arch/riscv/kernel/traps.c

   1 /*
   2  * Copyright (C) 2012 Regents of the University of California
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful,
   9  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  *   GNU General Public License for more details.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/sched.h>
  17 #include <linux/sched/debug.h>
  18 #include <linux/sched/signal.h>
  19 #include <linux/signal.h>
  20 #include <linux/kdebug.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/mm.h>
  23 #include <linux/module.h>
  24 #include <linux/irq.h>
  25
  26 #include <asm/processor.h>
  27 #include <asm/ptrace.h>
  28 #include <asm/csr.h>
  29
  30 int show_unhandled_signals = 1;
  31
  32 extern asmlinkage void handle_exception(void);
  33
  34 static DEFINE_SPINLOCK(die_lock);
  35
  36 void die(struct pt_regs *regs, const char *str)
  37 {
  38         static int die_counter;
  39         int ret;
  40
  41         oops_enter();
  42
  43         spin_lock_irq(&die_lock);
  44         console_verbose();
  45         bust_spinlocks(1);
  46
  47         pr_emerg("%s [#%d]\n", str, ++die_counter);
  48         print_modules();
  49         show_regs(regs);
  50
  51         ret = notify_die(DIE_OOPS, str, regs, 0, regs->scause, SIGSEGV);
  52
  53         bust_spinlocks(0);
  54         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
  55         spin_unlock_irq(&die_lock);
  56         oops_exit();
  57
  58         if (in_interrupt())
  59                 panic("Fatal exception in interrupt");
  60         if (panic_on_oops)
  61                 panic("Fatal exception");
  62         if (ret != NOTIFY_STOP)
  63                 do_exit(SIGSEGV);
  64 }
  65
  66 void do_trap(struct pt_regs *regs, int signo, int code,
  67         unsigned long addr, struct task_struct *tsk)
  68 {
  69         if (show_unhandled_signals && unhandled_signal(tsk, signo)
  70             && printk_ratelimit()) {
  71                 pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
  72                         tsk->comm, task_pid_nr(tsk), signo, code, addr);
  73                 print_vma_addr(KERN_CONT " in ", GET_IP(regs));
  74                 pr_cont("\n");
  75                 show_regs(regs);
  76         }
  77
  78         force_sig_fault(signo, code, (void __user *)addr, tsk);
  79 }
  80
  81 static void do_trap_error(struct pt_regs *regs, int signo, int code,
  82         unsigned long addr, const char *str)
  83 {
  84         if (user_mode(regs)) {
  85                 do_trap(regs, signo, code, addr, current);
  86         } else {
  87                 if (!fixup_exception(regs))
  88                         die(regs, str);
  89         }
  90 }
  91
  92 #define DO_ERROR_INFO(name, signo, code, str)                           \
  93 asmlinkage void name(struct pt_regs *regs)                              \
  94 {                                                                       \
  95         do_trap_error(regs, signo, code, regs->sepc, "Oops - " str);    \
  96 }
  97
  98 DO_ERROR_INFO(do_trap_unknown,
  99         SIGILL, ILL_ILLTRP, "unknown exception");
 100 DO_ERROR_INFO(do_trap_insn_misaligned,
 101         SIGBUS, BUS_ADRALN, "instruction address misaligned");
 102 DO_ERROR_INFO(do_trap_insn_fault,
 103         SIGSEGV, SEGV_ACCERR, "instruction access fault");
 104 DO_ERROR_INFO(do_trap_insn_illegal,
 105         SIGILL, ILL_ILLOPC, "illegal instruction");
 106 DO_ERROR_INFO(do_trap_load_misaligned,
 107         SIGBUS, BUS_ADRALN, "load address misaligned");
 108 DO_ERROR_INFO(do_trap_load_fault,
 109         SIGSEGV, SEGV_ACCERR, "load access fault");
 110 DO_ERROR_INFO(do_trap_store_misaligned,
 111         SIGBUS, BUS_ADRALN, "store (or AMO) address misaligned");
 112 DO_ERROR_INFO(do_trap_store_fault,
 113         SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
 114 DO_ERROR_INFO(do_trap_ecall_u,
 115         SIGILL, ILL_ILLTRP, "environment call from U-mode");
 116 DO_ERROR_INFO(do_trap_ecall_s,
 117         SIGILL, ILL_ILLTRP, "environment call from S-mode");
 118 DO_ERROR_INFO(do_trap_ecall_m,
 119         SIGILL, ILL_ILLTRP, "environment call from M-mode");
 120
 121 asmlinkage void do_trap_break(struct pt_regs *regs)
 122 {
 123 #ifdef CONFIG_GENERIC_BUG
 124         if (!user_mode(regs)) {
 125                 enum bug_trap_type type;
 126
 127                 type = report_bug(regs->sepc, regs);
 128                 switch (type) {
 129                 case BUG_TRAP_TYPE_NONE:
 130                         break;
 131                 case BUG_TRAP_TYPE_WARN:
 132                         regs->sepc += sizeof(bug_insn_t);
 133                         return;
 134                 case BUG_TRAP_TYPE_BUG:
 135                         die(regs, "Kernel BUG");
 136                 }
 137         }
 138 #endif /* CONFIG_GENERIC_BUG */
 139
 140         force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)(regs->sepc), current);
 141 }
 142
 143 #ifdef CONFIG_GENERIC_BUG
 144 int is_valid_bugaddr(unsigned long pc)
 145 {
 146         bug_insn_t insn;
 147
 148         if (pc < PAGE_OFFSET)
 149                 return 0;
 150         if (probe_kernel_address((bug_insn_t *)pc, insn))
 151                 return 0;
 152         return (insn == __BUG_INSN);
 153 }
 154 #endif /* CONFIG_GENERIC_BUG */
 155
 156 void __init trap_init(void)
 157 {
 158         /*
 159          * Set sup0 scratch register to 0, indicating to exception vector
 160          * that we are presently executing in the kernel
 161          */
 162         csr_write(sscratch, 0);
 163         /* Set the exception vector address */
 164         csr_write(stvec, &handle_exception);
 165         /* Enable all interrupts */
 166         csr_write(sie, -1);
 167 }