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 <linux/bug.h> 27 #include <asm/asm-extable.h> 28 #include <asm/irqflags.h> 29 #include <asm/ptrace.h> 30 #include <asm/vtime.h> 31 #include <asm/fpu.h> 32 #include <asm/fault.h> 33 #include "entry.h" 34 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 46 #ifdef CONFIG_GENERIC_BUG 47 int is_valid_bugaddr(unsigned long addr) 48 { 49 return 1; 50 } 51 #endif 52 53 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str) 54 { 55 if (user_mode(regs)) { 56 force_sig_fault(si_signo, si_code, get_trap_ip(regs)); 57 report_user_fault(regs, si_signo, 0); 58 } else { 59 if (!fixup_exception(regs)) 60 die(regs, str); 61 } 62 } 63 64 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str) 65 { 66 if (notify_die(DIE_TRAP, str, regs, 0, regs->int_code, si_signo) == NOTIFY_STOP) 67 return; 68 do_report_trap(regs, si_signo, si_code, str); 69 } 70 NOKPROBE_SYMBOL(do_trap); 71 72 void do_per_trap(struct pt_regs *regs) 73 { 74 if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP) 75 return; 76 if (!current->ptrace) 77 return; 78 force_sig_fault(SIGTRAP, TRAP_HWBKPT, (void __force __user *)current->thread.per_event.address); 79 } 80 NOKPROBE_SYMBOL(do_per_trap); 81 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, "addressing exception") 98 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV, "fixpoint divide exception") 99 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN, "execute exception") 100 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV, "HFP divide exception") 101 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF, "HFP overflow exception") 102 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES, "HFP significance exception") 103 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV, "HFP square root exception") 104 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND, "HFP underflow exception") 105 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN, "operand exception") 106 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF, "fixpoint overflow exception") 107 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC, "privileged operation") 108 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN, "special operation exception") 109 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN, "specification exception"); 110 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN, "transaction constraint exception") 111 112 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc) 113 { 114 int si_code = 0; 115 116 /* FPC[2] is Data Exception Code */ 117 if ((fpc & 0x00000300) == 0) { 118 /* bits 6 and 7 of DXC are 0 iff IEEE exception */ 119 if (fpc & 0x8000) /* invalid fp operation */ 120 si_code = FPE_FLTINV; 121 else if (fpc & 0x4000) /* div by 0 */ 122 si_code = FPE_FLTDIV; 123 else if (fpc & 0x2000) /* overflow */ 124 si_code = FPE_FLTOVF; 125 else if (fpc & 0x1000) /* underflow */ 126 si_code = FPE_FLTUND; 127 else if (fpc & 0x0800) /* inexact */ 128 si_code = FPE_FLTRES; 129 } 130 do_trap(regs, SIGFPE, si_code, "floating point exception"); 131 } 132 133 static void translation_specification_exception(struct pt_regs *regs) 134 { 135 /* May never happen. */ 136 panic("Translation-Specification Exception"); 137 } 138 139 static void illegal_op(struct pt_regs *regs) 140 { 141 int is_uprobe_insn = 0; 142 u16 __user *location; 143 int signal = 0; 144 u16 opcode; 145 146 location = get_trap_ip(regs); 147 if (user_mode(regs)) { 148 if (get_user(opcode, location)) 149 return; 150 if (opcode == S390_BREAKPOINT_U16) { 151 if (current->ptrace) 152 force_sig_fault(SIGTRAP, TRAP_BRKPT, location); 153 else 154 signal = SIGILL; 155 #ifdef CONFIG_UPROBES 156 } else if (opcode == UPROBE_SWBP_INSN) { 157 is_uprobe_insn = 1; 158 #endif 159 } else { 160 signal = SIGILL; 161 } 162 } 163 /* 164 * This is either an illegal op in kernel mode, or user space trapped 165 * on a uprobes illegal instruction. See if kprobes or uprobes picks 166 * it up. If not, SIGILL. 