root/arch/riscv/kernel/traps.c

DEFINITIONS

1. die
2. do_trap
3. do_trap_error
4. get_break_insn_length
5. do_trap_break
6. is_valid_bugaddr
7. trap_init

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Regents of the University of California
   4  */
   5 
   6 #include <linux/cpu.h>
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/debug.h>
  11 #include <linux/sched/signal.h>
  12 #include <linux/signal.h>
  13 #include <linux/kdebug.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/mm.h>
  16 #include <linux/module.h>
  17 #include <linux/irq.h>
  18 
  19 #include <asm/processor.h>
  20 #include <asm/ptrace.h>
  21 #include <asm/csr.h>
  22 
  23 int show_unhandled_signals = 1;
  24 
  25 extern asmlinkage void handle_exception(void);
  26 
  27 static DEFINE_SPINLOCK(die_lock);
  28 
  29 void die(struct pt_regs *regs, const char *str)
  30 {
  31         static int die_counter;
  32         int ret;
  33 
  34         oops_enter();
  35 
  36         spin_lock_irq(&die_lock);
  37         console_verbose();
  38         bust_spinlocks(1);
  39 
  40         pr_emerg("%s [#%d]\n", str, ++die_counter);
  41         print_modules();
  42         show_regs(regs);
  43 
  44         ret = notify_die(DIE_OOPS, str, regs, 0, regs->scause, SIGSEGV);
  45 
  46         bust_spinlocks(0);
  47         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
  48         spin_unlock_irq(&die_lock);
  49         oops_exit();
  50 
  51         if (in_interrupt())
  52                 panic("Fatal exception in interrupt");
  53         if (panic_on_oops)
  54                 panic("Fatal exception");
  55         if (ret != NOTIFY_STOP)
  56                 do_exit(SIGSEGV);
  57 }
  58 
  59 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
  60 {
  61         struct task_struct *tsk = current;
  62 
  63         if (show_unhandled_signals && unhandled_signal(tsk, signo)
  64             && printk_ratelimit()) {
  65                 pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
  66                         tsk->comm, task_pid_nr(tsk), signo, code, addr);
  67                 print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
  68                 pr_cont("\n");
  69                 show_regs(regs);
  70         }
  71 
  72         force_sig_fault(signo, code, (void __user *)addr);
  73 }
  74 
  75 static void do_trap_error(struct pt_regs *regs, int signo, int code,
  76         unsigned long addr, const char *str)
  77 {
  78         if (user_mode(regs)) {
  79                 do_trap(regs, signo, code, addr);
  80         } else {
  81                 if (!fixup_exception(regs))
  82                         die(regs, str);
  83         }
  84 }
  85 
  86 #define DO_ERROR_INFO(name, signo, code, str)                           \
  87 asmlinkage __visible void name(struct pt_regs *regs)                    \
  88 {                                                                       \
  89         do_trap_error(regs, signo, code, regs->sepc, "Oops - " str);    \
  90 }
  91 
  92 DO_ERROR_INFO(do_trap_unknown,
  93         SIGILL, ILL_ILLTRP, "unknown exception");
  94 DO_ERROR_INFO(do_trap_insn_misaligned,
  95         SIGBUS, BUS_ADRALN, "instruction address misaligned");
  96 DO_ERROR_INFO(do_trap_insn_fault,
  97         SIGSEGV, SEGV_ACCERR, "instruction access fault");
  98 DO_ERROR_INFO(do_trap_insn_illegal,
  99         SIGILL, ILL_ILLOPC, "illegal instruction");
 100 DO_ERROR_INFO(do_trap_load_misaligned,
 101         SIGBUS, BUS_ADRALN, "load address misaligned");
 102 DO_ERROR_INFO(do_trap_load_fault,
 103         SIGSEGV, SEGV_ACCERR, "load access fault");
 104 DO_ERROR_INFO(do_trap_store_misaligned,
 105         SIGBUS, BUS_ADRALN, "store (or AMO) address misaligned");
 106 DO_ERROR_INFO(do_trap_store_fault,
 107         SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
 108 DO_ERROR_INFO(do_trap_ecall_u,
 109         SIGILL, ILL_ILLTRP, "environment call from U-mode");
 110 DO_ERROR_INFO(do_trap_ecall_s,
 111         SIGILL, ILL_ILLTRP, "environment call from S-mode");
 112 DO_ERROR_INFO(do_trap_ecall_m,
 113         SIGILL, ILL_ILLTRP, "environment call from M-mode");
 114 
 115 static inline unsigned long get_break_insn_length(unsigned long pc)
 116 {
 117         bug_insn_t insn;
 118 
 119         if (probe_kernel_address((bug_insn_t *)pc, insn))
 120                 return 0;
 121         return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
 122 }
 123 
 124 asmlinkage __visible void do_trap_break(struct pt_regs *regs)
 125 {
 126         if (user_mode(regs))
 127                 force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->sepc);
 128         else if (report_bug(regs->sepc, regs) == BUG_TRAP_TYPE_WARN)
 129                 regs->sepc += get_break_insn_length(regs->sepc);
 130         else
 131                 die(regs, "Kernel BUG");
 132 }
 133 
 134 #ifdef CONFIG_GENERIC_BUG
 135 int is_valid_bugaddr(unsigned long pc)
 136 {
 137         bug_insn_t insn;
 138 
 139         if (pc < VMALLOC_START)
 140                 return 0;
 141         if (probe_kernel_address((bug_insn_t *)pc, insn))
 142                 return 0;
 143         if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
 144                 return (insn == __BUG_INSN_32);
 145         else
 146                 return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
 147 }
 148 #endif /* CONFIG_GENERIC_BUG */
 149 
 150 void __init trap_init(void)
 151 {
 152         /*
 153          * Set sup0 scratch register to 0, indicating to exception vector
 154          * that we are presently executing in the kernel
 155          */
 156         csr_write(CSR_SSCRATCH, 0);
 157         /* Set the exception vector address */
 158         csr_write(CSR_STVEC, &handle_exception);
 159         /* Enable all interrupts */
 160         csr_write(CSR_SIE, -1);
 161 }