code.vuplus.com Git - vuplus_openvuplus/blob - meta-openvuplus/recipes-kernel/linux-libc-headers/linux-libc-headers-2.6.31/0001-implement-TIF_RESTORE_SIGMASK-support-and-enable-the.patch

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   2 From: Mikael Pettersson <mikpe@it.uu.se>
   3 Newsgroups: gmane.linux.ports.arm.kernel
   4 Subject: [PATCH][v3] ARM support for
   5         TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait
   6 Date: Sat, 15 Aug 2009 13:09:28 +0200 (MEST)
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  67
  68 This patch adds support for TIF_RESTORE_SIGMASK to ARM's signal handling,
  69 which allows to hook up the pselect6, ppoll, and epoll_pwait syscalls on ARM.
  70
  71 Tested here with eabi userspace and a test program with a deliberate race
  72 between a child's exit and the parent's sigprocmask/select sequence.
  73 Using sys_pselect6() instead of sigprocmask/select reliably prevents the race.
  74
  75 The other arch's support for TIF_RESTORE_SIGMASK has evolved over time:
  76
  77 In 2.6.16:
  78 - add TIF_RESTORE_SIGMASK which parallels TIF_SIGPENDING
  79 - test both when checking for pending signal [bad, changed later]
  80 - reimplement sys_sigsuspend() to use current->saved_sigmask,
  81   TIF_RESTORE_SIGMASK [changed later], and -ERESTARTNOHAND;
  82   ditto for sys_rt_sigsuspend(), but drop private code and
  83   use common code via __ARCH_WANT_SYS_RT_SIGSUSPEND;
  84 - there are now no "extra" calls to do_signal() so its oldset
  85   parameter is always &current->blocked so need not be passed,
  86   also its return value is changed to void
  87 - change handle_signal() to return 0/-errno
  88 - change do_signal() to honor TIF_RESTORE_SIGMASK:
  89   + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK is set
  90   + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
  91   + if no signal was delivered and TIF_RESTORE_SIGMASK is set then
  92     clear it and restore the sigmask
  93 - hook up sys_pselect6() and sys_ppoll()
  94
  95 In 2.6.19:
  96 - hook up sys_epoll_pwait()
  97
  98 In 2.6.26:
  99 - allow archs to override how TIF_RESTORE_SIGMASK is implemented;
 100   default set_restore_sigmask() sets both TIF_RESTORE_SIGMASK and
 101   TIF_SIGPENDING; archs need now just test TIF_SIGPENDING again
 102   when checking for pending signal work; some archs now implement
 103   TIF_RESTORE_SIGMASK as a secondary/non-atomic thread flag bit
 104 - call set_restore_sigmask() in sys_sigsuspend() instead of setting
 105   TIF_RESTORE_SIGMASK
 106
 107 In 2.6.29-rc:
 108 - kill sys_pselect7() which no arch wanted
 109
 110 So for 2.6.31-rc6/ARM this patch does the following:
 111 - Add TIF_RESTORE_SIGMASK. Use the generic set_restore_sigmask()
 112   which sets both TIF_SIGPENDING and TIF_RESTORE_SIGMASK, so
 113   TIF_RESTORE_SIGMASK need not claim one of the scarce low thread
 114   flags, and existing TIF_SIGPENDING and _TIF_WORK_MASK tests need
 115   not be extended for TIF_RESTORE_SIGMASK.
 116 - sys_sigsuspend() is reimplemented to use current->saved_sigmask and
 117   set_restore_sigmask(), making it identical to most other archs.
 118 - The private code for sys_rt_sigsuspend() is removed, instead generic
 119   code supplies it via __ARCH_WANT_SYS_RT_SIGSUSPEND.
 120 - sys_sigsuspend() and sys_rt_sigsuspend() no longer need a pt_regs
 121   parameter, so their assembly code wrappers are removed.
 122 - handle_signal() is changed to return 0 on success or -errno.
 123 - The oldset parameter to do_signal() is now redundant and removed,
 124   and the return value is now also redundant so it's changed to void.
 125 - do_signal() is changed to honor TIF_RESTORE_SIGMASK:
 126   + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK is set
 127   + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
 128   + if no signal was delivered and TIF_RESTORE_SIGMASK is set then
 129     clear it and restore the sigmask
 130 - Hook up sys_pselect6, sys_ppoll, and sys_epoll_pwait.
