xref: /openbmc/linux/arch/s390/kernel/traps.c (revision fbb6b31a) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  S390 version
4  *    Copyright IBM Corp. 1999, 2000
5  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
6  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
7  *
8  *  Derived from "arch/i386/kernel/traps.c"
9  *    Copyright (C) 1991, 1992 Linus Torvalds
10  */
11 
12 /*
13  * 'Traps.c' handles hardware traps and faults after we have saved some
14  * state in 'asm.s'.
15  */
16 #include "asm/irqflags.h"
17 #include "asm/ptrace.h"
18 #include <linux/kprobes.h>
19 #include <linux/kdebug.h>
20 #include <linux/randomize_kstack.h>
21 #include <linux/extable.h>
22 #include <linux/ptrace.h>
23 #include <linux/sched.h>
24 #include <linux/sched/debug.h>
25 #include <linux/mm.h>
26 #include <linux/slab.h>
27 #include <linux/uaccess.h>
28 #include <linux/cpu.h>
29 #include <linux/entry-common.h>
30 #include <asm/asm-extable.h>
31 #include <asm/fpu/api.h>
32 #include <asm/vtime.h>
33 #include "entry.h"
34 
35 static inline void __user *get_trap_ip(struct pt_regs *regs)
36 {
37 	unsigned long address;
38 
39 	if (regs->int_code & 0x200)
40 		address = current->thread.trap_tdb.data[3];
41 	else
42 		address = regs->psw.addr;
43 	return (void __user *) (address - (regs->int_code >> 16));
44 }
45 
46 int is_valid_bugaddr(unsigned long addr)
47 {
48 	return 1;
49 }
50 
51 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
52 {
53 	if (user_mode(regs)) {
54 		force_sig_fault(si_signo, si_code, get_trap_ip(regs));
55 		report_user_fault(regs, si_signo, 0);
56         } else {
57 		if (!fixup_exception(regs))
58 			die(regs, str);
59         }
60 }
61 
62 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
63 {
64 	if (notify_die(DIE_TRAP, str, regs, 0,
65 		       regs->int_code, si_signo) == NOTIFY_STOP)
66 		return;
67 	do_report_trap(regs, si_signo, si_code, str);
68 }
69 NOKPROBE_SYMBOL(do_trap);
70 
71 void do_per_trap(struct pt_regs *regs)
72 {
73 	if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
74 		return;
75 	if (!current->ptrace)
76 		return;
77 	force_sig_fault(SIGTRAP, TRAP_HWBKPT,
78 		(void __force __user *) current->thread.per_event.address);
79 }
80 NOKPROBE_SYMBOL(do_per_trap);
81 
82 static void default_trap_handler(struct pt_regs *regs)
83 {
84 	if (user_mode(regs)) {
85 		report_user_fault(regs, SIGSEGV, 0);
86 		force_exit_sig(SIGSEGV);
87 	} else
88 		die(regs, "Unknown program exception");
89 }
90 
91 #define DO_ERROR_INFO(name, signr, sicode, str) \
92 static void name(struct pt_regs *regs)		\
93 {						\
94 	do_trap(regs, signr, sicode, str);	\
95 }
96 
97 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
98 	      "addressing exception")
99 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
100 	      "execute exception")
101 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
102 	      "fixpoint divide exception")
103 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
104 	      "fixpoint overflow exception")
105 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
106 	      "HFP overflow exception")
107 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
108 	      "HFP underflow exception")
109 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
110 	      "HFP significance exception")
111 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
112 	      "HFP divide exception")
113 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
114 	      "HFP square root exception")
115 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
116 	      "operand exception")
117 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
118 	      "privileged operation")
119 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
120 	      "special operation exception")
121 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
122 	      "transaction constraint exception")
123 
124 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
125 {
126 	int si_code = 0;
127 	/* FPC[2] is Data Exception Code */
128 	if ((fpc & 0x00000300) == 0) {
129 		/* bits 6 and 7 of DXC are 0 iff IEEE exception */
130 		if (fpc & 0x8000) /* invalid fp operation */
131 			si_code = FPE_FLTINV;
132 		else if (fpc & 0x4000) /* div by 0 */
133 			si_code = FPE_FLTDIV;
134 		else if (fpc & 0x2000) /* overflow */
135 			si_code = FPE_FLTOVF;
136 		else if (fpc & 0x1000) /* underflow */
137 			si_code = FPE_FLTUND;
138 		else if (fpc & 0x0800) /* inexact */
139 			si_code = FPE_FLTRES;
140 	}
141 	do_trap(regs, SIGFPE, si_code, "floating point exception");
142 }
143 
144 static void translation_specification_exception(struct pt_regs *regs)
145 {
146 	/* May never happen. */
147 	panic("Translation-Specification Exception");
148 }
149 
150 static void illegal_op(struct pt_regs *regs)
151 {
152         __u8 opcode[6];
153 	__u16 __user *location;
154 	int is_uprobe_insn = 0;
155 	int signal = 0;
156 
157 	location = get_trap_ip(regs);
158 
159 	if (user_mode(regs)) {
160 		if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
161 			return;
162 		if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
163 			if (current->ptrace)
164 				force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
165 			else
166 				signal = SIGILL;
167 #ifdef CONFIG_UPROBES
168 		} else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
169 			is_uprobe_insn = 1;
170 #endif
171 		} else
172 			signal = SIGILL;
173 	}
174 	/*
175 	 * We got either an illegal op in kernel mode, or user space trapped
176 	 * on a uprobes illegal instruction. See if kprobes or uprobes picks
177 	 * it up. If not, SIGILL.
