signal.c 16 KB

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  1. /*
  2. * Copyright IBM Corp. 1999, 2006
  3. * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
  4. *
  5. * Based on Intel version
  6. *
  7. * Copyright (C) 1991, 1992 Linus Torvalds
  8. *
  9. * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
  10. */
  11. #include <linux/sched.h>
  12. #include <linux/mm.h>
  13. #include <linux/smp.h>
  14. #include <linux/kernel.h>
  15. #include <linux/signal.h>
  16. #include <linux/errno.h>
  17. #include <linux/wait.h>
  18. #include <linux/ptrace.h>
  19. #include <linux/unistd.h>
  20. #include <linux/stddef.h>
  21. #include <linux/tty.h>
  22. #include <linux/personality.h>
  23. #include <linux/binfmts.h>
  24. #include <linux/tracehook.h>
  25. #include <linux/syscalls.h>
  26. #include <linux/compat.h>
  27. #include <asm/ucontext.h>
  28. #include <asm/uaccess.h>
  29. #include <asm/lowcore.h>
  30. #include <asm/switch_to.h>
  31. #include "entry.h"
  32. /*
  33. * Layout of an old-style signal-frame:
  34. * -----------------------------------------
  35. * | save area (_SIGNAL_FRAMESIZE) |
  36. * -----------------------------------------
  37. * | struct sigcontext |
  38. * | oldmask |
  39. * | _sigregs * |
  40. * -----------------------------------------
  41. * | _sigregs with |
  42. * | _s390_regs_common |
  43. * | _s390_fp_regs |
  44. * -----------------------------------------
  45. * | int signo |
  46. * -----------------------------------------
  47. * | _sigregs_ext with |
  48. * | gprs_high 64 byte (opt) |
  49. * | vxrs_low 128 byte (opt) |
  50. * | vxrs_high 256 byte (opt) |
  51. * | reserved 128 byte (opt) |
  52. * -----------------------------------------
  53. * | __u16 svc_insn |
  54. * -----------------------------------------
  55. * The svc_insn entry with the sigreturn system call opcode does not
  56. * have a fixed position and moves if gprs_high or vxrs exist.
  57. * Future extensions will be added to _sigregs_ext.
  58. */
  59. struct sigframe
  60. {
  61. __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  62. struct sigcontext sc;
  63. _sigregs sregs;
  64. int signo;
  65. _sigregs_ext sregs_ext;
  66. __u16 svc_insn; /* Offset of svc_insn is NOT fixed! */
  67. };
  68. /*
  69. * Layout of an rt signal-frame:
  70. * -----------------------------------------
  71. * | save area (_SIGNAL_FRAMESIZE) |
  72. * -----------------------------------------
  73. * | svc __NR_rt_sigreturn 2 byte |
  74. * -----------------------------------------
  75. * | struct siginfo |
  76. * -----------------------------------------
  77. * | struct ucontext_extended with |
  78. * | unsigned long uc_flags |
  79. * | struct ucontext *uc_link |
  80. * | stack_t uc_stack |
  81. * | _sigregs uc_mcontext with |
  82. * | _s390_regs_common |
  83. * | _s390_fp_regs |
  84. * | sigset_t uc_sigmask |
  85. * | _sigregs_ext uc_mcontext_ext |
  86. * | gprs_high 64 byte (opt) |
  87. * | vxrs_low 128 byte (opt) |
  88. * | vxrs_high 256 byte (opt)|
  89. * | reserved 128 byte (opt) |
  90. * -----------------------------------------
  91. * Future extensions will be added to _sigregs_ext.
