linux/arch/s390/kernel/traps.c
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   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/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
  34static 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
  45int is_valid_bugaddr(unsigned long addr)
  46{
  47        return 1;
  48}
  49
  50void 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
  63static 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}
  70NOKPROBE_SYMBOL(do_trap);
  71
  72void 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}
  81NOKPROBE_SYMBOL(do_per_trap);
  82
  83static void default_trap_handler(struct pt_regs *regs)
  84{
  85        if (user_mode(regs)) {
  86                report_user_fault(regs, SIGSEGV, 0);
  87                do_exit(SIGSEGV);
  88        } else
  89                die(regs, "Unknown program exception");
  90}
  91
  92#define DO_ERROR_INFO(name, signr, sicode, str) \
  93static void name(struct pt_regs *regs)          \
  94{                                               \
  95        do_trap(regs, signr, sicode, str);      \
  96}
  97
  98DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
  99              "addressing exception")
 100DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 101              "execute exception")
 102DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 103              "fixpoint divide exception")
 104DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 105              "fixpoint overflow exception")
 106DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 107              "HFP overflow exception")
 108DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 109              "HFP underflow exception")
 110DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 111              "HFP significance exception")
 112DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 113              "HFP divide exception")
 114DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 115              "HFP square root exception")
 116DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 117              "operand exception")
 118DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 119              "privileged operation")
 120DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 121              "special operation exception")
 122DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 123              "transaction constraint exception")
 124
 125static 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
 145static void translation_exception(struct pt_regs *regs)
 146{
 147        /* May never happen. */
 148        panic("Translation exception");
 149}
 150
 151static 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}
 188NOKPROBE_SYMBOL(illegal_op);
 189
 190DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 191              "specification exception");
 192
 193static 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
 227static 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
 236static 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
 245static 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
 266void 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}
 274NOKPROBE_SYMBOL(kernel_stack_overflow);
 275
 276static 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
 292void __init trap_init(void)
 293{
 294        sort_extable(__start_dma_ex_table, __stop_dma_ex_table);
 295        local_mcck_enable();
 296        test_monitor_call();
 297}
 298
 299static void (*pgm_check_table[128])(struct pt_regs *regs);
 300
 301void noinstr __do_pgm_check(struct pt_regs *regs)
 302{
 303        unsigned long last_break = S390_lowcore.breaking_event_addr;
 304        unsigned int trapnr;
 305        irqentry_state_t state;
 306
 307        regs->int_code = *(u32 *)&S390_lowcore.pgm_ilc;
 308        regs->int_parm_long = S390_lowcore.trans_exc_code;
 309
 310        state = irqentry_enter(regs);
 311
 312        if (user_mode(regs)) {
 313                update_timer_sys();
 314                if (last_break < 4096)
 315                        last_break = 1;
 316                current->thread.last_break = last_break;
 317                regs->args[0] = 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);
 348out:
 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 */
 358static 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
 407COND_TRAP(do_secure_storage_access);
 408COND_TRAP(do_non_secure_storage_access);
 409COND_TRAP(do_secure_storage_violation);
 410