| 1 | /* |
| 2 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 3 | * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs |
| 4 | * |
| 5 | * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson |
| 6 | * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes |
| 7 | * 2000-2002 x86-64 support by Andi Kleen |
| 8 | */ |
| 9 | |
| 10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 11 | |
| 12 | #include <linux/sched.h> |
| 13 | #include <linux/mm.h> |
| 14 | #include <linux/smp.h> |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/errno.h> |
| 17 | #include <linux/wait.h> |
| 18 | #include <linux/tracehook.h> |
| 19 | #include <linux/unistd.h> |
| 20 | #include <linux/stddef.h> |
| 21 | #include <linux/personality.h> |
| 22 | #include <linux/uaccess.h> |
| 23 | #include <linux/user-return-notifier.h> |
| 24 | #include <linux/uprobes.h> |
| 25 | #include <linux/context_tracking.h> |
| 26 | |
| 27 | #include <asm/processor.h> |
| 28 | #include <asm/ucontext.h> |
| 29 | #include <asm/fpu/internal.h> |
| 30 | #include <asm/fpu/signal.h> |
| 31 | #include <asm/vdso.h> |
| 32 | #include <asm/mce.h> |
| 33 | #include <asm/sighandling.h> |
| 34 | #include <asm/vm86.h> |
| 35 | |
| 36 | #ifdef CONFIG_X86_64 |
| 37 | #include <asm/proto.h> |
| 38 | #include <asm/ia32_unistd.h> |
| 39 | #endif /* CONFIG_X86_64 */ |
| 40 | |
| 41 | #include <asm/syscall.h> |
| 42 | #include <asm/syscalls.h> |
| 43 | |
| 44 | #include <asm/sigframe.h> |
| 45 | |
| 46 | #define COPY(x) do { \ |
| 47 | get_user_ex(regs->x, &sc->x); \ |
| 48 | } while (0) |
| 49 | |
| 50 | #define GET_SEG(seg) ({ \ |
| 51 | unsigned short tmp; \ |
| 52 | get_user_ex(tmp, &sc->seg); \ |
| 53 | tmp; \ |
| 54 | }) |
| 55 | |
| 56 | #define COPY_SEG(seg) do { \ |
| 57 | regs->seg = GET_SEG(seg); \ |
| 58 | } while (0) |
| 59 | |
| 60 | #define COPY_SEG_CPL3(seg) do { \ |
| 61 | regs->seg = GET_SEG(seg) | 3; \ |
| 62 | } while (0) |
| 63 | |
| 64 | #ifdef CONFIG_X86_64 |
| 65 | /* |
| 66 | * If regs->ss will cause an IRET fault, change it. Otherwise leave it |
| 67 | * alone. Using this generally makes no sense unless |
| 68 | * user_64bit_mode(regs) would return true. |
| 69 | */ |
| 70 | static void force_valid_ss(struct pt_regs *regs) |
| 71 | { |
| 72 | u32 ar; |
| 73 | asm volatile ("lar %[old_ss], %[ar]\n\t" |
| 74 | "jz 1f\n\t" /* If invalid: */ |
| 75 | "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ |
| 76 | "1:" |
| 77 | : [ar] "=r" (ar) |
| 78 | : [old_ss] "rm" ((u16)regs->ss)); |
| 79 | |
| 80 | /* |
| 81 | * For a valid 64-bit user context, we need DPL 3, type |
| 82 | * read-write data or read-write exp-down data, and S and P |
| 83 | * set. We can't use VERW because VERW doesn't check the |
| 84 | * P bit. |
| 85 | */ |
| 86 | ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; |
| 87 | if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && |
| 88 | ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) |
| 89 | regs->ss = __USER_DS; |
| 90 | } |
| 91 | #endif |
| 92 | |
| 93 | static int restore_sigcontext(struct pt_regs *regs, |
| 94 | struct sigcontext __user *sc, |
| 95 | unsigned long uc_flags) |
| 96 | { |
| 97 | unsigned long buf_val; |
| 98 | void __user *buf; |
| 99 | unsigned int tmpflags; |
| 100 | unsigned int err = 0; |
| 101 | |
| 102 | /* Always make any pending restarted system calls return -EINTR */ |
| 103 | current->restart_block.fn = do_no_restart_syscall; |
| 104 | |
| 105 | get_user_try { |
| 106 | |
| 107 | #ifdef CONFIG_X86_32 |
| 108 | set_user_gs(regs, GET_SEG(gs)); |
| 109 | COPY_SEG(fs); |
| 110 | COPY_SEG(es); |
| 111 | COPY_SEG(ds); |
| 112 | #endif /* CONFIG_X86_32 */ |
