xref: /openbmc/linux/arch/s390/kernel/traps.c (revision 4a44a19b) 
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 0x%X ", regs->int_code);
53 	print_vma_addr("in ", regs->psw.addr & PSW_ADDR_INSN);
54 	printk("\n");
55 	show_regs(regs);
56 }
57 
58 int is_valid_bugaddr(unsigned long addr)
59 {
60 	return 1;
61 }
62 
63 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
64 {
65 	siginfo_t info;
66 
67 	if (user_mode(regs)) {
68 		info.si_signo = si_signo;
69 		info.si_errno = 0;
70 		info.si_code = si_code;
71 		info.si_addr = get_trap_ip(regs);
72 		force_sig_info(si_signo, &info, current);
73 		report_user_fault(regs, si_signo);
74         } else {
75                 const struct exception_table_entry *fixup;
76                 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
77                 if (fixup)
78 			regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
79 		else {
80 			enum bug_trap_type btt;
81 
82 			btt = report_bug(regs->psw.addr & PSW_ADDR_INSN, regs);
83 			if (btt == BUG_TRAP_TYPE_WARN)
84 				return;
85 			die(regs, str);
86 		}
87         }
88 }
89 
90 static void __kprobes do_trap(struct pt_regs *regs, int si_signo, int si_code,
91 			      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 
99 void __kprobes do_per_trap(struct pt_regs *regs)
100 {
101 	siginfo_t info;
102 
103 	if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
104 		return;
105 	if (!current->ptrace)
106 		return;
107 	info.si_signo = SIGTRAP;
108 	info.si_errno = 0;
109 	info.si_code = TRAP_HWBKPT;
110 	info.si_addr =
111 		(void __force __user *) current->thread.per_event.address;
112 	force_sig_info(SIGTRAP, &info, current);
113 }
114 
115 void default_trap_handler(struct pt_regs *regs)
116 {
117 	if (user_mode(regs)) {
118 		report_user_fault(regs, SIGSEGV);
119 		do_exit(SIGSEGV);
120 	} else
121 		die(regs, "Unknown program exception");
122 }
123 
124 #define DO_ERROR_INFO(name, signr, sicode, str) \
125 void name(struct pt_regs *regs)			\
126 {						\
127 	do_trap(regs, signr, sicode, str);	\
128 }
129 
130 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
131 	      "addressing exception")
132 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
133 	      "execute exception")
134 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
135 	      "fixpoint divide exception")
136 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
137 	      "fixpoint overflow exception")
138 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
139 	      "HFP overflow exception")
140 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
141 	      "HFP underflow exception")
142 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
143 	      "HFP significance exception")
144 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
145 	      "HFP divide exception")
146 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
147 	      "HFP square root exception")
148 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
149 	      "operand exception")
150 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
151 	      "privileged operation")
152 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
153 	      "special operation exception")
154 DO_ERROR_INFO(translation_exception, SIGILL, ILL_ILLOPN,
155 	      "translation 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 __kprobes illegal_op(struct pt_regs *regs)
183 {
184 	siginfo_t info;
185         __u8 opcode[6];
186 	__u16 __user *location;
187 	int is_uprobe_insn = 0;
188 	int signal = 0;
189 
190 	location = get_trap_ip(regs);
191 
192 	if (user_mode(regs)) {
193 		if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
194 			return;
195 		if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
196 			if (current->ptrace) {
197 				info.si_signo = SIGTRAP;
198 				info.si_errno = 0;
199 				info.si_code = TRAP_BRKPT;
200 				info.si_addr = location;
201 				force_sig_info(SIGTRAP, &info, current);
202 			} else
203 				signal = SIGILL;
204 #ifdef CONFIG_UPROBES
205 		} else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
206 			is_uprobe_insn = 1;
207 #endif
208 #ifdef CONFIG_MATHEMU
209 		} else if (opcode[0] == 0xb3) {
210 			if (get_user(*((__u16 *) (opcode+2)), location+1))
211 				return;
212 			signal = math_emu_b3(opcode, regs);
213                 } else if (opcode[0] == 0xed) {
214 			if (get_user(*((__u32 *) (opcode+2)),
215 				     (__u32 __user *)(location+1)))
216 				return;
217 			signal = math_emu_ed(opcode, regs);
218 		} else if (*((__u16 *) opcode) == 0xb299) {
219 			if (get_user(*((__u16 *) (opcode+2)), location+1))
220 				return;
221 			signal = math_emu_srnm(opcode, regs);
222 		} else if (*((__u16 *) opcode) == 0xb29c) {
223 			if (get_user(*((__u16 *) (opcode+2)), location+1))
224 				return;
225 			signal = math_emu_stfpc(opcode, regs);
226 		} else if (*((__u16 *) opcode) == 0xb29d) {
227 			if (get_user(*((__u16 *) (opcode+2)), location+1))
228 				return;
229 			signal = math_emu_lfpc(opcode, regs);
230 #endif
231 		} else
232 			signal = SIGILL;
233 	}
234 	/*
235 	 * We got either an illegal op in kernel mode, or user space trapped
236 	 * on a uprobes illegal instruction. See if kprobes or uprobes picks
237 	 * it up. If not, SIGILL.
