arch/s390/kernel/traps.c

   1 /*
   2  *  S390 version
   3  *    Copyright IBM Corp. 1999, 2000
   4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
   5  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
   6  *
   7  *  Derived from "arch/i386/kernel/traps.c"
   8  *    Copyright (C) 1991, 1992 Linus Torvalds
   9  */
  10
  11 /*
  12  * 'Traps.c' handles hardware traps and faults after we have saved some
  13  * state in 'asm.s'.
  14  */
  15 #include <linux/kprobes.h>
  16 #include <linux/kdebug.h>
  17 #include <linux/module.h>
  18 #include <linux/ptrace.h>
  19 #include <linux/sched.h>
  20 #include <linux/mm.h>
  21 #include <linux/slab.h>
  22 #include <asm/switch_to.h>
  23 #include "entry.h"
  24
  25 int show_unhandled_signals = 1;
  26
  27 static inline void __user *get_trap_ip(struct pt_regs *regs)
  28 {
  29         unsigned long address;
  30
  31         if (regs->int_code & 0x200)
  32                 address = *(unsigned long *)(current->thread.trap_tdb + 24);
  33         else
  34                 address = regs->psw.addr;
  35         return (void __user *)
  36                 ((address - (regs->int_code >> 16)) & PSW_ADDR_INSN);
  37 }
  38
  39 static inline void report_user_fault(struct pt_regs *regs, int signr)
  40 {
  41         if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
  42                 return;
  43         if (!unhandled_signal(current, signr))
  44                 return;
  45         if (!printk_ratelimit())
  46                 return;
  47         printk("User process fault: interruption code %04x ilc:%d ",
  48                regs->int_code & 0xffff, regs->int_code >> 17);
  49         print_vma_addr("in ", regs->psw.addr & PSW_ADDR_INSN);
  50         printk("\n");
  51         show_regs(regs);
  52 }
  53
  54 int is_valid_bugaddr(unsigned long addr)
  55 {
  56         return 1;
  57 }
  58
  59 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  60 {
  61         siginfo_t info;
  62
  63         if (user_mode(regs)) {
  64                 info.si_signo = si_signo;
  65                 info.si_errno = 0;
  66                 info.si_code = si_code;
  67                 info.si_addr = get_trap_ip(regs);
  68                 force_sig_info(si_signo, &info, current);
  69                 report_user_fault(regs, si_signo);
  70         } else {
  71                 const struct exception_table_entry *fixup;
  72                 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
  73                 if (fixup)
  74                         regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
  75                 else {
  76                         enum bug_trap_type btt;
  77
  78                         btt = report_bug(regs->psw.addr & PSW_ADDR_INSN, regs);
  79                         if (btt == BUG_TRAP_TYPE_WARN)
  80                                 return;
  81                         die(regs, str);
  82                 }
  83         }
  84 }
  85
  86 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  87 {
  88         if (notify_die(DIE_TRAP, str, regs, 0,
  89                        regs->int_code, si_signo) == NOTIFY_STOP)
  90                 return;
  91         do_report_trap(regs, si_signo, si_code, str);
  92 }
  93 NOKPROBE_SYMBOL(do_trap);
  94
  95 void do_per_trap(struct pt_regs *regs)
  96 {
  97         siginfo_t info;
  98
  99         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
 100                 return;
 101         if (!current->ptrace)
 102                 return;
 103         info.si_signo = SIGTRAP;
 104         info.si_errno = 0;
 105         info.si_code = TRAP_HWBKPT;
 106         info.si_addr =
 107                 (void __force __user *) current->thread.per_event.address;
 108         force_sig_info(SIGTRAP, &info, current);
 109 }
 110 NOKPROBE_SYMBOL(do_per_trap);
 111
 112 void default_trap_handler(struct pt_regs *regs)
 113 {
 114         if (user_mode(regs)) {
 115                 report_user_fault(regs, SIGSEGV);
 116                 do_exit(SIGSEGV);
 117         } else
 118                 die(regs, "Unknown program exception");
 119 }
 120
 121 #define DO_ERROR_INFO(name, signr, sicode, str) \
 122 void name(struct pt_regs *regs)                 \
 123 {                                               \
 124         do_trap(regs, signr, sicode, str);      \
 125 }
 126
 127 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
 128               "addressing exception")
 129 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 130               "execute exception")
 131 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 132               "fixpoint divide exception")
 133 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 134               "fixpoint overflow exception")
 135 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 136               "HFP overflow exception")
 137 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 138               "HFP underflow exception")
 139 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 140               "HFP significance exception")
 141 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 142               "HFP divide exception")
 143 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 144               "HFP square root exception")
 145 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 146               "operand exception")
 147 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 148               "privileged operation")
 149 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 150               "special operation exception")
 151 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 152               "transaction constraint exception")
 153
 154 static inline void do_fp_trap(struct pt_regs *regs, int fpc)
 155 {
 156         int si_code = 0;
 157         /* FPC[2] is Data Exception Code */
 158         if ((fpc & 0x00000300) == 0) {
 159                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 160                 if (fpc & 0x8000) /* invalid fp operation */
 161                         si_code = FPE_FLTINV;
 162                 else if (fpc & 0x4000) /* div by 0 */
 163                         si_code = FPE_FLTDIV;
 164                 else if (fpc & 0x2000) /* overflow */
 165                         si_code = FPE_FLTOVF;
 166                 else if (fpc & 0x1000) /* underflow */
 167                         si_code = FPE_FLTUND;
 168                 else if (fpc & 0x0800) /* inexact */
 169                         si_code = FPE_FLTRES;
 170         }
 171         do_trap(regs, SIGFPE, si_code, "floating point exception");
 172 }
 173
 174 void translation_exception(struct pt_regs *regs)
 175 {
 176         /* May never happen. */
 177         panic("Translation exception");
 178 }
 179
 180 void illegal_op(struct pt_regs *regs)
 181 {
 182         siginfo_t info;
 183         __u8 opcode[6];
 184         __u16 __user *location;
 185         int is_uprobe_insn = 0;
 186         int signal = 0;
 187
 188         location = get_trap_ip(regs);
 189
 190         if (user_mode(regs)) {
 191                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 192                         return;
 193                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 194                         if (current->ptrace) {
 195                                 info.si_signo = SIGTRAP;
 196                                 info.si_errno = 0;
 197                                 info.si_code = TRAP_BRKPT;
 198                                 info.si_addr = location;
 199                                 force_sig_info(SIGTRAP, &info, current);
 200                         } else
 201                                 signal = SIGILL;
 202 #ifdef CONFIG_UPROBES
 203                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 204                         is_uprobe_insn = 1;
 205 #endif
 206                 } else
 207                         signal = SIGILL;
 208         }
 209         /*
 210          * We got either an illegal op in kernel mode, or user space trapped
 211          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 212          * it up. If not, SIGILL.
