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 die(const char * str,struct pt_regs * regs,long err)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 die_if_kernel(const char * str,struct pt_regs * regs,long err)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 */ die_if_no_fixup(const char * str,struct pt_regs * regs,long err)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 handle_BUG(struct pt_regs * regs)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 is_valid_bugaddr(unsigned long addr)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 */ BUILD_TRAP_HANDLER(debug)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 */ BUILD_TRAP_HANDLER(bug)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 BUILD_TRAP_HANDLER(nmi)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 } 199