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         if (user_mode(regs)) {
  48                 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
  49                 report_user_fault(regs, si_signo, 0);
  50         } else {
  51                 const struct exception_table_entry *fixup;
  52                 fixup = s390_search_extables(regs->psw.addr);
  53                 if (!fixup || !ex_handle(fixup, regs))
  54                         die(regs, str);
  55         }
  56 }
  57
  58 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  59 {
  60         if (notify_die(DIE_TRAP, str, regs, 0,
  61                        regs->int_code, si_signo) == NOTIFY_STOP)
  62                 return;
  63         do_report_trap(regs, si_signo, si_code, str);
  64 }
  65 NOKPROBE_SYMBOL(do_trap);
  66
  67 void do_per_trap(struct pt_regs *regs)
  68 {
  69         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
  70                 return;
  71         if (!current->ptrace)
  72                 return;
  73         force_sig_fault(SIGTRAP, TRAP_HWBKPT,
  74                 (void __force __user *) current->thread.per_event.address);
  75 }
  76 NOKPROBE_SYMBOL(do_per_trap);
  77
  78 void default_trap_handler(struct pt_regs *regs)
  79 {
  80         if (user_mode(regs)) {
  81                 report_user_fault(regs, SIGSEGV, 0);
  82                 do_exit(SIGSEGV);
  83         } else
  84                 die(regs, "Unknown program exception");
  85 }
  86
  87 #define DO_ERROR_INFO(name, signr, sicode, str) \
  88 void name(struct pt_regs *regs)                 \
  89 {                                               \
  90         do_trap(regs, signr, sicode, str);      \
  91 }
  92
  93 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
  94               "addressing exception")
  95 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
  96               "execute exception")
  97 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
  98               "fixpoint divide exception")
  99 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 100               "fixpoint overflow exception")
 101 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 102               "HFP overflow exception")
 103 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 104               "HFP underflow exception")
 105 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 106               "HFP significance exception")
 107 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 108               "HFP divide exception")
 109 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 110               "HFP square root exception")
 111 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 112               "operand exception")
 113 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 114               "privileged operation")
 115 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 116               "special operation exception")
 117 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 118               "transaction constraint exception")
 119
 120 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
 121 {
 122         int si_code = 0;
 123         /* FPC[2] is Data Exception Code */
 124         if ((fpc & 0x00000300) == 0) {
 125                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 126                 if (fpc & 0x8000) /* invalid fp operation */
 127                         si_code = FPE_FLTINV;
 128                 else if (fpc & 0x4000) /* div by 0 */
 129                         si_code = FPE_FLTDIV;
 130                 else if (fpc & 0x2000) /* overflow */
 131                         si_code = FPE_FLTOVF;
 132                 else if (fpc & 0x1000) /* underflow */
 133                         si_code = FPE_FLTUND;
 134                 else if (fpc & 0x0800) /* inexact */
 135                         si_code = FPE_FLTRES;
 136         }
 137         do_trap(regs, SIGFPE, si_code, "floating point exception");
 138 }
 139
 140 void translation_exception(struct pt_regs *regs)
 141 {
 142         /* May never happen. */
 143         panic("Translation exception");
 144 }
 145
 146 void illegal_op(struct pt_regs *regs)
 147 {
 148         __u8 opcode[6];
 149         __u16 __user *location;
 150         int is_uprobe_insn = 0;
 151         int signal = 0;
 152
 153         location = get_trap_ip(regs);
 154
 155         if (user_mode(regs)) {
 156                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 157                         return;
 158                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 159                         if (current->ptrace)
 160                                 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
 161                         else
 162                                 signal = SIGILL;
 163 #ifdef CONFIG_UPROBES
 164                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 165                         is_uprobe_insn = 1;
 166 #endif
 167                 } else
 168                         signal = SIGILL;
 169         }
 170         /*
 171          * We got either an illegal op in kernel mode, or user space trapped
 172          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 173          * it up. If not, SIGILL.
 174          */
 175         if (is_uprobe_insn || !user_mode(regs)) {
 176                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 177                                3, SIGTRAP) != NOTIFY_STOP)
 178                         signal = SIGILL;
 179         }
 180         if (signal)
 181                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 182 }
 183 NOKPROBE_SYMBOL(illegal_op);
 184
 185 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 186               "specification exception");
 187
 188 void vector_exception(struct pt_regs *regs)
 189 {
 190         int si_code, vic;
 191
 192         if (!MACHINE_HAS_VX) {
 193                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 194                 return;
 195         }
 196
 197         /* get vector interrupt code from fpc */
 198         save_fpu_regs();
 199         vic = (current->thread.fpu.fpc & 0xf00) >> 8;
 200         switch (vic) {
 201         case 1: /* invalid vector operation */
 202                 si_code = FPE_FLTINV;
 203                 break;
 204         case 2: /* division by zero */
 205                 si_code = FPE_FLTDIV;
 206                 break;
 207         case 3: /* overflow */
 208                 si_code = FPE_FLTOVF;
 209                 break;
 210         case 4: /* underflow */
 211                 si_code = FPE_FLTUND;
 212                 break;
 213         case 5: /* inexact */
 214                 si_code = FPE_FLTRES;
 215                 break;
 216         default: /* unknown cause */
 217                 si_code = 0;
 218         }
 219         do_trap(regs, SIGFPE, si_code, "vector exception");
 220 }
 221
 222 void data_exception(struct pt_regs *regs)
 223 {
 224         save_fpu_regs();
 225         if (current->thread.fpu.fpc & FPC_DXC_MASK)
 226                 do_fp_trap(regs, current->thread.fpu.fpc);
 227         else
 228                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 229 }
 230
 231 void space_switch_exception(struct pt_regs *regs)
 232 {
 233         /* Set user psw back to home space mode. */
 234         if (user_mode(regs))
 235                 regs->psw.mask |= PSW_ASC_HOME;
 236         /* Send SIGILL. */
 237         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 238 }
 239
 240 void monitor_event_exception(struct pt_regs *regs)
 241 {
 242         const struct exception_table_entry *fixup;
 243
 244         if (user_mode(regs))
 245                 return;
 246
 247         switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
 248         case BUG_TRAP_TYPE_NONE:
 249                 fixup = s390_search_extables(regs->psw.addr);
 250                 if (fixup)
 251                         ex_handle(fixup, 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         asm volatile(
 276                 "       mc      0,0\n"
 277                 "0:     xgr     %0,%0\n"
 278                 "1:\n"
 279                 EX_TABLE(0b,1b)
 280                 : "+d" (val));
 281         if (!val)
 282                 panic("Monitor call doesn't work!\n");
 283 }
 284
 285 void __init trap_init(void)
 286 {
 287         sort_extable(__start_dma_ex_table, __stop_dma_ex_table);
 288         local_mcck_enable();
 289         test_monitor_call();
 290 }