 131
 132 Signed-off-by: Mikael Pettersson
 133 ---
 134 Changes from previous versions:
 135
 136 v2 (only posted as incremental diff against v1):
 137 - moved sigmask restoration in no-signal-delivered case into
 138   "if (syscall)" block for extra protection against exception
 139   path also invoking do_signal()
 140 v3 (this version):
 141 - moved oldset initialisation into "if (signr > 0)" block,
 142   as requested by Russell
 143
 144  arch/arm/include/asm/thread_info.h |    2
 145  arch/arm/include/asm/unistd.h      |    7 +--
 146  arch/arm/kernel/calls.S            |   10 ++--
 147  arch/arm/kernel/entry-common.S     |   10 ----
 148  arch/arm/kernel/signal.c           |   86 +++++++++++++++----------------------
 149  5 files changed, 48 insertions(+), 67 deletions(-)
 150
 151 diff -rupN linux-2.6.31-rc6/arch/arm/include/asm/thread_info.h linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/include/asm/thread_info.h
 152 --- linux-2.6.31-rc6/arch/arm/include/asm/thread_info.h 2009-08-14 11:11:10.000000000 +0200
 153 +++ linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/include/asm/thread_info.h  2009-08-14 11:26:44.000000000 +0200
 154 @@ -140,6 +140,7 @@ extern void vfp_sync_state(struct thread
 155  #define TIF_USING_IWMMXT       17
 156  #define TIF_MEMDIE             18
 157  #define TIF_FREEZE             19
 158 +#define TIF_RESTORE_SIGMASK    20
 159
 160  #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
 161  #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
 162 @@ -147,6 +148,7 @@ extern void vfp_sync_state(struct thread
 163  #define _TIF_POLLING_NRFLAG    (1 << TIF_POLLING_NRFLAG)
 164  #define _TIF_USING_IWMMXT      (1 << TIF_USING_IWMMXT)
 165  #define _TIF_FREEZE            (1 << TIF_FREEZE)
 166 +#define _TIF_RESTORE_SIGMASK   (1 << TIF_RESTORE_SIGMASK)
 167
 168  /*
 169   * Change these and you break ASM code in entry-common.S
 170 diff -rupN linux-2.6.31-rc6/arch/arm/include/asm/unistd.h linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/include/asm/unistd.h
 171 --- linux-2.6.31-rc6/arch/arm/include/asm/unistd.h      2009-08-14 11:11:10.000000000 +0200
 172 +++ linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/include/asm/unistd.h       2009-08-14 11:26:44.000000000 +0200
 173 @@ -360,8 +360,8 @@
 174  #define __NR_readlinkat                        (__NR_SYSCALL_BASE+332)
 175  #define __NR_fchmodat                  (__NR_SYSCALL_BASE+333)
 176  #define __NR_faccessat                 (__NR_SYSCALL_BASE+334)
 177 -                                       /* 335 for pselect6 */
 178 -                                       /* 336 for ppoll */
 179 +#define __NR_pselect6                  (__NR_SYSCALL_BASE+335)
 180 +#define __NR_ppoll                     (__NR_SYSCALL_BASE+336)
 181  #define __NR_unshare                   (__NR_SYSCALL_BASE+337)
 182  #define __NR_set_robust_list           (__NR_SYSCALL_BASE+338)
 183  #define __NR_get_robust_list           (__NR_SYSCALL_BASE+339)
 184 @@ -372,7 +372,7 @@
 185  #define __NR_vmsplice                  (__NR_SYSCALL_BASE+343)
 186  #define __NR_move_pages                        (__NR_SYSCALL_BASE+344)
 187  #define __NR_getcpu                    (__NR_SYSCALL_BASE+345)
 188 -                                       /* 346 for epoll_pwait */
 189 +#define __NR_epoll_pwait               (__NR_SYSCALL_BASE+346)
 190  #define __NR_kexec_load                        (__NR_SYSCALL_BASE+347)
 191  #define __NR_utimensat                 (__NR_SYSCALL_BASE+348)
 192  #define __NR_signalfd                  (__NR_SYSCALL_BASE+349)
 193 @@ -432,6 +432,7 @@
