xref: /openbmc/linux/arch/s390/kernel/traps.c (revision e0bf6c5c) 
1 /*
2  *  S390 version
3  *    Copyright IBM Corp. 1999, 2000
4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
5  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
6  *
7  *  Derived from "arch/i386/kernel/traps.c"
8  *    Copyright (C) 1991, 1992 Linus Torvalds
9  */
10 
11 /*
12  * 'Traps.c' handles hardware traps and faults after we have saved some
13  * state in 'asm.s'.
14  */
15 #include <linux/kprobes.h>
16 #include <linux/kdebug.h>
17 #include <linux/module.h>
18 #include <linux/ptrace.h>
19 #include <linux/sched.h>
20 #include <linux/mm.h>
21 #include <linux/slab.h>
22 #include <asm/switch_to.h>
23 #include "entry.h"
24 
25 int show_unhandled_signals = 1;
26 
27 static inline void __user *get_trap_ip(struct pt_regs *regs)
28 {
29 #ifdef CONFIG_64BIT
30 	unsigned long address;
31 
32 	if (regs->int_code & 0x200)
33 		address = *(unsigned long *)(current->thread.trap_tdb + 24);
34 	else
35 		address = regs->psw.addr;
36 	return (void __user *)
37 		((address - (regs->int_code >> 16)) & PSW_ADDR_INSN);
38 #else
39 	return (void __user *)
40 		((regs->psw.addr - (regs->int_code >> 16)) & PSW_ADDR_INSN);
41 #endif
42 }
43 
44 static inline void report_user_fault(struct pt_regs *regs, int signr)
45 {
46 	if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
47 		return;
48 	if (!unhandled_signal(current, signr))
49 		return;
50 	if (!printk_ratelimit())
51 		return;
52 	printk("User process fault: interruption code %04x ilc:%d ",
53 	       regs->int_code & 0xffff, regs->int_code >> 17);
54 	print_vma_addr("in ", regs->psw.addr & PSW_ADDR_INSN);
55 	printk("\n");
56 	show_regs(regs);
57 }
58 
59 int is_valid_bugaddr(unsigned long addr)
60 {
61 	return 1;
62 }
63 
64 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
65 {
66 	siginfo_t info;
67 
68 	if (user_mode(regs)) {
69 		info.si_signo = si_signo;
70 		info.si_errno = 0;
71 		info.si_code = si_code;
72 		info.si_addr = get_trap_ip(regs);
73 		force_sig_info(si_signo, &info, current);
74 		report_user_fault(regs, si_signo);
75         } else {
76                 const struct exception_table_entry *fixup;
77                 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
78                 if (fixup)
79 			regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
80 		else {
81 			enum bug_trap_type btt;
82 
83 			btt = report_bug(regs->psw.addr & PSW_ADDR_INSN, regs);
84 			if (btt == BUG_TRAP_TYPE_WARN)
85 				return;
86 			die(regs, str);
87 		}
88         }
89 }
90 
91 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
92 {
93 	if (notify_die(DIE_TRAP, str, regs, 0,
94 		       regs->int_code, si_signo) == NOTIFY_STOP)
95 		return;
96 	do_report_trap(regs, si_signo, si_code, str);
97 }
98 NOKPROBE_SYMBOL(do_trap);
99 
100 void do_per_trap(struct pt_regs *regs)
101 {
102 	siginfo_t info;
103 
104 	if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
105 		return;
106 	if (!current->ptrace)
107 		return;
108 	info.si_signo = SIGTRAP;
109 	info.si_errno = 0;
110 	info.si_code = TRAP_HWBKPT;
111 	info.si_addr =
112 		(void __force __user *) current->thread.per_event.address;
113 	force_sig_info(SIGTRAP, &info, current);
114 }
115 NOKPROBE_SYMBOL(do_per_trap);
116 
117 void default_trap_handler(struct pt_regs *regs)
118 {
119 	if (user_mode(regs)) {
120 		report_user_fault(regs, SIGSEGV);
121 		do_exit(SIGSEGV);
122 	} else
123 		die(regs, "Unknown program exception");
124 }
125 
126 #define DO_ERROR_INFO(name, signr, sicode, str) \
127 void name(struct pt_regs *regs)			\
128 {						\
129 	do_trap(regs, signr, sicode, str);	\
130 }
131 
132 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
133 	      "addressing exception")
134 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
135 	      "execute exception")
