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