xref: /linux/arch/s390/kernel/traps.c (revision 905e46acd3272d04566fec49afbd7ad9e2ed9ae3)
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/extable.h>
18 #include <linux/ptrace.h>
19 #include <linux/sched.h>
20 #include <linux/sched/debug.h>
21 #include <linux/mm.h>
22 #include <linux/slab.h>
23 #include <linux/uaccess.h>
24 #include <asm/fpu/api.h>
25 #include "entry.h"
26 
27 static inline void __user *get_trap_ip(struct pt_regs *regs)
28 {
29 	unsigned long address;
30 
31 	if (regs->int_code & 0x200)
32 		address = *(unsigned long *)(current->thread.trap_tdb + 24);
33 	else
34 		address = regs->psw.addr;
35 	return (void __user *) (address - (regs->int_code >> 16));
36 }
37 
38 int is_valid_bugaddr(unsigned long addr)
39 {
40 	return 1;
41 }
42 
43 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
44 {
45 	siginfo_t info;
46 
47 	if (user_mode(regs)) {
48 		info.si_signo = si_signo;
49 		info.si_errno = 0;
50 		info.si_code = si_code;
51 		info.si_addr = get_trap_ip(regs);
52 		force_sig_info(si_signo, &info, current);
53 		report_user_fault(regs, si_signo, 0);
54         } else {
55                 const struct exception_table_entry *fixup;
56 		fixup = search_exception_tables(regs->psw.addr);
57                 if (fixup)
58 			regs->psw.addr = extable_fixup(fixup);
59 		else {
60 			enum bug_trap_type btt;
61 
62 			btt = report_bug(regs->psw.addr, regs);
63 			if (btt == BUG_TRAP_TYPE_WARN)
64 				return;
65 			die(regs, str);
66 		}
67         }
68 }
69 
70 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
71 {
72 	if (notify_die(DIE_TRAP, str, regs, 0,
73 		       regs->int_code, si_signo) == NOTIFY_STOP)
74 		return;
75 	do_report_trap(regs, si_signo, si_code, str);
76 }
77 NOKPROBE_SYMBOL(do_trap);
78 
79 void do_per_trap(struct pt_regs *regs)
80 {
81 	siginfo_t info;
82 
83 	if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
84 		return;
85 	if (!current->ptrace)
86 		return;
87 	info.si_signo = SIGTRAP;
88 	info.si_errno = 0;
89 	info.si_code = TRAP_HWBKPT;
90 	info.si_addr =
91 		(void __force __user *) current->thread.per_event.address;
92 	force_sig_info(SIGTRAP, &info, current);
93 }
94 NOKPROBE_SYMBOL(do_per_trap);
95 
96 void default_trap_handler(struct pt_regs *regs)
97 {
98 	if (user_mode(regs)) {
99 		report_user_fault(regs, SIGSEGV, 0);
100 		do_exit(SIGSEGV);
101 	} else
102 		die(regs, "Unknown program exception");
103 }
104 
105 #define DO_ERROR_INFO(name, signr, sicode, str) \
106 void name(struct pt_regs *regs)			\
107 {						\
108 	do_trap(regs, signr, sicode, str);	\
109 }
110 
111 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
112 	      "addressing exception")
113 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
114 	      "execute exception")
115 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
116 	      "fixpoint divide exception")
117 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
118 	      "fixpoint overflow exception")
119 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
120 	      "HFP overflow exception")
121 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
122 	      "HFP underflow exception")
123 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
124 	      "HFP significance exception")
125 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
126 	      "HFP divide exception")
127 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
128 	      "HFP square root exception")
129 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
130 	      "operand exception")
131 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
132 	      "privileged operation")
133 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
134 	      "special operation exception")
135 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
136 	      "transaction constraint exception")
137 
138 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
139 {
140 	int si_code = 0;