136 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
137 	      "fixpoint divide exception")
138 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
139 	      "fixpoint overflow exception")
140 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
141 	      "HFP overflow exception")
142 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
143 	      "HFP underflow exception")
144 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
145 	      "HFP significance exception")
146 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
147 	      "HFP divide exception")
148 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
149 	      "HFP square root exception")
150 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
151 	      "operand exception")
152 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
153 	      "privileged operation")
154 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
155 	      "special operation exception")
156 
157 #ifdef CONFIG_64BIT
158 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
159 	      "transaction constraint exception")
160 #endif
161 
162 static inline void do_fp_trap(struct pt_regs *regs, int fpc)
163 {
164 	int si_code = 0;
165 	/* FPC[2] is Data Exception Code */
166 	if ((fpc & 0x00000300) == 0) {
167 		/* bits 6 and 7 of DXC are 0 iff IEEE exception */
168 		if (fpc & 0x8000) /* invalid fp operation */
169 			si_code = FPE_FLTINV;
170 		else if (fpc & 0x4000) /* div by 0 */
171 			si_code = FPE_FLTDIV;
172 		else if (fpc & 0x2000) /* overflow */
173 			si_code = FPE_FLTOVF;
174 		else if (fpc & 0x1000) /* underflow */
175 			si_code = FPE_FLTUND;
176 		else if (fpc & 0x0800) /* inexact */
177 			si_code = FPE_FLTRES;
178 	}
179 	do_trap(regs, SIGFPE, si_code, "floating point exception");
180 }
181 
182 void translation_exception(struct pt_regs *regs)
183 {
184 	/* May never happen. */
185 	die(regs, "Translation exception");
186 }
187 
188 void illegal_op(struct pt_regs *regs)
189 {
190 	siginfo_t info;
191         __u8 opcode[6];
192 	__u16 __user *location;
193 	int is_uprobe_insn = 0;
194 	int signal = 0;
195 
196 	location = get_trap_ip(regs);
197 
198 	if (user_mode(regs)) {
199 		if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
200 			return;
201 		if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
202 			if (current->ptrace) {
203 				info.si_signo = SIGTRAP;
204 				info.si_errno = 0;
205 				info.si_code = TRAP_BRKPT;
206 				info.si_addr = location;
207 				force_sig_info(SIGTRAP, &info, current);
208 			} else
209 				signal = SIGILL;
210 #ifdef CONFIG_UPROBES
211 		} else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
212 			is_uprobe_insn = 1;
213 #endif
214 #ifdef CONFIG_MATHEMU
215 		} else if (opcode[0] == 0xb3) {
216 			if (get_user(*((__u16 *) (opcode+2)), location+1))
217 				return;
218 			signal = math_emu_b3(opcode, regs);
219                 } else if (opcode[0] == 0xed) {
220 			if (get_user(*((__u32 *) (opcode+2)),
221 				     (__u32 __user *)(location+1)))
222 				return;
223 			signal = math_emu_ed(opcode, regs);
224 		} else if (*((__u16 *) opcode) == 0xb299) {
225 			if (get_user(*((__u16 *) (opcode+2)), location+1))
226 				return;
227 			signal = math_emu_srnm(opcode, regs);
228 		} else if (*((__u16 *) opcode) == 0xb29c) {
229 			if (get_user(*((__u16 *) (opcode+2)), location+1))
230 				return;
231 			signal = math_emu_stfpc(opcode, regs);
232 		} else if (*((__u16 *) opcode) == 0xb29d) {
233 			if (get_user(*((__u16 *) (opcode+2)), location+1))
234 				return;
235 			signal = math_emu_lfpc(opcode, regs);
236 #endif
237 		} else
238 			signal = SIGILL;
239 	}
240 	/*
241 	 * We got either an illegal op in kernel mode, or user space trapped
242 	 * on a uprobes illegal instruction. See if kprobes or uprobes picks
243 	 * it up. If not, SIGILL.
