traps.c (4340B)
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 21static DEFINE_SPINLOCK(die_lock); 22 23void __noreturn 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: ", KERN_DEFAULT, regs->regs[15], 42 THREAD_SIZE + (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 make_task_dead(SIGSEGV); 61} 62 63void 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 */ 75void 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 90static 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 111invalid: 112 die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff); 113} 114 115int is_valid_bugaddr(unsigned long addr) 116{ 117 insn_size_t opcode; 118 119 if (addr < PAGE_OFFSET) 120 return 0; 121 if (get_kernel_nofault(opcode, (insn_size_t *)addr)) 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 */ 133BUILD_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); 145} 146 147/* 148 * Special handler for BUG() traps. 149 */ 150BUILD_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); 171} 172 173#ifdef CONFIG_DYNAMIC_FTRACE 174extern void arch_ftrace_nmi_enter(void); 175extern void arch_ftrace_nmi_exit(void); 176#else 177static inline void arch_ftrace_nmi_enter(void) { } 178static inline void arch_ftrace_nmi_exit(void) { } 179#endif 180 181BUILD_TRAP_HANDLER(nmi) 182{ 183 TRAP_HANDLER_DECL; 184 185 arch_ftrace_nmi_enter(); 186 187 nmi_enter(); 188 this_cpu_inc(irq_stat.__nmi_count); 189 190 switch (notify_die(DIE_NMI, "NMI", regs, 0, vec & 0xff, SIGINT)) { 191 case NOTIFY_OK: 192 case NOTIFY_STOP: 193 break; 194 case NOTIFY_BAD: 195 die("Fatal Non-Maskable Interrupt", regs, SIGINT); 196 default: 197 printk(KERN_ALERT "Got NMI, but nobody cared. Ignoring...\n"); 198 break; 199 } 200 201 nmi_exit(); 202 203 arch_ftrace_nmi_exit(); 204}