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 ([email protected]),
   6  *               Denis Joseph Barrow ([email protected],[email protected]),
   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/randomize_kstack.h>
  21 #include <linux/extable.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/sched.h>
  24 #include <linux/sched/debug.h>
  25 #include <linux/mm.h>
  26 #include <linux/slab.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/cpu.h>
  29 #include <linux/entry-common.h>
  30 #include <asm/fpu/api.h>
  31 #include <asm/vtime.h>
  32 #include "entry.h"
  33
  34 static inline void __user *get_trap_ip(struct pt_regs *regs)
  35 {
  36         unsigned long address;
  37
  38         if (regs->int_code & 0x200)
  39                 address = current->thread.trap_tdb.data[3];
  40         else
  41                 address = regs->psw.addr;
  42         return (void __user *) (address - (regs->int_code >> 16));
  43 }
  44
  45 int is_valid_bugaddr(unsigned long addr)
  46 {
  47         return 1;
  48 }
  49
  50 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  51 {
  52         if (user_mode(regs)) {
  53                 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
  54                 report_user_fault(regs, si_signo, 0);
  55         } else {
  56                 const struct exception_table_entry *fixup;
  57                 fixup = s390_search_extables(regs->psw.addr);
  58                 if (!fixup || !ex_handle(fixup, regs))
  59                         die(regs, str);
  60         }
  61 }
  62
  63 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  64 {
  65         if (notify_die(DIE_TRAP, str, regs, 0,
  66                        regs->int_code, si_signo) == NOTIFY_STOP)
  67                 return;
  68         do_report_trap(regs, si_signo, si_code, str);
  69 }
  70 NOKPROBE_SYMBOL(do_trap);
  71
  72 void do_per_trap(struct pt_regs *regs)
  73 {
  74         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
  75                 return;
  76         if (!current->ptrace)
  77                 return;
  78         force_sig_fault(SIGTRAP, TRAP_HWBKPT,
  79                 (void __force __user *) current->thread.per_event.address);
  80 }
  81 NOKPROBE_SYMBOL(do_per_trap);
  82
  83 static void default_trap_handler(struct pt_regs *regs)
  84 {
  85         if (user_mode(regs)) {
  86                 report_user_fault(regs, SIGSEGV, 0);
  87                 force_exit_sig(SIGSEGV);
  88         } else
  89                 die(regs, "Unknown program exception");
  90 }
  91
  92 #define DO_ERROR_INFO(name, signr, sicode, str) \
  93 static void name(struct pt_regs *regs)          \
  94 {                                               \
  95         do_trap(regs, signr, sicode, str);      \
  96 }
  97
  98 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
  99               "addressing exception")
 100 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 101               "execute exception")
 102 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 103               "fixpoint divide exception")
 104 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 105               "fixpoint overflow exception")
 106 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 107               "HFP overflow exception")
 108 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 109               "HFP underflow exception")
 110 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 111               "HFP significance exception")
 112 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 113               "HFP divide exception")
 114 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 115               "HFP square root exception")
 116 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 117               "operand exception")
 118 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 119               "privileged operation")
 120 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 121               "special operation exception")
 122 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 123               "transaction constraint exception")
 124
 125 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
 126 {
 127         int si_code = 0;
 128         /* FPC[2] is Data Exception Code */
 129         if ((fpc & 0x00000300) == 0) {
 130                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 131                 if (fpc & 0x8000) /* invalid fp operation */
 132                         si_code = FPE_FLTINV;
 133                 else if (fpc & 0x4000) /* div by 0 */
 134                         si_code = FPE_FLTDIV;
 135                 else if (fpc & 0x2000) /* overflow */
 136                         si_code = FPE_FLTOVF;
 137                 else if (fpc & 0x1000) /* underflow */
 138                         si_code = FPE_FLTUND;
 139                 else if (fpc & 0x0800) /* inexact */
 140                         si_code = FPE_FLTRES;
 141         }
 142         do_trap(regs, SIGFPE, si_code, "floating point exception");
 143 }
 144
 145 static void translation_exception(struct pt_regs *regs)
 146 {
 147         /* May never happen. */
 148         panic("Translation exception");
 149 }
 150
 151 static void illegal_op(struct pt_regs *regs)
 152 {
 153         __u8 opcode[6];
 154         __u16 __user *location;
 155         int is_uprobe_insn = 0;
 156         int signal = 0;
 157
 158         location = get_trap_ip(regs);
 159
 160         if (user_mode(regs)) {
 161                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 162                         return;
 163                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 164                         if (current->ptrace)
 165                                 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
 166                         else
 167                                 signal = SIGILL;
 168 #ifdef CONFIG_UPROBES
 169                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 170                         is_uprobe_insn = 1;
 171 #endif
 172                 } else
 173                         signal = SIGILL;
 174         }
 175         /*
 176          * We got either an illegal op in kernel mode, or user space trapped
 177          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 178          * it up. If not, SIGILL.