244 	 */
245 	if (is_uprobe_insn || !user_mode(regs)) {
246 		if (notify_die(DIE_BPT, "bpt", regs, 0,
247 			       3, SIGTRAP) != NOTIFY_STOP)
248 			signal = SIGILL;
249 	}
250 
251 #ifdef CONFIG_MATHEMU
252         if (signal == SIGFPE)
253 		do_fp_trap(regs, current->thread.fp_regs.fpc);
254 	else if (signal == SIGSEGV)
255 		do_trap(regs, signal, SEGV_MAPERR, "user address fault");
256 	else
257 #endif
258 	if (signal)
259 		do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
260 }
261 NOKPROBE_SYMBOL(illegal_op);
262 
263 #ifdef CONFIG_MATHEMU
264 void specification_exception(struct pt_regs *regs)
265 {
266         __u8 opcode[6];
267 	__u16 __user *location = NULL;
268 	int signal = 0;
269 
270 	location = (__u16 __user *) get_trap_ip(regs);
271 
272 	if (user_mode(regs)) {
273 		get_user(*((__u16 *) opcode), location);
274 		switch (opcode[0]) {
275 		case 0x28: /* LDR Rx,Ry   */
276 			signal = math_emu_ldr(opcode);
277 			break;
278 		case 0x38: /* LER Rx,Ry   */
279 			signal = math_emu_ler(opcode);
280 			break;
281 		case 0x60: /* STD R,D(X,B) */
282 			get_user(*((__u16 *) (opcode+2)), location+1);
283 			signal = math_emu_std(opcode, regs);
284 			break;
285 		case 0x68: /* LD R,D(X,B) */
286 			get_user(*((__u16 *) (opcode+2)), location+1);
287 			signal = math_emu_ld(opcode, regs);
288 			break;
289 		case 0x70: /* STE R,D(X,B) */
290 			get_user(*((__u16 *) (opcode+2)), location+1);
291 			signal = math_emu_ste(opcode, regs);
292 			break;
293 		case 0x78: /* LE R,D(X,B) */
294 			get_user(*((__u16 *) (opcode+2)), location+1);
295 			signal = math_emu_le(opcode, regs);
296 			break;
297 		default:
298 			signal = SIGILL;
299 			break;
300                 }
301         } else
302 		signal = SIGILL;
303 
304         if (signal == SIGFPE)
305 		do_fp_trap(regs, current->thread.fp_regs.fpc);
306 	else if (signal)
307 		do_trap(regs, signal, ILL_ILLOPN, "specification exception");
308 }
309 #else
310 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
311 	      "specification exception");
312 #endif
313 
314 #ifdef CONFIG_64BIT
315 int alloc_vector_registers(struct task_struct *tsk)
316 {
317 	__vector128 *vxrs;
318 	int i;
319 
320 	/* Allocate vector register save area. */
321 	vxrs = kzalloc(sizeof(__vector128) * __NUM_VXRS,
322 		       GFP_KERNEL|__GFP_REPEAT);
323 	if (!vxrs)
324 		return -ENOMEM;
325 	preempt_disable();
326 	if (tsk == current)
327 		save_fp_regs(tsk->thread.fp_regs.fprs);
328 	/* Copy the 16 floating point registers */
329 	for (i = 0; i < 16; i++)
330 		*(freg_t *) &vxrs[i] = tsk->thread.fp_regs.fprs[i];
331 	tsk->thread.vxrs = vxrs;
332 	if (tsk == current) {
333 		__ctl_set_bit(0, 17);
334 		restore_vx_regs(vxrs);
335 	}
336 	preempt_enable();
337 	return 0;
338 }
339 
340 void vector_exception(struct pt_regs *regs)
341 {
342 	int si_code, vic;
343 
344 	if (!MACHINE_HAS_VX) {
345 		do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
346 		return;
347 	}
348 
349 	/* get vector interrupt code from fpc */
350 	asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
351 	vic = (current->thread.fp_regs.fpc & 0xf00) >> 8;
352 	switch (vic) {
353 	case 1: /* invalid vector operation */
354 		si_code = FPE_FLTINV;
355 		break;
356 	case 2: /* division by zero */
357 		si_code = FPE_FLTDIV;
358 		break;
359 	case 3: /* overflow */
360 		si_code = FPE_FLTOVF;
361 		break;
362 	case 4: /* underflow */
363 		si_code = FPE_FLTUND;
364 		break;
365 	case 5:	/* inexact */
366 		si_code = FPE_FLTRES;
367 		break;
368 	default: /* unknown cause */
369 		si_code = 0;
370 	}
371 	do_trap(regs, SIGFPE, si_code, "vector exception");
