1/* 2 * linux/arch/arm/kernel/signal.c 3 * 4 * Copyright (C) 1995-2009 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10#include <linux/errno.h> 11#include <linux/random.h> 12#include <linux/signal.h> 13#include <linux/personality.h> 14#include <linux/uaccess.h> 15#include <linux/tracehook.h> 16#include <linux/uprobes.h> 17 18#include <asm/elf.h> 19#include <asm/cacheflush.h> 20#include <asm/traps.h> 21#include <asm/ucontext.h> 22#include <asm/unistd.h> 23#include <asm/vfp.h> 24 25extern const unsigned long sigreturn_codes[7]; 26 27static unsigned long signal_return_offset; 28 29#ifdef CONFIG_CRUNCH 30static int preserve_crunch_context(struct crunch_sigframe __user *frame) 31{ 32 char kbuf[sizeof(*frame) + 8]; 33 struct crunch_sigframe *kframe; 34 35 /* the crunch context must be 64 bit aligned */ 36 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 37 kframe->magic = CRUNCH_MAGIC; 38 kframe->size = CRUNCH_STORAGE_SIZE; 39 crunch_task_copy(current_thread_info(), &kframe->storage); 40 return __copy_to_user(frame, kframe, sizeof(*frame)); 41} 42 43static int restore_crunch_context(struct crunch_sigframe __user *frame) 44{ 45 char kbuf[sizeof(*frame) + 8]; 46 struct crunch_sigframe *kframe; 47 48 /* the crunch context must be 64 bit aligned */ 49 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 50 if (__copy_from_user(kframe, frame, sizeof(*frame))) 51 return -1; 52 if (kframe->magic != CRUNCH_MAGIC || 53 kframe->size != CRUNCH_STORAGE_SIZE) 54 return -1; 55 crunch_task_restore(current_thread_info(), &kframe->storage); 56 return 0; 57} 58#endif 59 60#ifdef CONFIG_IWMMXT 61 62static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame) 63{ 64 char kbuf[sizeof(*frame) + 8]; 65 struct iwmmxt_sigframe *kframe; 66 67 /* the iWMMXt context must be 64 bit aligned */ 68 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 69 kframe->magic = IWMMXT_MAGIC; 70 kframe->size = IWMMXT_STORAGE_SIZE; 71 iwmmxt_task_copy(current_thread_info(), &kframe->storage); 72 return __copy_to_user(frame, kframe, sizeof(*frame)); 73} 74 75static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame) 76{ 77 char kbuf[sizeof(*frame) + 8]; 78 struct iwmmxt_sigframe *kframe; 79 80 /* the iWMMXt context must be 64 bit aligned */ 81 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 82 if (__copy_from_user(kframe, frame, sizeof(*frame))) 83 return -1; 84 if (kframe->magic != IWMMXT_MAGIC || 85 kframe->size != IWMMXT_STORAGE_SIZE) 86 return -1; 87 iwmmxt_task_restore(current_thread_info(), &kframe->storage); 88 return 0; 89} 90 91#endif 92 93#ifdef CONFIG_VFP 94 95static int preserve_vfp_context(struct vfp_sigframe __user *frame) 96{ 97 const unsigned long magic = VFP_MAGIC; 98 const unsigned long size = VFP_STORAGE_SIZE; 99 int err = 0; 100 101 __put_user_error(magic, &frame->magic, err); 102 __put_user_error(size, &frame->size, err); 103 104 if (err) 105 return -EFAULT; 106 107 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc); 108} 109 110static int restore_vfp_context(struct vfp_sigframe __user *frame) 111{ 112 unsigned long magic; 113 unsigned long size; 114 int err = 0; 115 116 __get_user_error(magic, &frame->magic, err); 117 __get_user_error(size, &frame->size, err); 118 119 if (err) 120 return -EFAULT; 121 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) 122 return -EINVAL; 123 124 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc); 125} 126 127#endif 128 129/* 130 * Do a signal return; undo the signal stack. These are aligned to 64-bit. 131 */ 132struct sigframe { 133 struct ucontext uc; 134 unsigned long retcode[2]; 135}; 136 137struct rt_sigframe { 138 struct siginfo info; 139 struct sigframe sig; 140}; 141 142static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) 143{ 144 struct aux_sigframe __user *aux; 145 sigset_t set; 146 int err; 147 148 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); 149 if (err == 0) 150 set_current_blocked(&set); 151 152 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 153 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 154 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 155 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 156 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 157 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 158 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 159 