1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Kernel traps/events for Hexagon processor
4 *
5 * Copyright (c) 2010-2014, The Linux Foundation. All rights reserved.
6 */
7
8 #include <linux/init.h>
9 #include <linux/sched/signal.h>
10 #include <linux/sched/debug.h>
11 #include <linux/sched/task_stack.h>
12 #include <linux/module.h>
13 #include <linux/kallsyms.h>
14 #include <linux/kdebug.h>
15 #include <linux/syscalls.h>
16 #include <linux/signal.h>
17 #include <linux/ptrace.h>
18 #include <asm/traps.h>
19 #include <asm/vm_fault.h>
20 #include <asm/syscall.h>
21 #include <asm/registers.h>
22 #include <asm/unistd.h>
23 #include <asm/sections.h>
24 #ifdef CONFIG_KGDB
25 # include <linux/kgdb.h>
26 #endif
27
28 #define TRAP_SYSCALL 1
29 #define TRAP_DEBUG 0xdb
30
31 #ifdef CONFIG_GENERIC_BUG
32 /* Maybe should resemble arch/sh/kernel/traps.c ?? */
is_valid_bugaddr(unsigned long addr)33 int is_valid_bugaddr(unsigned long addr)
34 {
35 return 1;
36 }
37 #endif /* CONFIG_GENERIC_BUG */
38
ex_name(int ex)39 static const char *ex_name(int ex)
40 {
41 switch (ex) {
42 case HVM_GE_C_XPROT:
43 case HVM_GE_C_XUSER:
44 return "Execute protection fault";
45 case HVM_GE_C_RPROT:
46 case HVM_GE_C_RUSER:
47 return "Read protection fault";
48 case HVM_GE_C_WPROT:
49 case HVM_GE_C_WUSER:
50 return "Write protection fault";
51 case HVM_GE_C_XMAL:
52 return "Misaligned instruction";
53 case HVM_GE_C_WREG:
54 return "Multiple writes to same register in packet";
55 case HVM_GE_C_PCAL:
56 return "Program counter values that are not properly aligned";
57 case HVM_GE_C_RMAL:
58 return "Misaligned data load";
59 case HVM_GE_C_WMAL:
60 return "Misaligned data store";
61 case HVM_GE_C_INVI:
62 case HVM_GE_C_PRIVI:
63 return "Illegal instruction";
64 case HVM_GE_C_BUS:
65 return "Precise bus error";
66 case HVM_GE_C_CACHE:
67 return "Cache error";
68
69 case 0xdb:
70 return "Debugger trap";
71
72 default:
73 return "Unrecognized exception";
74 }
75 }
76
do_show_stack(struct task_struct * task,unsigned long * fp,unsigned long ip,const char * loglvl)77 static void do_show_stack(struct task_struct *task, unsigned long *fp,
78 unsigned long ip, const char *loglvl)
79 {
80 int kstack_depth_to_print = 24;
81 unsigned long offset, size;
82 const char *name = NULL;
83 unsigned long *newfp;
84 unsigned long low, high;
85 char tmpstr[128];
86 char *modname;
87 int i;
88
89 if (task == NULL)
90 task = current;
91
92 printk("%sCPU#%d, %s/%d, Call Trace:\n", loglvl, raw_smp_processor_id(),
93 task->comm, task_pid_nr(task));
94
95 if (fp == NULL) {
96 if (task == current) {
97 asm("%0 = r30" : "=r" (fp));
98 } else {
99 fp = (unsigned long *)
100 ((struct hexagon_switch_stack *)
101 task->thread.switch_sp)->fp;
102 }
103 }
104
105 if ((((unsigned long) fp) & 0x3) || ((unsigned long) fp < 0x1000)) {
106 printk("%s-- Corrupt frame pointer %p\n", loglvl, fp);
107 return;
108 }
109
110 /* Saved link reg is one word above FP */
111 if (!ip)
112 ip = *(fp+1);
113
114 /* Expect kernel stack to be in-bounds */
115 low = (unsigned long)task_stack_page(task);
116 high = low + THREAD_SIZE - 8;
117 low += sizeof(struct thread_info);
118
119 for (i = 0; i < kstack_depth_to_print; i++) {
120
121 name = kallsyms_lookup(ip, &size, &offset, &modname, tmpstr);
122
123 printk("%s[%p] 0x%lx: %s + 0x%lx", loglvl, fp, ip, name, offset);
124 if (((unsigned long) fp < low) || (high < (unsigned long) fp))
125 printk(KERN_CONT " (FP out of bounds!)");
126 if (modname)
127 printk(KERN_CONT " [%s] ", modname);
128 printk(KERN_CONT "\n");
129
130 newfp = (unsigned long *) *fp;
131
132 if (((unsigned long) newfp) & 0x3) {
133 printk("%s-- Corrupt frame pointer %p\n", loglvl, newfp);
134 break;
135 }
136
137 /* Attempt to continue past exception. */
138 if (0 == newfp) {
