1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * S390 version
4 * Copyright IBM Corp. 1999, 2000
5 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
6 * Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
7 *
8 * Derived from "arch/i386/kernel/traps.c"
9 * Copyright (C) 1991, 1992 Linus Torvalds
10 */
11
12 /*
13 * 'Traps.c' handles hardware traps and faults after we have saved some
14 * state in 'asm.s'.
15 */
16 #include "asm/irqflags.h"
17 #include "asm/ptrace.h"
18 #include <linux/kprobes.h>
19 #include <linux/kdebug.h>
20 #include <linux/randomize_kstack.h>
21 #include <linux/extable.h>
22 #include <linux/ptrace.h>
23 #include <linux/sched.h>
24 #include <linux/sched/debug.h>
25 #include <linux/mm.h>
26 #include <linux/slab.h>
27 #include <linux/uaccess.h>
28 #include <linux/cpu.h>
29 #include <linux/entry-common.h>
30 #include <linux/kmsan.h>
31 #include <asm/asm-extable.h>
32 #include <asm/vtime.h>
33 #include <asm/fpu.h>
34 #include "entry.h"
35
36 static inline void __user *get_trap_ip(struct pt_regs *regs)
37 {
38 unsigned long address;
39
40 if (regs->int_code & 0x200)
41 address = current->thread.trap_tdb.data[3];
42 else
43 address = regs->psw.addr;
44 return (void __user *) (address - (regs->int_code >> 16));
45 }
46
47 #ifdef CONFIG_GENERIC_BUG
48 int is_valid_bugaddr(unsigned long addr)
49 {
50 return 1;
51 }
52 #endif
53
54 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
55 {
56 if (user_mode(regs)) {
57 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
58 report_user_fault(regs, si_signo, 0);
59 } else {
60 if (!fixup_exception(regs))
61 die(regs, str);
62 }
63 }
64
65 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
66 {
67 if (notify_die(DIE_TRAP, str, regs, 0,
68 regs->int_code, si_signo) == NOTIFY_STOP)
69 return;
70 do_report_trap(regs, si_signo, si_code, str);
71 }
72 NOKPROBE_SYMBOL(do_trap);
73
74 void do_per_trap(struct pt_regs *regs)
75 {
76 if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
77 return;
78 if (!current->ptrace)
79 return;
80 force_sig_fault(SIGTRAP, TRAP_HWBKPT,
81 (void __force __user *) current->thread.per_event.address);
82 }
83 NOKPROBE_SYMBOL(do_per_trap);
84
85 static void default_trap_handler(struct pt_regs *regs)
86 {
87 if (user_mode(regs)) {
88 report_user_fault(regs, SIGSEGV, 0);
89 force_exit_sig(SIGSEGV);
90 } else
91 die(regs, "Unknown program exception");
92 }
93
94 #define DO_ERROR_INFO(name, signr, sicode, str) \
95 static void name(struct pt_regs *regs) \
96 { \
97 do_trap(regs, signr, sicode, str); \
98 }
99
100 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
101 "addressing exception")
102 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
103 "execute exception")
104 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
105 "fixpoint divide exception")
106 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
107 "fixpoint overflow exception")
108 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
109 "HFP overflow exception")
110 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
111 "HFP underflow exception")
112 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
113 "HFP significance exception")
114 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
115 "HFP divide exception")
116 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
117 "HFP square root exception")
118 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
119 "operand exception")
120 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
121 "privileged operation")
122 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
123 "special operation exception")
124 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
125 "transaction constraint exception")
126
127 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
128 {
129 int si_code = 0;
130 /* FPC[2] is Data Exception Code */
131 if ((fpc & 0x00000300) == 0) {
132 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
133 if (fpc & 0x8000) /* invalid fp operation */
134 si_code = FPE_FLTINV;
135 else if (fpc & 0x4000) /* div by 0 */
136 si_code = FPE_FLTDIV;
137 else if (fpc & 0x2000) /* overflow */
138 si_code = FPE_FLTOVF;
139 else if (fpc & 0x1000) /* underflow */
140 si_code = FPE_FLTUND;
141 else if (fpc & 0x0800) /* inexact */
142 si_code = FPE_FLTRES;
143 }
144 do_trap(regs, SIGFPE, si_code, "floating point exception");
145 }
146
147 static void translation_specification_exception(struct pt_regs *regs)
148 {
149 /* May never happen. */
150 panic("Translation-Specification Exception");
151 }
152
153 static void illegal_op(struct pt_regs *regs)
154 {
155 __u8 opcode[6];
156 __u16 __user *location;
157 int is_uprobe_insn = 0;
158 int signal = 0;
159
160 location = get_trap_ip(regs);
161
162 if (user_mode(regs)) {
163 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
164 return;
165 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
166 if (current->ptrace)
167 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
168 else
169 signal = SIGILL;
170 #ifdef CONFIG_UPROBES
171 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
172 is_uprobe_insn = 1;
173 #endif
174 } else
175 signal = SIGILL;
176 }
177 /*
178 * We got either an illegal op in kernel mode, or user space trapped
179 * on a uprobes illegal instruction. See if kprobes or uprobes picks
180 * it up. If not, SIGILL.
