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 "asm/irqflags.h"
  17 #include "asm/ptrace.h"
  18 #include <linux/kprobes.h>
  19 #include <linux/kdebug.h>
  20 #include <linux/extable.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/sched.h>
  23 #include <linux/sched/debug.h>
  24 #include <linux/mm.h>
  25 #include <linux/slab.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/cpu.h>
  28 #include <linux/entry-common.h>
  29 #include <asm/fpu/api.h>
  30 #include <asm/vtime.h>
  31 #include "entry.h"
  32
  33 static inline void __user *get_trap_ip(struct pt_regs *regs)
  34 {
  35         unsigned long address;
  36
  37         if (regs->int_code & 0x200)
  38                 address = *(unsigned long *)(current->thread.trap_tdb + 24);
  39         else
  40                 address = regs->psw.addr;
  41         return (void __user *) (address - (regs->int_code >> 16));
  42 }
  43
  44 int is_valid_bugaddr(unsigned long addr)
  45 {
  46         return 1;
  47 }
  48
  49 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  50 {
  51         if (user_mode(regs)) {
  52                 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
  53                 report_user_fault(regs, si_signo, 0);
  54         } else {
  55                 const struct exception_table_entry *fixup;
  56                 fixup = s390_search_extables(regs->psw.addr);
  57                 if (!fixup || !ex_handle(fixup, regs))
  58                         die(regs, str);
  59         }
  60 }
  61
  62 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  63 {
  64         if (notify_die(DIE_TRAP, str, regs, 0,
  65                        regs->int_code, si_signo) == NOTIFY_STOP)
  66                 return;
  67         do_report_trap(regs, si_signo, si_code, str);
  68 }
  69 NOKPROBE_SYMBOL(do_trap);
  70
  71 void do_per_trap(struct pt_regs *regs)
  72 {
  73         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
  74                 return;
  75         if (!current->ptrace)
  76                 return;
  77         force_sig_fault(SIGTRAP, TRAP_HWBKPT,
  78                 (void __force __user *) current->thread.per_event.address);
  79 }
  80 NOKPROBE_SYMBOL(do_per_trap);
  81
  82 void default_trap_handler(struct pt_regs *regs)
  83 {
  84         if (user_mode(regs)) {
  85                 report_user_fault(regs, SIGSEGV, 0);
  86                 do_exit(SIGSEGV);
  87         } else
  88                 die(regs, "Unknown program exception");
  89 }
  90
  91 #define DO_ERROR_INFO(name, signr, sicode, str) \
  92 void name(struct pt_regs *regs)                 \
  93 {                                               \
  94         do_trap(regs, signr, sicode, str);      \
  95 }
  96
  97 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
  98               "addressing exception")
  99 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 100               "execute exception")
 101 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 102               "fixpoint divide exception")
 103 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 104               "fixpoint overflow exception")
 105 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 106               "HFP overflow exception")
 107 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 108               "HFP underflow exception")
 109 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 110               "HFP significance exception")
 111 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 112               "HFP divide exception")
 113 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 114               "HFP square root exception")
 115 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 116               "operand exception")
 117 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 118               "privileged operation")
 119 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 120               "special operation exception")
 121 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 122               "transaction constraint exception")
 123
 124 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
 125 {
 126         int si_code = 0;
 127         /* FPC[2] is Data Exception Code */
 128         if ((fpc & 0x00000300) == 0) {
 129                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 130                 if (fpc & 0x8000) /* invalid fp operation */
 131                         si_code = FPE_FLTINV;
 132                 else if (fpc & 0x4000) /* div by 0 */
 133                         si_code = FPE_FLTDIV;
 134                 else if (fpc & 0x2000) /* overflow */
 135                         si_code = FPE_FLTOVF;
 136                 else if (fpc & 0x1000) /* underflow */
 137                         si_code = FPE_FLTUND;
 138                 else if (fpc & 0x0800) /* inexact */
 139                         si_code = FPE_FLTRES;
 140         }
 141         do_trap(regs, SIGFPE, si_code, "floating point exception");
 142 }
 143
 144 void translation_exception(struct pt_regs *regs)
 145 {
 146         /* May never happen. */
 147         panic("Translation exception");
 148 }
 149
 150 void illegal_op(struct pt_regs *regs)
 151 {
 152         __u8 opcode[6];
 153         __u16 __user *location;
 154         int is_uprobe_insn = 0;
 155         int signal = 0;
 156
 157         location = get_trap_ip(regs);
 158
 159         if (user_mode(regs)) {
 160                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 161                         return;
 162                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 163                         if (current->ptrace)
 164                                 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
 165                         else
 166                                 signal = SIGILL;
 167 #ifdef CONFIG_UPROBES
 168                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 169                         is_uprobe_insn = 1;
 170 #endif
 171                 } else
 172                         signal = SIGILL;
 173         }
 174         /*
 175          * We got either an illegal op in kernel mode, or user space trapped
 176          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 177          * it up. If not, SIGILL.