141 	/* FPC[2] is Data Exception Code */
142 	if ((fpc & 0x00000300) == 0) {
143 		/* bits 6 and 7 of DXC are 0 iff IEEE exception */
144 		if (fpc & 0x8000) /* invalid fp operation */
145 			si_code = FPE_FLTINV;
146 		else if (fpc & 0x4000) /* div by 0 */
147 			si_code = FPE_FLTDIV;
148 		else if (fpc & 0x2000) /* overflow */
149 			si_code = FPE_FLTOVF;
150 		else if (fpc & 0x1000) /* underflow */
151 			si_code = FPE_FLTUND;
152 		else if (fpc & 0x0800) /* inexact */
153 			si_code = FPE_FLTRES;
154 	}
155 	do_trap(regs, SIGFPE, si_code, "floating point exception");
156 }
157 
158 void translation_exception(struct pt_regs *regs)
159 {
160 	/* May never happen. */
161 	panic("Translation exception");
162 }
163 
164 void illegal_op(struct pt_regs *regs)
165 {
166 	siginfo_t info;
167         __u8 opcode[6];
168 	__u16 __user *location;
169 	int is_uprobe_insn = 0;
170 	int signal = 0;
171 
172 	location = get_trap_ip(regs);
173 
174 	if (user_mode(regs)) {
175 		if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
176 			return;
177 		if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
178 			if (current->ptrace) {
179 				info.si_signo = SIGTRAP;
180 				info.si_errno = 0;
181 				info.si_code = TRAP_BRKPT;
182 				info.si_addr = location;
183 				force_sig_info(SIGTRAP, &info, current);
184 			} else
185 				signal = SIGILL;
186 #ifdef CONFIG_UPROBES
187 		} else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
188 			is_uprobe_insn = 1;
189 #endif
190 		} else
191 			signal = SIGILL;
192 	}
193 	/*
194 	 * We got either an illegal op in kernel mode, or user space trapped
195 	 * on a uprobes illegal instruction. See if kprobes or uprobes picks
196 	 * it up. If not, SIGILL.
197 	 */
198 	if (is_uprobe_insn || !user_mode(regs)) {
199 		if (notify_die(DIE_BPT, "bpt", regs, 0,
200 			       3, SIGTRAP) != NOTIFY_STOP)
201 			signal = SIGILL;
202 	}
203 	if (signal)
204 		do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
205 }
206 NOKPROBE_SYMBOL(illegal_op);
207 
208 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
209 	      "specification exception");
210 
211 void vector_exception(struct pt_regs *regs)
212 {
213 	int si_code, vic;
214 
215 	if (!MACHINE_HAS_VX) {
216 		do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
217 		return;
218 	}
219 
220 	/* get vector interrupt code from fpc */
221 	save_fpu_regs();
222 	vic = (current->thread.fpu.fpc & 0xf00) >> 8;
223 	switch (vic) {
224 	case 1: /* invalid vector operation */
225 		si_code = FPE_FLTINV;
226 		break;
227 	case 2: /* division by zero */
228 		si_code = FPE_FLTDIV;
229 		break;
230 	case 3: /* overflow */
231 		si_code = FPE_FLTOVF;
232 		break;
233 	case 4: /* underflow */
234 		si_code = FPE_FLTUND;
235 		break;
236 	case 5:	/* inexact */
237 		si_code = FPE_FLTRES;
238 		break;
239 	default: /* unknown cause */
240 		si_code = 0;
241 	}
242 	do_trap(regs, SIGFPE, si_code, "vector exception");
243 }
244 
245 void data_exception(struct pt_regs *regs)
246 {
247 	int signal = 0;
248 
249 	save_fpu_regs();
250 	if (current->thread.fpu.fpc & FPC_DXC_MASK)
251 		signal = SIGFPE;
252 	else
253 		signal = SIGILL;
254 	if (signal == SIGFPE)
255 		do_fp_trap(regs, current->thread.fpu.fpc);
256 	else if (signal)
257 		do_trap(regs, signal, ILL_ILLOPN, "data exception");
258 }
259 
260 void space_switch_exception(struct pt_regs *regs)
261 {
262 	/* Set user psw back to home space mode. */
263 	if (user_mode(regs))
264 		regs->psw.mask |= PSW_ASC_HOME;
265 	/* Send SIGILL. */
266 	do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
267 }
268 
269 void kernel_stack_overflow(struct pt_regs *regs)
270 {
271 	bust_spinlocks(1);
272 	printk("Kernel stack overflow.\n");
273 	show_regs(regs);
274 	bust_spinlocks(0);
275 	panic("Corrupt kernel stack, can't continue.");
276 }
277 NOKPROBE_SYMBOL(kernel_stack_overflow);
278 
279 void __init trap_init(void)
280 {
281 	local_mcck_enable();
282 }
283