181 */
182 if (is_uprobe_insn || !user_mode(regs)) {
183 if (notify_die(DIE_BPT, "bpt", regs, 0,
184 3, SIGTRAP) != NOTIFY_STOP)
185 signal = SIGILL;
186 }
187 if (signal)
188 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
189 }
190 NOKPROBE_SYMBOL(illegal_op);
191
192 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
193 "specification exception");
194
195 static void vector_exception(struct pt_regs *regs)
196 {
197 int si_code, vic;
198
199 if (!cpu_has_vx()) {
200 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
201 return;
202 }
203
204 /* get vector interrupt code from fpc */
205 save_user_fpu_regs();
206 vic = (current->thread.ufpu.fpc & 0xf00) >> 8;
207 switch (vic) {
208 case 1: /* invalid vector operation */
209 si_code = FPE_FLTINV;
210 break;
211 case 2: /* division by zero */
212 si_code = FPE_FLTDIV;
213 break;
214 case 3: /* overflow */
215 si_code = FPE_FLTOVF;
216 break;
217 case 4: /* underflow */
218 si_code = FPE_FLTUND;
219 break;
220 case 5: /* inexact */
221 si_code = FPE_FLTRES;
222 break;
223 default: /* unknown cause */
224 si_code = 0;
225 }
226 do_trap(regs, SIGFPE, si_code, "vector exception");
227 }
228
229 static void data_exception(struct pt_regs *regs)
230 {
231 save_user_fpu_regs();
232 if (current->thread.ufpu.fpc & FPC_DXC_MASK)
233 do_fp_trap(regs, current->thread.ufpu.fpc);
234 else
235 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
236 }
237
238 static void space_switch_exception(struct pt_regs *regs)
239 {
240 /* Set user psw back to home space mode. */
241 if (user_mode(regs))
242 regs->psw.mask |= PSW_ASC_HOME;
243 /* Send SIGILL. */
244 do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
245 }
246
247 static void monitor_event_exception(struct pt_regs *regs)
248 {
249 if (user_mode(regs))
250 return;
251
252 switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
253 case BUG_TRAP_TYPE_NONE:
254 fixup_exception(regs);
255 break;
256 case BUG_TRAP_TYPE_WARN:
257 break;
258 case BUG_TRAP_TYPE_BUG:
259 die(regs, "monitor event");
260 break;
261 }
262 }
263
264 void kernel_stack_overflow(struct pt_regs *regs)
265 {
266 /*
267 * Normally regs are unpoisoned by the generic entry code, but
268 * kernel_stack_overflow() is a rare case that is called bypassing it.
