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 #include <linux/entry-common.h> 21 22 #include <asm/asm-prototypes.h> 23 #include <asm/bug.h> 24 #include <asm/cfi.h> 25 #include <asm/csr.h> 26 #include <asm/processor.h> 27 #include <asm/ptrace.h> 28 #include <asm/syscall.h> 29 #include <asm/thread_info.h> 30 #include <asm/vector.h> 31 #include <asm/irq_stack.h> 32 33 int show_unhandled_signals = 1; 34 35 static DEFINE_SPINLOCK(die_lock); 36 37 static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs) 38 { 39 char str[sizeof("0000 ") * 12 + 2 + 1], *p = str; 40 const u16 *insns = (u16 *)instruction_pointer(regs); 41 long bad; 42 u16 val; 43 int i; 44 45 for (i = -10; i < 2; i++) { 46 bad = get_kernel_nofault(val, &insns[i]); 47 if (!bad) { 48 p += sprintf(p, i == 0 ? "(%04hx) " : "%04hx ", val); 49 } else { 50 printk("%sCode: Unable to access instruction at 0x%px.\n", 51 loglvl, &insns[i]); 52 return; 53 } 54 } 55 printk("%sCode: %s\n", loglvl, str); 56 } 57 58 void die(struct pt_regs *regs, const char *str) 59 { 60 static int die_counter; 61 int ret; 62 long cause; 63 unsigned long flags; 64 65 oops_enter(); 66 67 spin_lock_irqsave(&die_lock, flags); 68 console_verbose(); 69 bust_spinlocks(1); 70 71 pr_emerg("%s [#%d]\n", str, ++die_counter); 72 print_modules(); 73 if (regs) { 74 show_regs(regs); 75 dump_kernel_instr(KERN_EMERG, regs); 76 } 77 78 cause = regs ? regs->cause : -1; 79 ret = notify_die(DIE_OOPS, str, regs, 0, cause, SIGSEGV); 80 81 if (kexec_should_crash(current)) 82 crash_kexec(regs); 83 84 bust_spinlocks(0); 85 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 86 spin_unlock_irqrestore(&die_lock, flags); 87 oops_exit(); 88 89 if (in_interrupt()) 90 panic("Fatal exception in interrupt"); 91 if (panic_on_oops) 92 panic("Fatal exception"); 93 if (ret != NOTIFY_STOP) 94 make_task_dead(SIGSEGV); 95 } 96 97 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) 98 { 99 struct task_struct *tsk = current; 100 101 if (show_unhandled_signals && unhandled_signal(tsk, signo) 102 && printk_ratelimit()) { 103 pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT, 104 tsk->comm, task_pid_nr(tsk), signo, code, addr); 105 print_vma_addr(KERN_CONT " in ", instruction_pointer(regs)); 106 pr_cont("\n"); 107 __show_regs(regs); 108 } 109 110 force_sig_fault(signo, code, (void __user *)addr); 111 } 112 113 static void do_trap_error(struct pt_regs *regs, int signo, int code, 114 unsigned long addr, const char *str) 115 { 116 current->thread.bad_cause = regs->cause; 117 118 if (user_mode(regs)) { 119 do_trap(regs, signo, code, addr); 120 } else { 121 if (!fixup_exception(regs)) 122 die(regs, str); 123 } 124 } 125 126 #if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE) 127 #define __trap_section __noinstr_section(".xip.traps") 128 #else 129 #define __trap_section noinstr 130 #endif 131 #define DO_ERROR_INFO(name, signo, code, str) \ 132 asmlinkage __visible __trap_section void name(struct pt_regs *regs) \ 133 { \ 134 if (user_mode(regs)) { \ 135 irqentry_enter_from_user_mode(regs); \ 136 do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ 137 irqentry_exit_to_user_mode(regs); \ 138 } else { \ 139 irqentry_state_t state = irqentry_nmi_enter(regs); \ 140 do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ 141 irqentry_nmi_exit(regs, state); \ 142 } \ 143 } 144 145 DO_ERROR_INFO(do_trap_unknown, 146 SIGILL, ILL_ILLTRP, "unknown exception"); 147 DO_ERROR_INFO(do_trap_insn_misaligned, 148 SIGBUS, BUS_ADRALN, "instruction address misaligned"); 149 DO_ERROR_INFO(do_trap_insn_fault, 150 SIGSEGV, SEGV_ACCERR, "instruction access fault"); 151 152 asmlinkage __visible __trap_section void do_trap_insn_illegal(struct pt_regs *regs) 153 { 154 bool handled; 155 156 if (user_mode(regs)) { 157 irqentry_enter_from_user_mode(regs); 158 159 local_irq_enable(); 160 161 handled = riscv_v_first_use_handler(regs); 162 163 local_irq_disable(); 164 165 if (!handled) 166 do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc, 167 "Oops - illegal instruction"); 168 169 