| 113 | |
| 114 | COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); |
| 115 | COPY(dx); COPY(cx); COPY(ip); COPY(ax); |
| 116 | |
| 117 | #ifdef CONFIG_X86_64 |
| 118 | COPY(r8); |
| 119 | COPY(r9); |
| 120 | COPY(r10); |
| 121 | COPY(r11); |
| 122 | COPY(r12); |
| 123 | COPY(r13); |
| 124 | COPY(r14); |
| 125 | COPY(r15); |
| 126 | #endif /* CONFIG_X86_64 */ |
| 127 | |
| 128 | COPY_SEG_CPL3(cs); |
| 129 | COPY_SEG_CPL3(ss); |
| 130 | |
| 131 | #ifdef CONFIG_X86_64 |
| 132 | /* |
| 133 | * Fix up SS if needed for the benefit of old DOSEMU and |
| 134 | * CRIU. |
| 135 | */ |
| 136 | if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && |
| 137 | user_64bit_mode(regs))) |
| 138 | force_valid_ss(regs); |
| 139 | #endif |
| 140 | |
| 141 | get_user_ex(tmpflags, &sc->flags); |
| 142 | regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); |
| 143 | regs->orig_ax = -1; /* disable syscall checks */ |
| 144 | |
| 145 | get_user_ex(buf_val, &sc->fpstate); |
| 146 | buf = (void __user *)buf_val; |
| 147 | } get_user_catch(err); |
| 148 | |
| 149 | err |= fpu__restore_sig(buf, config_enabled(CONFIG_X86_32)); |
| 150 | |
| 151 | force_iret(); |
| 152 | |
| 153 | return err; |
| 154 | } |
| 155 | |
| 156 | int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, |
| 157 | struct pt_regs *regs, unsigned long mask) |
| 158 | { |
| 159 | int err = 0; |
| 160 | |
| 161 | put_user_try { |
| 162 | |
| 163 | #ifdef CONFIG_X86_32 |
| 164 | put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs); |
| 165 | put_user_ex(regs->fs, (unsigned int __user *)&sc->fs); |
| 166 | put_user_ex(regs->es, (unsigned int __user *)&sc->es); |
| 167 | put_user_ex(regs->ds, (unsigned int __user *)&sc->ds); |
| 168 | #endif /* CONFIG_X86_32 */ |
| 169 | |
| 170 | put_user_ex(regs->di, &sc->di); |
| 171 | put_user_ex(regs->si, &sc->si); |
| 172 | put_user_ex(regs->bp, &sc->bp); |
| 173 | put_user_ex(regs->sp, &sc->sp); |
| 174 | put_user_ex(regs->bx, &sc->bx); |
| 175 | put_user_ex(regs->dx, &sc->dx); |
| 176 | put_user_ex(regs->cx, &sc->cx); |
| 177 | put_user_ex(regs->ax, &sc->ax); |
| 178 | #ifdef CONFIG_X86_64 |
| 179 | put_user_ex(regs->r8, &sc->r8); |
| 180 | put_user_ex(regs->r9, &sc->r9); |
| 181 | put_user_ex(regs->r10, &sc->r10); |
| 182 | put_user_ex(regs->r11, &sc->r11); |
| 183 | put_user_ex(regs->r12, &sc->r12); |
| 184 | put_user_ex(regs->r13, &sc->r13); |
| 185 | put_user_ex(regs->r14, &sc->r14); |
| 186 | put_user_ex(regs->r15, &sc->r15); |
| 187 | #endif /* CONFIG_X86_64 */ |
| 188 | |
| 189 | put_user_ex(current->thread.trap_nr, &sc->trapno); |
| 190 | put_user_ex(current->thread.error_code, &sc->err); |
| 191 | put_user_ex(regs->ip, &sc->ip); |
| 192 | #ifdef CONFIG_X86_32 |
| 193 | put_user_ex(regs->cs, (unsigned int __user *)&sc->cs); |
| 194 | put_user_ex(regs->flags, &sc->flags); |
| 195 | put_user_ex(regs->sp, &sc->sp_at_signal); |
| 196 | put_user_ex(regs->ss, (unsigned int __user *)&sc->ss); |
| 197 | #else /* !CONFIG_X86_32 */ |
| 198 | put_user_ex(regs->flags, &sc->flags); |
| 199 | put_user_ex(regs->cs, &sc->cs); |
| 200 | put_user_ex(0, &sc->gs); |
| 201 | put_user_ex(0, &sc->fs); |
| 202 | put_user_ex(regs->ss, &sc->ss); |
| 203 | #endif /* CONFIG_X86_32 */ |
| 204 | |
| 205 | put_user_ex(fpstate, &sc->fpstate); |
| 206 | |
| 207 | /* non-iBCS2 extensions.. */ |
| 208 | put_user_ex(mask, &sc->oldmask); |
| 209 | put_user_ex(current->thread.cr2, &sc->cr2); |
| 210 | } put_user_catch(err); |
| 211 | |
| 212 | return err; |
| 213 | } |
| 214 | |
| 215 | /* |
| 216 | * Set up a signal frame. |
| 217 | */ |
| 218 | |
| 219 | /* |
| 220 | * Determine which stack to use.. |