238 	 */
239 	if (is_uprobe_insn || !user_mode(regs)) {
240 		if (notify_die(DIE_BPT, "bpt", regs, 0,
241 			       3, SIGTRAP) != NOTIFY_STOP)
242 			signal = SIGILL;
243 	}
244 
245 #ifdef CONFIG_MATHEMU
246         if (signal == SIGFPE)
247 		do_fp_trap(regs, current->thread.fp_regs.fpc);
248 	else if (signal == SIGSEGV)
249 		do_trap(regs, signal, SEGV_MAPERR, "user address fault");
250 	else
251 #endif
252 	if (signal)
253 		do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
254 }
255 
256 
257 #ifdef CONFIG_MATHEMU
258 void specification_exception(struct pt_regs *regs)
259 {
260         __u8 opcode[6];
261 	__u16 __user *location = NULL;
262 	int signal = 0;
263 
264 	location = (__u16 __user *) get_trap_ip(regs);
265 
266 	if (user_mode(regs)) {
267 		get_user(*((__u16 *) opcode), location);
268 		switch (opcode[0]) {
269 		case 0x28: /* LDR Rx,Ry   */
270 			signal = math_emu_ldr(opcode);
271 			break;
272 		case 0x38: /* LER Rx,Ry   */
273 			signal = math_emu_ler(opcode);
274 			break;
275 		case 0x60: /* STD R,D(X,B) */
276 			get_user(*((__u16 *) (opcode+2)), location+1);
277 			signal = math_emu_std(opcode, regs);
278 			break;
279 		case 0x68: /* LD R,D(X,B) */
280 			get_user(*((__u16 *) (opcode+2)), location+1);
281 			signal = math_emu_ld(opcode, regs);
282 			break;
283 		case 0x70: /* STE R,D(X,B) */
284 			get_user(*((__u16 *) (opcode+2)), location+1);
285 			signal = math_emu_ste(opcode, regs);
286 			break;
287 		case 0x78: /* LE R,D(X,B) */
288 			get_user(*((__u16 *) (opcode+2)), location+1);
289 			signal = math_emu_le(opcode, regs);
290 			break;
291 		default:
292 			signal = SIGILL;
293 			break;
294                 }
295         } else
296 		signal = SIGILL;
297 
298         if (signal == SIGFPE)
299 		do_fp_trap(regs, current->thread.fp_regs.fpc);
300 	else if (signal)
301 		do_trap(regs, signal, ILL_ILLOPN, "specification exception");
302 }
303 #else
304 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
305 	      "specification exception");
306 #endif
307 
308 #ifdef CONFIG_64BIT
309 int alloc_vector_registers(struct task_struct *tsk)
310 {
311 	__vector128 *vxrs;
312 	int i;
313 
314 	/* Allocate vector register save area. */
315 	vxrs = kzalloc(sizeof(__vector128) * __NUM_VXRS,
316 		       GFP_KERNEL|__GFP_REPEAT);
317 	if (!vxrs)
318 		return -ENOMEM;
319 	preempt_disable();
320 	if (tsk == current)
321 		save_fp_regs(tsk->thread.fp_regs.fprs);
322 	/* Copy the 16 floating point registers */
323 	for (i = 0; i < 16; i++)
324 		*(freg_t *) &vxrs[i] = tsk->thread.fp_regs.fprs[i];
325 	tsk->thread.vxrs = vxrs;
326 	if (tsk == current) {
327 		__ctl_set_bit(0, 17);
328 		restore_vx_regs(vxrs);
329 	}
330 	preempt_enable();
331 	return 0;
332 }
333 
334 void vector_exception(struct pt_regs *regs)
335 {
336 	int si_code, vic;
337 
338 	if (!MACHINE_HAS_VX) {
339 		do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
340 		return;
341 	}
342 
343 	/* get vector interrupt code from fpc */
344 	asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
345 	vic = (current->thread.fp_regs.fpc & 0xf00) >> 8;
346 	switch (vic) {
347 	case 1: /* invalid vector operation */
348 		si_code = FPE_FLTINV;
349 		break;
350 	case 2: /* division by zero */
351 		si_code = FPE_FLTDIV;
352 		break;
353 	case 3: /* overflow */
354 		si_code = FPE_FLTOVF;
355 		break;
356 	case 4: /* underflow */
357 		si_code = FPE_FLTUND;
358 		break;
359 	case 5:	/* inexact */
360 		si_code = FPE_FLTRES;
361 		break;
362 	default: /* unknown cause */
363 		si_code = 0;
364 	}
365 	do_trap(regs, SIGFPE, si_code, "vector exception");