 178          */
 179         if (is_uprobe_insn || !user_mode(regs)) {
 180                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 181                                3, SIGTRAP) != NOTIFY_STOP)
 182                         signal = SIGILL;
 183         }
 184         if (signal)
 185                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 186 }
 187 NOKPROBE_SYMBOL(illegal_op);
 188
 189 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 190               "specification exception");
 191
 192 void vector_exception(struct pt_regs *regs)
 193 {
 194         int si_code, vic;
 195
 196         if (!MACHINE_HAS_VX) {
 197                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 198                 return;
 199         }
 200
 201         /* get vector interrupt code from fpc */
 202         save_fpu_regs();
 203         vic = (current->thread.fpu.fpc & 0xf00) >> 8;
 204         switch (vic) {
 205         case 1: /* invalid vector operation */
 206                 si_code = FPE_FLTINV;
 207                 break;
 208         case 2: /* division by zero */
 209                 si_code = FPE_FLTDIV;
 210                 break;
 211         case 3: /* overflow */
 212                 si_code = FPE_FLTOVF;
 213                 break;
 214         case 4: /* underflow */
 215                 si_code = FPE_FLTUND;
 216                 break;
 217         case 5: /* inexact */
 218                 si_code = FPE_FLTRES;
 219                 break;
 220         default: /* unknown cause */
 221                 si_code = 0;
 222         }
 223         do_trap(regs, SIGFPE, si_code, "vector exception");
 224 }
 225
 226 void data_exception(struct pt_regs *regs)
 227 {
 228         save_fpu_regs();
 229         if (current->thread.fpu.fpc & FPC_DXC_MASK)
 230                 do_fp_trap(regs, current->thread.fpu.fpc);
 231         else
 232                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 233 }
 234
 235 void space_switch_exception(struct pt_regs *regs)
 236 {
 237         /* Set user psw back to home space mode. */
 238         if (user_mode(regs))
 239                 regs->psw.mask |= PSW_ASC_HOME;
 240         /* Send SIGILL. */
 241         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 242 }
 243
 244 void monitor_event_exception(struct pt_regs *regs)
 245 {
 246         const struct exception_table_entry *fixup;
 247
 248         if (user_mode(regs))
 249                 return;
 250
 251         switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
 252         case BUG_TRAP_TYPE_NONE:
 253                 fixup = s390_search_extables(regs->psw.addr);
 254                 if (fixup)
 255                         ex_handle(fixup, regs);
 256                 break;
 257         case BUG_TRAP_TYPE_WARN:
 258                 break;
 259         case BUG_TRAP_TYPE_BUG:
 260                 die(regs, "monitor event");
 261                 break;
 262         }
 263 }
 264
 265 void kernel_stack_overflow(struct pt_regs *regs)
 266 {
 267         bust_spinlocks(1);
 268         printk("Kernel stack overflow.\n");
 269         show_regs(regs);
 270         bust_spinlocks(0);
 271         panic("Corrupt kernel stack, can't continue.");
 272 }
 273 NOKPROBE_SYMBOL(kernel_stack_overflow);
 274
 275 static void __init test_monitor_call(void)
 276 {
 277         int val = 1;
 278
 279         asm volatile(
 280                 "       mc      0,0\n"
 281                 "0:     xgr     %0,%0\n"
 282                 "1:\n"
 283                 EX_TABLE(0b,1b)
 284                 : "+d" (val));
 285         if (!val)
 286                 panic("Monitor call doesn't work!\n");
 287 }
 288
 289 void __init trap_init(void)
 290 {
 291         sort_extable(__start_dma_ex_table, __stop_dma_ex_table);
 292         local_mcck_enable();
 293         test_monitor_call();
 294 }
 295
 296 void noinstr __do_pgm_check(struct pt_regs *regs)
 297 {
 298         unsigned long last_break = S390_lowcore.breaking_event_addr;
 299         unsigned int trapnr, syscall_redirect = 0;
 300         irqentry_state_t state;
 301
 302         regs->int_code = *(u32 *)&S390_lowcore.pgm_ilc;
 303         regs->int_parm_long = S390_lowcore.trans_exc_code;
 304
 305         state = irqentry_enter(regs);
 306
 307         if (user_mode(regs)) {
 308                 update_timer_sys();
 309                 if (last_break < 4096)
 310                         last_break = 1;
 311                 current->thread.last_break = last_break;
 312                 regs->args[0] = last_break;
 313         }
 314
 315         if (S390_lowcore.pgm_code & 0x0200) {
 316                 /* transaction abort */
 317                 memcpy(&current->thread.trap_tdb, &S390_lowcore.pgm_tdb, 256);
 318         }
 319
 320         if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
 321                 if (user_mode(regs)) {
 322                         struct per_event *ev = &current->thread.per_event;
 323
 324                         set_thread_flag(TIF_PER_TRAP);
 325                         ev->address = S390_lowcore.per_address;
 326                         ev->cause = *(u16 *)&S390_lowcore.per_code;
 327                         ev->paid = S390_lowcore.per_access_id;
 328                 } else {
 329                         /* PER event in kernel is kprobes */
 330                         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 331                         do_per_trap(regs);
 332                         goto out;
 333                 }
 334         }
 335
 336         if (!irqs_disabled_flags(regs->psw.mask))
 337                 trace_hardirqs_on();
 338         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 339
 340         trapnr = regs->int_code & PGM_INT_CODE_MASK;
 341         if (trapnr)
 342                 pgm_check_table[trapnr](regs);
 343         syscall_redirect = user_mode(regs) && test_pt_regs_flag(regs, PIF_SYSCALL);
 344 out:
 345         local_irq_disable();
 346         irqentry_exit(regs, state);
 347
 348         if (syscall_redirect) {
 349                 enter_from_user_mode(regs);
 350                 local_irq_enable();
 351                 regs->orig_gpr2 = regs->gprs[2];
 352                 do_syscall(regs);
 353                 exit_to_user_mode();
 354         }
 355 }