  92. */
  93. struct rt_sigframe
  94. {
  95. __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  96. __u16 svc_insn;
  97. struct siginfo info;
  98. struct ucontext_extended uc;
  99. };
  100. /* Store registers needed to create the signal frame */
  101. static void store_sigregs(void)
  102. {
  103. save_access_regs(current->thread.acrs);
  104. save_fp_ctl(&current->thread.fp_regs.fpc);
  105. if (current->thread.vxrs) {
  106. int i;
  107. save_vx_regs(current->thread.vxrs);
  108. for (i = 0; i < __NUM_FPRS; i++)
  109. current->thread.fp_regs.fprs[i] =
  110. *(freg_t *)(current->thread.vxrs + i);
  111. } else
  112. save_fp_regs(current->thread.fp_regs.fprs);
  113. }
  114. /* Load registers after signal return */
  115. static void load_sigregs(void)
  116. {
  117. restore_access_regs(current->thread.acrs);
  118. /* restore_fp_ctl is done in restore_sigregs */
  119. if (current->thread.vxrs) {
  120. int i;
  121. for (i = 0; i < __NUM_FPRS; i++)
  122. *(freg_t *)(current->thread.vxrs + i) =
  123. current->thread.fp_regs.fprs[i];
  124. restore_vx_regs(current->thread.vxrs);
  125. } else
  126. restore_fp_regs(current->thread.fp_regs.fprs);
  127. }
  128. /* Returns non-zero on fault. */
  129. static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
  130. {
  131. _sigregs user_sregs;
  132. /* Copy a 'clean' PSW mask to the user to avoid leaking
  133. information about whether PER is currently on. */
  134. user_sregs.regs.psw.mask = PSW_USER_BITS |
  135. (regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
  136. user_sregs.regs.psw.addr = regs->psw.addr;
  137. memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
  138. memcpy(&user_sregs.regs.acrs, current->thread.acrs,
  139. sizeof(user_sregs.regs.acrs));
  140. memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
  141. sizeof(user_sregs.fpregs));
  142. if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
  143. return -EFAULT;
  144. return 0;
  145. }
  146. static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
  147. {
  148. _sigregs user_sregs;
  149. /* Alwys make any pending restarted system call return -EINTR */
  150. current->restart_block.fn = do_no_restart_syscall;
  151. if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
  152. return -EFAULT;
  153. if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
  154. return -EINVAL;
  155. /* Loading the floating-point-control word can fail. Do that first. */
  156. if (restore_fp_ctl(&user_sregs.fpregs.fpc))
  157. return -EINVAL;
  158. /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
  159. regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
  160. (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
  161. /* Check for invalid user address space control. */
  162. if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
  163. regs->psw.mask = PSW_ASC_PRIMARY |
  164. (regs->psw.mask & ~PSW_MASK_ASC);
  165. /* Check for invalid amode */
  166. if (regs->psw.mask & PSW_MASK_EA)
  167. regs->psw.mask |= PSW_MASK_BA;
  168. regs->psw.addr = user_sregs.regs.psw.addr;
  169. memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
  170. memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
  171. sizeof(current->thread.acrs));
  172. memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
  173. sizeof(current->thread.fp_regs));
  174. clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
  175. return 0;
  176. }
  177. /* Returns non-zero on fault. */
  178. static int save_sigregs_ext(struct pt_regs *regs,
  179. _sigregs_ext __user *sregs_ext)
  180. {
  181. __u64 vxrs[__NUM_VXRS_LOW];
