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 <asm/fault.h>
35 #include "entry.h"
36
get_trap_ip(struct pt_regs * regs)37 static inline void __user *get_trap_ip(struct pt_regs *regs)
38 {
39 unsigned long address;
40
41 if (regs->int_code & 0x200)
42 address = current->thread.trap_tdb.data[3];
43 else
44 address = regs->psw.addr;
45 return (void __user *) (address - (regs->int_code >> 16));
46 }
47
48 #ifdef CONFIG_GENERIC_BUG
is_valid_bugaddr(unsigned long addr)49 int is_valid_bugaddr(unsigned long addr)
50 {
51 return 1;
52 }
53 #endif
54
do_report_trap(struct pt_regs * regs,int si_signo,int si_code,char * str)55 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
56 {
57 if (user_mode(regs)) {
58 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
59 report_user_fault(regs, si_signo, 0);
60 } else {
61 if (!fixup_exception(regs))
62 die(regs, str);
63 }
64 }
65
do_trap(struct pt_regs * regs,int si_signo,int si_code,char * str)66 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
67 {
68 if (notify_die(DIE_TRAP, str, regs, 0,
69 regs->int_code, si_signo) == NOTIFY_STOP)
70 return;
71 do_report_trap(regs, si_signo, si_code, str);
72 }
73 NOKPROBE_SYMBOL(do_trap);
74
do_per_trap(struct pt_regs * regs)75 void do_per_trap(struct pt_regs *regs)
76 {
77 if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
78 return;
79 if (!current->ptrace)
80 return;
81 force_sig_fault(SIGTRAP, TRAP_HWBKPT,
82 (void __force __user *) current->thread.per_event.address);
83 }
84 NOKPROBE_SYMBOL(do_per_trap);
85
default_trap_handler(struct pt_regs * regs)86 static void default_trap_handler(struct pt_regs *regs)
87 {
88 if (user_mode(regs)) {
89 report_user_fault(regs, SIGSEGV, 0);
90 force_exit_sig(SIGSEGV);
91 } else
92 die(regs, "Unknown program exception");
93 }
94
95 #define DO_ERROR_INFO(name, signr, sicode, str) \
96 static void name(struct pt_regs *regs) \
97 { \
98 do_trap(regs, signr, sicode, str); \
99 }
100
101 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
102 "addressing exception")
103 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
104 "execute exception")
105 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
106 "fixpoint divide exception")
107 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
108 "fixpoint overflow exception")
109 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
110 "HFP overflow exception")
111 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
112 "HFP underflow exception")
113 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
114 "HFP significance exception")
115 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
116 "HFP divide exception")
117 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
118 "HFP square root exception")
119 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
120 "operand exception")
121 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
122 "privileged operation")
123 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
124 "special operation exception")
125 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
126 "transaction constraint exception")
127
do_fp_trap(struct pt_regs * regs,__u32 fpc)128 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
129 {
130 int si_code = 0;
131 /* FPC[2] is Data Exception Code */
132 if ((fpc & 0x00000300) == 0) {
133 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
134 if (fpc & 0x8000) /* invalid fp operation */
135 si_code = FPE_FLTINV;
136 else if (fpc & 0x4000) /* div by 0 */
137 si_code = FPE_FLTDIV;
138 else if (fpc & 0x2000) /* overflow */
139 si_code = FPE_FLTOVF;
140 else if (fpc & 0x1000) /* underflow */
141 si_code = FPE_FLTUND;
142 else if (fpc & 0x0800) /* inexact */
143 si_code = FPE_FLTRES;
144 }
145 do_trap(regs, SIGFPE, si_code, "floating point exception");
146 }
147
translation_specification_exception(struct pt_regs * regs)148 static void translation_specification_exception(struct pt_regs *regs)
149 {
150 /* May never happen. */
151 panic("Translation-Specification Exception");
152 }
153
illegal_op(struct pt_regs * regs)154 static void illegal_op(struct pt_regs *regs)
155 {
156 __u8 opcode[6];
157 __u16 __user *location;
158 int is_uprobe_insn = 0;
159 int signal = 0;
160
161 location = get_trap_ip(regs);
162
163 if (user_mode(regs)) {
164 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
165 return;
166 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
167 if (current->ptrace)
168 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
169 else
170 signal = SIGILL;
171 #ifdef CONFIG_UPROBES
172 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
173 is_uprobe_insn = 1;
174 #endif
175 } else
176 signal = SIGILL;
177 }
178 /*
179 * We got either an illegal op in kernel mode, or user space trapped
180 * on a uprobes illegal instruction. See if kprobes or uprobes picks
181 * it up. If not, SIGILL.
