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