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 <linux/kmsan.h>
  31 #include <asm/asm-extable.h>
  32 #include <asm/vtime.h>
  33 #include <asm/fpu.h>
  34 #include <asm/fault.h>
  35 #include "entry.h"
  36
  37 static inline void __user *get_trap_ip(struct pt_regs *regs)
  38 {
  39         unsigned long address;
  40
  41         if (regs->int_code & 0x200)
  42                 address = current->thread.trap_tdb.data[3];
  43         else
  44                 address = regs->psw.addr;
  45         return (void __user *) (address - (regs->int_code >> 16));
  46 }
  47
  48 #ifdef CONFIG_GENERIC_BUG
  49 int is_valid_bugaddr(unsigned long addr)
  50 {
  51         return 1;
  52 }
  53 #endif
  54
  55 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  56 {
  57         if (user_mode(regs)) {
  58                 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
  59                 report_user_fault(regs, si_signo, 0);
  60         } else {
  61                 if (!fixup_exception(regs))
  62                         die(regs, str);
  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);
  83 }
  84 NOKPROBE_SYMBOL(do_per_trap);
  85
  86 static void default_trap_handler(struct pt_regs *regs)
  87 {
  88         if (user_mode(regs)) {
  89                 report_user_fault(regs, SIGSEGV, 0);
  90                 force_exit_sig(SIGSEGV);
  91         } else
  92                 die(regs, "Unknown program exception");
  93 }
  94
  95 #define DO_ERROR_INFO(name, signr, sicode, str) \
  96 static 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 static void translation_specification_exception(struct pt_regs *regs)
 149 {
 150         /* May never happen. */
 151         panic("Translation-Specification Exception");
 152 }
 153
 154 static 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);
 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 static void vector_exception(struct pt_regs *regs)
 197 {
 198         int si_code, vic;
 199
 200         if (!cpu_has_vx()) {
 201                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 202                 return;
 203         }
 204
 205         /* get vector interrupt code from fpc */
 206         save_user_fpu_regs();
 207         vic = (current->thread.ufpu.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 static void data_exception(struct pt_regs *regs)
 231 {
 232         save_user_fpu_regs();
 233         if (current->thread.ufpu.fpc & FPC_DXC_MASK)
 234                 do_fp_trap(regs, current->thread.ufpu.fpc);
 235         else
 236                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 237 }
 238
 239 static void space_switch_exception(struct pt_regs *regs)
 240 {
 241         /* Set user psw back to home space mode. */
 242         if (user_mode(regs))
 243                 regs->psw.mask |= PSW_ASC_HOME;
 244         /* Send SIGILL. */
 245         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 246 }
 247
 248 static void monitor_event_exception(struct pt_regs *regs)
 249 {
 250         if (user_mode(regs))
 251                 return;
 252
 253         switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
 254         case BUG_TRAP_TYPE_NONE:
 255                 fixup_exception(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         /*
 268          * Normally regs are unpoisoned by the generic entry code, but
 269          * kernel_stack_overflow() is a rare case that is called bypassing it.
 270          */
 271         kmsan_unpoison_entry_regs(regs);
 272         bust_spinlocks(1);
 273         printk("Kernel stack overflow.\n");
 274         show_regs(regs);
 275         bust_spinlocks(0);
 276         panic("Corrupt kernel stack, can't continue.");
 277 }
 278 NOKPROBE_SYMBOL(kernel_stack_overflow);
 279
 280 static void __init test_monitor_call(void)
 281 {
 282         int val = 1;
 283
 284         if (!IS_ENABLED(CONFIG_BUG))
 285                 return;
 286         asm volatile(
 287                 "       mc      0,0\n"
 288                 "0:     xgr     %0,%0\n"
 289                 "1:\n"
 290                 EX_TABLE(0b,1b)
 291                 : "+d" (val));
 292         if (!val)
 293                 panic("Monitor call doesn't work!\n");
 294 }
 295
 296 void __init trap_init(void)
 297 {
 298         struct lowcore *lc = get_lowcore();
 299         unsigned long flags;
 300         struct ctlreg cr0;
 301
 302         local_irq_save(flags);
 303         cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
 304         psw_bits(lc->external_new_psw).mcheck = 1;
 305         psw_bits(lc->program_new_psw).mcheck = 1;
 306         psw_bits(lc->svc_new_psw).mcheck = 1;
 307         psw_bits(lc->io_new_psw).mcheck = 1;
 308         local_ctl_load(0, &cr0);
 309         local_irq_restore(flags);
 310         local_mcck_enable();
 311         test_monitor_call();
 312 }
 313
 314 static void (*pgm_check_table[128])(struct pt_regs *regs);
 315
 316 void noinstr __do_pgm_check(struct pt_regs *regs)
 317 {
 318         struct lowcore *lc = get_lowcore();
 319         irqentry_state_t state;
 320         unsigned int trapnr;
 321         union teid teid;
 322
 323         teid.val = lc->trans_exc_code;
 324         regs->int_code = lc->pgm_int_code;
 325         regs->int_parm_long = teid.val;
 326
 327         /*
 328          * In case of a guest fault, short-circuit the fault handler and return.