| 221 | */ |
| 222 | static unsigned long align_sigframe(unsigned long sp) |
| 223 | { |
| 224 | #ifdef CONFIG_X86_32 |
| 225 | /* |
| 226 | * Align the stack pointer according to the i386 ABI, |
| 227 | * i.e. so that on function entry ((sp + 4) & 15) == 0. |
| 228 | */ |
| 229 | sp = ((sp + 4) & -16ul) - 4; |
| 230 | #else /* !CONFIG_X86_32 */ |
| 231 | sp = round_down(sp, 16) - 8; |
| 232 | #endif |
| 233 | return sp; |
| 234 | } |
| 235 | |
| 236 | static void __user * |
| 237 | get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, |
| 238 | void __user **fpstate) |
| 239 | { |
| 240 | /* Default to using normal stack */ |
| 241 | unsigned long math_size = 0; |
| 242 | unsigned long sp = regs->sp; |
| 243 | unsigned long buf_fx = 0; |
| 244 | int onsigstack = on_sig_stack(sp); |
| 245 | struct fpu *fpu = ¤t->thread.fpu; |
| 246 | |
| 247 | /* redzone */ |
| 248 | if (config_enabled(CONFIG_X86_64)) |
| 249 | sp -= 128; |
| 250 | |
| 251 | /* This is the X/Open sanctioned signal stack switching. */ |
| 252 | if (ka->sa.sa_flags & SA_ONSTACK) { |
| 253 | if (sas_ss_flags(sp) == 0) |
| 254 | sp = current->sas_ss_sp + current->sas_ss_size; |
| 255 | } else if (config_enabled(CONFIG_X86_32) && |
| 256 | !onsigstack && |
| 257 | (regs->ss & 0xffff) != __USER_DS && |
| 258 | !(ka->sa.sa_flags & SA_RESTORER) && |
| 259 | ka->sa.sa_restorer) { |
| 260 | /* This is the legacy signal stack switching. */ |
| 261 | sp = (unsigned long) ka->sa.sa_restorer; |
| 262 | } |
| 263 | |
| 264 | if (fpu->fpstate_active) { |
| 265 | sp = fpu__alloc_mathframe(sp, config_enabled(CONFIG_X86_32), |
| 266 | &buf_fx, &math_size); |
| 267 | *fpstate = (void __user *)sp; |
| 268 | } |
| 269 | |
| 270 | sp = align_sigframe(sp - frame_size); |
| 271 | |
| 272 | /* |
| 273 | * If we are on the alternate signal stack and would overflow it, don't. |
| 274 | * Return an always-bogus address instead so we will die with SIGSEGV. |
| 275 | */ |
| 276 | if (onsigstack && !likely(on_sig_stack(sp))) |
| 277 | return (void __user *)-1L; |
| 278 | |
| 279 | /* save i387 and extended state */ |
| 280 | if (fpu->fpstate_active && |
| 281 | copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0) |
| 282 | return (void __user *)-1L; |
| 283 | |
| 284 | return (void __user *)sp; |
| 285 | } |
| 286 | |
| 287 | #ifdef CONFIG_X86_32 |
| 288 | static const struct { |
| 289 | u16 poplmovl; |
| 290 | u32 val; |
| 291 | u16 int80; |
| 292 | } __attribute__((packed)) retcode = { |
| 293 | 0xb858, /* popl %eax; movl $..., %eax */ |
| 294 | __NR_sigreturn, |
| 295 | 0x80cd, /* int $0x80 */ |
| 296 | }; |
| 297 | |
| 298 | static const struct { |
| 299 | u8 movl; |
| 300 | u32 val; |
| 301 | u16 int80; |
| 302 | u8 pad; |
| 303 | } __attribute__((packed)) rt_retcode = { |
| 304 | 0xb8, /* movl $..., %eax */ |
| 305 | __NR_rt_sigreturn, |
| 306 | 0x80cd, /* int $0x80 */ |
| 307 | 0 |
| 308 | }; |
| 309 | |
| 310 | static int |
| 311 | __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, |
| 312 | struct pt_regs *regs) |
| 313 | { |
| 314 | struct sigframe __user *frame; |
| 315 | void __user *restorer; |
| 316 | int err = 0; |
| 317 | void __user *fpstate = NULL; |
| 318 | |
| 319 | frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); |
| 320 | |
| 321 | if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) |
| 322 | return -EFAULT; |
| 323 | |
| 324 | if (__put_user(sig, &frame->sig)) |
| 325 | return -EFAULT; |
| 326 | |
| 327 | if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0])) |
| 328 | return -EFAULT; |
| 329 | |
| 330 | if (_NSIG_WORDS > 1) { |
| 331 | if (__copy_to_user(&frame->extramask, &set->sig[1], |