irqentry_exit_to_user_mode(regs); 170 } else { 171 irqentry_state_t state = irqentry_nmi_enter(regs); 172 173 do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc, 174 "Oops - illegal instruction"); 175 176 irqentry_nmi_exit(regs, state); 177 } 178 } 179 180 DO_ERROR_INFO(do_trap_load_fault, 181 SIGSEGV, SEGV_ACCERR, "load access fault"); 182 183 asmlinkage __visible __trap_section void do_trap_load_misaligned(struct pt_regs *regs) 184 { 185 if (user_mode(regs)) { 186 irqentry_enter_from_user_mode(regs); 187 188 if (handle_misaligned_load(regs)) 189 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, 190 "Oops - load address misaligned"); 191 192 irqentry_exit_to_user_mode(regs); 193 } else { 194 irqentry_state_t state = irqentry_nmi_enter(regs); 195 196 if (handle_misaligned_load(regs)) 197 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, 198 "Oops - load address misaligned"); 199 200 irqentry_nmi_exit(regs, state); 201 } 202 } 203 204 asmlinkage __visible __trap_section void do_trap_store_misaligned(struct pt_regs *regs) 205 { 206 if (user_mode(regs)) { 207 irqentry_enter_from_user_mode(regs); 208 209 if (handle_misaligned_store(regs)) 210 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, 211 "Oops - store (or AMO) address misaligned"); 212 213 irqentry_exit_to_user_mode(regs); 214 } else { 215 irqentry_state_t state = irqentry_nmi_enter(regs); 216 217 if (handle_misaligned_store(regs)) 218 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, 219 "Oops - store (or AMO) address misaligned"); 220 221 irqentry_nmi_exit(regs, state); 222 } 223 } 224 DO_ERROR_INFO(do_trap_store_fault, 225 SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault"); 226 DO_ERROR_INFO(do_trap_ecall_s, 227 SIGILL, ILL_ILLTRP, "environment call from S-mode"); 228 DO_ERROR_INFO(do_trap_ecall_m, 229 SIGILL, ILL_ILLTRP, "environment call from M-mode"); 230 231 static inline unsigned long get_break_insn_length(unsigned long pc) 232 { 233 bug_insn_t insn; 234 235 if (get_kernel_nofault(insn, (bug_insn_t *)pc)) 236 return 0; 237 238 return GET_INSN_LENGTH(insn); 239 } 240 241 void handle_break(struct pt_regs *regs) 242 { 243 #ifdef CONFIG_KPROBES 244 if (kprobe_single_step_handler(regs)) 245 return; 246 247 if (kprobe_breakpoint_handler(regs)) 248 return; 249 #endif 250 #ifdef CONFIG_UPROBES 251 if (uprobe_single_step_handler(regs)) 252 return; 253 254 if (uprobe_breakpoint_handler(regs)) 255 return; 256 #endif 257 current->thread.bad_cause = regs->cause; 258 259 if (user_mode(regs)) 260 force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc); 261 #ifdef CONFIG_KGDB 262 else if (notify_die(DIE_TRAP, "EBREAK", regs, 0, regs->cause, SIGTRAP) 263 == NOTIFY_STOP) 264 return; 265 #endif 266 else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN || 267 handle_cfi_failure(regs) == BUG_TRAP_TYPE_WARN) 268 regs->epc += get_break_insn_length(regs->epc); 269 else 270 die(regs, "Kernel BUG"); 271 } 272 273 asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs) 274 { 275 if (user_mode(regs)) { 276 irqentry_enter_from_user_mode(regs); 277 278 handle_break(regs); 279 280 irqentry_exit_to_user_mode(regs); 281 } else { 282 irqentry_state_t state = irqentry_nmi_enter(regs); 283 284 handle_break(regs); 285 286 irqentry_nmi_exit(regs, state); 287 } 288 } 289 290 asmlinkage __visible __trap_section void do_trap_ecall_u(struct pt_regs *regs) 291 { 292 if (user_mode(regs)) { 293 long syscall = regs->a7; 294 295 regs->epc += 4; 296 regs->orig_a0 = regs->a0; 297 298 riscv_v_vstate_discard(regs); 299 300 syscall = syscall_enter_from_user_mode(regs, syscall); 301 302 if (syscall >= 0 && syscall < NR_syscalls) 303 syscall_handler(regs, syscall); 304 else if (syscall != -1) 305 regs->a0 = -ENOSYS; 306 307 syscall_exit_to_user_mode(regs); 308 } else { 309 irqentry_state_t state = irqentry_nmi_enter(regs); 310 311 do_trap_error(regs, SIGILL, ILL_ILLTRP, regs->epc, 312 "Oops - environment call from U-mode"); 313 314 irqentry_nmi_exit(regs, state); 315 } 316 317 } 318 319 #ifdef CONFIG_MMU 320 asmlinkage __visible noinstr void do_page_fault(struct pt_regs *regs) 321 { 322 irqentry_state_t state = irqentry_enter(regs); 323 324 handle_page_fault(regs); 325 326 local_irq_disable(); 327 328 irqentry_exit(regs, state); 329 } 330 #endif 331 332 static void noinstr handle_riscv_irq(struct pt_regs *regs) 333 { 334 struct pt_regs *old_regs; 335 336 irq_enter_rcu(); 337 old_regs = set_irq_regs(regs); 338 handle_arch_irq(regs); 339 set_irq_regs(old_regs); 340 irq_exit_rcu(); 341 } 342 343 asmlinkage void noinstr do_irq(struct pt_regs *regs) 344 { 345 irqentry_state_t state = irqentry_enter(regs); 346 #ifdef CONFIG_IRQ_STACKS 347 if (on_thread_stack()) { 348 ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id()) 349 + IRQ_STACK_SIZE/sizeof(ulong); 350 __asm__ __volatile( 351 "addi sp, sp, -"RISCV_SZPTR "\n" 352 REG_S" ra, (sp) \n" 353 "addi sp, sp, -"RISCV_SZPTR "\n" 354 REG_S" s0, (sp) \n" 355 "addi s0, sp, 2*"RISCV_SZPTR "\n" 356 "move sp, %[sp] \n" 357 "move a0, %[regs] \n" 358 "call handle_riscv_irq \n" 359 "addi sp, s0, -2*"RISCV_SZPTR"\n" 360 REG_L" s0, (sp) \n" 361 "addi sp, sp, "RISCV_SZPTR "\n" 362 REG_L" ra, (sp) \n" 363 "addi sp, sp, "RISCV_SZPTR "\n" 364 : 365 : [sp] "r" (sp), [regs] "r" (regs) 366 : "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7", 367 "t0", "t1", "t2", "t3", "t4", "t5", "t6", 368 #ifndef CONFIG_FRAME_POINTER 369 "s0", 370 #endif 371 "memory"); 372 } else 373 #endif 374 handle_riscv_irq(regs); 375 376 irqentry_exit(regs, state); 377 } 378 379 #ifdef CONFIG_GENERIC_BUG 380 int is_valid_bugaddr(unsigned long pc) 381 { 382 bug_insn_t insn; 383 384 if (pc < VMALLOC_START) 385 return 0; 386 if (get_kernel_nofault(insn, (bug_insn_t *)pc)) 387 return 0; 388 if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) 389 return (insn == __BUG_INSN_32); 390 else 391 return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16); 392 } 393 #endif /* CONFIG_GENERIC_BUG */ 394 395 #ifdef CONFIG_VMAP_STACK 396 /* 397 * Extra stack space that allows us to provide panic messages when the kernel 398 * has overflowed its stack. 399 */ 400 static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], 401 overflow_stack)__aligned(16); 402 /* 403 * A temporary stack for use by handle_kernel_stack_overflow. This is used so 404 * we can call into C code to get the per-hart overflow stack. Usage of this 405 * stack must be protected by spin_shadow_stack. 406 */ 407 long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)] __aligned(16); 408 409 /* 410 * A pseudo spinlock to protect the shadow stack from being used by multiple 411 * harts concurrently. This isn't a real spinlock because the lock side must 412 * be taken without a valid stack and only a single register, it's only taken 413 * while in the process of panicing anyway so the performance and error 414 * checking a proper spinlock gives us doesn't matter. 415 */ 416 unsigned long spin_shadow_stack; 417 418 asmlinkage unsigned long get_overflow_stack(void) 419 { 420 return (unsigned long)this_cpu_ptr(overflow_stack) + 421 OVERFLOW_STACK_SIZE; 422 } 423 424 asmlinkage void handle_bad_stack(struct pt_regs *regs) 425 { 426 unsigned long tsk_stk = (unsigned long)current->stack; 427 unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); 428 429 /* 430 * We're done with the shadow stack by this point, as we're on the 431 * overflow stack. Tell any other concurrent overflowing harts that 432 * they can proceed with panicing by releasing the pseudo-spinlock. 433 * 434 * This pairs with an amoswap.aq in handle_kernel_stack_overflow. 435 */ 436 smp_store_release(&spin_shadow_stack, 0); 437 438 console_verbose(); 439 440 pr_emerg("Insufficient stack space to handle exception!\n"); 441 pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", 442 tsk_stk, tsk_stk + THREAD_SIZE); 443 pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", 444 ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); 445 446 __show_regs(regs); 447 panic("Kernel stack overflow"); 448 449 for (;;) 450 wait_for_interrupt(); 451 } 452 #endif 453