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/kprobes.h> 16 #include <linux/mm.h> 17 #include <linux/module.h> 18 #include <linux/irq.h> 19 #include <linux/kexec.h> 20 21 #include <asm/asm-prototypes.h> 22 #include <asm/bug.h> 23 #include <asm/csr.h> 24 #include <asm/processor.h> 25 #include <asm/ptrace.h> 26 #include <asm/thread_info.h> 27 28 int show_unhandled_signals = 1; 29 30 static DEFINE_SPINLOCK(die_lock); 31 32 static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs) 33 { 34 char str[sizeof("0000 ") * 12 + 2 + 1], *p = str; 35 const u16 *insns = (u16 *)instruction_pointer(regs); 36 long bad; 37 u16 val; 38 int i; 39 40 for (i = -10; i < 2; i++) { 41 bad = get_kernel_nofault(val, &insns[i]); 42 if (!bad) { 43 p += sprintf(p, i == 0 ? "(%04hx) " : "%04hx ", val); 44 } else { 45 printk("%sCode: Unable to access instruction at 0x%px.\n", 46 loglvl, &insns[i]); 47 return; 48 } 49 } 50 printk("%sCode: %s\n", loglvl, str); 51 } 52 53 void die(struct pt_regs *regs, const char *str) 54 { 55 static int die_counter; 56 int ret; 57 long cause; 58 unsigned long flags; 59 60 oops_enter(); 61 62 spin_lock_irqsave(&die_lock, flags); 63 console_verbose(); 64 bust_spinlocks(1); 65 66 pr_emerg("%s [#%d]\n", str, ++die_counter); 67 print_modules(); 68 if (regs) { 69 show_regs(regs); 70 dump_kernel_instr(KERN_EMERG, regs); 71 } 72 73 cause = regs ? regs->cause : -1; 74 ret = notify_die(DIE_OOPS, str, regs, 0, cause, SIGSEGV); 75 76 if (kexec_should_crash(current)) 77 crash_kexec(regs); 78 79 bust_spinlocks(0); 80 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 81 spin_unlock_irqrestore(&die_lock, flags); 82 oops_exit(); 83 84 if (in_interrupt()) 85 panic("Fatal exception in interrupt"); 86 if (panic_on_oops) 87 panic("Fatal exception"); 88 if (ret != NOTIFY_STOP) 89 make_task_dead(SIGSEGV); 90 } 91 92 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) 93 { 94 struct task_struct *tsk = current; 95 96 if (show_unhandled_signals && unhandled_signal(tsk, signo) 97 && printk_ratelimit()) { 98 pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT, 99 tsk->comm, task_pid_nr(tsk), signo, code, addr); 100 print_vma_addr(KERN_CONT " in ", instruction_pointer(regs)); 101 pr_cont("\n"); 102 __show_regs(regs); 103 } 104 105 force_sig_fault(signo, code, (void __user *)addr); 106 } 107 108 static void do_trap_error(struct pt_regs *regs, int signo, int code, 109 unsigned long addr, const char *str) 110 { 111 current->thread.bad_cause = regs->cause; 112 113 if (user_mode(regs)) { 114 do_trap(regs, signo, code, addr); 115 } else { 116 if (!fixup_exception(regs)) 117 die(regs, str); 118 } 119 } 120 121 #if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE) 122 #define __trap_section __section(".xip.traps") 123 #else 124 #define __trap_section 125 #endif 126 #define DO_ERROR_INFO(name, signo, code, str) \ 127 asmlinkage __visible __trap_section void name(struct pt_regs *regs) \ 128 { \ 129 do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ 130 } 131 132 DO_ERROR_INFO(do_trap_unknown, 133 SIGILL, ILL_ILLTRP, "unknown exception"); 134 DO_ERROR_INFO(do_trap_insn_misaligned, 135 SIGBUS, BUS_ADRALN, "instruction address misaligned"); 136 DO_ERROR_INFO(do_trap_insn_fault, 137 SIGSEGV, SEGV_ACCERR, "instruction access fault"); 138 DO_ERROR_INFO(do_trap_insn_illegal, 139 SIGILL, ILL_ILLOPC, "illegal instruction"); 140 DO_ERROR_INFO(do_trap_load_fault, 141 SIGSEGV, SEGV_ACCERR, "load access fault"); 142 #ifndef CONFIG_RISCV_M_MODE 143 DO_ERROR_INFO(do_trap_load_misaligned, 144 SIGBUS, BUS_ADRALN, "Oops - load address misaligned"); 145 DO_ERROR_INFO(do_trap_store_misaligned, 146 SIGBUS, BUS_ADRALN, "Oops - store (or AMO) address misaligned"); 147 #else 148 int handle_misaligned_load(struct pt_regs *regs); 149 int handle_misaligned_store(struct pt_regs *regs); 150 151 asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs) 152 { 153 if (!handle_misaligned_load(regs)) 154 return; 155 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, 156 "Oops - load address misaligned"); 157 } 158 159 asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs) 160 { 161 if (!handle_misaligned_store(regs)) 