 329          * This way the sie64a() function will return 0; fault address and
 330          * other relevant bits are saved in current->thread.gmap_teid, and
 331          * the fault number in current->thread.gmap_int_code. KVM will be
 332          * able to use this information to handle the fault.
 333          */
 334         if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) {
 335                 current->thread.gmap_teid.val = regs->int_parm_long;
 336                 current->thread.gmap_int_code = regs->int_code & 0xffff;
 337                 return;
 338         }
 339
 340         state = irqentry_enter(regs);
 341
 342         if (user_mode(regs)) {
 343                 update_timer_sys();
 344                 if (!static_branch_likely(&cpu_has_bear)) {
 345                         if (regs->last_break < 4096)
 346                                 regs->last_break = 1;
 347                 }
 348                 current->thread.last_break = regs->last_break;
 349         }
 350
 351         if (lc->pgm_code & 0x0200) {
 352                 /* transaction abort */
 353                 current->thread.trap_tdb = lc->pgm_tdb;
 354         }
 355
 356         if (lc->pgm_code & PGM_INT_CODE_PER) {
 357                 if (user_mode(regs)) {
 358                         struct per_event *ev = &current->thread.per_event;
 359
 360                         set_thread_flag(TIF_PER_TRAP);
 361                         ev->address = lc->per_address;
 362                         ev->cause = lc->per_code_combined;
 363                         ev->paid = lc->per_access_id;
 364                 } else {
 365                         /* PER event in kernel is kprobes */
 366                         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 367                         do_per_trap(regs);
 368                         goto out;
 369                 }
 370         }
 371
 372         if (!irqs_disabled_flags(regs->psw.mask))
 373                 trace_hardirqs_on();
 374         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 375
 376         trapnr = regs->int_code & PGM_INT_CODE_MASK;
 377         if (trapnr)
 378                 pgm_check_table[trapnr](regs);
 379 out:
 380         local_irq_disable();
 381         irqentry_exit(regs, state);
 382 }
 383
 384 /*
 385  * The program check table contains exactly 128 (0x00-0x7f) entries. Each
 386  * line defines the function to be called corresponding to the program check
 387  * interruption code.
 388  */
 389 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
 390         [0x00]          = default_trap_handler,
 391         [0x01]          = illegal_op,
 392         [0x02]          = privileged_op,
 393         [0x03]          = execute_exception,
 394         [0x04]          = do_protection_exception,
 395         [0x05]          = addressing_exception,
 396         [0x06]          = specification_exception,
 397         [0x07]          = data_exception,
 398         [0x08]          = overflow_exception,
 399         [0x09]          = divide_exception,
 400         [0x0a]          = overflow_exception,
 401         [0x0b]          = divide_exception,
 402         [0x0c]          = hfp_overflow_exception,
 403         [0x0d]          = hfp_underflow_exception,
 404         [0x0e]          = hfp_significance_exception,
 405         [0x0f]          = hfp_divide_exception,
 406         [0x10]          = do_dat_exception,
 407         [0x11]          = do_dat_exception,
 408         [0x12]          = translation_specification_exception,
 409         [0x13]          = special_op_exception,
 410         [0x14]          = default_trap_handler,
 411         [0x15]          = operand_exception,
 412         [0x16]          = default_trap_handler,
 413         [0x17]          = default_trap_handler,
 414         [0x18]          = transaction_exception,
 415         [0x19]          = default_trap_handler,
 416         [0x1a]          = default_trap_handler,
 417         [0x1b]          = vector_exception,
 418         [0x1c]          = space_switch_exception,
 419         [0x1d]          = hfp_sqrt_exception,
 420         [0x1e ... 0x37] = default_trap_handler,
 421         [0x38]          = do_dat_exception,
 422         [0x39]          = do_dat_exception,
 423         [0x3a]          = do_dat_exception,
 424         [0x3b]          = do_dat_exception,
 425         [0x3c]          = default_trap_handler,
 426         [0x3d]          = do_secure_storage_access,
 427         [0x3e]          = default_trap_handler,
 428         [0x3f]          = default_trap_handler,
 429         [0x40]          = monitor_event_exception,
 430         [0x41 ... 0x7f] = default_trap_handler,
 431 };
 432
 433 #define COND_TRAP(x) asm(                       \
 434         ".weak " __stringify(x) "\n\t"          \
 435         ".set  " __stringify(x) ","             \
 436         __stringify(default_trap_handler))
 437
 438 COND_TRAP(do_secure_storage_access);