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/asm-extable.h>
  31 #include <asm/vtime.h>
  32 #include <asm/fpu.h>
  33 #include "entry.h"
  34
  35 static inline void __user *get_trap_ip(struct pt_regs *regs)
  36 {
  37         unsigned long address;
  38
  39         if (regs->int_code & 0x200)
  40                 address = current->thread.trap_tdb.data[3];
  41         else
  42                 address = regs->psw.addr;
  43         return (void __user *) (address - (regs->int_code >> 16));
  44 }
  45
  46 #ifdef CONFIG_GENERIC_BUG
  47 int is_valid_bugaddr(unsigned long addr)
  48 {
  49         return 1;
  50 }
  51 #endif
  52
  53 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  54 {
  55         if (user_mode(regs)) {
  56                 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
  57                 report_user_fault(regs, si_signo, 0);
  58         } else {
  59                 if (!fixup_exception(regs))
  60                         die(regs, str);
  61         }
  62 }
  63
  64 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  65 {
  66         if (notify_die(DIE_TRAP, str, regs, 0,
  67                        regs->int_code, si_signo) == NOTIFY_STOP)
  68                 return;
  69         do_report_trap(regs, si_signo, si_code, str);
  70 }
  71 NOKPROBE_SYMBOL(do_trap);
  72
  73 void do_per_trap(struct pt_regs *regs)
  74 {
  75         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
  76                 return;
  77         if (!current->ptrace)
  78                 return;
  79         force_sig_fault(SIGTRAP, TRAP_HWBKPT,
  80                 (void __force __user *) current->thread.per_event.address);
  81 }
  82 NOKPROBE_SYMBOL(do_per_trap);
  83
  84 static void default_trap_handler(struct pt_regs *regs)
  85 {
  86         if (user_mode(regs)) {
  87                 report_user_fault(regs, SIGSEGV, 0);
  88                 force_exit_sig(SIGSEGV);
  89         } else
  90                 die(regs, "Unknown program exception");
  91 }
  92
  93 #define DO_ERROR_INFO(name, signr, sicode, str) \
  94 static void name(struct pt_regs *regs)          \
  95 {                                               \
  96         do_trap(regs, signr, sicode, str);      \
  97 }
  98
  99 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
 100               "addressing exception")
 101 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 102               "execute exception")
 103 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 104               "fixpoint divide exception")
 105 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 106               "fixpoint overflow exception")
 107 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 108               "HFP overflow exception")
 109 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 110               "HFP underflow exception")
 111 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 112               "HFP significance exception")
 113 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 114               "HFP divide exception")
 115 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 116               "HFP square root exception")
 117 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 118               "operand exception")
 119 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 120               "privileged operation")
 121 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 122               "special operation exception")
 123 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 124               "transaction constraint exception")
 125
 126 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
 127 {
 128         int si_code = 0;
 129         /* FPC[2] is Data Exception Code */
 130         if ((fpc & 0x00000300) == 0) {
 131                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 132                 if (fpc & 0x8000) /* invalid fp operation */
 133                         si_code = FPE_FLTINV;
 134                 else if (fpc & 0x4000) /* div by 0 */
 135                         si_code = FPE_FLTDIV;
 136                 else if (fpc & 0x2000) /* overflow */
 137                         si_code = FPE_FLTOVF;
 138                 else if (fpc & 0x1000) /* underflow */
 139                         si_code = FPE_FLTUND;
 140                 else if (fpc & 0x0800) /* inexact */
 141                         si_code = FPE_FLTRES;
 142         }
 143         do_trap(regs, SIGFPE, si_code, "floating point exception");
 144 }
 145
 146 static void translation_specification_exception(struct pt_regs *regs)
 147 {
 148         /* May never happen. */
 149         panic("Translation-Specification Exception");
 150 }
 151
 152 static void illegal_op(struct pt_regs *regs)
 153 {
 154         __u8 opcode[6];
 155         __u16 __user *location;
 156         int is_uprobe_insn = 0;
 157         int signal = 0;
 158
 159         location = get_trap_ip(regs);
 160
 161         if (user_mode(regs)) {
 162                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 163                         return;
 164                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 165                         if (current->ptrace)
 166                                 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
 167                         else
 168                                 signal = SIGILL;
 169 #ifdef CONFIG_UPROBES
 170                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 171                         is_uprobe_insn = 1;
 172 #endif
 173                 } else
 174                         signal = SIGILL;
 175         }
 176         /*
 177          * We got either an illegal op in kernel mode, or user space trapped
 178          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 179          * it up. If not, SIGILL.
