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 <asm/asm-extable.h>
31 #include <asm/fpu/api.h>
32 #include <asm/vtime.h>
33 #include "entry.h"
34
get_trap_ip(struct pt_regs * regs)35 static inline void __user *get_trap_ip(struct pt_regs *regs)
36 {
37 unsigned long address;
38
39 if (regs->int_code & 0x200)
40 address = current->thread.trap_tdb.data[3];
41 else
42 address = regs->psw.addr;
43 return (void __user *) (address - (regs->int_code >> 16));
44 }
45
is_valid_bugaddr(unsigned long addr)46 int is_valid_bugaddr(unsigned long addr)
47 {
48 return 1;
49 }
50
do_report_trap(struct pt_regs * regs,int si_signo,int si_code,char * str)51 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
52 {
53 if (user_mode(regs)) {
54 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
55 report_user_fault(regs, si_signo, 0);
56 } else {
57 if (!fixup_exception(regs))
58 die(regs, str);
59 }
60 }
61
do_trap(struct pt_regs * regs,int si_signo,int si_code,char * str)62 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
63 {
64 if (notify_die(DIE_TRAP, str, regs, 0,
65 regs->int_code, si_signo) == NOTIFY_STOP)
66 return;
67 do_report_trap(regs, si_signo, si_code, str);
68 }
69 NOKPROBE_SYMBOL(do_trap);
70
do_per_trap(struct pt_regs * regs)71 void do_per_trap(struct pt_regs *regs)
72 {
73 if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
74 return;
75 if (!current->ptrace)
76 return;
77 force_sig_fault(SIGTRAP, TRAP_HWBKPT,
78 (void __force __user *) current->thread.per_event.address);
79 }
80 NOKPROBE_SYMBOL(do_per_trap);
81
default_trap_handler(struct pt_regs * regs)82 static void default_trap_handler(struct pt_regs *regs)
83 {
84 if (user_mode(regs)) {
85 report_user_fault(regs, SIGSEGV, 0);
86 force_exit_sig(SIGSEGV);
87 } else
88 die(regs, "Unknown program exception");
89 }
90
91 #define DO_ERROR_INFO(name, signr, sicode, str) \
92 static void name(struct pt_regs *regs) \
93 { \
94 do_trap(regs, signr, sicode, str); \
95 }
96
97 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
98 "addressing exception")
99 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
100 "execute exception")
101 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
102 "fixpoint divide exception")
103 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
104 "fixpoint overflow exception")
105 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
106 "HFP overflow exception")
107 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
108 "HFP underflow exception")
109 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
110 "HFP significance exception")
111 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
112 "HFP divide exception")
113 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
114 "HFP square root exception")
115 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
116 "operand exception")
117 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
118 "privileged operation")
119 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
120 "special operation exception")
121 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
122 "transaction constraint exception")
123
do_fp_trap(struct pt_regs * regs,__u32 fpc)124 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
125 {
126 int si_code = 0;
127 /* FPC[2] is Data Exception Code */
128 if ((fpc & 0x00000300) == 0) {
129 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
130 if (fpc & 0x8000) /* invalid fp operation */
131 si_code = FPE_FLTINV;
132 else if (fpc & 0x4000) /* div by 0 */
133 si_code = FPE_FLTDIV;
134 else if (fpc & 0x2000) /* overflow */
135 si_code = FPE_FLTOVF;
136 else if (fpc & 0x1000) /* underflow */
137 si_code = FPE_FLTUND;
138 else if (fpc & 0x0800) /* inexact */
139 si_code = FPE_FLTRES;
140 }
141 do_trap(regs, SIGFPE, si_code, "floating point exception");
142 }
143
translation_specification_exception(struct pt_regs * regs)144 static void translation_specification_exception(struct pt_regs *regs)
145 {
146 /* May never happen. */
147 panic("Translation-Specification Exception");
148 }
149
illegal_op(struct pt_regs * regs)150 static void illegal_op(struct pt_regs *regs)
151 {
152 __u8 opcode[6];
153 __u16 __user *location;
154 int is_uprobe_insn = 0;
155 int signal = 0;
156
157 location = get_trap_ip(regs);
158
159 if (user_mode(regs)) {
160 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
161 return;
162 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
163 if (current->ptrace)
164 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
165 else
166 signal = SIGILL;
167 #ifdef CONFIG_UPROBES
168 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
169 is_uprobe_insn = 1;
170 #endif
171 } else
172 signal = SIGILL;
173 }
174 /*
175 * We got either an illegal op in kernel mode, or user space trapped
176 * on a uprobes illegal instruction. See if kprobes or uprobes picks
177 * it up. If not, SIGILL.