| 332 | sizeof(frame->extramask))) |
| 333 | return -EFAULT; |
| 334 | } |
| 335 | |
| 336 | if (current->mm->context.vdso) |
| 337 | restorer = current->mm->context.vdso + |
| 338 | vdso_image_32.sym___kernel_sigreturn; |
| 339 | else |
| 340 | restorer = &frame->retcode; |
| 341 | if (ksig->ka.sa.sa_flags & SA_RESTORER) |
| 342 | restorer = ksig->ka.sa.sa_restorer; |
| 343 | |
| 344 | /* Set up to return from userspace. */ |
| 345 | err |= __put_user(restorer, &frame->pretcode); |
| 346 | |
| 347 | /* |
| 348 | * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 |
| 349 | * |
| 350 | * WE DO NOT USE IT ANY MORE! It's only left here for historical |
| 351 | * reasons and because gdb uses it as a signature to notice |
| 352 | * signal handler stack frames. |
| 353 | */ |
| 354 | err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode); |
| 355 | |
| 356 | if (err) |
| 357 | return -EFAULT; |
| 358 | |
| 359 | /* Set up registers for signal handler */ |
| 360 | regs->sp = (unsigned long)frame; |
| 361 | regs->ip = (unsigned long)ksig->ka.sa.sa_handler; |
| 362 | regs->ax = (unsigned long)sig; |
| 363 | regs->dx = 0; |
| 364 | regs->cx = 0; |
| 365 | |
| 366 | regs->ds = __USER_DS; |
| 367 | regs->es = __USER_DS; |
| 368 | regs->ss = __USER_DS; |
| 369 | regs->cs = __USER_CS; |
| 370 | |
| 371 | return 0; |
| 372 | } |
| 373 | |
| 374 | static int __setup_rt_frame(int sig, struct ksignal *ksig, |
| 375 | sigset_t *set, struct pt_regs *regs) |
| 376 | { |
| 377 | struct rt_sigframe __user *frame; |
| 378 | void __user *restorer; |
| 379 | int err = 0; |
| 380 | void __user *fpstate = NULL; |
| 381 | |
| 382 | frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); |
| 383 | |
| 384 | if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) |
| 385 | return -EFAULT; |
| 386 | |
| 387 | put_user_try { |
| 388 | put_user_ex(sig, &frame->sig); |
| 389 | put_user_ex(&frame->info, &frame->pinfo); |
| 390 | put_user_ex(&frame->uc, &frame->puc); |
| 391 | |
| 392 | /* Create the ucontext. */ |
| 393 | if (boot_cpu_has(X86_FEATURE_XSAVE)) |
| 394 | put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); |
| 395 | else |
| 396 | put_user_ex(0, &frame->uc.uc_flags); |
| 397 | put_user_ex(0, &frame->uc.uc_link); |
| 398 | save_altstack_ex(&frame->uc.uc_stack, regs->sp); |
| 399 | |
| 400 | /* Set up to return from userspace. */ |
| 401 | restorer = current->mm->context.vdso + |
| 402 | vdso_image_32.sym___kernel_rt_sigreturn; |
| 403 | if (ksig->ka.sa.sa_flags & SA_RESTORER) |
| 404 | restorer = ksig->ka.sa.sa_restorer; |
| 405 | put_user_ex(restorer, &frame->pretcode); |
| 406 | |
| 407 | /* |
| 408 | * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 |
| 409 | * |
| 410 | * WE DO NOT USE IT ANY MORE! It's only left here for historical |
| 411 | * reasons and because gdb uses it as a signature to notice |
| 412 | * signal handler stack frames. |
| 413 | */ |
| 414 | put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode); |
| 415 | } put_user_catch(err); |
| 416 | |
| 417 | err |= copy_siginfo_to_user(&frame->info, &ksig->info); |
| 418 | err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, |
| 419 | regs, set->sig[0]); |
| 420 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); |
| 421 | |
| 422 | if (err) |
| 423 | return -EFAULT; |
| 424 | |
| 425 | /* Set up registers for signal handler */ |
| 426 | regs->sp = (unsigned long)frame; |
| 427 | regs->ip = (unsigned long)ksig->ka.sa.sa_handler; |
| 428 | regs->ax = (unsigned long)sig; |
| 429 | regs->dx = (unsigned long)&frame->info; |
| 430 | regs->cx = (unsigned long)&frame->uc; |
| 431 | |
| 432 | regs->ds = __USER_DS; |