  182. int i;
  183. /* Save vector registers to signal stack */
  184. if (current->thread.vxrs) {
  185. for (i = 0; i < __NUM_VXRS_LOW; i++)
  186. vxrs[i] = *((__u64 *)(current->thread.vxrs + i) + 1);
  187. if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
  188. sizeof(sregs_ext->vxrs_low)) ||
  189. __copy_to_user(&sregs_ext->vxrs_high,
  190. current->thread.vxrs + __NUM_VXRS_LOW,
  191. sizeof(sregs_ext->vxrs_high)))
  192. return -EFAULT;
  193. }
  194. return 0;
  195. }
  196. static int restore_sigregs_ext(struct pt_regs *regs,
  197. _sigregs_ext __user *sregs_ext)
  198. {
  199. __u64 vxrs[__NUM_VXRS_LOW];
  200. int i;
  201. /* Restore vector registers from signal stack */
  202. if (current->thread.vxrs) {
  203. if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
  204. sizeof(sregs_ext->vxrs_low)) ||
  205. __copy_from_user(current->thread.vxrs + __NUM_VXRS_LOW,
  206. &sregs_ext->vxrs_high,
  207. sizeof(sregs_ext->vxrs_high)))
  208. return -EFAULT;
  209. for (i = 0; i < __NUM_VXRS_LOW; i++)
  210. *((__u64 *)(current->thread.vxrs + i) + 1) = vxrs[i];
  211. }
  212. return 0;
  213. }
  214. SYSCALL_DEFINE0(sigreturn)
  215. {
  216. struct pt_regs *regs = task_pt_regs(current);
  217. struct sigframe __user *frame =
  218. (struct sigframe __user *) regs->gprs[15];
  219. sigset_t set;
  220. if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
  221. goto badframe;
  222. set_current_blocked(&set);
  223. if (restore_sigregs(regs, &frame->sregs))
  224. goto badframe;
  225. if (restore_sigregs_ext(regs, &frame->sregs_ext))
  226. goto badframe;
  227. load_sigregs();
  228. return regs->gprs[2];
  229. badframe:
  230. force_sig(SIGSEGV, current);
  231. return 0;
  232. }
  233. SYSCALL_DEFINE0(rt_sigreturn)
  234. {
  235. struct pt_regs *regs = task_pt_regs(current);
  236. struct rt_sigframe __user *frame =
  237. (struct rt_sigframe __user *)regs->gprs[15];
  238. sigset_t set;
  239. if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
  240. goto badframe;
  241. set_current_blocked(&set);
  242. if (restore_altstack(&frame->uc.uc_stack))
  243. goto badframe;
  244. if (restore_sigregs(regs, &frame->uc.uc_mcontext))
  245. goto badframe;
  246. if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
  247. goto badframe;
  248. load_sigregs();
  249. return regs->gprs[2];
  250. badframe:
  251. force_sig(SIGSEGV, current);
  252. return 0;
  253. }
  254. /*
  255. * Determine which stack to use..
  256. */
  257. static inline void __user *
  258. get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
  259. {
  260. unsigned long sp;
  261. /* Default to using normal stack */
  262. sp = regs->gprs[15];
  263. /* Overflow on alternate signal stack gives SIGSEGV. */
  264. if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
  265. return (void __user *) -1UL;
  266. /* This is the X/Open sanctioned signal stack switching. */
  267. if (ka->sa.sa_flags & SA_ONSTACK) {
  268. if (! sas_ss_flags(sp))
  269. sp = current->sas_ss_sp + current->sas_ss_size;
  270. }
  271. return (void __user *)((sp - frame_size) & -8ul);
  272. }
  273. static int setup_frame(int sig, struct k_sigaction *ka,
  274. sigset_t *set, struct pt_regs * regs)
  275. {
  276. struct sigframe __user *frame;
  277. struct sigcontext sc;
  278. unsigned long restorer;
  279. size_t frame_size;
  280. /*
  281. * gprs_high are only present for a 31-bit task running on
  282. * a 64-bit kernel (see compat_signal.c) but the space for
  283. * gprs_high need to be allocated if vector registers are
  284. * included in the signal frame on a 31-bit system.