182 */
183 if (is_uprobe_insn || !user_mode(regs)) {
184 if (notify_die(DIE_BPT, "bpt", regs, 0,
185 3, SIGTRAP) != NOTIFY_STOP)
186 signal = SIGILL;
187 }
188 if (signal)
189 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
190 }
191 NOKPROBE_SYMBOL(illegal_op);
192
193 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
194 "specification exception");
195
vector_exception(struct pt_regs * regs)196 static void vector_exception(struct pt_regs *regs)
197 {
198 int si_code, vic;
199
200 if (!cpu_has_vx()) {
201 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
202 return;
203 }
204
205 /* get vector interrupt code from fpc */
206 save_user_fpu_regs();
207 vic = (current->thread.ufpu.fpc & 0xf00) >> 8;
208 switch (vic) {
209 case 1: /* invalid vector operation */
210 si_code = FPE_FLTINV;
211 break;
212 case 2: /* division by zero */
213 si_code = FPE_FLTDIV;
214 break;
215 case 3: /* overflow */
216 si_code = FPE_FLTOVF;
217 break;
218 case 4: /* underflow */
219 si_code = FPE_FLTUND;
220 break;
221 case 5: /* inexact */
222 si_code = FPE_FLTRES;
223 break;
224 default: /* unknown cause */
225 si_code = 0;
226 }
227 do_trap(regs, SIGFPE, si_code, "vector exception");
228 }
229
data_exception(struct pt_regs * regs)230 static void data_exception(struct pt_regs *regs)
231 {
232 save_user_fpu_regs();
233 if (current->thread.ufpu.fpc & FPC_DXC_MASK)
234 do_fp_trap(regs, current->thread.ufpu.fpc);
235 else
236 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
237 }
238
space_switch_exception(struct pt_regs * regs)239 static void space_switch_exception(struct pt_regs *regs)
240 {
241 /* Set user psw back to home space mode. */
242 if (user_mode(regs))
243 regs->psw.mask |= PSW_ASC_HOME;
244 /* Send SIGILL. */
245 do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
246 }
247
monitor_event_exception(struct pt_regs * regs)248 static void monitor_event_exception(struct pt_regs *regs)
249 {
250 if (user_mode(regs))
251 return;
252
253 switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
254 case BUG_TRAP_TYPE_NONE:
255 fixup_exception(regs);
256 break;
257 case BUG_TRAP_TYPE_WARN:
258 break;
259 case BUG_TRAP_TYPE_BUG:
260 die(regs, "monitor event");
261 break;
262 }
263 }
264
kernel_stack_overflow(struct pt_regs * regs)265 void kernel_stack_overflow(struct pt_regs *regs)
266 {
267 /*
268 * Normally regs are unpoisoned by the generic entry code, but
269 * kernel_stack_overflow() is a rare case that is called bypassing it.
270 */
271 kmsan_unpoison_entry_regs(regs);
272 bust_spinlocks(1);
273 printk("Kernel stack overflow.\n");
274 show_regs(regs);
275 bust_spinlocks(0);
276 panic("Corrupt kernel stack, can't continue.");
277 }
278 NOKPROBE_SYMBOL(kernel_stack_overflow);
279
test_monitor_call(void)280 static void __init test_monitor_call(void)
281 {
282 int val = 1;
283
284 if (!IS_ENABLED(CONFIG_BUG))
285 return;
286 asm volatile(
287 " mc 0,0\n"
288 "0: lhi %[val],0\n"
289 "1:\n"
290 EX_TABLE(0b, 1b)
291 : [val] "+d" (val));
292 if (!val)
293 panic("Monitor call doesn't work!\n");
294 }
295
trap_init(void)296 void __init trap_init(void)
297 {
298 struct lowcore *lc = get_lowcore();
299 unsigned long flags;
300 struct ctlreg cr0;
301
302 local_irq_save(flags);
303 cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
304 psw_bits(lc->external_new_psw).mcheck = 1;
305 psw_bits(lc->program_new_psw).mcheck = 1;
306 psw_bits(lc->svc_new_psw).mcheck = 1;
307 psw_bits(lc->io_new_psw).mcheck = 1;
308 local_ctl_load(0, &cr0);
309 local_irq_restore(flags);
310 local_mcck_enable();
311 test_monitor_call();
312 }
313
314 static void (*pgm_check_table[128])(struct pt_regs *regs);
315
__do_pgm_check(struct pt_regs * regs)316 void noinstr __do_pgm_check(struct pt_regs *regs)
317 {
318 struct lowcore *lc = get_lowcore();
319 irqentry_state_t state;
320 unsigned int trapnr;
321 union teid teid;
322
323 teid.val = lc->trans_exc_code;
324 regs->int_code = lc->pgm_int_code;
325 regs->int_parm_long = teid.val;
326
327 /*
328 * In case of a guest fault, short-circuit the fault handler and return.
