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#include <linux/cpufeature.h>
13#include <linux/kprobes.h>
14#include <linux/kdebug.h>
15#include <linux/randomize_kstack.h>
16#include <linux/extable.h>
17#include <linux/ptrace.h>
18#include <linux/sched.h>
19#include <linux/sched/debug.h>
20#include <linux/mm.h>
21#include <linux/slab.h>
22#include <linux/uaccess.h>
23#include <linux/cpu.h>
24#include <linux/entry-common.h>
25#include <linux/kmsan.h>
26#include <asm/asm-extable.h>
27#include <asm/irqflags.h>
28#include <asm/ptrace.h>
29#include <asm/vtime.h>
30#include <asm/fpu.h>
31#include <asm/fault.h>
32#include "entry.h"
33
34static inline void __user *get_trap_ip(struct pt_regs *regs)
35{
36 unsigned long address;
37
38 if (regs->int_code & 0x200)
39 address = current->thread.trap_tdb.data[3];
40 else
41 address = regs->psw.addr;
42 return (void __user *)(address - (regs->int_code >> 16));
43}
44
45#ifdef CONFIG_GENERIC_BUG
46int is_valid_bugaddr(unsigned long addr)
47{
48 return 1;
49}
50#endif
51
52void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
53{
54 if (user_mode(regs)) {
55 force_sig_fault(sig: si_signo, code: si_code, addr: get_trap_ip(regs));
56 report_user_fault(regs, si_signo, 0);
57 } else {
58 if (!fixup_exception(regs))
59 die(regs, str);
60 }
61}
62
63static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
64{
65 if (notify_die(val: DIE_TRAP, str, regs, err: 0, trap: regs->int_code, sig: si_signo) == NOTIFY_STOP)
66 return;
67 do_report_trap(regs, si_signo, si_code, str);
68}
69NOKPROBE_SYMBOL(do_trap);
70
71void do_per_trap(struct pt_regs *regs)
72{
73 if (notify_die(val: DIE_SSTEP, str: "sstep", regs, err: 0, trap: 0, SIGTRAP) == NOTIFY_STOP)
74 return;
75 if (!current->ptrace)
76 return;
77 force_sig_fault(SIGTRAP, TRAP_HWBKPT, addr: (void __force __user *)current->thread.per_event.address);
78}
79NOKPROBE_SYMBOL(do_per_trap);
80
81static void default_trap_handler(struct pt_regs *regs)
82{
83 if (user_mode(regs)) {
84 report_user_fault(regs, SIGSEGV, 0);
85 force_exit_sig(SIGSEGV);
86 } else
87 die(regs, "Unknown program exception");
88}
89
90#define DO_ERROR_INFO(name, signr, sicode, str) \
91static void name(struct pt_regs *regs) \
92{ \
93 do_trap(regs, signr, sicode, str); \
94}
95
96DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR, "addressing exception")
97DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV, "fixpoint divide exception")
98DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN, "execute exception")
99DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV, "HFP divide exception")
100DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF, "HFP overflow exception")
101DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES, "HFP significance exception")
102DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV, "HFP square root exception")
103DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND, "HFP underflow exception")
104DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN, "operand exception")
105DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF, "fixpoint overflow exception")
106DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC, "privileged operation")
107DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN, "special operation exception")
108DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN, "specification exception");
109DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN, "transaction constraint exception")
110
111static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
112{
113 int si_code = 0;
114
115 /* FPC[2] is Data Exception Code */
116 if ((fpc & 0x00000300) == 0) {
117 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
118 if (fpc & 0x8000) /* invalid fp operation */
119 si_code = FPE_FLTINV;
120 else if (fpc & 0x4000) /* div by 0 */
121 si_code = FPE_FLTDIV;
122 else if (fpc & 0x2000) /* overflow */
123 si_code = FPE_FLTOVF;
124 else if (fpc & 0x1000) /* underflow */
125 si_code = FPE_FLTUND;
126 else if (fpc & 0x0800) /* inexact */
127 si_code = FPE_FLTRES;
128 }
129 do_trap(regs, SIGFPE, si_code, str: "floating point exception");
130}
131
132static void translation_specification_exception(struct pt_regs *regs)
133{
134 /* May never happen. */
135 panic(fmt: "Translation-Specification Exception");
136}
137
138static void illegal_op(struct pt_regs *regs)
139{
140 int is_uprobe_insn = 0;
141 u16 __user *location;
142 int signal = 0;
143 u16 opcode;
144
145 location = get_trap_ip(regs);
146 if (user_mode(regs)) {
147 if (get_user(opcode, location))
148 return;
149 if (opcode == S390_BREAKPOINT_U16) {
150 if (current->ptrace)
151 force_sig_fault(SIGTRAP, TRAP_BRKPT, addr: location);
152 else
153 signal = SIGILL;
154#ifdef CONFIG_UPROBES
155 } else if (opcode == UPROBE_SWBP_INSN) {
156 is_uprobe_insn = 1;
157#endif
158 } else {
159 signal = SIGILL;
160 }
161 }
162 /*
163 * This is either an illegal op in kernel mode, or user space trapped
164 * on a uprobes illegal instruction. See if kprobes or uprobes picks
165 * it up. If not, SIGILL.