 180          */
 181         if (is_uprobe_insn || !user_mode(regs)) {
 182                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 183                                3, SIGTRAP) != NOTIFY_STOP)
 184                         signal = SIGILL;
 185         }
 186         if (signal)
 187                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 188 }
 189 NOKPROBE_SYMBOL(illegal_op);
 190
 191 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 192               "specification exception");
 193
 194 static void vector_exception(struct pt_regs *regs)
 195 {
 196         int si_code, vic;
 197
 198         if (!cpu_has_vx()) {
 199                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 200                 return;
 201         }
 202
 203         /* get vector interrupt code from fpc */
 204         save_user_fpu_regs();
 205         vic = (current->thread.ufpu.fpc & 0xf00) >> 8;
 206         switch (vic) {
 207         case 1: /* invalid vector operation */
 208                 si_code = FPE_FLTINV;
 209                 break;
 210         case 2: /* division by zero */
 211                 si_code = FPE_FLTDIV;
 212                 break;
 213         case 3: /* overflow */
 214                 si_code = FPE_FLTOVF;
 215                 break;
 216         case 4: /* underflow */
 217                 si_code = FPE_FLTUND;
 218                 break;
 219         case 5: /* inexact */
 220                 si_code = FPE_FLTRES;
 221                 break;
 222         default: /* unknown cause */
 223                 si_code = 0;
 224         }
 225         do_trap(regs, SIGFPE, si_code, "vector exception");
 226 }
 227
 228 static void data_exception(struct pt_regs *regs)
 229 {
 230         save_user_fpu_regs();
 231         if (current->thread.ufpu.fpc & FPC_DXC_MASK)
 232                 do_fp_trap(regs, current->thread.ufpu.fpc);
 233         else
 234                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 235 }
 236
 237 static void space_switch_exception(struct pt_regs *regs)
 238 {
 239         /* Set user psw back to home space mode. */
 240         if (user_mode(regs))
 241                 regs->psw.mask |= PSW_ASC_HOME;
 242         /* Send SIGILL. */
 243         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 244 }
 245
 246 static void monitor_event_exception(struct pt_regs *regs)
 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_exception(regs);
 254                 break;
 255         case BUG_TRAP_TYPE_WARN:
 256                 break;
 257         case BUG_TRAP_TYPE_BUG:
 258                 die(regs, "monitor event");
 259                 break;
 260         }
 261 }
 262
 263 void kernel_stack_overflow(struct pt_regs *regs)
 264 {
 265         bust_spinlocks(1);
 266         printk("Kernel stack overflow.\n");
 267         show_regs(regs);
 268         bust_spinlocks(0);
 269         panic("Corrupt kernel stack, can't continue.");
 270 }
 271 NOKPROBE_SYMBOL(kernel_stack_overflow);
 272
 273 static void __init test_monitor_call(void)
 274 {
 275         int val = 1;
 276
 277         if (!IS_ENABLED(CONFIG_BUG))
 278                 return;
 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         unsigned long flags;
 292         struct ctlreg cr0;
 293
 294         local_irq_save(flags);
 295         cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
 296         psw_bits(S390_lowcore.external_new_psw).mcheck = 1;
 297         psw_bits(S390_lowcore.program_new_psw).mcheck = 1;
 298         psw_bits(S390_lowcore.svc_new_psw).mcheck = 1;
 299         psw_bits(S390_lowcore.io_new_psw).mcheck = 1;
 300         local_ctl_load(0, &cr0);
 301         local_irq_restore(flags);
 302         local_mcck_enable();
 303         test_monitor_call();
 304 }
 305
 306 static void (*pgm_check_table[128])(struct pt_regs *regs);
 307
 308 void noinstr __do_pgm_check(struct pt_regs *regs)
 309 {
 310         unsigned int trapnr;
 311         irqentry_state_t state;
 312
 313         regs->int_code = S390_lowcore.pgm_int_code;
 314         regs->int_parm_long = S390_lowcore.trans_exc_code;
 315
 316         state = irqentry_enter(regs);
 317
 318         if (user_mode(regs)) {
 319                 update_timer_sys();
 320                 if (!static_branch_likely(&cpu_has_bear)) {