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 160 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 161 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 162 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 163 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 164 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 165 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 166 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 167 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 168 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 169 170 err |= !valid_user_regs(regs); 171 172 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 173#ifdef CONFIG_CRUNCH 174 if (err == 0) 175 err |= restore_crunch_context(&aux->crunch); 176#endif 177#ifdef CONFIG_IWMMXT 178 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 179 err |= restore_iwmmxt_context(&aux->iwmmxt); 180#endif 181#ifdef CONFIG_VFP 182 if (err == 0) 183 err |= restore_vfp_context(&aux->vfp); 184#endif 185 186 return err; 187} 188 189asmlinkage int sys_sigreturn(struct pt_regs *regs) 190{ 191 struct sigframe __user *frame; 192 193 /* Always make any pending restarted system calls return -EINTR */ 194 current->restart_block.fn = do_no_restart_syscall; 195 196 /* 197 * Since we stacked the signal on a 64-bit boundary, 198 * then 'sp' should be word aligned here. If it's 199 * not, then the user is trying to mess with us. 200 */ 201 if (regs->ARM_sp & 7) 202 goto badframe; 203 204 frame = (struct sigframe __user *)regs->ARM_sp; 205 206 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 207 goto badframe; 208 209 if (restore_sigframe(regs, frame)) 210 goto badframe; 211 212 return regs->ARM_r0; 213 214badframe: 215 force_sig(SIGSEGV, current); 216 return 0; 217} 218 219asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) 220{ 221 struct rt_sigframe __user *frame; 222 223 /* Always make any pending restarted system calls return -EINTR */ 224 current->restart_block.fn = do_no_restart_syscall; 225 226 /* 227 * Since we stacked the signal on a 64-bit boundary, 228 * then 'sp' should be word aligned here. If it's 229 * not, then the user is trying to mess with us. 230 */ 231 if (regs->ARM_sp & 7) 232 goto badframe; 233 234 frame = (struct rt_sigframe __user *)regs->ARM_sp; 235 236 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 237 goto badframe; 238 239 if (restore_sigframe(regs, &frame->sig)) 240 goto badframe; 241 242 if (restore_altstack(&frame->sig.uc.uc_stack)) 243 goto badframe; 244 245 return regs->ARM_r0; 246 247badframe: 248 force_sig(SIGSEGV, current); 249 return 0; 250} 251 252static int 253setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) 254{ 255 struct aux_sigframe __user *aux; 256 int err = 0; 257 258 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 259 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 260 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 261 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 262 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 263 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 264 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 265 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 266 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 267 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 268 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 269 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 270 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 271 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 272 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 273 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 274 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 275 276 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err); 277 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err); 278 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err); 279 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); 280 281 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); 282 283 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 284#ifdef CONFIG_CRUNCH 285 if (err == 0) 286 err |= preserve_crunch_context(&aux->crunch); 287#endif 288#ifdef CONFIG_IWMMXT 289 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 290 err |= preserve_iwmmxt_context(&aux->iwmmxt); 291#endif 292#ifdef CONFIG_VFP 293 if (err == 0) 294 err |= preserve_vfp_context(&aux->vfp); 295#endif 296 __put_user_error(0, &aux->end_magic, err); 297 298 return err; 299} 300 301static inline void __user * 302get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) 303{ 304 unsigned long sp = sigsp(regs->ARM_sp, ksig); 305 void __user *frame; 306 307 /* 308 * ATPCS B01 mandates 8-byte alignment 309 */ 310 frame = (void __user *)((sp - framesize) & ~7); 311 312 /* 313 * Check that we can actually write to the signal frame. 