 		    (td->td_frame != NULL) ? td->td_frame : frame);
354 #else
355 		panic("No debugger in kernel.\n");
356 #endif
357 		frame->tf_elr += 4;
358 		break;
359 	case EXCP_WATCHPT_EL1:
360 	case EXCP_SOFTSTP_EL1:
361 #ifdef KDB
362 		kdb_trap(exception, 0,
363 		    (td->td_frame != NULL) ? td->td_frame : frame);
364 #else
365 		panic("No debugger in kernel.\n");
366 #endif
367 		break;
368 	case EXCP_UNKNOWN:
369 		if (undef_insn(1, frame))
370 			break;
371 		/* FALLTHROUGH */
372 	default:
373 		print_registers(frame);
374 		panic("Unknown kernel exception %x esr_el1 %lx\n", exception,
375 		    esr);
376 	}
377 
378 	td->td_frame = oframe;
379 }
380 
381 void
382 do_el0_sync(struct thread *td, struct trapframe *frame)
383 {
384 	pcpu_bp_harden bp_harden;
385 	uint32_t exception;
386 	uint64_t esr, far;
387 
388 	/* Check we have a sane environment when entering from userland */
389 	KASSERT((uintptr_t)get_pcpu() >= VM_MIN_KERNEL_ADDRESS,
390 	    ("Invalid pcpu address from userland: %p (tpidr %lx)",
391 	     get_pcpu(), READ_SPECIALREG(tpidr_el1)));
392 
393 	esr = frame->tf_esr;
394 	exception = ESR_ELx_EXCEPTION(esr);
395 	switch (exception) {
396 	case EXCP_INSN_ABORT_L:
397 		far = READ_SPECIALREG(far_el1);
398 
399 		/*
400 		 * Userspace may be trying to train the branch predictor to
401 		 * attack the kernel. If we are on a CPU affected by this
402 		 * call the handler to clear the branch predictor state.
403 		 */
404 		if (far > VM_MAXUSER_ADDRESS) {
405 			bp_harden = PCPU_GET(bp_harden);
406 			if (bp_harden != NULL)
407 				bp_harden();
408 		}
409 		break;
410 	case EXCP_UNKNOWN:
411 	case EXCP_DATA_ABORT_L:
412 	case EXCP_DATA_ABORT:
413 		far = READ_SPECIALREG(far_el1);
414 		break;
415 	}
416 	intr_enable();
417 
418 	CTR4(KTR_TRAP,
419 	    "do_el0_sync: curthread: %p, esr %lx, elr: %lx, frame: %p", td, esr,
420 	    frame->tf_elr, frame);
421 
422 	switch(exception) {
423 	case EXCP_FP_SIMD:
424 	case EXCP_TRAP_FP:
425 #ifdef VFP
426 		vfp_restore_state();
427 #else
428 		panic("VFP exception in userland");
429 #endif
430 		break;
431 	case EXCP_SVC32:
432 	case EXCP_SVC64:
433 		svc_handler(td, frame);
434 		break;
435 	case EXCP_INSN_ABORT_L:
436 	case EXCP_DATA_ABORT_L:
437 	case EXCP_DATA_ABORT:
438 		data_abort(td, frame, esr, far, 1);
439 		break;
440 	case EXCP_UNKNOWN:
441 		if (!undef_insn(0, frame))
442 			call_trapsignal(td, SIGILL, ILL_ILLTRP, (void *)far);
443 		userret(td, frame);
444 		break;
445 	case EXCP_SP_ALIGN:
446 		call_trapsignal(td, SIGBUS, BUS_ADRALN, (void *)frame->tf_sp);
447 		userret(td, frame);
448 		break;
449 	case EXCP_PC_ALIGN:
450 		call_trapsignal(td, SIGBUS, BUS_ADRALN, (void *)frame->tf_elr);
451 		userret(td, frame);
452 		break;
453 	case EXCP_BRK:
454 		call_trapsignal(td, SIGTRAP, TRAP_BRKPT, (void *)frame->tf_elr);
455 		userret(td, frame);
456 		break;
457 	case EXCP_MSR:
458 		call_trapsignal(td, SIGILL, ILL_PRVOPC, (void *)frame->tf_elr);
459 		userret(td, frame);
460 		break;
461 	case EXCP_SOFTSTP_EL0:
462 		td->td_frame->tf_spsr &= ~PSR_SS;
463 		td->td_pcb->pcb_flags &= ~PCB_SINGLE_STEP;
464 		WRITE_SPECIALREG(MDSCR_EL1,
465 		    READ_SPECIALREG(MDSCR_EL1) & ~DBG_MDSCR_SS);
466 		call_trapsignal(td, SIGTRAP, TRAP_TRACE,
467 		    (void *)frame->tf_elr);
468 		userret(td, frame);
469 		break;
470 	default:
471 		call_trapsignal(td, SIGBUS, BUS_OBJERR, (void *)frame->tf_elr);
472 		userret(td, frame);
473 		break;
474 	}
475 
476 	KASSERT((td->td_pcb->pcb_fpflags & ~PCB_FP_USERMASK) == 0,
477 	    ("Kernel VFP flags set while entering userspace"));
478 	KASSERT(
479 	    td->td_pcb->pcb_fpusaved == &td->td_pcb->pcb_fpustate,
480 	    ("Kernel VFP state in use when entering userspace"));
481 }
482 
483 /*
484  * TODO: We will need to handle these later when we support ARMv8.2 RAS.
485  */
486 void
487 do_serror(struct trapframe *frame)
488 {
489 	uint64_t esr, far;
490 
491 	far = READ_SPECIALREG(far_el1);
492 	esr = frame->tf_esr;
493 
494 	print_registers(frame);
495 	printf(" far: %16lx\n", far);
496 	printf(" esr:         %.8lx\n", esr);
497 	panic("Unhandled System Error");
498 }
499 
500 void
501 unhandled_exception(struct trapframe *frame)
502 {
503 	uint64_t esr, far;
504 
505 	far = READ_SPECIALREG(far_el1);
506 	esr = frame->tf_esr;
507 
508 	print_registers(frame);
509 	printf(" far: %16lx\n", far);
510 	printf(" esr:         %.8lx\n", esr);
511 	panic("Unhandled exception");
512 }
513