166 */
167 if (is_uprobe_insn || !user_mode(regs)) {
168 if (notify_die(val: DIE_BPT, str: "bpt", regs, err: 0, trap: 3, SIGTRAP) != NOTIFY_STOP)
169 signal = SIGILL;
170 }
171 if (signal)
172 do_trap(regs, si_signo: signal, ILL_ILLOPC, str: "illegal operation");
173}
174NOKPROBE_SYMBOL(illegal_op);
175
176static void vector_exception(struct pt_regs *regs)
177{
178 int si_code, vic;
179
180 /* get vector interrupt code from fpc */
181 save_user_fpu_regs();
182 vic = (current->thread.ufpu.fpc & 0xf00) >> 8;
183 switch (vic) {
184 case 1: /* invalid vector operation */
185 si_code = FPE_FLTINV;
186 break;
187 case 2: /* division by zero */
188 si_code = FPE_FLTDIV;
189 break;
190 case 3: /* overflow */
191 si_code = FPE_FLTOVF;
192 break;
193 case 4: /* underflow */
194 si_code = FPE_FLTUND;
195 break;
196 case 5: /* inexact */
197 si_code = FPE_FLTRES;
198 break;
199 default: /* unknown cause */
200 si_code = 0;
201 }
202 do_trap(regs, SIGFPE, si_code, str: "vector exception");
203}
204
205static void data_exception(struct pt_regs *regs)
206{
207 save_user_fpu_regs();
208 if (current->thread.ufpu.fpc & FPC_DXC_MASK)
209 do_fp_trap(regs, current->thread.ufpu.fpc);
210 else
211 do_trap(regs, SIGILL, ILL_ILLOPN, str: "data exception");
212}
213
214static void space_switch_exception(struct pt_regs *regs)
215{
216 /* Set user psw back to home space mode. */
217 if (user_mode(regs))
218 regs->psw.mask |= PSW_ASC_HOME;
219 /* Send SIGILL. */
220 do_trap(regs, SIGILL, ILL_PRVOPC, str: "space switch event");
221}
222
223static void monitor_event_exception(struct pt_regs *regs)
224{
225 if (user_mode(regs))
226 return;
227 switch (report_bug(bug_addr: regs->psw.addr - (regs->int_code >> 16), regs)) {
228 case BUG_TRAP_TYPE_NONE:
229 fixup_exception(regs);
230 break;
231 case BUG_TRAP_TYPE_WARN:
232 break;
233 case BUG_TRAP_TYPE_BUG:
234 die(regs, "monitor event");
235 break;
236 }
237}
238
239void kernel_stack_invalid(struct pt_regs *regs)
240{
241 /*
242 * Normally regs are unpoisoned by the generic entry code, but
243 * kernel_stack_overflow() is a rare case that is called bypassing it.
244 */
245 kmsan_unpoison_entry_regs(regs);
246 bust_spinlocks(yes: 1);
247 pr_emerg("Kernel stack pointer invalid\n");
248 show_regs(regs);
249 bust_spinlocks(yes: 0);
250 panic(fmt: "Invalid kernel stack pointer, cannot continue");
251}
252NOKPROBE_SYMBOL(kernel_stack_invalid);
253
254static void __init test_monitor_call(void)
255{
256 int val = 1;
257
258 if (!IS_ENABLED(CONFIG_BUG))
259 return;
260 asm_inline volatile(
261 " mc 0,0\n"
262 "0: lhi %[val],0\n"
263 "1:\n"
264 EX_TABLE(0b, 1b)
265 : [val] "+d" (val));
266 if (!val)
267 panic(fmt: "Monitor call doesn't work!\n");
268}
269
270void __init trap_init(void)
271{
272 struct lowcore *lc = get_lowcore();
273 unsigned long flags;
274 struct ctlreg cr0;
275
276 local_irq_save(flags);
277 cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
278 psw_bits(lc->external_new_psw).mcheck = 1;
279 psw_bits(lc->program_new_psw).mcheck = 1;
280 psw_bits(lc->svc_new_psw).mcheck = 1;
281 psw_bits(lc->io_new_psw).mcheck = 1;
282 local_ctl_load(0, &cr0);
283 local_irq_restore(flags);
284 local_mcck_enable();
285 test_monitor_call();
286}
287
288static void (*pgm_check_table[128])(struct pt_regs *regs);
289
290void noinstr __do_pgm_check(struct pt_regs *regs)
291{
292 struct lowcore *lc = get_lowcore();
293 irqentry_state_t state;
294 unsigned int trapnr;
295 union teid teid;
296
297 teid.val = lc->trans_exc_code;
298 regs->int_code = lc->pgm_int_code;
299 regs->int_parm_long = teid.val;
300 /*
301 * In case of a guest fault, short-circuit the fault handler and return.