| 433 | regs->es = __USER_DS; |
| 434 | regs->ss = __USER_DS; |
| 435 | regs->cs = __USER_CS; |
| 436 | |
| 437 | return 0; |
| 438 | } |
| 439 | #else /* !CONFIG_X86_32 */ |
| 440 | static unsigned long frame_uc_flags(struct pt_regs *regs) |
| 441 | { |
| 442 | unsigned long flags; |
| 443 | |
| 444 | if (boot_cpu_has(X86_FEATURE_XSAVE)) |
| 445 | flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; |
| 446 | else |
| 447 | flags = UC_SIGCONTEXT_SS; |
| 448 | |
| 449 | if (likely(user_64bit_mode(regs))) |
| 450 | flags |= UC_STRICT_RESTORE_SS; |
| 451 | |
| 452 | return flags; |
| 453 | } |
| 454 | |
| 455 | static int __setup_rt_frame(int sig, struct ksignal *ksig, |
| 456 | sigset_t *set, struct pt_regs *regs) |
| 457 | { |
| 458 | struct rt_sigframe __user *frame; |
| 459 | void __user *fp = NULL; |
| 460 | int err = 0; |
| 461 | |
| 462 | frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); |
| 463 | |
| 464 | if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) |
| 465 | return -EFAULT; |
| 466 | |
| 467 | if (ksig->ka.sa.sa_flags & SA_SIGINFO) { |
| 468 | if (copy_siginfo_to_user(&frame->info, &ksig->info)) |
| 469 | return -EFAULT; |
| 470 | } |
| 471 | |
| 472 | put_user_try { |
| 473 | /* Create the ucontext. */ |
| 474 | put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags); |
| 475 | put_user_ex(0, &frame->uc.uc_link); |
| 476 | save_altstack_ex(&frame->uc.uc_stack, regs->sp); |
| 477 | |
| 478 | /* Set up to return from userspace. If provided, use a stub |
| 479 | already in userspace. */ |
| 480 | /* x86-64 should always use SA_RESTORER. */ |
| 481 | if (ksig->ka.sa.sa_flags & SA_RESTORER) { |
| 482 | put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode); |
| 483 | } else { |
| 484 | /* could use a vstub here */ |
| 485 | err |= -EFAULT; |
| 486 | } |
| 487 | } put_user_catch(err); |
| 488 | |
| 489 | err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); |
| 490 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); |
| 491 | |
| 492 | if (err) |
| 493 | return -EFAULT; |
| 494 | |
| 495 | /* Set up registers for signal handler */ |
| 496 | regs->di = sig; |
| 497 | /* In case the signal handler was declared without prototypes */ |
| 498 | regs->ax = 0; |
| 499 | |
| 500 | /* This also works for non SA_SIGINFO handlers because they expect the |
| 501 | next argument after the signal number on the stack. */ |
| 502 | regs->si = (unsigned long)&frame->info; |
| 503 | regs->dx = (unsigned long)&frame->uc; |
| 504 | regs->ip = (unsigned long) ksig->ka.sa.sa_handler; |
| 505 | |
| 506 | regs->sp = (unsigned long)frame; |
| 507 | |
| 508 | /* |
| 509 | * Set up the CS and SS registers to run signal handlers in |
| 510 | * 64-bit mode, even if the handler happens to be interrupting |
| 511 | * 32-bit or 16-bit code. |
| 512 | * |
| 513 | * SS is subtle. In 64-bit mode, we don't need any particular |
| 514 | * SS descriptor, but we do need SS to be valid. It's possible |
| 515 | * that the old SS is entirely bogus -- this can happen if the |
| 516 | * signal we're trying to deliver is #GP or #SS caused by a bad |
| 517 | * SS value. We also have a compatbility issue here: DOSEMU |
| 518 | * relies on the contents of the SS register indicating the |
| 519 | * SS value at the time of the signal, even though that code in |
| 520 | * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU |
| 521 | * avoids relying on sigreturn to restore SS; instead it uses |
| 522 | * a trampoline.) So we do our best: if the old SS was valid, |
| 523 | * we keep it. Otherwise we replace it. |
| 524 | */ |
| 525 | regs->cs = __USER_CS; |
| 526 | |
| 527 | if (unlikely(regs->ss != __USER_DS)) |
