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Linux/arch/s390/kernel/traps.c

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  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 <linux/kprobes.h>
 17 #include <linux/kdebug.h>
 18 #include <linux/extable.h>
 19 #include <linux/ptrace.h>
 20 #include <linux/sched.h>
 21 #include <linux/sched/debug.h>
 22 #include <linux/mm.h>
 23 #include <linux/slab.h>
 24 #include <linux/uaccess.h>
 25 #include <linux/cpu.h>
 26 #include <asm/fpu/api.h>
 27 #include "entry.h"
 28 
 29 static inline void __user *get_trap_ip(struct pt_regs *regs)
 30 {
 31         unsigned long address;
 32 
 33         if (regs->int_code & 0x200)
 34                 address = *(unsigned long *)(current->thread.trap_tdb + 24);
 35         else
 36                 address = regs->psw.addr;
 37         return (void __user *) (address - (regs->int_code >> 16));
 38 }
 39 
 40 int is_valid_bugaddr(unsigned long addr)
 41 {
 42         return 1;
 43 }
 44 
 45 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
 46 {
 47         siginfo_t info;
 48 
 49         if (user_mode(regs)) {
 50                 info.si_signo = si_signo;
 51                 info.si_errno = 0;
 52                 info.si_code = si_code;
 53                 info.si_addr = get_trap_ip(regs);
 54                 force_sig_info(si_signo, &info, current);
 55                 report_user_fault(regs, si_signo, 0);
 56         } else {
 57                 const struct exception_table_entry *fixup;
 58                 fixup = search_exception_tables(regs->psw.addr);
 59                 if (fixup)
 60                         regs->psw.addr = extable_fixup(fixup);
 61                 else {
 62                         enum bug_trap_type btt;
 63 
 64                         btt = report_bug(regs->psw.addr, regs);
 65                         if (btt == BUG_TRAP_TYPE_WARN)
 66                                 return;
 67                         die(regs, str);
 68                 }
 69         }
 70 }
 71 
 72 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
 73 {
 74         if (notify_die(DIE_TRAP, str, regs, 0,
 75                        regs->int_code, si_signo) == NOTIFY_STOP)
 76                 return;
 77         do_report_trap(regs, si_signo, si_code, str);
 78 }
 79 NOKPROBE_SYMBOL(do_trap);
 80 
 81 void do_per_trap(struct pt_regs *regs)
 82 {
 83         siginfo_t info;
 84 
 85         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
 86                 return;
 87         if (!current->ptrace)
 88                 return;
 89         info.si_signo = SIGTRAP;
 90         info.si_errno = 0;
 91         info.si_code = TRAP_HWBKPT;
 92         info.si_addr =
 93                 (void __force __user *) current->thread.per_event.address;
 94         force_sig_info(SIGTRAP, &info, current);
 95 }
 96 NOKPROBE_SYMBOL(do_per_trap);
 97 
 98 void default_trap_handler(struct pt_regs *regs)
 99 {
100         if (user_mode(regs)) {
101                 report_user_fault(regs, SIGSEGV, 0);
102                 do_exit(SIGSEGV);
103         } else
104                 die(regs, "Unknown program exception");
105 }
106 
107 #define DO_ERROR_INFO(name, signr, sicode, str) \
108 void name(struct pt_regs *regs)                 \
109 {                                               \
110         do_trap(regs, signr, sicode, str);      \
111 }
112 
113 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
114               "addressing exception")
115 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
116               "execute exception")
117 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
118               "fixpoint divide exception")
119 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
120               "fixpoint overflow exception")
121 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
122               "HFP overflow exception")
123 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
124               "HFP underflow exception")
125 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
126               "HFP significance exception")
127 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
128               "HFP divide exception")
129 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
130               "HFP square root exception")
131 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
132               "operand exception")
133 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
134               "privileged operation")
135 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
136               "special operation exception")
137 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
138               "transaction constraint exception")
139 
140 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
141 {
142         int si_code = 0;
143         /* FPC[2] is Data Exception Code */
144         if ((fpc & 0x00000300) == 0) {
145                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