314 */ 315 if (!access_ok(VERIFY_WRITE, frame, framesize)) 316 frame = NULL; 317 318 return frame; 319} 320 321static int 322setup_return(struct pt_regs *regs, struct ksignal *ksig, 323 unsigned long __user *rc, void __user *frame) 324{ 325 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; 326 unsigned long retcode; 327 int thumb = 0; 328 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); 329 330 cpsr |= PSR_ENDSTATE; 331 332 /* 333 * Maybe we need to deliver a 32-bit signal to a 26-bit task. 334 */ 335 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO) 336 cpsr = (cpsr & ~MODE_MASK) | USR_MODE; 337 338#ifdef CONFIG_ARM_THUMB 339 if (elf_hwcap & HWCAP_THUMB) { 340 /* 341 * The LSB of the handler determines if we're going to 342 * be using THUMB or ARM mode for this signal handler. 343 */ 344 thumb = handler & 1; 345 346#if __LINUX_ARM_ARCH__ >= 6 347 /* 348 * Clear the If-Then Thumb-2 execution state. ARM spec 349 * requires this to be all 000s in ARM mode. Snapdragon 350 * S4/Krait misbehaves on a Thumb=>ARM signal transition 351 * without this. 352 * 353 * We must do this whenever we are running on a Thumb-2 354 * capable CPU, which includes ARMv6T2. However, we elect 355 * to do this whenever we're on an ARMv6 or later CPU for 356 * simplicity. 357 */ 358 cpsr &= ~PSR_IT_MASK; 359#endif 360 361 if (thumb) { 362 cpsr |= PSR_T_BIT; 363 } else 364 cpsr &= ~PSR_T_BIT; 365 } 366#endif 367 368 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 369 retcode = (unsigned long)ksig->ka.sa.sa_restorer; 370 } else { 371 unsigned int idx = thumb << 1; 372 373 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 374 idx += 3; 375 376 /* 377 * Put the sigreturn code on the stack no matter which return 378 * mechanism we use in order to remain ABI compliant 379 */ 380 if (__put_user(sigreturn_codes[idx], rc) || 381 __put_user(sigreturn_codes[idx+1], rc+1)) 382 return 1; 383 384#ifdef CONFIG_MMU 385 if (cpsr & MODE32_BIT) { 386 struct mm_struct *mm = current->mm; 387 388 /* 389 * 32-bit code can use the signal return page 390 * except when the MPU has protected the vectors 391 * page from PL0 392 */ 393 retcode = mm->context.sigpage + signal_return_offset + 394 (idx << 2) + thumb; 395 } else 396#endif 397 { 398 /* 399 * Ensure that the instruction cache sees 400 * the return code written onto the stack. 401 */ 402 flush_icache_range((unsigned long)rc, 403 (unsigned long)(rc + 2)); 404 405 retcode = ((unsigned long)rc) + thumb; 406 } 407 } 408 409 regs->ARM_r0 = ksig->sig; 410 regs->ARM_sp = (unsigned long)frame; 411 regs->ARM_lr = retcode; 412 regs->ARM_pc = handler; 413 regs->ARM_cpsr = cpsr; 414 415 return 0; 416} 417 418static int 419setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 420{ 421 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 422 int err = 0; 423 424 if (!frame) 425 return 1; 426 427 /* 428 * Set uc.uc_flags to a value which sc.trap_no would never have. 429 */ 430 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); 431 432 err |= setup_sigframe(frame, regs, set); 433 if (err == 0) 434 err = setup_return(regs, ksig, frame->retcode, frame); 435 436 return err; 437} 438 439static int 440setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 441{ 442 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 443 int err = 0; 444 445 if (!frame) 446 return 1; 447 448 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 449 450 __put_user_error(0, &frame->sig.uc.uc_flags, err); 451 __put_user_error(NULL, &frame->sig.uc.uc_link, err); 452 453 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); 454 err |= setup_sigframe(&frame->sig, regs, set); 455 if (err == 0) 456 err = setup_return(regs, ksig, frame->sig.retcode, frame); 457 458 if (err == 0) { 459 /* 460 * For realtime signals we must also set the second and third 461 * arguments for the signal handler. 