167 */ 168 if (is_uprobe_insn || !user_mode(regs)) { 169 if (notify_die(DIE_BPT, "bpt", regs, 0, 3, SIGTRAP) != NOTIFY_STOP) 170 signal = SIGILL; 171 } 172 if (signal) 173 do_trap(regs, signal, ILL_ILLOPC, "illegal operation"); 174 } 175 NOKPROBE_SYMBOL(illegal_op); 176 177 static void vector_exception(struct pt_regs *regs) 178 { 179 int si_code, vic; 180 181 /* get vector interrupt code from fpc */ 182 save_user_fpu_regs(); 183 vic = (current->thread.ufpu.fpc & 0xf00) >> 8; 184 switch (vic) { 185 case 1: /* invalid vector operation */ 186 si_code = FPE_FLTINV; 187 break; 188 case 2: /* division by zero */ 189 si_code = FPE_FLTDIV; 190 break; 191 case 3: /* overflow */ 192 si_code = FPE_FLTOVF; 193 break; 194 case 4: /* underflow */ 195 si_code = FPE_FLTUND; 196 break; 197 case 5: /* inexact */ 198 si_code = FPE_FLTRES; 199 break; 200 default: /* unknown cause */ 201 si_code = 0; 202 } 203 do_trap(regs, SIGFPE, si_code, "vector exception"); 204 } 205 206 static void data_exception(struct pt_regs *regs) 207 { 208 save_user_fpu_regs(); 209 if (current->thread.ufpu.fpc & FPC_DXC_MASK) 210 do_fp_trap(regs, current->thread.ufpu.fpc); 211 else 212 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception"); 213 } 214 215 static void space_switch_exception(struct pt_regs *regs) 216 { 217 /* Set user psw back to home space mode. */ 218 if (user_mode(regs)) 219 regs->psw.mask |= PSW_ASC_HOME; 220 /* Send SIGILL. */ 221 do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event"); 222 } 223 224 #if defined(CONFIG_BUG) && defined(CONFIG_CC_HAS_ASM_IMMEDIATE_STRINGS) 225 226 void *__warn_args(struct arch_va_list *args, struct pt_regs *regs) 227 { 228 struct stack_frame *stack_frame; 229 230 /* 231 * Generate va_list from pt_regs. See ELF Application Binary Interface 232 * s390x Supplement documentation for details. 233 * 234 * - __overflow_arg_area needs to point to the parameter area, which 235 * is right above the standard stack frame (160 bytes) 236 * 237 * - __reg_save_area needs to point to a register save area where 238 * general registers (%r2 - %r6) can be found at offset 16. Which 239 * means that the gprs save area of pt_regs can be used 240 * 241 * - __gpr must be set to one, since the first parameter has been 242 * processed (pointer to bug_entry) 243 */ 244 stack_frame = (struct stack_frame *)regs->gprs[15]; 245 args->__overflow_arg_area = stack_frame + 1; 246 args->__reg_save_area = regs->gprs; 247 args->__gpr = 1; 248 return args; 249 } 250 251 #endif /* CONFIG_BUG && CONFIG_CC_HAS_ASM_IMMEDIATE_STRINGS */ 252 253 static void monitor_event_exception(struct pt_regs *regs) 254 { 255 enum bug_trap_type btt; 256 257 if (user_mode(regs)) 258 return; 259 if (regs->monitor_code == MONCODE_BUG_ARG) { 260 regs->psw.addr = regs->gprs[14]; 261 btt = report_bug_entry((struct bug_entry *)regs->gprs[2], regs); 262 } else { 263 btt = report_bug(regs->psw.addr - (regs->int_code >> 16), regs); 264 } 265 switch (btt) { 266 case BUG_TRAP_TYPE_NONE: 267 fixup_exception(regs); 268 break; 269 case BUG_TRAP_TYPE_WARN: 270 break; 271 case BUG_TRAP_TYPE_BUG: 272 die(regs, "monitor event"); 273 break; 274 } 275 } 276 277 void kernel_stack_invalid(struct pt_regs *regs) 278 { 279 /* 280 * Normally regs are unpoisoned by the generic entry code, but 281 * kernel_stack_overflow() is a rare case that is called bypassing it. 282 */ 283 kmsan_unpoison_entry_regs(regs); 284 bust_spinlocks(1); 285 pr_emerg("Kernel stack pointer invalid\n"); 286 show_regs(regs); 287 bust_spinlocks(0); 288 panic("Invalid kernel stack pointer, cannot continue"); 289 } 290 NOKPROBE_SYMBOL(kernel_stack_invalid); 291 292 static void __init test_monitor_call(void) 293 { 294 int val = 1; 295 296 if (!IS_ENABLED(CONFIG_BUG)) 297 return; 298 asm_inline volatile( 299 " mc %[monc](%%r0),0\n" 300 "0: lhi %[val],0\n" 301 "1:\n" 302 EX_TABLE(0b, 1b) 303 : [val] "+d" (val) 304 : [monc] "i" (MONCODE_BUG)); 305 if (!val) 306 panic("Monitor call doesn't work!