139 struct pt_regs *regs = (struct pt_regs *) (((void *)fp)
140 + 8);
141
142 if (regs->syscall_nr != -1) {
143 printk("%s-- trap0 -- syscall_nr: %ld", loglvl,
144 regs->syscall_nr);
145 printk(KERN_CONT " psp: %lx elr: %lx\n",
146 pt_psp(regs), pt_elr(regs));
147 break;
148 } else {
149 /* really want to see more ... */
150 kstack_depth_to_print += 6;
151 printk("%s-- %s (0x%lx) badva: %lx\n", loglvl,
152 ex_name(pt_cause(regs)), pt_cause(regs),
153 pt_badva(regs));
154 }
155
156 newfp = (unsigned long *) regs->r30;
157 ip = pt_elr(regs);
158 } else {
159 ip = *(newfp + 1);
160 }
161
162 /* If link reg is null, we are done. */
163 if (ip == 0x0)
164 break;
165
166 /* If newfp isn't larger, we're tracing garbage. */
167 if (newfp > fp)
168 fp = newfp;
169 else
170 break;
171 }
172 }
173
show_stack(struct task_struct * task,unsigned long * fp,const char * loglvl)174 void show_stack(struct task_struct *task, unsigned long *fp, const char *loglvl)
175 {
176 /* Saved link reg is one word above FP */
177 do_show_stack(task, fp, 0, loglvl);
178 }
179
die(const char * str,struct pt_regs * regs,long err)180 int die(const char *str, struct pt_regs *regs, long err)
181 {
182 static struct {
183 spinlock_t lock;
184 int counter;
185 } die = {
186 .lock = __SPIN_LOCK_UNLOCKED(die.lock),
187 .counter = 0
188 };
189
190 console_verbose();
191 oops_enter();
192
193 spin_lock_irq(&die.lock);
194 bust_spinlocks(1);
195 printk(KERN_EMERG "Oops: %s[#%d]:\n", str, ++die.counter);
196
197 if (notify_die(DIE_OOPS, str, regs, err, pt_cause(regs), SIGSEGV) ==
198 NOTIFY_STOP) {
199 spin_unlock_irq(&die.lock);
200 return 1;
201 }
202
203 print_modules();
204 show_regs(regs);
205 do_show_stack(current, ®s->r30, pt_elr(regs), KERN_EMERG);
206
207 bust_spinlocks(0);
208 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
209
210 spin_unlock_irq(&die.lock);
211
212 if (in_interrupt())
213 panic("Fatal exception in interrupt");
214
215 if (panic_on_oops)
216 panic("Fatal exception");
217
218 oops_exit();
219 make_task_dead(err);
220 return 0;
221 }
222
die_if_kernel(char * str,struct pt_regs * regs,long err)223 int die_if_kernel(char *str, struct pt_regs *regs, long err)
224 {
225 if (!user_mode(regs))
226 return die(str, regs, err);
227 else
228 return 0;
229 }
230
231 /*
232 * It's not clear that misaligned fetches are ever recoverable.
233 */
misaligned_instruction(struct pt_regs * regs)234 static void misaligned_instruction(struct pt_regs *regs)
235 {
236 die_if_kernel("Misaligned Instruction", regs, 0);
237 force_sig(SIGBUS);
238 }
239
240 /*
241 * Misaligned loads and stores, on the other hand, can be
242 * emulated, and probably should be, some day. But for now
243 * they will be considered fatal.
244 */
misaligned_data_load(struct pt_regs * regs)245 static void misaligned_data_load(struct pt_regs *regs)
246 {
247 die_if_kernel("Misaligned Data Load", regs, 0);
248 force_sig(SIGBUS);
249 }
250
misaligned_data_store(struct pt_regs * regs)251 static void misaligned_data_store(struct pt_regs *regs)
252 {
253 die_if_kernel("Misaligned Data Store", regs, 0);
254 force_sig(SIGBUS);
255 }
256
illegal_instruction(struct pt_regs * regs)257 static void illegal_instruction(struct pt_regs *regs)
258 {
259 die_if_kernel("Illegal Instruction", regs, 0);
260 force_sig(SIGILL);
261 }
262
263 /*
264 * Precise bus errors may be recoverable with a a retry,
265 * but for now, treat them as irrecoverable.
266 */
precise_bus_error(struct pt_regs * regs)267 static void precise_bus_error(struct pt_regs *regs)
268 {
269 die_if_kernel("Precise Bus Error", regs, 0);
270 force_sig(SIGBUS);
271 }
272
273 /*
274 * If anything is to be done here other than panic,
275 * it will probably be complex and migrate to another
276 * source module. For now, just die.