| 528 | force_valid_ss(regs); |
| 529 | |
| 530 | return 0; |
| 531 | } |
| 532 | #endif /* CONFIG_X86_32 */ |
| 533 | |
| 534 | static int x32_setup_rt_frame(struct ksignal *ksig, |
| 535 | compat_sigset_t *set, |
| 536 | struct pt_regs *regs) |
| 537 | { |
| 538 | #ifdef CONFIG_X86_X32_ABI |
| 539 | struct rt_sigframe_x32 __user *frame; |
| 540 | void __user *restorer; |
| 541 | int err = 0; |
| 542 | void __user *fpstate = NULL; |
| 543 | |
| 544 | frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); |
| 545 | |
| 546 | if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) |
| 547 | return -EFAULT; |
| 548 | |
| 549 | if (ksig->ka.sa.sa_flags & SA_SIGINFO) { |
| 550 | if (copy_siginfo_to_user32(&frame->info, &ksig->info)) |
| 551 | return -EFAULT; |
| 552 | } |
| 553 | |
| 554 | put_user_try { |
| 555 | /* Create the ucontext. */ |
| 556 | put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags); |
| 557 | put_user_ex(0, &frame->uc.uc_link); |
| 558 | compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); |
| 559 | put_user_ex(0, &frame->uc.uc__pad0); |
| 560 | |
| 561 | if (ksig->ka.sa.sa_flags & SA_RESTORER) { |
| 562 | restorer = ksig->ka.sa.sa_restorer; |
| 563 | } else { |
| 564 | /* could use a vstub here */ |
| 565 | restorer = NULL; |
| 566 | err |= -EFAULT; |
| 567 | } |
| 568 | put_user_ex(restorer, &frame->pretcode); |
| 569 | } put_user_catch(err); |
| 570 | |
| 571 | err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, |
| 572 | regs, set->sig[0]); |
| 573 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); |
| 574 | |
| 575 | if (err) |
| 576 | return -EFAULT; |
| 577 | |
| 578 | /* Set up registers for signal handler */ |
| 579 | regs->sp = (unsigned long) frame; |
| 580 | regs->ip = (unsigned long) ksig->ka.sa.sa_handler; |
| 581 | |
| 582 | /* We use the x32 calling convention here... */ |
| 583 | regs->di = ksig->sig; |
| 584 | regs->si = (unsigned long) &frame->info; |
| 585 | regs->dx = (unsigned long) &frame->uc; |
| 586 | |
| 587 | loadsegment(ds, __USER_DS); |
| 588 | loadsegment(es, __USER_DS); |
| 589 | |
| 590 | regs->cs = __USER_CS; |
| 591 | regs->ss = __USER_DS; |
| 592 | #endif /* CONFIG_X86_X32_ABI */ |
| 593 | |
| 594 | return 0; |
| 595 | } |
| 596 | |
| 597 | /* |
| 598 | * Do a signal return; undo the signal stack. |
| 599 | */ |
| 600 | #ifdef CONFIG_X86_32 |
| 601 | asmlinkage unsigned long sys_sigreturn(void) |
| 602 | { |
| 603 | struct pt_regs *regs = current_pt_regs(); |
| 604 | struct sigframe __user *frame; |
| 605 | sigset_t set; |
| 606 | |
| 607 | frame = (struct sigframe __user *)(regs->sp - 8); |
| 608 | |
| 609 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) |
| 610 | goto badframe; |
| 611 | if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1 |
| 612 | && __copy_from_user(&set.sig[1], &frame->extramask, |
| 613 | sizeof(frame->extramask)))) |
| 614 | goto badframe; |
| 615 | |
| 616 | set_current_blocked(&set); |
| 617 | |
| 618 | /* |
| 619 | * x86_32 has no uc_flags bits relevant to restore_sigcontext. |
| 620 | * Save a few cycles by skipping the __get_user. |
| 621 | */ |
| 622 | if (restore_sigcontext(regs, &frame->sc, 0)) |
| 623 | goto badframe; |
| 624 | return regs->ax; |
| 625 | |
| 626 | badframe: |
| 627 | signal_fault(regs, frame, "sigreturn"); |
| 628 | |
| 629 | return 0; |
| 630 | } |
| 631 | #endif /* CONFIG_X86_32 */ |
| 632 | |
| 633 | asmlinkage long sys_rt_sigreturn(void) |
| 634 | { |
| 635 | struct pt_regs *regs = current_pt_regs(); |
| 636 | struct rt_sigframe __user *frame; |
| 637 | sigset_t set; |
| 638 | unsigned long uc_flags; |
| 639 | |
