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