178 	 */
179 	if (is_uprobe_insn || !user_mode(regs)) {
180 		if (notify_die(DIE_BPT, "bpt", regs, 0,
181 			       3, SIGTRAP) != NOTIFY_STOP)
182 			signal = SIGILL;
183 	}
184 	if (signal)
185 		do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
186 }
187 NOKPROBE_SYMBOL(illegal_op);
188 
189 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
190 	      "specification exception");
191 
192 static void vector_exception(struct pt_regs *regs)
193 {
194 	int si_code, vic;
195 
196 	if (!MACHINE_HAS_VX) {
197 		do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
198 		return;
199 	}
200 
201 	/* get vector interrupt code from fpc */
202 	save_fpu_regs();
203 	vic = (current->thread.fpu.fpc & 0xf00) >> 8;
204 	switch (vic) {
205 	case 1: /* invalid vector operation */
206 		si_code = FPE_FLTINV;
207 		break;
208 	case 2: /* division by zero */
209 		si_code = FPE_FLTDIV;
210 		break;
211 	case 3: /* overflow */
212 		si_code = FPE_FLTOVF;
213 		break;
214 	case 4: /* underflow */
215 		si_code = FPE_FLTUND;
216 		break;
217 	case 5:	/* inexact */
218 		si_code = FPE_FLTRES;
219 		break;
220 	default: /* unknown cause */
221 		si_code = 0;
222 	}
223 	do_trap(regs, SIGFPE, si_code, "vector exception");
224 }
225 
226 static void data_exception(struct pt_regs *regs)
227 {
228 	save_fpu_regs();
229 	if (current->thread.fpu.fpc & FPC_DXC_MASK)
230 		do_fp_trap(regs, current->thread.fpu.fpc);
231 	else
232 		do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
233 }
234 
235 static void space_switch_exception(struct pt_regs *regs)
236 {
237 	/* Set user psw back to home space mode. */
238 	if (user_mode(regs))
239 		regs->psw.mask |= PSW_ASC_HOME;
240 	/* Send SIGILL. */
241 	do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
242 }
243 
244 static void monitor_event_exception(struct pt_regs *regs)
245 {
246 	if (user_mode(regs))
247 		return;
248 
249 	switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
250 	case BUG_TRAP_TYPE_NONE:
251 		fixup_exception(regs);
252 		break;
253 	case BUG_TRAP_TYPE_WARN:
254 		break;
255 	case BUG_TRAP_TYPE_BUG:
256 		die(regs, "monitor event");
257 		break;
258 	}
259 }
260 
261 void kernel_stack_overflow(struct pt_regs *regs)
262 {
263 	bust_spinlocks(1);
264 	printk("Kernel stack overflow.\n");
265 	show_regs(regs);
266 	bust_spinlocks(0);
267 	panic("Corrupt kernel stack, can't continue.");
268 }
269 NOKPROBE_SYMBOL(kernel_stack_overflow);
270 
271 static void __init test_monitor_call(void)
272 {
273 	int val = 1;
274 
275 	if (!IS_ENABLED(CONFIG_BUG))
276 		return;
277 	asm volatile(
278 		"	mc	0,0\n"
279 		"0:	xgr	%0,%0\n"
280 		"1:\n"
281 		EX_TABLE(0b,1b)
282 		: "+d" (val));
283 	if (!val)
284 		panic("Monitor call doesn't work!\n");
285 }
286 
287 void __init trap_init(void)
288 {
289 	local_mcck_enable();
290 	test_monitor_call();
291 }
292 
293 static void (*pgm_check_table[128])(struct pt_regs *regs);
294 
295 void noinstr __do_pgm_check(struct pt_regs *regs)
296 {
297 	unsigned int trapnr;
298 	irqentry_state_t state;
299 
300 	regs->int_code = S390_lowcore.pgm_int_code;
301 	regs->int_parm_long = S390_lowcore.trans_exc_code;
302 
303 	state = irqentry_enter(regs);
304 
305 	if (user_mode(regs)) {
306 		update_timer_sys();