\n"); 307 } 308 309 void __init trap_init(void) 310 { 311 struct lowcore *lc = get_lowcore(); 312 unsigned long flags; 313 struct ctlreg cr0; 314 315 local_irq_save(flags); 316 cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT); 317 psw_bits(lc->external_new_psw).mcheck = 1; 318 psw_bits(lc->program_new_psw).mcheck = 1; 319 psw_bits(lc->svc_new_psw).mcheck = 1; 320 psw_bits(lc->io_new_psw).mcheck = 1; 321 local_ctl_load(0, &cr0); 322 local_irq_restore(flags); 323 local_mcck_enable(); 324 test_monitor_call(); 325 } 326 327 static void (*pgm_check_table[128])(struct pt_regs *regs); 328 329 void noinstr __do_pgm_check(struct pt_regs *regs) 330 { 331 struct lowcore *lc = get_lowcore(); 332 irqentry_state_t state; 333 unsigned int trapnr; 334 union teid teid; 335 336 teid.val = lc->trans_exc_code; 337 regs->int_code = lc->pgm_int_code; 338 regs->int_parm_long = teid.val; 339 regs->monitor_code = lc->monitor_code; 340 /* 341 * In case of a guest fault, short-circuit the fault handler and return. 342 * This way the sie64a() function will return 0; fault address and 343 * other relevant bits are saved in current->thread.gmap_teid, and 344 * the fault number in current->thread.gmap_int_code. KVM will be 345 * able to use this information to handle the fault. 346 */ 347 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) { 348 current->thread.gmap_teid.val = regs->int_parm_long; 349 current->thread.gmap_int_code = regs->int_code & 0xffff; 350 return; 351 } 352 state = irqentry_enter(regs); 353 if (user_mode(regs)) { 354 update_timer_sys(); 355 if (!cpu_has_bear()) { 356 if (regs->last_break < 4096) 357 regs->last_break = 1; 358 } 359 current->thread.last_break = regs->last_break; 360 } 361 if (lc->pgm_code & 0x0200) { 362 /* transaction abort */ 363 current->thread.trap_tdb = lc->pgm_tdb; 364 } 365 if (lc->pgm_code & PGM_INT_CODE_PER) { 366 if (user_mode(regs)) { 367 struct per_event *ev = ¤t->thread.per_event; 368 369 set_thread_flag(TIF_PER_TRAP); 370 ev->address = lc->per_address; 371 ev->cause = lc->per_code_combined; 372 ev->paid = lc->per_access_id; 373 } else { 374 /* PER event in kernel is kprobes */ 375 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER); 376 do_per_trap(regs); 377 goto out; 378 } 379 } 380 if (!irqs_disabled_flags(regs->psw.mask)) 381 trace_hardirqs_on(); 382 __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER); 383 trapnr = regs->int_code & PGM_INT_CODE_MASK; 384 if (trapnr) 385 pgm_check_table[trapnr](regs); 386 out: 387 local_irq_disable(); 388 irqentry_exit(regs, state); 389 } 390 391 /* 392 * The program check table contains exactly 128 (0x00-0x7f) entries. Each 393 * line defines the function to be called corresponding to the program check 394 * interruption code. 395 */ 396 static void (*pgm_check_table[128])(struct pt_regs *regs) = { 397 [0x00] = default_trap_handler, 398 [0x01] = illegal_op, 399 [0x02] = privileged_op, 400 [0x03] = execute_exception, 401 [0x04] = do_protection_exception, 402 [0x05] = addressing_exception, 403 [0x06] = specification_exception, 404 [0x07] = data_exception, 405 [0x08] = overflow_exception, 406 [0x09] = divide_exception, 407 [0x0a] = overflow_exception, 408 [0x0b] = divide_exception, 409 [0x0c] = hfp_overflow_exception, 410 [0x0d] = hfp_underflow_exception, 411 [0x0e] = hfp_significance_exception, 412 [0x0f] = hfp_divide_exception, 413 [0x10] = do_dat_exception, 414 [0x11] = do_dat_exception, 415 [0x12] = translation_specification_exception, 416 [0x13] = special_op_exception, 417 [0x14] = default_trap_handler, 418 [0x15] = operand_exception, 419 [0x16] = default_trap_handler, 420 [0x17] = default_trap_handler, 421 [0x18] = transaction_exception, 422 [0x19] = default_trap_handler, 423 [0x1a] = default_trap_handler, 424 [0x1b] = vector_exception, 425 [0x1c] = space_switch_exception, 426 [0x1d] = hfp_sqrt_exception, 427 [0x1e ... 0x37] = default_trap_handler, 428 [0x38] = do_dat_exception, 429 [0x39] = do_dat_exception, 430 [0x3a] = do_dat_exception, 431 [0x3b] = do_dat_exception, 432 [0x3c] = default_trap_handler, 433 [0x3d] = do_secure_storage_access, 434 [0x3e] = default_trap_handler, 435 [0x3f] = default_trap_handler, 436 [0x40] = monitor_event_exception, 437 [0x41 ... 0x7f] = default_trap_handler, 438 }; 439 440 #define COND_TRAP(x) asm( \ 441 ".weak " __stringify(x) "\n\t" \ 442 ".set " __stringify(x) "," \ 443 __stringify(default_trap_handler)) 444 445 COND_TRAP(do_secure_storage_access); 446