| 640 | frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); |
| 641 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) |
| 642 | goto badframe; |
| 643 | if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) |
| 644 | goto badframe; |
| 645 | if (__get_user(uc_flags, &frame->uc.uc_flags)) |
| 646 | goto badframe; |
| 647 | |
| 648 | set_current_blocked(&set); |
| 649 | |
| 650 | if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) |
| 651 | goto badframe; |
| 652 | |
| 653 | if (restore_altstack(&frame->uc.uc_stack)) |
| 654 | goto badframe; |
| 655 | |
| 656 | return regs->ax; |
| 657 | |
| 658 | badframe: |
| 659 | signal_fault(regs, frame, "rt_sigreturn"); |
| 660 | return 0; |
| 661 | } |
| 662 | |
| 663 | static inline int is_ia32_compat_frame(void) |
| 664 | { |
| 665 | return config_enabled(CONFIG_IA32_EMULATION) && |
| 666 | test_thread_flag(TIF_IA32); |
| 667 | } |
| 668 | |
| 669 | static inline int is_ia32_frame(void) |
| 670 | { |
| 671 | return config_enabled(CONFIG_X86_32) || is_ia32_compat_frame(); |
| 672 | } |
| 673 | |
| 674 | static inline int is_x32_frame(void) |
| 675 | { |
| 676 | return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32); |
| 677 | } |
| 678 | |
| 679 | static int |
| 680 | setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) |
| 681 | { |
| 682 | int usig = ksig->sig; |
| 683 | sigset_t *set = sigmask_to_save(); |
| 684 | compat_sigset_t *cset = (compat_sigset_t *) set; |
| 685 | |
| 686 | /* Set up the stack frame */ |
| 687 | if (is_ia32_frame()) { |
| 688 | if (ksig->ka.sa.sa_flags & SA_SIGINFO) |
| 689 | return ia32_setup_rt_frame(usig, ksig, cset, regs); |
| 690 | else |
| 691 | return ia32_setup_frame(usig, ksig, cset, regs); |
| 692 | } else if (is_x32_frame()) { |
| 693 | return x32_setup_rt_frame(ksig, cset, regs); |
| 694 | } else { |
| 695 | return __setup_rt_frame(ksig->sig, ksig, set, regs); |
| 696 | } |
| 697 | } |
| 698 | |
| 699 | static void |
| 700 | handle_signal(struct ksignal *ksig, struct pt_regs *regs) |
| 701 | { |
| 702 | bool stepping, failed; |
| 703 | struct fpu *fpu = ¤t->thread.fpu; |
| 704 | |
| 705 | if (v8086_mode(regs)) |
| 706 | save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); |
| 707 | |
| 708 | /* Are we from a system call? */ |
| 709 | if (syscall_get_nr(current, regs) >= 0) { |
| 710 | /* If so, check system call restarting.. */ |
| 711 | switch (syscall_get_error(current, regs)) { |
| 712 | case -ERESTART_RESTARTBLOCK: |
| 713 | case -ERESTARTNOHAND: |
| 714 | regs->ax = -EINTR; |
| 715 | break; |
| 716 | |
| 717 | case -ERESTARTSYS: |
| 718 | if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { |
| 719 | regs->ax = -EINTR; |
| 720 | break; |
| 721 | } |
| 722 | /* fallthrough */ |
| 723 | case -ERESTARTNOINTR: |
| 724 | regs->ax = regs->orig_ax; |
| 725 | regs->ip -= 2; |
| 726 | break; |
| 727 | } |
| 728 | } |
| 729 | |
| 730 | /* |
| 731 | * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now |
| 732 | * so that register information in the sigcontext is correct and |
| 733 | * then notify the tracer before entering the signal handler. |
| 734 | */ |
| 735 | stepping = test_thread_flag(TIF_SINGLESTEP); |
| 736 | if (stepping) |
| 737 | user_disable_single_step(current); |
| 738 | |
| 739 | failed = (setup_rt_frame(ksig, regs) < 0); |
| 740 | if (!failed) { |
| 741 | /* |
| 742 | * Clear the direction flag as per the ABI for function entry. |
| 743 | * |
| 744 | * Clear RF when entering the signal handler, because |
| 745 | * it might disable possible debug exception from the |
| 746 | * signal handler. |
| 747 | * |
| 748 | * Clear TF for the case when it wasn't set by debugger to |