302 * This way the sie64a() function will return 0; fault address and
303 * other relevant bits are saved in current->thread.gmap_teid, and
304 * the fault number in current->thread.gmap_int_code. KVM will be
305 * able to use this information to handle the fault.
306 */
307 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) {
308 current->thread.gmap_teid.val = regs->int_parm_long;
309 current->thread.gmap_int_code = regs->int_code & 0xffff;
310 return;
311 }
312 state = irqentry_enter(regs);
313 if (user_mode(regs)) {
314 update_timer_sys();
315 if (!cpu_has_bear()) {
316 if (regs->last_break < 4096)
317 regs->last_break = 1;
318 }
319 current->thread.last_break = regs->last_break;
320 }
321 if (lc->pgm_code & 0x0200) {
322 /* transaction abort */
323 current->thread.trap_tdb = lc->pgm_tdb;
324 }
325 if (lc->pgm_code & PGM_INT_CODE_PER) {
326 if (user_mode(regs)) {
327 struct per_event *ev = &current->thread.per_event;
328
329 set_thread_flag(TIF_PER_TRAP);
330 ev->address = lc->per_address;
331 ev->cause = lc->per_code_combined;
332 ev->paid = lc->per_access_id;
333 } else {
334 /* PER event in kernel is kprobes */
335 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
336 do_per_trap(regs);
337 goto out;
338 }
339 }
340 if (!irqs_disabled_flags(regs->psw.mask))
341 trace_hardirqs_on();
342 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
343 trapnr = regs->int_code & PGM_INT_CODE_MASK;
344 if (trapnr)
345 pgm_check_table[trapnr](regs);
346out:
347 local_irq_disable();
348 irqentry_exit(regs, state);
349}
350
351/*
352 * The program check table contains exactly 128 (0x00-0x7f) entries. Each
353 * line defines the function to be called corresponding to the program check
354 * interruption code.
355 */
356static void (*pgm_check_table[128])(struct pt_regs *regs) = {
357 [0x00] = default_trap_handler,
358 [0x01] = illegal_op,
359 [0x02] = privileged_op,
360 [0x03] = execute_exception,
361 [0x04] = do_protection_exception,
362 [0x05] = addressing_exception,
363 [0x06] = specification_exception,
364 [0x07] = data_exception,
365 [0x08] = overflow_exception,
366 [0x09] = divide_exception,
367 [0x0a] = overflow_exception,
368 [0x0b] = divide_exception,
369 [0x0c] = hfp_overflow_exception,
370 [0x0d] = hfp_underflow_exception,
371 [0x0e] = hfp_significance_exception,
372 [0x0f] = hfp_divide_exception,
373 [0x10] = do_dat_exception,
374 [0x11] = do_dat_exception,
375 [0x12] = translation_specification_exception,
376 [0x13] = special_op_exception,
377 [0x14] = default_trap_handler,
378 [0x15] = operand_exception,
379 [0x16] = default_trap_handler,
380 [0x17] = default_trap_handler,
381 [0x18] = transaction_exception,
382 [0x19] = default_trap_handler,
383 [0x1a] = default_trap_handler,
384 [0x1b] = vector_exception,
385 [0x1c] = space_switch_exception,
386 [0x1d] = hfp_sqrt_exception,
387 [0x1e ... 0x37] = default_trap_handler,
388 [0x38] = do_dat_exception,
389 [0x39] = do_dat_exception,
390 [0x3a] = do_dat_exception,
391 [0x3b] = do_dat_exception,
392 [0x3c] = default_trap_handler,
393 [0x3d] = do_secure_storage_access,
394 [0x3e] = default_trap_handler,
395 [0x3f] = default_trap_handler,
396 [0x40] = monitor_event_exception,
397 [0x41 ... 0x7f] = default_trap_handler,
398};
399
400#define COND_TRAP(x) asm( \
401 ".weak " __stringify(x) "\n\t" \
402 ".set " __stringify(x) "," \
403 __stringify(default_trap_handler))
404
405COND_TRAP(do_secure_storage_access);
406

source code of linux/arch/s390/kernel/traps.c