1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2012 Regents of the University of California
7 #include <linux/kernel.h>
8 #include <linux/init.h>
9 #include <linux/randomize_kstack.h>
10 #include <linux/sched.h>
11 #include <linux/sched/debug.h>
12 #include <linux/sched/signal.h>
13 #include <linux/signal.h>
14 #include <linux/kdebug.h>
15 #include <linux/uaccess.h>
16 #include <linux/kprobes.h>
17 #include <linux/uprobes.h>
18 #include <asm/uprobes.h>
20 #include <linux/module.h>
21 #include <linux/irq.h>
22 #include <linux/kexec.h>
23 #include <linux/entry-common.h>
25 #include <asm/asm-prototypes.h>
29 #include <asm/processor.h>
30 #include <asm/ptrace.h>
31 #include <asm/syscall.h>
32 #include <asm/thread_info.h>
33 #include <asm/vector.h>
34 #include <asm/irq_stack.h>
36 int show_unhandled_signals = 1;
38 static DEFINE_SPINLOCK(die_lock);
40 static int copy_code(struct pt_regs *regs, u16 *val, const u16 *insns)
42 const void __user *uaddr = (__force const void __user *)insns;
45 return get_kernel_nofault(*val, insns);
47 /* The user space code from other tasks cannot be accessed. */
48 if (regs != task_pt_regs(current))
51 return copy_from_user_nofault(val, uaddr, sizeof(*val));
54 static void dump_instr(const char *loglvl, struct pt_regs *regs)
56 char str[sizeof("0000 ") * 12 + 2 + 1], *p = str;
57 const u16 *insns = (u16 *)instruction_pointer(regs);
62 for (i = -10; i < 2; i++) {
63 bad = copy_code(regs, &val, &insns[i]);
65 p += sprintf(p, i == 0 ? "(%04hx) " : "%04hx ", val);
67 printk("%sCode: Unable to access instruction at 0x%px.\n",
72 printk("%sCode: %s\n", loglvl, str);
75 void die(struct pt_regs *regs, const char *str)
77 static int die_counter;
84 spin_lock_irqsave(&die_lock, flags);
88 pr_emerg("%s [#%d]\n", str, ++die_counter);
92 dump_instr(KERN_EMERG, regs);
95 cause = regs ? regs->cause : -1;
96 ret = notify_die(DIE_OOPS, str, regs, 0, cause, SIGSEGV);
98 if (kexec_should_crash(current))
102 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
103 spin_unlock_irqrestore(&die_lock, flags);
107 panic("Fatal exception in interrupt");
109 panic("Fatal exception");
110 if (ret != NOTIFY_STOP)
111 make_task_dead(SIGSEGV);
114 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
116 struct task_struct *tsk = current;
118 if (show_unhandled_signals && unhandled_signal(tsk, signo)
119 && printk_ratelimit()) {
120 pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
121 tsk->comm, task_pid_nr(tsk), signo, code, addr);
122 print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
125 dump_instr(KERN_EMERG, regs);
128 force_sig_fault(signo, code, (void __user *)addr);
131 static void do_trap_error(struct pt_regs *regs, int signo, int code,
132 unsigned long addr, const char *str)
134 current->thread.bad_cause = regs->cause;
136 if (user_mode(regs)) {
137 do_trap(regs, signo, code, addr);
139 if (!fixup_exception(regs))
144 #if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE)
145 #define __trap_section __noinstr_section(".xip.traps")
147 #define __trap_section noinstr
149 #define DO_ERROR_INFO(name, signo, code, str) \
150 asmlinkage __visible __trap_section void name(struct pt_regs *regs) \
152 if (user_mode(regs)) { \
153 irqentry_enter_from_user_mode(regs); \
154 do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \
155 irqentry_exit_to_user_mode(regs); \
157 irqentry_state_t state = irqentry_nmi_enter(regs); \
158 do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \
159 irqentry_nmi_exit(regs, state); \
163 DO_ERROR_INFO(do_trap_unknown,
164 SIGILL, ILL_ILLTRP, "unknown exception");
165 DO_ERROR_INFO(do_trap_insn_misaligned,
166 SIGBUS, BUS_ADRALN, "instruction address misaligned");
167 DO_ERROR_INFO(do_trap_insn_fault,
168 SIGSEGV, SEGV_ACCERR, "instruction access fault");
170 asmlinkage __visible __trap_section void do_trap_insn_illegal(struct pt_regs *regs)
174 if (user_mode(regs)) {
175 irqentry_enter_from_user_mode(regs);
179 handled = riscv_v_first_use_handler(regs);
184 do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc,
185 "Oops - illegal instruction");
187 irqentry_exit_to_user_mode(regs);
189 irqentry_state_t state = irqentry_nmi_enter(regs);
191 do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc,
192 "Oops - illegal instruction");
194 irqentry_nmi_exit(regs, state);
198 DO_ERROR_INFO(do_trap_load_fault,
199 SIGSEGV, SEGV_ACCERR, "load access fault");
201 asmlinkage __visible __trap_section void do_trap_load_misaligned(struct pt_regs *regs)
203 if (user_mode(regs)) {
204 irqentry_enter_from_user_mode(regs);
206 if (handle_misaligned_load(regs))
207 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
208 "Oops - load address misaligned");
210 irqentry_exit_to_user_mode(regs);
212 irqentry_state_t state = irqentry_nmi_enter(regs);
214 if (handle_misaligned_load(regs))
215 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
216 "Oops - load address misaligned");