 179          */
 180         if (is_uprobe_insn || !user_mode(regs)) {
 181                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 182                                3, SIGTRAP) != NOTIFY_STOP)
 183                         signal = SIGILL;
 184         }
 185         if (signal)
 186                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 187 }
 188 NOKPROBE_SYMBOL(illegal_op);
 189
 190 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 191               "specification exception");
 192
 193 static void vector_exception(struct pt_regs *regs)
 194 {
 195         int si_code, vic;
 196
 197         if (!MACHINE_HAS_VX) {
 198                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 199                 return;
 200         }
 201
 202         /* get vector interrupt code from fpc */
 203         save_fpu_regs();
 204         vic = (current->thread.fpu.fpc & 0xf00) >> 8;
 205         switch (vic) {
 206         case 1: /* invalid vector operation */
 207                 si_code = FPE_FLTINV;
 208                 break;
 209         case 2: /* division by zero */
 210                 si_code = FPE_FLTDIV;
 211                 break;
 212         case 3: /* overflow */
 213                 si_code = FPE_FLTOVF;
 214                 break;
 215         case 4: /* underflow */
 216                 si_code = FPE_FLTUND;
 217                 break;
 218         case 5: /* inexact */
 219                 si_code = FPE_FLTRES;
 220                 break;
 221         default: /* unknown cause */
 222                 si_code = 0;
 223         }
 224         do_trap(regs, SIGFPE, si_code, "vector exception");
 225 }
 226
 227 static void data_exception(struct pt_regs *regs)
 228 {
 229         save_fpu_regs();
 230         if (current->thread.fpu.fpc & FPC_DXC_MASK)
 231                 do_fp_trap(regs, current->thread.fpu.fpc);
 232         else
 233                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 234 }
 235
 236 static void space_switch_exception(struct pt_regs *regs)
 237 {
 238         /* Set user psw back to home space mode. */
 239         if (user_mode(regs))
 240                 regs->psw.mask |= PSW_ASC_HOME;
 241         /* Send SIGILL. */
 242         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 243 }
 244
 245 static void monitor_event_exception(struct pt_regs *regs)
 246 {
 247         const struct exception_table_entry *fixup;
 248
 249         if (user_mode(regs))
 250                 return;
 251
 252         switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
 253         case BUG_TRAP_TYPE_NONE:
 254                 fixup = s390_search_extables(regs->psw.addr);
 255                 if (fixup)
 256                         ex_handle(fixup, regs);
 257                 break;
 258         case BUG_TRAP_TYPE_WARN:
 259                 break;
 260         case BUG_TRAP_TYPE_BUG:
 261                 die(regs, "monitor event");
 262                 break;
 263         }
 264 }
 265
 266 void kernel_stack_overflow(struct pt_regs *regs)
 267 {
 268         bust_spinlocks(1);
 269         printk("Kernel stack overflow.\n");
 270         show_regs(regs);
 271         bust_spinlocks(0);
 272         panic("Corrupt kernel stack, can't continue.");
 273 }
 274 NOKPROBE_SYMBOL(kernel_stack_overflow);
 275
 276 static void __init test_monitor_call(void)
 277 {
 278         int val = 1;
 279
 280         if (!IS_ENABLED(CONFIG_BUG))
 281                 return;
 282         asm volatile(
 283                 "       mc      0,0\n"
 284                 "0:     xgr     %0,%0\n"
 285                 "1:\n"
 286                 EX_TABLE(0b,1b)
 287                 : "+d" (val));
 288         if (!val)
 289                 panic("Monitor call doesn't work!\n");
 290 }
 291
 292 void __init trap_init(void)
 293 {
 294         sort_extable(__start_amode31_ex_table, __stop_amode31_ex_table);
 295         local_mcck_enable();
 296         test_monitor_call();
 297 }
 298
 299 static void (*pgm_check_table[128])(struct pt_regs *regs);
 300
 301 void noinstr __do_pgm_check(struct pt_regs *regs)
 302 {
 303         unsigned int trapnr;
 304         irqentry_state_t state;
 305
 306         regs->int_code = *(u32 *)&S390_lowcore.pgm_ilc;
 307         regs->int_parm_long = S390_lowcore.trans_exc_code;
 308
 309         state = irqentry_enter(regs);
 310
 311         if (user_mode(regs)) {
 312                 update_timer_sys();