178 */
179 if (is_uprobe_insn || !user_mode(regs)) {
180 if (notify_die(DIE_BPT, "bpt", regs, 0,
181 3, SIGTRAP) != NOTIFY_STOP)
182 signal = SIGILL;
183 }
184 if (signal)
185 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
186 }
187 NOKPROBE_SYMBOL(illegal_op);
188
189 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
190 "specification exception");
191
vector_exception(struct pt_regs * regs)192 static void vector_exception(struct pt_regs *regs)
193 {
194 int si_code, vic;
195
196 if (!MACHINE_HAS_VX) {
197 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
198 return;
199 }
200
201 /* get vector interrupt code from fpc */
202 save_fpu_regs();
203 vic = (current->thread.fpu.fpc & 0xf00) >> 8;
204 switch (vic) {
205 case 1: /* invalid vector operation */
206 si_code = FPE_FLTINV;
207 break;
208 case 2: /* division by zero */
209 si_code = FPE_FLTDIV;
210 break;
211 case 3: /* overflow */
212 si_code = FPE_FLTOVF;
213 break;
214 case 4: /* underflow */
215 si_code = FPE_FLTUND;
216 break;
217 case 5: /* inexact */
218 si_code = FPE_FLTRES;
219 break;
220 default: /* unknown cause */
221 si_code = 0;
222 }
223 do_trap(regs, SIGFPE, si_code, "vector exception");
224 }
225
data_exception(struct pt_regs * regs)226 static void data_exception(struct pt_regs *regs)
227 {
228 save_fpu_regs();
229 if (current->thread.fpu.fpc & FPC_DXC_MASK)
230 do_fp_trap(regs, current->thread.fpu.fpc);
231 else
232 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
233 }
234
space_switch_exception(struct pt_regs * regs)235 static void space_switch_exception(struct pt_regs *regs)
236 {
237 /* Set user psw back to home space mode. */
238 if (user_mode(regs))
239 regs->psw.mask |= PSW_ASC_HOME;
240 /* Send SIGILL. */
241 do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
242 }
243
monitor_event_exception(struct pt_regs * regs)244 static void monitor_event_exception(struct pt_regs *regs)
245 {
246 if (user_mode(regs))
247 return;
248
249 switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
250 case BUG_TRAP_TYPE_NONE:
251 fixup_exception(regs);
252 break;
253 case BUG_TRAP_TYPE_WARN:
254 break;
255 case BUG_TRAP_TYPE_BUG:
256 die(regs, "monitor event");
257 break;
258 }
259 }
260
kernel_stack_overflow(struct pt_regs * regs)261 void kernel_stack_overflow(struct pt_regs *regs)
262 {
263 bust_spinlocks(1);
264 printk("Kernel stack overflow.\n");
265 show_regs(regs);
266 bust_spinlocks(0);
267 panic("Corrupt kernel stack, can't continue.");
268 }
269 NOKPROBE_SYMBOL(kernel_stack_overflow);
270
test_monitor_call(void)271 static void __init test_monitor_call(void)
272 {
273 int val = 1;
274
275 if (!IS_ENABLED(CONFIG_BUG))
276 return;
277 asm volatile(
278 " mc 0,0\n"
279 "0: xgr %0,%0\n"
280 "1:\n"
281 EX_TABLE(0b,1b)
282 : "+d" (val));
283 if (!val)
284 panic("Monitor call doesn't work!\n");
285 }
286
trap_init(void)287 void __init trap_init(void)
288 {
289 local_mcck_enable();
290 test_monitor_call();
291 }
292
293 static void (*pgm_check_table[128])(struct pt_regs *regs);
294
__do_pgm_check(struct pt_regs * regs)295 void noinstr __do_pgm_check(struct pt_regs *regs)
296 {
297 unsigned int trapnr;
298 irqentry_state_t state;
299
300 regs->int_code = S390_lowcore.pgm_int_code;