462 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06 463 */ 464 regs->ARM_r1 = (unsigned long)&frame->info; 465 regs->ARM_r2 = (unsigned long)&frame->sig.uc; 466 } 467 468 return err; 469} 470 471/* 472 * OK, we're invoking a handler 473 */ 474static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 475{ 476 sigset_t *oldset = sigmask_to_save(); 477 int ret; 478 479 /* 480 * Set up the stack frame 481 */ 482 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 483 ret = setup_rt_frame(ksig, oldset, regs); 484 else 485 ret = setup_frame(ksig, oldset, regs); 486 487 /* 488 * Check that the resulting registers are actually sane. 489 */ 490 ret |= !valid_user_regs(regs); 491 492 signal_setup_done(ret, ksig, 0); 493} 494 495/* 496 * Note that 'init' is a special process: it doesn't get signals it doesn't 497 * want to handle. Thus you cannot kill init even with a SIGKILL even by 498 * mistake. 499 * 500 * Note that we go through the signals twice: once to check the signals that 501 * the kernel can handle, and then we build all the user-level signal handling 502 * stack-frames in one go after that. 503 */ 504static int do_signal(struct pt_regs *regs, int syscall) 505{ 506 unsigned int retval = 0, continue_addr = 0, restart_addr = 0; 507 struct ksignal ksig; 508 int restart = 0; 509 510 /* 511 * If we were from a system call, check for system call restarting... 512 */ 513 if (syscall) { 514 continue_addr = regs->ARM_pc; 515 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4); 516 retval = regs->ARM_r0; 517 518 /* 519 * Prepare for system call restart. We do this here so that a 520 * debugger will see the already changed PSW. 521 */ 522 switch (retval) { 523 case -ERESTART_RESTARTBLOCK: 524 restart -= 2; 525 case -ERESTARTNOHAND: 526 case -ERESTARTSYS: 527 case -ERESTARTNOINTR: 528 restart++; 529 regs->ARM_r0 = regs->ARM_ORIG_r0; 530 regs->ARM_pc = restart_addr; 531 break; 532 } 533 } 534 535 /* 536 * Get the signal to deliver. When running under ptrace, at this 537 * point the debugger may change all our registers ... 538 */ 539 /* 540 * Depending on the signal settings we may need to revert the 541 * decision to restart the system call. But skip this if a 542 * debugger has chosen to restart at a different PC. 543 */ 544 if (get_signal(&ksig)) { 545 /* handler */ 546 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 547 if (retval == -ERESTARTNOHAND || 548 retval == -ERESTART_RESTARTBLOCK 549 || (retval == -ERESTARTSYS 550 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 551 regs->ARM_r0 = -EINTR; 552 regs->ARM_pc = continue_addr; 553 } 554 } 555 handle_signal(&ksig, regs); 556 } else { 557 /* no handler */ 558 restore_saved_sigmask(); 559 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 560 regs->ARM_pc = continue_addr; 561 return restart; 562 } 563 } 564 return 0; 565} 566 567asmlinkage int 568do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) 569{ 570 do { 571 if (likely(thread_flags & _TIF_NEED_RESCHED)) { 572 schedule(); 573 } else { 574 if (unlikely(!user_mode(regs))) 575 return 0; 576 local_irq_enable(); 577 if (thread_flags & _TIF_SIGPENDING) { 578 int restart = do_signal(regs, syscall); 579 if (unlikely(restart)) { 580 /* 581 * Restart without handlers. 582 * Deal with it without leaving 583 * the kernel space. 584 */ 585 return restart; 586 } 587 syscall = 0; 588 } else if (thread_flags & _TIF_UPROBE) { 589 uprobe_notify_resume(regs); 590 } else { 591 clear_thread_flag(TIF_NOTIFY_RESUME); 592 tracehook_notify_resume(regs); 593 } 594 } 595 local_irq_disable(); 596 thread_flags = current_thread_info()->flags; 597 } while (thread_flags & _TIF_WORK_MASK); 598 return 0; 599} 600 601struct page *get_signal_page(void) 602{ 603 unsigned long ptr; 604 unsigned offset; 605 struct page *page; 606 void *addr; 607 608 page = alloc_pages(GFP_KERNEL, 0); 609 610 if (!page) 611 return NULL; 612 613 addr = page_address(page); 614 615 /* Give the signal return code some randomness */ 616 offset = 0x200 + (get_random_int() & 0x7fc); 617 signal_return_offset = offset; 618 619 /* 620 * Copy signal return handlers into the vector page, and 621 * set sigreturn to be a pointer to these. 622 */ 623 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); 624 625 ptr = (unsigned long)addr + offset; 626 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); 627 628 return page; 629} 630