arch/s390/kernel/traps.c

   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 }