301 regs->int_parm_long = S390_lowcore.trans_exc_code;
302
303 state = irqentry_enter(regs);
304
305 if (user_mode(regs)) {
306 update_timer_sys();
307 if (!static_branch_likely(&cpu_has_bear)) {
308 if (regs->last_break < 4096)
309 regs->last_break = 1;
310 }
311 current->thread.last_break = regs->last_break;
312 }
313
314 if (S390_lowcore.pgm_code & 0x0200) {
315 /* transaction abort */
316 current->thread.trap_tdb = S390_lowcore.pgm_tdb;
317 }
318
319 if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
320 if (user_mode(regs)) {
321 struct per_event *ev = ¤t->thread.per_event;
322
323 set_thread_flag(TIF_PER_TRAP);
324 ev->address = S390_lowcore.per_address;
325 ev->cause = S390_lowcore.per_code_combined;
326 ev->paid = S390_lowcore.per_access_id;
327 } else {
328 /* PER event in kernel is kprobes */
329 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
330 do_per_trap(regs);
331 goto out;
332 }
333 }
334
335 if (!irqs_disabled_flags(regs->psw.mask))
336 trace_hardirqs_on();
337 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
338
339 trapnr = regs->int_code & PGM_INT_CODE_MASK;
340 if (trapnr)
341 pgm_check_table[trapnr](regs);
342 out:
343 local_irq_disable();
344 irqentry_exit(regs, state);
345 }
346
347 /*
348 * The program check table contains exactly 128 (0x00-0x7f) entries. Each
349 * line defines the function to be called corresponding to the program check
350 * interruption code.
351 */
352 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
353 [0x00] = default_trap_handler,
354 [0x01] = illegal_op,
355 [0x02] = privileged_op,
356 [0x03] = execute_exception,
357 [0x04] = do_protection_exception,
358 [0x05] = addressing_exception,
359 [0x06] = specification_exception,
360 [0x07] = data_exception,
361 [0x08] = overflow_exception,
362 [0x09] = divide_exception,
363 [0x0a] = overflow_exception,
364 [0x0b] = divide_exception,
365 [0x0c] = hfp_overflow_exception,
366 [0x0d] = hfp_underflow_exception,
367 [0x0e] = hfp_significance_exception,
368 [0x0f] = hfp_divide_exception,
369 [0x10] = do_dat_exception,
370 [0x11] = do_dat_exception,
371 [0x12] = translation_specification_exception,
372 [0x13] = special_op_exception,
373 [0x14] = default_trap_handler,
374 [0x15] = operand_exception,
375 [0x16] = default_trap_handler,
376 [0x17] = default_trap_handler,
377 [0x18] = transaction_exception,
378 [0x19] = default_trap_handler,
379 [0x1a] = default_trap_handler,
380 [0x1b] = vector_exception,
381 [0x1c] = space_switch_exception,
382 [0x1d] = hfp_sqrt_exception,
383 [0x1e ... 0x37] = default_trap_handler,
384 [0x38] = do_dat_exception,
385 [0x39] = do_dat_exception,
386 [0x3a] = do_dat_exception,
387 [0x3b] = do_dat_exception,
388 [0x3c] = default_trap_handler,
389 [0x3d] = do_secure_storage_access,
390 [0x3e] = do_non_secure_storage_access,
391 [0x3f] = do_secure_storage_violation,
392 [0x40] = monitor_event_exception,
393 [0x41 ... 0x7f] = default_trap_handler,
394 };
395
396 #define COND_TRAP(x) asm( \
397 ".weak " __stringify(x) "\n\t" \
398 ".set " __stringify(x) "," \
399 __stringify(default_trap_handler))
400
401 COND_TRAP(do_secure_storage_access);
402 COND_TRAP(do_non_secure_storage_access);
403 COND_TRAP(do_secure_storage_violation);
404