 313                 if (!static_branch_likely(&cpu_has_bear)) {
 314                         if (regs->last_break < 4096)
 315                                 regs->last_break = 1;
 316                 }
 317                 current->thread.last_break = regs->last_break;
 318         }
 319
 320         if (S390_lowcore.pgm_code & 0x0200) {
 321                 /* transaction abort */
 322                 current->thread.trap_tdb = S390_lowcore.pgm_tdb;
 323         }
 324
 325         if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
 326                 if (user_mode(regs)) {
 327                         struct per_event *ev = &current->thread.per_event;
 328
 329                         set_thread_flag(TIF_PER_TRAP);
 330                         ev->address = S390_lowcore.per_address;
 331                         ev->cause = *(u16 *)&S390_lowcore.per_code;
 332                         ev->paid = S390_lowcore.per_access_id;
 333                 } else {
 334                         /* PER event in kernel is kprobes */
 335                         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 336                         do_per_trap(regs);
 337                         goto out;
 338                 }
 339         }
 340
 341         if (!irqs_disabled_flags(regs->psw.mask))
 342                 trace_hardirqs_on();
 343         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 344
 345         trapnr = regs->int_code & PGM_INT_CODE_MASK;
 346         if (trapnr)
 347                 pgm_check_table[trapnr](regs);
 348 out:
 349         local_irq_disable();
 350         irqentry_exit(regs, state);
 351 }
 352
 353 /*
 354  * The program check table contains exactly 128 (0x00-0x7f) entries. Each
 355  * line defines the function to be called corresponding to the program check
 356  * interruption code.
 357  */
 358 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
 359         [0x00]          = default_trap_handler,
 360         [0x01]          = illegal_op,
 361         [0x02]          = privileged_op,
 362         [0x03]          = execute_exception,
 363         [0x04]          = do_protection_exception,
 364         [0x05]          = addressing_exception,
 365         [0x06]          = specification_exception,
 366         [0x07]          = data_exception,
 367         [0x08]          = overflow_exception,
 368         [0x09]          = divide_exception,
 369         [0x0a]          = overflow_exception,
 370         [0x0b]          = divide_exception,
 371         [0x0c]          = hfp_overflow_exception,
 372         [0x0d]          = hfp_underflow_exception,
 373         [0x0e]          = hfp_significance_exception,
 374         [0x0f]          = hfp_divide_exception,
 375         [0x10]          = do_dat_exception,
 376         [0x11]          = do_dat_exception,
 377         [0x12]          = translation_exception,
 378         [0x13]          = special_op_exception,
 379         [0x14]          = default_trap_handler,
 380         [0x15]          = operand_exception,
 381         [0x16]          = default_trap_handler,
 382         [0x17]          = default_trap_handler,
 383         [0x18]          = transaction_exception,
 384         [0x19]          = default_trap_handler,
 385         [0x1a]          = default_trap_handler,
 386         [0x1b]          = vector_exception,
 387         [0x1c]          = space_switch_exception,
 388         [0x1d]          = hfp_sqrt_exception,
 389         [0x1e ... 0x37] = default_trap_handler,
 390         [0x38]          = do_dat_exception,
 391         [0x39]          = do_dat_exception,
 392         [0x3a]          = do_dat_exception,
 393         [0x3b]          = do_dat_exception,
 394         [0x3c]          = default_trap_handler,
 395         [0x3d]          = do_secure_storage_access,
 396         [0x3e]          = do_non_secure_storage_access,
 397         [0x3f]          = do_secure_storage_violation,
 398         [0x40]          = monitor_event_exception,
 399         [0x41 ... 0x7f] = default_trap_handler,
 400 };
 401
 402 #define COND_TRAP(x) asm(                       \
 403         ".weak " __stringify(x) "\n\t"          \
 404         ".set  " __stringify(x) ","             \
 405         __stringify(default_trap_handler))
 406
 407 COND_TRAP(do_secure_storage_access);
 408 COND_TRAP(do_non_secure_storage_access);
 409 COND_TRAP(do_secure_storage_violation);