329 * This way the sie64a() function will return 0; fault address and
330 * other relevant bits are saved in current->thread.gmap_teid, and
331 * the fault number in current->thread.gmap_int_code. KVM will be
332 * able to use this information to handle the fault.
333 */
334 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) {
335 current->thread.gmap_teid.val = regs->int_parm_long;
336 current->thread.gmap_int_code = regs->int_code & 0xffff;
337 return;
338 }
339
340 state = irqentry_enter(regs);
341
342 if (user_mode(regs)) {
343 update_timer_sys();
344 if (!static_branch_likely(&cpu_has_bear)) {
345 if (regs->last_break < 4096)
346 regs->last_break = 1;
347 }
348 current->thread.last_break = regs->last_break;
349 }
350
351 if (lc->pgm_code & 0x0200) {
352 /* transaction abort */
353 current->thread.trap_tdb = lc->pgm_tdb;
354 }
355
356 if (lc->pgm_code & PGM_INT_CODE_PER) {
357 if (user_mode(regs)) {
358 struct per_event *ev = ¤t->thread.per_event;
359
360 set_thread_flag(TIF_PER_TRAP);
361 ev->address = lc->per_address;
362 ev->cause = lc->per_code_combined;
363 ev->paid = lc->per_access_id;
364 } else {
365 /* PER event in kernel is kprobes */
366 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
367 do_per_trap(regs);
368 goto out;
369 }
370 }
371
372 if (!irqs_disabled_flags(regs->psw.mask))
373 trace_hardirqs_on();
374 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
375
376 trapnr = regs->int_code & PGM_INT_CODE_MASK;
377 if (trapnr)
378 pgm_check_table[trapnr](regs);
379 out:
380 local_irq_disable();
381 irqentry_exit(regs, state);
382 }
383
384 /*
385 * The program check table contains exactly 128 (0x00-0x7f) entries. Each
386 * line defines the function to be called corresponding to the program check
387 * interruption code.
388 */
389 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
390 [0x00] = default_trap_handler,
391 [0x01] = illegal_op,
392 [0x02] = privileged_op,
393 [0x03] = execute_exception,
394 [0x04] = do_protection_exception,
395 [0x05] = addressing_exception,
396 [0x06] = specification_exception,
397 [0x07] = data_exception,
398 [0x08] = overflow_exception,
399 [0x09] = divide_exception,
400 [0x0a] = overflow_exception,
401 [0x0b] = divide_exception,
402 [0x0c] = hfp_overflow_exception,
403 [0x0d] = hfp_underflow_exception,
404 [0x0e] = hfp_significance_exception,
405 [0x0f] = hfp_divide_exception,
406 [0x10] = do_dat_exception,
407 [0x11] = do_dat_exception,
408 [0x12] = translation_specification_exception,
409 [0x13] = special_op_exception,
410 [0x14] = default_trap_handler,
411 [0x15] = operand_exception,
412 [0x16] = default_trap_handler,
413 [0x17] = default_trap_handler,
414 [0x18] = transaction_exception,
415 [0x19] = default_trap_handler,
416 [0x1a] = default_trap_handler,
417 [0x1b] = vector_exception,
418 [0x1c] = space_switch_exception,
419 [0x1d] = hfp_sqrt_exception,
420 [0x1e ... 0x37] = default_trap_handler,
421 [0x38] = do_dat_exception,
422 [0x39] = do_dat_exception,
423 [0x3a] = do_dat_exception,
424 [0x3b] = do_dat_exception,
425 [0x3c] = default_trap_handler,
426 [0x3d] = do_secure_storage_access,
427 [0x3e] = default_trap_handler,
428 [0x3f] = default_trap_handler,
429 [0x40] = monitor_event_exception,
430 [0x41 ... 0x7f] = default_trap_handler,
431 };
432
433 #define COND_TRAP(x) asm( \
434 ".weak " __stringify(x) "\n\t" \
435 ".set " __stringify(x) "," \
436 __stringify(default_trap_handler))
437
438 COND_TRAP(do_secure_storage_access);
439