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)
  54                         regs->psw.addr = extable_fixup(fixup);
  55                 else {
  56                         die(regs, str);
  57                 }
  58         }
  59 }
  60
  61 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  62 {
  63         if (notify_die(DIE_TRAP, str, regs, 0,
  64                        regs->int_code, si_signo) == NOTIFY_STOP)
  65                 return;
  66         do_report_trap(regs, si_signo, si_code, str);
  67 }
  68 NOKPROBE_SYMBOL(do_trap);
  69
  70 void do_per_trap(struct pt_regs *regs)
  71 {
  72         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
  73                 return;
  74         if (!current->ptrace)
  75                 return;
  76         force_sig_fault(SIGTRAP, TRAP_HWBKPT,
  77                 (void __force __user *) current->thread.per_event.address);
  78 }
  79 NOKPROBE_SYMBOL(do_per_trap);
  80
  81 void default_trap_handler(struct pt_regs *regs)
  82 {
  83         if (user_mode(regs)) {
  84                 report_user_fault(regs, SIGSEGV, 0);
  85                 do_exit(SIGSEGV);
  86         } else
  87                 die(regs, "Unknown program exception");
  88 }
  89
  90 #define DO_ERROR_INFO(name, signr, sicode, str) \
  91 void name(struct pt_regs *regs)                 \
  92 {                                               \
  93         do_trap(regs, signr, sicode, str);      \
  94 }
  95
  96 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
  97               "addressing exception")
  98 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
  99               "execute exception")
 100 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 101               "fixpoint divide exception")
 102 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 103               "fixpoint overflow exception")
 104 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 105               "HFP overflow exception")
 106 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 107               "HFP underflow exception")
 108 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 109               "HFP significance exception")
 110 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 111               "HFP divide exception")
 112 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 113               "HFP square root exception")
 114 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 115               "operand exception")
 116 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 117               "privileged operation")
 118 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 119               "special operation exception")
 120 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 121               "transaction constraint exception")
 122
 123 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
 124 {
 125         int si_code = 0;
 126         /* FPC[2] is Data Exception Code */
 127         if ((fpc & 0x00000300) == 0) {
 128                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 129                 if (fpc & 0x8000) /* invalid fp operation */
 130                         si_code = FPE_FLTINV;
 131                 else if (fpc & 0x4000) /* div by 0 */
 132                         si_code = FPE_FLTDIV;
 133                 else if (fpc & 0x2000) /* overflow */
 134                         si_code = FPE_FLTOVF;
 135                 else if (fpc & 0x1000) /* underflow */
 136                         si_code = FPE_FLTUND;
 137                 else if (fpc & 0x0800) /* inexact */
 138                         si_code = FPE_FLTRES;
 139         }
 140         do_trap(regs, SIGFPE, si_code, "floating point exception");
 141 }
 142
 143 void translation_exception(struct pt_regs *regs)
 144 {
 145         /* May never happen. */
 146         panic("Translation exception");
 147 }
 148
 149 void illegal_op(struct pt_regs *regs)
 150 {
 151         __u8 opcode[6];
 152         __u16 __user *location;
 153         int is_uprobe_insn = 0;
 154         int signal = 0;
 155
 156         location = get_trap_ip(regs);
 157
 158         if (user_mode(regs)) {
 159                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 160                         return;
 161                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 162                         if (current->ptrace)
 163                                 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
 164                         else
 165                                 signal = SIGILL;
 166 #ifdef CONFIG_UPROBES
 167                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 168                         is_uprobe_insn = 1;
 169 #endif
 170                 } else
 171                         signal = SIGILL;
 172         }
 173         /*
 174          * We got either an illegal op in kernel mode, or user space trapped
 175          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 176          * it up. If not, SIGILL.
 177          */
 178         if (is_uprobe_insn || !user_mode(regs)) {
 179                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 180                                3, SIGTRAP) != NOTIFY_STOP)
 181                         signal = SIGILL;
 182         }
 183         if (signal)
 184                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 185 }
 186 NOKPROBE_SYMBOL(illegal_op);
 187
 188 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 189               "specification exception");
 190
 191 void vector_exception(struct pt_regs *regs)
 192 {
 193         int si_code, vic;
 194
 195         if (!MACHINE_HAS_VX) {
 196                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 197                 return;
 198         }
 199
 200         /* get vector interrupt code from fpc */
 201         save_fpu_regs();
 202         vic = (current->thread.fpu.fpc & 0xf00) >> 8;
 203         switch (vic) {
 204         case 1: /* invalid vector operation */
 205                 si_code = FPE_FLTINV;
 206                 break;
 207         case 2: /* division by zero */
 208                 si_code = FPE_FLTDIV;
 209                 break;
 210         case 3: /* overflow */
 211                 si_code = FPE_FLTOVF;
 212                 break;
 213         case 4: /* underflow */
 214                 si_code = FPE_FLTUND;
 215                 break;
 216         case 5: /* inexact */
 217                 si_code = FPE_FLTRES;
 218                 break;
 219         default: /* unknown cause */
 220                 si_code = 0;
 221         }
 222         do_trap(regs, SIGFPE, si_code, "vector exception");
 223 }
 224
 225 void data_exception(struct pt_regs *regs)
 226 {
 227         save_fpu_regs();
 228         if (current->thread.fpu.fpc & FPC_DXC_MASK)
 229                 do_fp_trap(regs, current->thread.fpu.fpc);
 230         else
 231                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 232 }
 233
 234 void space_switch_exception(struct pt_regs *regs)
 235 {
 236         /* Set user psw back to home space mode. */
 237         if (user_mode(regs))
 238                 regs->psw.mask |= PSW_ASC_HOME;
 239         /* Send SIGILL. */
 240         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 241 }
 242
 243 void monitor_event_exception(struct pt_regs *regs)
 244 {
 245         const struct exception_table_entry *fixup;
 246
 247         if (user_mode(regs))
 248                 return;
 249
 250         switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
 251         case BUG_TRAP_TYPE_NONE:
 252                 fixup = s390_search_extables(regs->psw.addr);
 253                 if (fixup)
 254                         regs->psw.addr = extable_fixup(fixup);
 255                 break;
 256         case BUG_TRAP_TYPE_WARN:
 257                 break;
 258         case BUG_TRAP_TYPE_BUG:
 259                 die(regs, "monitor event");
 260                 break;
 261         }
 262 }
 263
 264 void kernel_stack_overflow(struct pt_regs *regs)
 265 {
 266         bust_spinlocks(1);
 267         printk("Kernel stack overflow.\n");
 268         show_regs(regs);
 269         bust_spinlocks(0);
 270         panic("Corrupt kernel stack, can't continue.");
 271 }
 272 NOKPROBE_SYMBOL(kernel_stack_overflow);
 273
 274 static void __init test_monitor_call(void)
 275 {
 276         int val = 1;
 277
 278         asm volatile(
 279                 "       mc      0,0\n"
 280                 "0:     xgr     %0,%0\n"
 281                 "1:\n"
 282                 EX_TABLE(0b,1b)
 283                 : "+d" (val));
 284         if (!val)
 285                 panic("Monitor call doesn't work!\n");
 286 }
 287
 288 void __init trap_init(void)
 289 {
 290         sort_extable(__start_dma_ex_table, __stop_dma_ex_table);
 291         local_mcck_enable();
 292         test_monitor_call();
 293 }