366 }
367 
368 static int __init disable_vector_extension(char *str)
369 {
370 	S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
371 	return 1;
372 }
373 __setup("novx", disable_vector_extension);
374 #endif
375 
376 void data_exception(struct pt_regs *regs)
377 {
378 	__u16 __user *location;
379 	int signal = 0;
380 
381 	location = get_trap_ip(regs);
382 
383 	if (MACHINE_HAS_IEEE)
384 		asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
385 
386 #ifdef CONFIG_MATHEMU
387 	else if (user_mode(regs)) {
388         	__u8 opcode[6];
389 		get_user(*((__u16 *) opcode), location);
390 		switch (opcode[0]) {
391 		case 0x28: /* LDR Rx,Ry   */
392 			signal = math_emu_ldr(opcode);
393 			break;
394 		case 0x38: /* LER Rx,Ry   */
395 			signal = math_emu_ler(opcode);
396 			break;
397 		case 0x60: /* STD R,D(X,B) */
398 			get_user(*((__u16 *) (opcode+2)), location+1);
399 			signal = math_emu_std(opcode, regs);
400 			break;
401 		case 0x68: /* LD R,D(X,B) */
402 			get_user(*((__u16 *) (opcode+2)), location+1);
403 			signal = math_emu_ld(opcode, regs);
404 			break;
405 		case 0x70: /* STE R,D(X,B) */
406 			get_user(*((__u16 *) (opcode+2)), location+1);
407 			signal = math_emu_ste(opcode, regs);
408 			break;
409 		case 0x78: /* LE R,D(X,B) */
410 			get_user(*((__u16 *) (opcode+2)), location+1);
411 			signal = math_emu_le(opcode, regs);
412 			break;
413 		case 0xb3:
414 			get_user(*((__u16 *) (opcode+2)), location+1);
415 			signal = math_emu_b3(opcode, regs);
416 			break;
417                 case 0xed:
418 			get_user(*((__u32 *) (opcode+2)),
419 				 (__u32 __user *)(location+1));
420 			signal = math_emu_ed(opcode, regs);
421 			break;
422 	        case 0xb2:
423 			if (opcode[1] == 0x99) {
424 				get_user(*((__u16 *) (opcode+2)), location+1);
425 				signal = math_emu_srnm(opcode, regs);
426 			} else if (opcode[1] == 0x9c) {
427 				get_user(*((__u16 *) (opcode+2)), location+1);
428 				signal = math_emu_stfpc(opcode, regs);
429 			} else if (opcode[1] == 0x9d) {
430 				get_user(*((__u16 *) (opcode+2)), location+1);
431 				signal = math_emu_lfpc(opcode, regs);
432 			} else
433 				signal = SIGILL;
434 			break;
435 		default:
436 			signal = SIGILL;
437 			break;
438                 }
439         }
440 #endif
441 #ifdef CONFIG_64BIT
442 	/* Check for vector register enablement */
443 	if (MACHINE_HAS_VX && !current->thread.vxrs &&
444 	    (current->thread.fp_regs.fpc & FPC_DXC_MASK) == 0xfe00) {
445 		alloc_vector_registers(current);
446 		/* Vector data exception is suppressing, rewind psw. */
447 		regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
448 		clear_pt_regs_flag(regs, PIF_PER_TRAP);
449 		return;
450 	}
451 #endif
452 
453 	if (current->thread.fp_regs.fpc & FPC_DXC_MASK)
454 		signal = SIGFPE;
455 	else
456 		signal = SIGILL;
457         if (signal == SIGFPE)
458 		do_fp_trap(regs, current->thread.fp_regs.fpc);
459 	else if (signal)
460 		do_trap(regs, signal, ILL_ILLOPN, "data exception");
461 }
462 
463 void space_switch_exception(struct pt_regs *regs)
464 {
465 	/* Set user psw back to home space mode. */
466 	if (user_mode(regs))
467 		regs->psw.mask |= PSW_ASC_HOME;
468 	/* Send SIGILL. */
469 	do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
470 }
471 
472 void __kprobes kernel_stack_overflow(struct pt_regs * regs)
473 {
474 	bust_spinlocks(1);
475 	printk("Kernel stack overflow.\n");
476 	show_regs(regs);
477 	bust_spinlocks(0);
478 	panic("Corrupt kernel stack, can't continue.");
479 }
480 
481 void __init trap_init(void)
482 {
483 	local_mcck_enable();
484 }
485