  285. */
  286. frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
  287. if (MACHINE_HAS_VX)
  288. frame_size += sizeof(frame->sregs_ext);
  289. frame = get_sigframe(ka, regs, frame_size);
  290. if (frame == (void __user *) -1UL)
  291. return -EFAULT;
  292. /* Set up backchain. */
  293. if (__put_user(regs->gprs[15], (addr_t __user *) frame))
  294. return -EFAULT;
  295. /* Create struct sigcontext on the signal stack */
  296. memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
  297. sc.sregs = (_sigregs __user __force *) &frame->sregs;
  298. if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
  299. return -EFAULT;
  300. /* Store registers needed to create the signal frame */
  301. store_sigregs();
  302. /* Create _sigregs on the signal stack */
  303. if (save_sigregs(regs, &frame->sregs))
  304. return -EFAULT;
  305. /* Place signal number on stack to allow backtrace from handler. */
  306. if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
  307. return -EFAULT;
  308. /* Create _sigregs_ext on the signal stack */
  309. if (save_sigregs_ext(regs, &frame->sregs_ext))
  310. return -EFAULT;
  311. /* Set up to return from userspace. If provided, use a stub
  312. already in userspace. */
  313. if (ka->sa.sa_flags & SA_RESTORER) {
  314. restorer = (unsigned long) ka->sa.sa_restorer | PSW_ADDR_AMODE;
  315. } else {
  316. /* Signal frame without vector registers are short ! */
  317. __u16 __user *svc = (void __user *) frame + frame_size - 2;
  318. if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
  319. return -EFAULT;
  320. restorer = (unsigned long) svc | PSW_ADDR_AMODE;
  321. }
  322. /* Set up registers for signal handler */
  323. regs->gprs[14] = restorer;
  324. regs->gprs[15] = (unsigned long) frame;
  325. /* Force default amode and default user address space control. */
  326. regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
  327. (PSW_USER_BITS & PSW_MASK_ASC) |
  328. (regs->psw.mask & ~PSW_MASK_ASC);
  329. regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
  330. regs->gprs[2] = sig;
  331. regs->gprs[3] = (unsigned long) &frame->sc;
  332. /* We forgot to include these in the sigcontext.
  333. To avoid breaking binary compatibility, they are passed as args. */
  334. if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
  335. sig == SIGTRAP || sig == SIGFPE) {
  336. /* set extra registers only for synchronous signals */
  337. regs->gprs[4] = regs->int_code & 127;
  338. regs->gprs[5] = regs->int_parm_long;
  339. regs->gprs[6] = task_thread_info(current)->last_break;
  340. }
  341. return 0;
  342. }
  343. static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
  344. struct pt_regs *regs)
  345. {
  346. struct rt_sigframe __user *frame;
  347. unsigned long uc_flags, restorer;
  348. size_t frame_size;
  349. frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
  350. /*
  351. * gprs_high are only present for a 31-bit task running on
  352. * a 64-bit kernel (see compat_signal.c) but the space for
  353. * gprs_high need to be allocated if vector registers are
  354. * included in the signal frame on a 31-bit system.
  355. */
  356. uc_flags = 0;
  357. if (MACHINE_HAS_VX) {
  358. frame_size += sizeof(_sigregs_ext);
  359. if (current->thread.vxrs)
  360. uc_flags |= UC_VXRS;
  361. }
  362. frame = get_sigframe(&ksig->ka, regs, frame_size);
  363. if (frame == (void __user *) -1UL)
  364. return -EFAULT;
  365. /* Set up backchain. */
  366. if (__put_user(regs->gprs[15], (addr_t __user *) frame))
  367. return -EFAULT;
  368. /* Set up to return from userspace. If provided, use a stub
  369. already in userspace. */
  370. if (ksig->ka.sa.sa_flags & SA_RESTORER) {
  371. restorer = (unsigned long)
  372. ksig->ka.sa.sa_restorer | PSW_ADDR_AMODE;
  373. } else {
  374. __u16 __user *svc = &frame->svc_insn;
  375. if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
  376. return -EFAULT;
  377. restorer = (unsigned long) svc | PSW_ADDR_AMODE;
  378. }
  379. /* Create siginfo on the signal stack */
  380. if (copy_siginfo_to_user(&frame->info, &ksig->info))
  381. return -EFAULT;
  382. /* Store registers needed to create the signal frame */
  383. store_sigregs();
  384. /* Create ucontext on the signal stack. */
  385. if (__put_user(uc_flags, &frame->uc.uc_flags) ||
  386. __put_user(NULL, &frame->uc.uc_link) ||
  387. __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
  388. save_sigregs(regs, &frame->uc.uc_mcontext) ||
  389. __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||
  390. save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
  391. return -EFAULT;
  392. /* Set up registers for signal handler */
  393. regs->gprs[14] = restorer;
  394. regs->gprs[15] = (unsigned long) frame;
  395. /* Force default amode and default user address space control. */
  396. regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
  397. (PSW_USER_BITS & PSW_MASK_ASC) |
  398. (regs->psw.mask & ~PSW_MASK_ASC);
  399. regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler | PSW_ADDR_AMODE;
  400. regs->gprs[2] = ksig->sig;
  401. regs->gprs[3] = (unsigned long) &frame->info;
  402. regs->gprs[4] = (unsigned long) &frame->uc;
  403. regs->gprs[5] = task_thread_info(current)->last_break;
  404. return 0;
  405. }
  406. static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
  407. struct pt_regs *regs)
  408. {
  409. int ret;
  410. /* Set up the stack frame */
  411. if (ksig->ka.sa.sa_flags & SA_SIGINFO)
  412. ret = setup_rt_frame(ksig, oldset, regs);
  413. else
  414. ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);
  415. signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
  416. }
  417. /*
  418. * Note that 'init' is a special process: it doesn't get signals it doesn't
  419. * want to handle. Thus you cannot kill init even with a SIGKILL even by
  420. * mistake.