 213          */
 214         if (is_uprobe_insn || !user_mode(regs)) {
 215                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 216                                3, SIGTRAP) != NOTIFY_STOP)
 217                         signal = SIGILL;
 218         }
 219         if (signal)
 220                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 221 }
 222 NOKPROBE_SYMBOL(illegal_op);
 223
 224 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 225               "specification exception");
 226
 227 int alloc_vector_registers(struct task_struct *tsk)
 228 {
 229         __vector128 *vxrs;
 230         int i;
 231
 232         /* Allocate vector register save area. */
 233         vxrs = kzalloc(sizeof(__vector128) * __NUM_VXRS,
 234                        GFP_KERNEL|__GFP_REPEAT);
 235         if (!vxrs)
 236                 return -ENOMEM;
 237         preempt_disable();
 238         if (tsk == current)
 239                 save_fp_regs(tsk->thread.fp_regs.fprs);
 240         /* Copy the 16 floating point registers */
 241         for (i = 0; i < 16; i++)
 242                 *(freg_t *) &vxrs[i] = tsk->thread.fp_regs.fprs[i];
 243         tsk->thread.vxrs = vxrs;
 244         if (tsk == current) {
 245                 __ctl_set_bit(0, 17);
 246                 restore_vx_regs(vxrs);
 247         }
 248         preempt_enable();
 249         return 0;
 250 }
 251
 252 void vector_exception(struct pt_regs *regs)
 253 {
 254         int si_code, vic;
 255
 256         if (!MACHINE_HAS_VX) {
 257                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 258                 return;
 259         }
 260
 261         /* get vector interrupt code from fpc */
 262         asm volatile("stfpc %0" : "=Q" (current->thread.fp_regs.fpc));
 263         vic = (current->thread.fp_regs.fpc & 0xf00) >> 8;
 264         switch (vic) {
 265         case 1: /* invalid vector operation */
 266                 si_code = FPE_FLTINV;
 267                 break;
 268         case 2: /* division by zero */
 269                 si_code = FPE_FLTDIV;
 270                 break;
 271         case 3: /* overflow */
 272                 si_code = FPE_FLTOVF;
 273                 break;
 274         case 4: /* underflow */
 275                 si_code = FPE_FLTUND;
 276                 break;
 277         case 5: /* inexact */
 278                 si_code = FPE_FLTRES;
 279                 break;
 280         default: /* unknown cause */
 281                 si_code = 0;
 282         }
 283         do_trap(regs, SIGFPE, si_code, "vector exception");
 284 }
 285
 286 static int __init disable_vector_extension(char *str)
 287 {
 288         S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
 289         return 1;
 290 }
 291 __setup("novx", disable_vector_extension);
 292
 293 void data_exception(struct pt_regs *regs)
 294 {
 295         __u16 __user *location;
 296         int signal = 0;
 297
 298         location = get_trap_ip(regs);
 299
 300         asm volatile("stfpc %0" : "=Q" (current->thread.fp_regs.fpc));
 301         /* Check for vector register enablement */
 302         if (MACHINE_HAS_VX && !current->thread.vxrs &&
 303             (current->thread.fp_regs.fpc & FPC_DXC_MASK) == 0xfe00) {
 304                 alloc_vector_registers(current);
 305                 /* Vector data exception is suppressing, rewind psw. */
 306                 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
 307                 clear_pt_regs_flag(regs, PIF_PER_TRAP);
 308                 return;
 309         }
 310         if (current->thread.fp_regs.fpc & FPC_DXC_MASK)
 311                 signal = SIGFPE;
 312         else
 313                 signal = SIGILL;
 314         if (signal == SIGFPE)
 315                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 316         else if (signal)
 317                 do_trap(regs, signal, ILL_ILLOPN, "data exception");
 318 }
 319
 320 void space_switch_exception(struct pt_regs *regs)
 321 {
 322         /* Set user psw back to home space mode. */
 323         if (user_mode(regs))
 324                 regs->psw.mask |= PSW_ASC_HOME;
 325         /* Send SIGILL. */
 326         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 327 }
 328
 329 void kernel_stack_overflow(struct pt_regs *regs)
 330 {
 331         bust_spinlocks(1);
 332         printk("Kernel stack overflow.\n");
 333         show_regs(regs);
 334         bust_spinlocks(0);
 335         panic("Corrupt kernel stack, can't continue.");
 336 }
 337 NOKPROBE_SYMBOL(kernel_stack_overflow);
 338
 339 void __init trap_init(void)
 340 {
 341         local_mcck_enable();
 342 }