146                 if (fpc & 0x8000) /* invalid fp operation */
147                         si_code = FPE_FLTINV;
148                 else if (fpc & 0x4000) /* div by 0 */
149                         si_code = FPE_FLTDIV;
150                 else if (fpc & 0x2000) /* overflow */
151                         si_code = FPE_FLTOVF;
152                 else if (fpc & 0x1000) /* underflow */
153                         si_code = FPE_FLTUND;
154                 else if (fpc & 0x0800) /* inexact */
155                         si_code = FPE_FLTRES;
156         }
157         do_trap(regs, SIGFPE, si_code, "floating point exception");
158 }
159 
160 void translation_exception(struct pt_regs *regs)
161 {
162         /* May never happen. */
163         panic("Translation exception");
164 }
165 
166 void illegal_op(struct pt_regs *regs)
167 {
168         siginfo_t info;
169         __u8 opcode[6];
170         __u16 __user *location;
171         int is_uprobe_insn = 0;
172         int signal = 0;
173 
174         location = get_trap_ip(regs);
175 
176         if (user_mode(regs)) {
177                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
178                         return;
179                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
180                         if (current->ptrace) {
181                                 info.si_signo = SIGTRAP;
182                                 info.si_errno = 0;
183                                 info.si_code = TRAP_BRKPT;
184                                 info.si_addr = location;
185                                 force_sig_info(SIGTRAP, &info, current);
186                         } else
187                                 signal = SIGILL;
188 #ifdef CONFIG_UPROBES
189                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
190                         is_uprobe_insn = 1;
191 #endif
192                 } else
193                         signal = SIGILL;
194         }
195         /*
196          * We got either an illegal op in kernel mode, or user space trapped
197          * on a uprobes illegal instruction. See if kprobes or uprobes picks
198          * it up. If not, SIGILL.
199          */
200         if (is_uprobe_insn || !user_mode(regs)) {
201                 if (notify_die(DIE_BPT, "bpt", regs, 0,
202                                3, SIGTRAP) != NOTIFY_STOP)
203                         signal = SIGILL;
204         }
205         if (signal)
206                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
207 }
208 NOKPROBE_SYMBOL(illegal_op);
209 
210 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
211               "specification exception");
212 
213 void vector_exception(struct pt_regs *regs)
214 {
215         int si_code, vic;
216 
217         if (!MACHINE_HAS_VX) {
218                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
219                 return;
220         }
221 
222         /* get vector interrupt code from fpc */
223         save_fpu_regs();
224         vic = (current->thread.fpu.fpc & 0xf00) >> 8;
225         switch (vic) {
226         case 1: /* invalid vector operation */
227                 si_code = FPE_FLTINV;
228                 break;
229         case 2: /* division by zero */
230                 si_code = FPE_FLTDIV;
231                 break;
232         case 3: /* overflow */
233                 si_code = FPE_FLTOVF;
234                 break;
235         case 4: /* underflow */
236                 si_code = FPE_FLTUND;
237                 break;
238         case 5: /* inexact */
239                 si_code = FPE_FLTRES;
240                 break;
241         default: /* unknown cause */
242                 si_code = 0;
243         }
244         do_trap(regs, SIGFPE, si_code, "vector exception");
245 }
246 
247 void data_exception(struct pt_regs *regs)
248 {
249         int signal = 0;
250 
251         save_fpu_regs();
252         if (current->thread.fpu.fpc & FPC_DXC_MASK)
253                 signal = SIGFPE;
254         else
255                 signal = SIGILL;
256         if (signal == SIGFPE)
257                 do_fp_trap(regs, current->thread.fpu.fpc);
258         else if (signal)
259                 do_trap(regs, signal, ILL_ILLOPN, "data exception");
260 }
261 
262 void space_switch_exception(struct pt_regs *regs)
263 {
264         /* Set user psw back to home space mode. */
265         if (user_mode(regs))
266                 regs->psw.mask |= PSW_ASC_HOME;
267         /* Send SIGILL. */
268         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
269 }
270 
271 void kernel_stack_overflow(struct pt_regs *regs)
272 {
273         bust_spinlocks(1);
274         printk("Kernel stack overflow.\n");
275         show_regs(regs);
276         bust_spinlocks(0);
277         panic("Corrupt kernel stack, can't continue.");
278 }
279 NOKPROBE_SYMBOL(kernel_stack_overflow);
280 
281 void __init trap_init(void)
282 {
283         local_mcck_enable();
284 }
285 

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