  421. *
  422. * Note that we go through the signals twice: once to check the signals that
  423. * the kernel can handle, and then we build all the user-level signal handling
  424. * stack-frames in one go after that.
  425. */
  426. void do_signal(struct pt_regs *regs)
  427. {
  428. struct ksignal ksig;
  429. sigset_t *oldset = sigmask_to_save();
  430. /*
  431. * Get signal to deliver. When running under ptrace, at this point
  432. * the debugger may change all our registers, including the system
  433. * call information.
  434. */
  435. current_thread_info()->system_call =
  436. test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
  437. if (get_signal(&ksig)) {
  438. /* Whee! Actually deliver the signal. */
  439. if (current_thread_info()->system_call) {
  440. regs->int_code = current_thread_info()->system_call;
  441. /* Check for system call restarting. */
  442. switch (regs->gprs[2]) {
  443. case -ERESTART_RESTARTBLOCK:
  444. case -ERESTARTNOHAND:
  445. regs->gprs[2] = -EINTR;
  446. break;
  447. case -ERESTARTSYS:
  448. if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
  449. regs->gprs[2] = -EINTR;
  450. break;
  451. }
  452. /* fallthrough */
  453. case -ERESTARTNOINTR:
  454. regs->gprs[2] = regs->orig_gpr2;
  455. regs->psw.addr =
  456. __rewind_psw(regs->psw,
  457. regs->int_code >> 16);
  458. break;
  459. }
  460. }
  461. /* No longer in a system call */
  462. clear_pt_regs_flag(regs, PIF_SYSCALL);
  463. if (is_compat_task())
  464. handle_signal32(&ksig, oldset, regs);
  465. else
  466. handle_signal(&ksig, oldset, regs);
  467. return;
  468. }
  469. /* No handlers present - check for system call restart */
  470. clear_pt_regs_flag(regs, PIF_SYSCALL);
  471. if (current_thread_info()->system_call) {
  472. regs->int_code = current_thread_info()->system_call;
  473. switch (regs->gprs[2]) {
  474. case -ERESTART_RESTARTBLOCK:
  475. /* Restart with sys_restart_syscall */
  476. regs->int_code = __NR_restart_syscall;
  477. /* fallthrough */
  478. case -ERESTARTNOHAND:
  479. case -ERESTARTSYS:
  480. case -ERESTARTNOINTR:
  481. /* Restart system call with magic TIF bit. */
  482. regs->gprs[2] = regs->orig_gpr2;
  483. set_pt_regs_flag(regs, PIF_SYSCALL);
  484. if (test_thread_flag(TIF_SINGLE_STEP))
  485. clear_pt_regs_flag(regs, PIF_PER_TRAP);
  486. break;
  487. }
  488. }
  489. /*
  490. * If there's no signal to deliver, we just put the saved sigmask back.
  491. */
  492. restore_saved_sigmask();
  493. }
  494. void do_notify_resume(struct pt_regs *regs)
  495. {
  496. clear_thread_flag(TIF_NOTIFY_RESUME);
  497. tracehook_notify_resume(regs);
  498. }