218 irqentry_nmi_exit(regs, state);
222 asmlinkage __visible __trap_section void do_trap_store_misaligned(struct pt_regs *regs)
224 if (user_mode(regs)) {
225 irqentry_enter_from_user_mode(regs);
227 if (handle_misaligned_store(regs))
228 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
229 "Oops - store (or AMO) address misaligned");
231 irqentry_exit_to_user_mode(regs);
233 irqentry_state_t state = irqentry_nmi_enter(regs);
235 if (handle_misaligned_store(regs))
236 do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
237 "Oops - store (or AMO) address misaligned");
239 irqentry_nmi_exit(regs, state);
242 DO_ERROR_INFO(do_trap_store_fault,
243 SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
244 DO_ERROR_INFO(do_trap_ecall_s,
245 SIGILL, ILL_ILLTRP, "environment call from S-mode");
246 DO_ERROR_INFO(do_trap_ecall_m,
247 SIGILL, ILL_ILLTRP, "environment call from M-mode");
249 static inline unsigned long get_break_insn_length(unsigned long pc)
253 if (get_kernel_nofault(insn, (bug_insn_t *)pc))
256 return GET_INSN_LENGTH(insn);
259 static bool probe_single_step_handler(struct pt_regs *regs)
261 bool user = user_mode(regs);
263 return user ? uprobe_single_step_handler(regs) : kprobe_single_step_handler(regs);
266 static bool probe_breakpoint_handler(struct pt_regs *regs)
268 bool user = user_mode(regs);
270 return user ? uprobe_breakpoint_handler(regs) : kprobe_breakpoint_handler(regs);
273 void handle_break(struct pt_regs *regs)
275 if (probe_single_step_handler(regs))
278 if (probe_breakpoint_handler(regs))
281 current->thread.bad_cause = regs->cause;
284 force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc);
286 else if (notify_die(DIE_TRAP, "EBREAK", regs, 0, regs->cause, SIGTRAP)
290 else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN ||
291 handle_cfi_failure(regs) == BUG_TRAP_TYPE_WARN)
292 regs->epc += get_break_insn_length(regs->epc);
294 die(regs, "Kernel BUG");
297 asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
299 if (user_mode(regs)) {
300 irqentry_enter_from_user_mode(regs);
304 irqentry_exit_to_user_mode(regs);
306 irqentry_state_t state = irqentry_nmi_enter(regs);
310 irqentry_nmi_exit(regs, state);
314 asmlinkage __visible __trap_section __no_stack_protector
315 void do_trap_ecall_u(struct pt_regs *regs)
317 if (user_mode(regs)) {
318 long syscall = regs->a7;
321 regs->orig_a0 = regs->a0;
323 riscv_v_vstate_discard(regs);
325 syscall = syscall_enter_from_user_mode(regs, syscall);
327 add_random_kstack_offset();
329 if (syscall >= 0 && syscall < NR_syscalls)
330 syscall_handler(regs, syscall);
331 else if (syscall != -1)
334 * Ultimately, this value will get limited by KSTACK_OFFSET_MAX(),
335 * so the maximum stack offset is 1k bytes (10 bits).
337 * The actual entropy will be further reduced by the compiler when
338 * applying stack alignment constraints: 16-byte (i.e. 4-bit) aligned
339 * for RV32I or RV64I.
341 * The resulting 6 bits of entropy is seen in SP[9:4].
343 choose_random_kstack_offset(get_random_u16());
345 syscall_exit_to_user_mode(regs);
347 irqentry_state_t state = irqentry_nmi_enter(regs);
349 do_trap_error(regs, SIGILL, ILL_ILLTRP, regs->epc,
350 "Oops - environment call from U-mode");
352 irqentry_nmi_exit(regs, state);
358 asmlinkage __visible noinstr void do_page_fault(struct pt_regs *regs)
360 irqentry_state_t state = irqentry_enter(regs);
362 handle_page_fault(regs);
366 irqentry_exit(regs, state);
370 static void noinstr handle_riscv_irq(struct pt_regs *regs)
372 struct pt_regs *old_regs;
375 old_regs = set_irq_regs(regs);
376 handle_arch_irq(regs);
377 set_irq_regs(old_regs);
381 asmlinkage void noinstr do_irq(struct pt_regs *regs)
383 irqentry_state_t state = irqentry_enter(regs);
385 if (IS_ENABLED(CONFIG_IRQ_STACKS) && on_thread_stack())
386 call_on_irq_stack(regs, handle_riscv_irq);
388 handle_riscv_irq(regs);
390 irqentry_exit(regs, state);
393 #ifdef CONFIG_GENERIC_BUG
394 int is_valid_bugaddr(unsigned long pc)
398 if (pc < VMALLOC_START)
400 if (get_kernel_nofault(insn, (bug_insn_t *)pc))
402 if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
403 return (insn == __BUG_INSN_32);
405 return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
407 #endif /* CONFIG_GENERIC_BUG */
409 #ifdef CONFIG_VMAP_STACK
410 DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)],
411 overflow_stack)__aligned(16);
413 asmlinkage void handle_bad_stack(struct pt_regs *regs)
415 unsigned long tsk_stk = (unsigned long)current->stack;
416 unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack);
420 pr_emerg("Insufficient stack space to handle exception!\n");
421 pr_emerg("Task stack: [0x%016lx..0x%016lx]\n",
422 tsk_stk, tsk_stk + THREAD_SIZE);
423 pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n",
424 ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE);
427 panic("Kernel stack overflow");
430 wait_for_interrupt();