269 */
270 kmsan_unpoison_entry_regs(regs);
271 bust_spinlocks(1);
272 printk("Kernel stack overflow.\n");
273 show_regs(regs);
274 bust_spinlocks(0);
275 panic("Corrupt kernel stack, can't continue.");
276 }
277 NOKPROBE_SYMBOL(kernel_stack_overflow);
278
279 static void __init test_monitor_call(void)
280 {
281 int val = 1;
282
283 if (!IS_ENABLED(CONFIG_BUG))
284 return;
285 asm volatile(
286 " mc 0,0\n"
287 "0: xgr %0,%0\n"
288 "1:\n"
289 EX_TABLE(0b,1b)
290 : "+d" (val));
291 if (!val)
292 panic("Monitor call doesn't work!\n");
293 }
294
295 void __init trap_init(void)
296 {
297 struct lowcore *lc = get_lowcore();
298 unsigned long flags;
299 struct ctlreg cr0;
300
301 local_irq_save(flags);
302 cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
303 psw_bits(lc->external_new_psw).mcheck = 1;
304 psw_bits(lc->program_new_psw).mcheck = 1;
305 psw_bits(lc->svc_new_psw).mcheck = 1;
306 psw_bits(lc->io_new_psw).mcheck = 1;
307 local_ctl_load(0, &cr0);
308 local_irq_restore(flags);
309 local_mcck_enable();
310 test_monitor_call();
311 }
312
313 static void (*pgm_check_table[128])(struct pt_regs *regs);
314
315 void noinstr __do_pgm_check(struct pt_regs *regs)
316 {
317 struct lowcore *lc = get_lowcore();
318 irqentry_state_t state;
319 unsigned int trapnr;
320
321 regs->int_code = lc->pgm_int_code;
322 regs->int_parm_long = lc->trans_exc_code;
323
324 state = irqentry_enter(regs);
325
326 if (user_mode(regs)) {
327 update_timer_sys();
328 if (!static_branch_likely(&cpu_has_bear)) {
329 if (regs->last_break < 4096)
330 regs->last_break = 1;
331 }
332 current->thread.last_break = regs->last_break;
333 }
334
335 if (lc->pgm_code & 0x0200) {
336 /* transaction abort */
337 current->thread.trap_tdb = lc->pgm_tdb;
338 }
339
340 if (lc->pgm_code & PGM_INT_CODE_PER) {
341 if (user_mode(regs)) {
342 struct per_event *ev = ¤t->thread.per_event;
343
344 set_thread_flag(TIF_PER_TRAP);
345 ev->address = lc->per_address;
346 ev->cause = lc->per_code_combined;
347 ev->paid = lc->per_access_id;
348 } else {
349 /* PER event in kernel is kprobes */
350 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
351 do_per_trap(regs);
352 goto out;
353 }
354 }
355
356 if (!irqs_disabled_flags(regs->psw.mask))
357 trace_hardirqs_on();
358 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
359
360 trapnr = regs->int_code & PGM_INT_CODE_MASK;
361 if (trapnr)
362 pgm_check_table[trapnr](regs);
363 out:
364 local_irq_disable();
365 irqentry_exit(regs, state);
366 }
367
368 /*
369 * The program check table contains exactly 128 (0x00-0x7f) entries. Each
370 * line defines the function to be called corresponding to the program check
371 * interruption code.
372 */
373 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
374 [0x00] = default_trap_handler,
375 [0x01] = illegal_op,
376 [0x02] = privileged_op,
377 [0x03] = execute_exception,
378 [0x04] = do_protection_exception,
379 [0x05] = addressing_exception,
380 [0x06] = specification_exception,
381 [0x07] = data_exception,
382 [0x08] = overflow_exception,
383 [0x09] = divide_exception,
384 [0x0a] = overflow_exception,
385 [0x0b] = divide_exception,
386 [0x0c] = hfp_overflow_exception,
387 [0x0d] = hfp_underflow_exception,
388 [0x0e] = hfp_significance_exception,
389 [0x0f] = hfp_divide_exception,
390 [0x10] = do_dat_exception,
391 [0x11] = do_dat_exception,
392 [0x12] = translation_specification_exception,
393 [0x13] = special_op_exception,
394 [0x14] = default_trap_handler,
395 [0x15] = operand_exception,
396 [0x16] = default_trap_handler,
397 [0x17] = default_trap_handler,
398 [0x18] = transaction_exception,
399 [0x19] = default_trap_handler,
400 [0x1a] = default_trap_handler,
401 [0x1b] = vector_exception,
402 [0x1c] = space_switch_exception,
403 [0x1d] = hfp_sqrt_exception,
404 [0x1e ... 0x37] = default_trap_handler,
405 [0x38] = do_dat_exception,
406 [0x39] = do_dat_exception,
407 [0x3a] = do_dat_exception,
408 [0x3b] = do_dat_exception,
409 [0x3c] = default_trap_handler,
410 [0x3d] = do_secure_storage_access,
411 [0x3e] = do_non_secure_storage_access,
412 [0x3f] = do_secure_storage_violation,
413 [0x40] = monitor_event_exception,
414 [0x41 ... 0x7f] = default_trap_handler,
415 };
416
417 #define COND_TRAP(x) asm( \
418 ".weak " __stringify(x) "\n\t" \
419 ".set " __stringify(x) "," \
420 __stringify(default_trap_handler))
421
422 COND_TRAP(do_secure_storage_access);
423 COND_TRAP(do_non_secure_storage_access);
424 COND_TRAP(do_secure_storage_violation);
425
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