arch/sh/kernel/traps.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/bug.h>
   3 #include <linux/io.h>
   4 #include <linux/types.h>
   5 #include <linux/kdebug.h>
   6 #include <linux/signal.h>
   7 #include <linux/sched.h>
   8 #include <linux/sched/debug.h>
   9 #include <linux/sched/task_stack.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/hardirq.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kexec.h>
  14 #include <linux/sched/signal.h>
  15
  16 #include <linux/extable.h>
  17 #include <linux/module.h>       /* print_modules */
  18
  19 #include <asm/ftrace.h>
  20 #include <asm/unwinder.h>
  21 #include <asm/traps.h>
  22
  23 static DEFINE_SPINLOCK(die_lock);
  24
  25 void __noreturn die(const char *str, struct pt_regs *regs, long err)
  26 {
  27         static int die_counter;
  28
  29         oops_enter();
  30
  31         spin_lock_irq(&die_lock);
  32         console_verbose();
  33         bust_spinlocks(1);
  34
  35         printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
  36         print_modules();
  37         show_regs(regs);
  38
  39         printk("Process: %s (pid: %d, stack limit = %p)\n", current->comm,
  40                         task_pid_nr(current), task_stack_page(current) + 1);
  41
  42         if (!user_mode(regs) || in_interrupt())
  43                 dump_mem("Stack: ", KERN_DEFAULT, regs->regs[15],
  44                         THREAD_SIZE + (unsigned long)task_stack_page(current));
  45
  46         notify_die(DIE_OOPS, str, regs, err, 255, SIGSEGV);
  47
  48         bust_spinlocks(0);
  49         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
  50         spin_unlock_irq(&die_lock);
  51         oops_exit();
  52
  53         if (kexec_should_crash(current))
  54                 crash_kexec(regs);
  55
  56         if (in_interrupt())
  57                 panic("Fatal exception in interrupt");
  58
  59         if (panic_on_oops)
  60                 panic("Fatal exception");
  61
  62         make_task_dead(SIGSEGV);
  63 }
  64
  65 void die_if_kernel(const char *str, struct pt_regs *regs, long err)
  66 {
  67         if (!user_mode(regs))
  68                 die(str, regs, err);
  69 }
  70
  71 /*
  72  * try and fix up kernelspace address errors
  73  * - userspace errors just cause EFAULT to be returned, resulting in SEGV
  74  * - kernel/userspace interfaces cause a jump to an appropriate handler
  75  * - other kernel errors are bad
  76  */
  77 void die_if_no_fixup(const char *str, struct pt_regs *regs, long err)
  78 {
  79         if (!user_mode(regs)) {
  80                 const struct exception_table_entry *fixup;
  81                 fixup = search_exception_tables(regs->pc);
  82                 if (fixup) {
  83                         regs->pc = fixup->fixup;
  84                         return;
  85                 }
  86
  87                 die(str, regs, err);
  88         }
  89 }
  90
  91 #ifdef CONFIG_GENERIC_BUG
  92 static void handle_BUG(struct pt_regs *regs)
  93 {
  94         const struct bug_entry *bug;
  95         unsigned long bugaddr = regs->pc;
  96         enum bug_trap_type tt;
  97
  98         if (!is_valid_bugaddr(bugaddr))
  99                 goto invalid;
 100
 101         bug = find_bug(bugaddr);
 102
 103         /* Switch unwinders when unwind_stack() is called */
 104         if (bug->flags & BUGFLAG_UNWINDER)
 105                 unwinder_faulted = 1;
 106
 107         tt = report_bug(bugaddr, regs);
 108         if (tt == BUG_TRAP_TYPE_WARN) {
 109                 regs->pc += instruction_size(bugaddr);
 110                 return;
 111         }
 112
 113 invalid:
 114         die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
 115 }
 116
 117 int is_valid_bugaddr(unsigned long addr)
 118 {
 119         insn_size_t opcode;
 120
 121         if (addr < PAGE_OFFSET)
 122                 return 0;
 123         if (get_kernel_nofault(opcode, (insn_size_t *)addr))
 124                 return 0;
 125         if (opcode == TRAPA_BUG_OPCODE)
 126                 return 1;
 127
 128         return 0;
 129 }
 130 #endif
 131
 132 /*
 133  * Generic trap handler.
 134  */
 135 BUILD_TRAP_HANDLER(debug)
 136 {
 137         TRAP_HANDLER_DECL;
 138
 139         /* Rewind */
 140         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 141
 142         if (notify_die(DIE_TRAP, "debug trap", regs, 0, vec & 0xff,
 143                        SIGTRAP) == NOTIFY_STOP)
 144                 return;
 145
 146         force_sig(SIGTRAP);
 147 }
 148
 149 /*
 150  * Special handler for BUG() traps.
 151  */
 152 BUILD_TRAP_HANDLER(bug)
 153 {
 154         TRAP_HANDLER_DECL;
 155
 156         /* Rewind */
 157         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 158
 159         if (notify_die(DIE_TRAP, "bug trap", regs, 0, TRAPA_BUG_OPCODE & 0xff,
 160                        SIGTRAP) == NOTIFY_STOP)
 161                 return;
 162
 163 #ifdef CONFIG_GENERIC_BUG
 164         if (__kernel_text_address(instruction_pointer(regs))) {
 165                 insn_size_t insn = *(insn_size_t *)instruction_pointer(regs);
 166                 if (insn == TRAPA_BUG_OPCODE)
 167                         handle_BUG(regs);
 168                 return;
 169         }
 170 #endif
 171
 172         force_sig(SIGTRAP);
 173 }
 174
 175 BUILD_TRAP_HANDLER(nmi)
 176 {
 177         TRAP_HANDLER_DECL;
 178
 179         arch_ftrace_nmi_enter();
 180
 181         nmi_enter();
 182         this_cpu_inc(irq_stat.__nmi_count);
 183
 184         switch (notify_die(DIE_NMI, "NMI", regs, 0, vec & 0xff, SIGINT)) {
 185         case NOTIFY_OK:
 186         case NOTIFY_STOP:
 187                 break;
 188         case NOTIFY_BAD:
 189                 die("Fatal Non-Maskable Interrupt", regs, SIGINT);
 190         default:
 191                 printk(KERN_ALERT "Got NMI, but nobody cared. Ignoring...\n");
 192                 break;
 193         }
 194
 195         nmi_exit();
 196
 197         arch_ftrace_nmi_exit();
 198 }