 321                         if (regs->last_break < 4096)
 322                                 regs->last_break = 1;
 323                 }
 324                 current->thread.last_break = regs->last_break;
 325         }
 326
 327         if (S390_lowcore.pgm_code & 0x0200) {
 328                 /* transaction abort */
 329                 current->thread.trap_tdb = S390_lowcore.pgm_tdb;
 330         }
 331
 332         if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
 333                 if (user_mode(regs)) {
 334                         struct per_event *ev = &current->thread.per_event;
 335
 336                         set_thread_flag(TIF_PER_TRAP);
 337                         ev->address = S390_lowcore.per_address;
 338                         ev->cause = S390_lowcore.per_code_combined;
 339                         ev->paid = S390_lowcore.per_access_id;
 340                 } else {
 341                         /* PER event in kernel is kprobes */
 342                         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 343                         do_per_trap(regs);
 344                         goto out;
 345                 }
 346         }
 347
 348         if (!irqs_disabled_flags(regs->psw.mask))
 349                 trace_hardirqs_on();
 350         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 351
 352         trapnr = regs->int_code & PGM_INT_CODE_MASK;
 353         if (trapnr)
 354                 pgm_check_table[trapnr](regs);
 355 out:
 356         local_irq_disable();
 357         irqentry_exit(regs, state);
 358 }
 359
 360 /*
 361  * The program check table contains exactly 128 (0x00-0x7f) entries. Each
 362  * line defines the function to be called corresponding to the program check
 363  * interruption code.
 364  */
 365 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
 366         [0x00]          = default_trap_handler,
 367         [0x01]          = illegal_op,
 368         [0x02]          = privileged_op,
 369         [0x03]          = execute_exception,
 370         [0x04]          = do_protection_exception,
 371         [0x05]          = addressing_exception,
 372         [0x06]          = specification_exception,
 373         [0x07]          = data_exception,
 374         [0x08]          = overflow_exception,
 375         [0x09]          = divide_exception,
 376         [0x0a]          = overflow_exception,
 377         [0x0b]          = divide_exception,
 378         [0x0c]          = hfp_overflow_exception,
 379         [0x0d]          = hfp_underflow_exception,
 380         [0x0e]          = hfp_significance_exception,
 381         [0x0f]          = hfp_divide_exception,
 382         [0x10]          = do_dat_exception,
 383         [0x11]          = do_dat_exception,
 384         [0x12]          = translation_specification_exception,
 385         [0x13]          = special_op_exception,
 386         [0x14]          = default_trap_handler,
 387         [0x15]          = operand_exception,
 388         [0x16]          = default_trap_handler,
 389         [0x17]          = default_trap_handler,
 390         [0x18]          = transaction_exception,
 391         [0x19]          = default_trap_handler,
 392         [0x1a]          = default_trap_handler,
 393         [0x1b]          = vector_exception,
 394         [0x1c]          = space_switch_exception,
 395         [0x1d]          = hfp_sqrt_exception,
 396         [0x1e ... 0x37] = default_trap_handler,
 397         [0x38]          = do_dat_exception,
 398         [0x39]          = do_dat_exception,
 399         [0x3a]          = do_dat_exception,
 400         [0x3b]          = do_dat_exception,
 401         [0x3c]          = default_trap_handler,
 402         [0x3d]          = do_secure_storage_access,
 403         [0x3e]          = do_non_secure_storage_access,
 404         [0x3f]          = do_secure_storage_violation,
 405         [0x40]          = monitor_event_exception,
 406         [0x41 ... 0x7f] = default_trap_handler,
 407 };
 408
 409 #define COND_TRAP(x) asm(                       \
 410         ".weak " __stringify(x) "\n\t"          \
 411         ".set  " __stringify(x) ","             \
 412         __stringify(default_trap_handler))
 413
 414 COND_TRAP(do_secure_storage_access);
 415 COND_TRAP(do_non_secure_storage_access);
 416 COND_TRAP(do_secure_storage_violation);