162 return; 163 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, 164 "Oops - store (or AMO) address misaligned"); 165 } 166 #endif 167 DO_ERROR_INFO(do_trap_store_fault, 168 SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault"); 169 DO_ERROR_INFO(do_trap_ecall_u, 170 SIGILL, ILL_ILLTRP, "environment call from U-mode"); 171 DO_ERROR_INFO(do_trap_ecall_s, 172 SIGILL, ILL_ILLTRP, "environment call from S-mode"); 173 DO_ERROR_INFO(do_trap_ecall_m, 174 SIGILL, ILL_ILLTRP, "environment call from M-mode"); 175 176 static inline unsigned long get_break_insn_length(unsigned long pc) 177 { 178 bug_insn_t insn; 179 180 if (get_kernel_nofault(insn, (bug_insn_t *)pc)) 181 return 0; 182 183 return GET_INSN_LENGTH(insn); 184 } 185 186 asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs) 187 { 188 #ifdef CONFIG_KPROBES 189 if (kprobe_single_step_handler(regs)) 190 return; 191 192 if (kprobe_breakpoint_handler(regs)) 193 return; 194 #endif 195 #ifdef CONFIG_UPROBES 196 if (uprobe_single_step_handler(regs)) 197 return; 198 199 if (uprobe_breakpoint_handler(regs)) 200 return; 201 #endif 202 current->thread.bad_cause = regs->cause; 203 204 if (user_mode(regs)) 205 force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc); 206 #ifdef CONFIG_KGDB 207 else if (notify_die(DIE_TRAP, "EBREAK", regs, 0, regs->cause, SIGTRAP) 208 == NOTIFY_STOP) 209 return; 210 #endif 211 else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN) 212 regs->epc += get_break_insn_length(regs->epc); 213 else 214 die(regs, "Kernel BUG"); 215 } 216 NOKPROBE_SYMBOL(do_trap_break); 217 218 #ifdef CONFIG_GENERIC_BUG 219 int is_valid_bugaddr(unsigned long pc) 220 { 221 bug_insn_t insn; 222 223 if (pc < VMALLOC_START) 224 return 0; 225 if (get_kernel_nofault(insn, (bug_insn_t *)pc)) 226 return 0; 227 if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) 228 return (insn == __BUG_INSN_32); 229 else 230 return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16); 231 } 232 #endif /* CONFIG_GENERIC_BUG */ 233 234 #ifdef CONFIG_VMAP_STACK 235 /* 236 * Extra stack space that allows us to provide panic messages when the kernel 237 * has overflowed its stack. 238 */ 239 static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], 240 overflow_stack)__aligned(16); 241 /* 242 * A temporary stack for use by handle_kernel_stack_overflow. This is used so 243 * we can call into C code to get the per-hart overflow stack. Usage of this 244 * stack must be protected by spin_shadow_stack. 245 */ 246 long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)] __aligned(16); 247 248 /* 249 * A pseudo spinlock to protect the shadow stack from being used by multiple 250 * harts concurrently. This isn't a real spinlock because the lock side must 251 * be taken without a valid stack and only a single register, it's only taken 252 * while in the process of panicing anyway so the performance and error 253 * checking a proper spinlock gives us doesn't matter. 254 */ 255 unsigned long spin_shadow_stack; 256 257 asmlinkage unsigned long get_overflow_stack(void) 258 { 259 return (unsigned long)this_cpu_ptr(overflow_stack) + 260 OVERFLOW_STACK_SIZE; 261 } 262 263 asmlinkage void handle_bad_stack(struct pt_regs *regs) 264 { 265 unsigned long tsk_stk = (unsigned long)current->stack; 266 unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); 267 268 /* 269 * We're done with the shadow stack by this point, as we're on the 270 * overflow stack. Tell any other concurrent overflowing harts that 271 * they can proceed with panicing by releasing the pseudo-spinlock. 272 * 273 * This pairs with an amoswap.aq in handle_kernel_stack_overflow. 274 */ 275 smp_store_release(&spin_shadow_stack, 0); 276 277 console_verbose(); 278 279 pr_emerg("Insufficient stack space to handle exception!\n"); 280 pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", 281 tsk_stk, tsk_stk + THREAD_SIZE); 282 pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", 283 ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); 284 285 __show_regs(regs); 286 panic("Kernel stack overflow"); 287 288 for (;;) 289 wait_for_interrupt(); 290 } 291 #endif 292