| 749 | * avoid the recursive send_sigtrap() in SIGTRAP handler. |
| 750 | */ |
| 751 | regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); |
| 752 | /* |
| 753 | * Ensure the signal handler starts with the new fpu state. |
| 754 | */ |
| 755 | if (fpu->fpstate_active) |
| 756 | fpu__clear(fpu); |
| 757 | } |
| 758 | signal_setup_done(failed, ksig, stepping); |
| 759 | } |
| 760 | |
| 761 | static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) |
| 762 | { |
| 763 | #ifdef CONFIG_X86_64 |
| 764 | if (in_ia32_syscall()) |
| 765 | return __NR_ia32_restart_syscall; |
| 766 | #endif |
| 767 | #ifdef CONFIG_X86_X32_ABI |
| 768 | return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); |
| 769 | #else |
| 770 | return __NR_restart_syscall; |
| 771 | #endif |
| 772 | } |
| 773 | |
| 774 | /* |
| 775 | * Note that 'init' is a special process: it doesn't get signals it doesn't |
| 776 | * want to handle. Thus you cannot kill init even with a SIGKILL even by |
| 777 | * mistake. |
| 778 | */ |
| 779 | void do_signal(struct pt_regs *regs) |
| 780 | { |
| 781 | struct ksignal ksig; |
| 782 | |
| 783 | if (get_signal(&ksig)) { |
| 784 | /* Whee! Actually deliver the signal. */ |
| 785 | handle_signal(&ksig, regs); |
| 786 | return; |
| 787 | } |
| 788 | |
| 789 | /* Did we come from a system call? */ |
| 790 | if (syscall_get_nr(current, regs) >= 0) { |
| 791 | /* Restart the system call - no handlers present */ |
| 792 | switch (syscall_get_error(current, regs)) { |
| 793 | case -ERESTARTNOHAND: |
| 794 | case -ERESTARTSYS: |
| 795 | case -ERESTARTNOINTR: |
| 796 | regs->ax = regs->orig_ax; |
| 797 | regs->ip -= 2; |
| 798 | break; |
| 799 | |
| 800 | case -ERESTART_RESTARTBLOCK: |
| 801 | regs->ax = get_nr_restart_syscall(regs); |
| 802 | regs->ip -= 2; |
| 803 | break; |
| 804 | } |
| 805 | } |
| 806 | |
| 807 | /* |
| 808 | * If there's no signal to deliver, we just put the saved sigmask |
| 809 | * back. |
| 810 | */ |
| 811 | restore_saved_sigmask(); |
| 812 | } |
| 813 | |
| 814 | void signal_fault(struct pt_regs *regs, void __user *frame, char *where) |
| 815 | { |
| 816 | struct task_struct *me = current; |
| 817 | |
| 818 | if (show_unhandled_signals && printk_ratelimit()) { |
| 819 | printk("%s" |
| 820 | "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", |
| 821 | task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, |
| 822 | me->comm, me->pid, where, frame, |
| 823 | regs->ip, regs->sp, regs->orig_ax); |
| 824 | print_vma_addr(" in ", regs->ip); |
| 825 | pr_cont("\n"); |
| 826 | } |
| 827 | |
| 828 | force_sig(SIGSEGV, me); |
| 829 | } |
| 830 | |
| 831 | #ifdef CONFIG_X86_X32_ABI |
| 832 | asmlinkage long sys32_x32_rt_sigreturn(void) |
| 833 | { |
| 834 | struct pt_regs *regs = current_pt_regs(); |
| 835 | struct rt_sigframe_x32 __user *frame; |
| 836 | sigset_t set; |
| 837 | unsigned long uc_flags; |
| 838 | |
| 839 | frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); |
| 840 | |
| 841 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) |
| 842 | goto badframe; |
| 843 | if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) |
| 844 | goto badframe; |
| 845 | if (__get_user(uc_flags, &frame->uc.uc_flags)) |
| 846 | goto badframe; |
| 847 | |
| 848 | set_current_blocked(&set); |
| 849 | |
| 850 | if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) |
| 851 | goto badframe; |
| 852 | |
| 853 | if (compat_restore_altstack(&frame->uc.uc_stack)) |
| 854 | goto badframe; |
| 855 | |
| 856 | return regs->ax; |
| 857 | |
| 858 | badframe: |
| 859 | signal_fault(regs, frame, "x32 rt_sigreturn"); |
| 860 | return 0; |
| 861 | } |
| 862 | #endif |