372 }
373 
374 static int __init disable_vector_extension(char *str)
375 {
376 	S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
377 	return 1;
378 }
379 __setup("novx", disable_vector_extension);
380 #endif
381 
382 void data_exception(struct pt_regs *regs)
383 {
384 	__u16 __user *location;
385 	int signal = 0;
386 
387 	location = get_trap_ip(regs);
388 
389 	if (MACHINE_HAS_IEEE)
390 		asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
391 
392 #ifdef CONFIG_MATHEMU
393 	else if (user_mode(regs)) {
394         	__u8 opcode[6];
395 		get_user(*((__u16 *) opcode), location);
396 		switch (opcode[0]) {
397 		case 0x28: /* LDR Rx,Ry   */
398 			signal = math_emu_ldr(opcode);
399 			break;
400 		case 0x38: /* LER Rx,Ry   */
401 			signal = math_emu_ler(opcode);
402 			break;
403 		case 0x60: /* STD R,D(X,B) */
404 			get_user(*((__u16 *) (opcode+2)), location+1);
405 			signal = math_emu_std(opcode, regs);
406 			break;
407 		case 0x68: /* LD R,D(X,B) */
408 			get_user(*((__u16 *) (opcode+2)), location+1);
409 			signal = math_emu_ld(opcode, regs);
410 			break;
411 		case 0x70: /* STE R,D(X,B) */
412 			get_user(*((__u16 *) (opcode+2)), location+1);
413 			signal = math_emu_ste(opcode, regs);
414 			break;
415 		case 0x78: /* LE R,D(X,B) */
416 			get_user(*((__u16 *) (opcode+2)), location+1);
417 			signal = math_emu_le(opcode, regs);
418 			break;
419 		case 0xb3:
420 			get_user(*((__u16 *) (opcode+2)), location+1);
421 			signal = math_emu_b3(opcode, regs);
422 			break;
423                 case 0xed:
424 			get_user(*((__u32 *) (opcode+2)),
425 				 (__u32 __user *)(location+1));
426 			signal = math_emu_ed(opcode, regs);
427 			break;
428 	        case 0xb2:
429 			if (opcode[1] == 0x99) {
430 				get_user(*((__u16 *) (opcode+2)), location+1);
431 				signal = math_emu_srnm(opcode, regs);
432 			} else if (opcode[1] == 0x9c) {
433 				get_user(*((__u16 *) (opcode+2)), location+1);
434 				signal = math_emu_stfpc(opcode, regs);
435 			} else if (opcode[1] == 0x9d) {
436 				get_user(*((__u16 *) (opcode+2)), location+1);
437 				signal = math_emu_lfpc(opcode, regs);
438 			} else
439 				signal = SIGILL;
440 			break;
441 		default:
442 			signal = SIGILL;
443 			break;
444                 }
445         }
446 #endif
447 #ifdef CONFIG_64BIT
448 	/* Check for vector register enablement */
449 	if (MACHINE_HAS_VX && !current->thread.vxrs &&
450 	    (current->thread.fp_regs.fpc & FPC_DXC_MASK) == 0xfe00) {
451 		alloc_vector_registers(current);
452 		/* Vector data exception is suppressing, rewind psw. */
453 		regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
454 		clear_pt_regs_flag(regs, PIF_PER_TRAP);
455 		return;
456 	}
457 #endif
458 
459 	if (current->thread.fp_regs.fpc & FPC_DXC_MASK)
460 		signal = SIGFPE;
461 	else
462 		signal = SIGILL;
463         if (signal == SIGFPE)
464 		do_fp_trap(regs, current->thread.fp_regs.fpc);
465 	else if (signal)
466 		do_trap(regs, signal, ILL_ILLOPN, "data exception");
467 }
468 
469 void space_switch_exception(struct pt_regs *regs)
470 {
471 	/* Set user psw back to home space mode. */
472 	if (user_mode(regs))
473 		regs->psw.mask |= PSW_ASC_HOME;
474 	/* Send SIGILL. */
475 	do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
476 }
477 
478 void kernel_stack_overflow(struct pt_regs *regs)
479 {
480 	bust_spinlocks(1);
481 	printk("Kernel stack overflow.\n");
482 	show_regs(regs);
483 	bust_spinlocks(0);
484 	panic("Corrupt kernel stack, can't continue.");
485 }
486 NOKPROBE_SYMBOL(kernel_stack_overflow);
487 
488 void __init trap_init(void)
489 {
490 	local_mcck_enable();
491 }
492