277 */
cache_error(struct pt_regs * regs)278 static void cache_error(struct pt_regs *regs)
279 {
280 die("Cache Error", regs, 0);
281 }
282
283 /*
284 * General exception handler
285 */
do_genex(struct pt_regs * regs)286 void do_genex(struct pt_regs *regs)
287 {
288 /*
289 * Decode Cause and Dispatch
290 */
291 switch (pt_cause(regs)) {
292 case HVM_GE_C_XPROT:
293 case HVM_GE_C_XUSER:
294 execute_protection_fault(regs);
295 break;
296 case HVM_GE_C_RPROT:
297 case HVM_GE_C_RUSER:
298 read_protection_fault(regs);
299 break;
300 case HVM_GE_C_WPROT:
301 case HVM_GE_C_WUSER:
302 write_protection_fault(regs);
303 break;
304 case HVM_GE_C_XMAL:
305 misaligned_instruction(regs);
306 break;
307 case HVM_GE_C_WREG:
308 illegal_instruction(regs);
309 break;
310 case HVM_GE_C_PCAL:
311 misaligned_instruction(regs);
312 break;
313 case HVM_GE_C_RMAL:
314 misaligned_data_load(regs);
315 break;
316 case HVM_GE_C_WMAL:
317 misaligned_data_store(regs);
318 break;
319 case HVM_GE_C_INVI:
320 case HVM_GE_C_PRIVI:
321 illegal_instruction(regs);
322 break;
323 case HVM_GE_C_BUS:
324 precise_bus_error(regs);
325 break;
326 case HVM_GE_C_CACHE:
327 cache_error(regs);
328 break;
329 default:
330 /* Halt and catch fire */
331 panic("Unrecognized exception 0x%lx\n", pt_cause(regs));
332 break;
333 }
334 }
335
336 /* Indirect system call dispatch */
sys_syscall(void)337 long sys_syscall(void)
338 {
339 printk(KERN_ERR "sys_syscall invoked!\n");
340 return -ENOSYS;
341 }
342
do_trap0(struct pt_regs * regs)343 void do_trap0(struct pt_regs *regs)
344 {
345 syscall_fn syscall;
346
347 switch (pt_cause(regs)) {
348 case TRAP_SYSCALL:
349 /* System call is trap0 #1 */
350
351 /* allow strace to catch syscall args */
352 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE) &&
353 ptrace_report_syscall_entry(regs)))
354 return; /* return -ENOSYS somewhere? */
355
356 /* Interrupts should be re-enabled for syscall processing */
357 __vmsetie(VM_INT_ENABLE);
358
359 /*
360 * System call number is in r6, arguments in r0..r5.
361 * Fortunately, no Linux syscall has more than 6 arguments,
362 * and Hexagon ABI passes first 6 arguments in registers.
363 * 64-bit arguments are passed in odd/even register pairs.
364 * Fortunately, we have no system calls that take more
365 * than three arguments with more than one 64-bit value.
366 * Should that change, we'd need to redesign to copy
367 * between user and kernel stacks.
368 */
369 regs->syscall_nr = regs->r06;
370
371 /*
372 * GPR R0 carries the first parameter, and is also used
373 * to report the return value. We need a backup of
374 * the user's value in case we need to do a late restart
375 * of the system call.
376 */
377 regs->restart_r0 = regs->r00;
378
379 if ((unsigned long) regs->syscall_nr >= __NR_syscalls) {
380 regs->r00 = -1;
381 } else {
382 syscall = (syscall_fn)
383 (sys_call_table[regs->syscall_nr]);
384 regs->r00 = syscall(regs->r00, regs->r01,
385 regs->r02, regs->r03,
386 regs->r04, regs->r05);
387 }
388
389 /* allow strace to get the syscall return state */
390 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE)))
391 ptrace_report_syscall_exit(regs, 0);
392
393 break;
394 case TRAP_DEBUG:
395 /* Trap0 0xdb is debug breakpoint */
396 if (user_mode(regs)) {
397 /*
398 * Some architecures add some per-thread state
399 * to distinguish between breakpoint traps and
400 * trace traps. We may want to do that, and
401 * set the si_code value appropriately, or we
402 * may want to use a different trap0 flavor.
403 */
404 force_sig_fault(SIGTRAP, TRAP_BRKPT,
405 (void __user *) pt_elr(regs));
406 } else {
407 #ifdef CONFIG_KGDB
408 kgdb_handle_exception(pt_cause(regs), SIGTRAP,
409 TRAP_BRKPT, regs);
410 #endif
411 }
412 break;
413 }
414 /* Ignore other trap0 codes for now, especially 0 (Angel calls) */
415 }
416
417 /*
418 * Machine check exception handler
419 */
do_machcheck(struct pt_regs * regs)420 void do_machcheck(struct pt_regs *regs)
421 {
422 /* Halt and catch fire */
423 __vmstop();
424 }
425
426 /*
427 * Treat this like the old 0xdb trap.
428 */
429
do_debug_exception(struct pt_regs * regs)430 void do_debug_exception(struct pt_regs *regs)
431 {
432 regs->hvmer.vmest &= ~HVM_VMEST_CAUSE_MSK;
433 regs->hvmer.vmest |= (TRAP_DEBUG << HVM_VMEST_CAUSE_SFT);
434 do_trap0(regs);
435 }
436