307 		if (!static_branch_likely(&cpu_has_bear)) {
308 			if (regs->last_break < 4096)
309 				regs->last_break = 1;
310 		}
311 		current->thread.last_break = regs->last_break;
312 	}
313 
314 	if (S390_lowcore.pgm_code & 0x0200) {
315 		/* transaction abort */
316 		current->thread.trap_tdb = S390_lowcore.pgm_tdb;
317 	}
318 
319 	if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
320 		if (user_mode(regs)) {
321 			struct per_event *ev = &current->thread.per_event;
322 
323 			set_thread_flag(TIF_PER_TRAP);
324 			ev->address = S390_lowcore.per_address;
325 			ev->cause = S390_lowcore.per_code_combined;
326 			ev->paid = S390_lowcore.per_access_id;
327 		} else {
328 			/* PER event in kernel is kprobes */
329 			__arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
330 			do_per_trap(regs);
331 			goto out;
332 		}
333 	}
334 
335 	if (!irqs_disabled_flags(regs->psw.mask))
336 		trace_hardirqs_on();
337 	__arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
338 
339 	trapnr = regs->int_code & PGM_INT_CODE_MASK;
340 	if (trapnr)
341 		pgm_check_table[trapnr](regs);
342 out:
343 	local_irq_disable();
344 	irqentry_exit(regs, state);
345 }
346 
347 /*
348  * The program check table contains exactly 128 (0x00-0x7f) entries. Each
349  * line defines the function to be called corresponding to the program check
350  * interruption code.
351  */
352 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
353 	[0x00]		= default_trap_handler,
354 	[0x01]		= illegal_op,
355 	[0x02]		= privileged_op,
356 	[0x03]		= execute_exception,
357 	[0x04]		= do_protection_exception,
358 	[0x05]		= addressing_exception,
359 	[0x06]		= specification_exception,
360 	[0x07]		= data_exception,
361 	[0x08]		= overflow_exception,
362 	[0x09]		= divide_exception,
363 	[0x0a]		= overflow_exception,
364 	[0x0b]		= divide_exception,
365 	[0x0c]		= hfp_overflow_exception,
366 	[0x0d]		= hfp_underflow_exception,
367 	[0x0e]		= hfp_significance_exception,
368 	[0x0f]		= hfp_divide_exception,
369 	[0x10]		= do_dat_exception,
370 	[0x11]		= do_dat_exception,
371 	[0x12]		= translation_specification_exception,
372 	[0x13]		= special_op_exception,
373 	[0x14]		= default_trap_handler,
374 	[0x15]		= operand_exception,
375 	[0x16]		= default_trap_handler,
376 	[0x17]		= default_trap_handler,
377 	[0x18]		= transaction_exception,
378 	[0x19]		= default_trap_handler,
379 	[0x1a]		= default_trap_handler,
380 	[0x1b]		= vector_exception,
381 	[0x1c]		= space_switch_exception,
382 	[0x1d]		= hfp_sqrt_exception,
383 	[0x1e ... 0x37] = default_trap_handler,
384 	[0x38]		= do_dat_exception,
385 	[0x39]		= do_dat_exception,
386 	[0x3a]		= do_dat_exception,
387 	[0x3b]		= do_dat_exception,
388 	[0x3c]		= default_trap_handler,
389 	[0x3d]		= do_secure_storage_access,
390 	[0x3e]		= do_non_secure_storage_access,
391 	[0x3f]		= do_secure_storage_violation,
392 	[0x40]		= monitor_event_exception,
393 	[0x41 ... 0x7f] = default_trap_handler,
394 };
395 
396 #define COND_TRAP(x) asm(			\
397 	".weak " __stringify(x) "\n\t"		\
398 	".set  " __stringify(x) ","		\
399 	__stringify(default_trap_handler))
400 
401 COND_TRAP(do_secure_storage_access);
402 COND_TRAP(do_non_secure_storage_access);
403 COND_TRAP(do_secure_storage_violation);
404