 194  #define __ARCH_WANT_SYS_SIGPENDING
 195  #define __ARCH_WANT_SYS_SIGPROCMASK
 196  #define __ARCH_WANT_SYS_RT_SIGACTION
 197 +#define __ARCH_WANT_SYS_RT_SIGSUSPEND
 198
 199  #if !defined(CONFIG_AEABI) || defined(CONFIG_OABI_COMPAT)
 200  #define __ARCH_WANT_SYS_TIME
 201 diff -rupN linux-2.6.31-rc6/arch/arm/kernel/calls.S linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/kernel/calls.S
 202 --- linux-2.6.31-rc6/arch/arm/kernel/calls.S    2009-08-14 11:11:10.000000000 +0200
 203 +++ linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/kernel/calls.S     2009-08-14 11:26:44.000000000 +0200
 204 @@ -81,7 +81,7 @@
 205                 CALL(sys_ni_syscall)            /* was sys_ssetmask */
 206  /* 70 */       CALL(sys_setreuid16)
 207                 CALL(sys_setregid16)
 208 -               CALL(sys_sigsuspend_wrapper)
 209 +               CALL(sys_sigsuspend)
 210                 CALL(sys_sigpending)
 211                 CALL(sys_sethostname)
 212  /* 75 */       CALL(sys_setrlimit)
 213 @@ -188,7 +188,7 @@
 214                 CALL(sys_rt_sigpending)
 215                 CALL(sys_rt_sigtimedwait)
 216                 CALL(sys_rt_sigqueueinfo)
 217 -               CALL(sys_rt_sigsuspend_wrapper)
 218 +               CALL(sys_rt_sigsuspend)
 219  /* 180 */      CALL(ABI(sys_pread64, sys_oabi_pread64))
 220                 CALL(ABI(sys_pwrite64, sys_oabi_pwrite64))
 221                 CALL(sys_chown16)
 222 @@ -344,8 +344,8 @@
 223                 CALL(sys_readlinkat)
 224                 CALL(sys_fchmodat)
 225                 CALL(sys_faccessat)
 226 -/* 335 */      CALL(sys_ni_syscall)            /* eventually pselect6 */
 227 -               CALL(sys_ni_syscall)            /* eventually ppoll */
 228 +/* 335 */      CALL(sys_pselect6)
 229 +               CALL(sys_ppoll)
 230                 CALL(sys_unshare)
 231                 CALL(sys_set_robust_list)
 232                 CALL(sys_get_robust_list)
 233 @@ -355,7 +355,7 @@
 234                 CALL(sys_vmsplice)
 235                 CALL(sys_move_pages)
 236  /* 345 */      CALL(sys_getcpu)
 237 -               CALL(sys_ni_syscall)            /* eventually epoll_pwait */
 238 +               CALL(sys_epoll_pwait)
 239                 CALL(sys_kexec_load)
 240                 CALL(sys_utimensat)
 241                 CALL(sys_signalfd)
 242 diff -rupN linux-2.6.31-rc6/arch/arm/kernel/entry-common.S linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/kernel/entry-common.S
 243 --- linux-2.6.31-rc6/arch/arm/kernel/entry-common.S     2009-08-14 11:11:10.000000000 +0200
 244 +++ linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/kernel/entry-common.S      2009-08-14 11:26:44.000000000 +0200
 245 @@ -373,16 +373,6 @@ sys_clone_wrapper:
 246                 b       sys_clone
 247  ENDPROC(sys_clone_wrapper)
 248
 249 -sys_sigsuspend_wrapper:
 250 -               add     r3, sp, #S_OFF
 251 -               b       sys_sigsuspend
 252 -ENDPROC(sys_sigsuspend_wrapper)
 253 -
 254 -sys_rt_sigsuspend_wrapper:
 255 -               add     r2, sp, #S_OFF
 256 -               b       sys_rt_sigsuspend
 257 -ENDPROC(sys_rt_sigsuspend_wrapper)
 258 -
 259  sys_sigreturn_wrapper:
 260                 add     r0, sp, #S_OFF
 261                 b       sys_sigreturn
 262 diff -rupN linux-2.6.31-rc6/arch/arm/kernel/signal.c linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/kernel/signal.c
 263 --- linux-2.6.31-rc6/arch/arm/kernel/signal.c   2009-08-14 11:11:10.000000000 +0200
 264 +++ linux-2.6.31-rc6.arm-restore-sigmask-v3/arch/arm/kernel/signal.c    2009-08-14 11:26:44.000000000 +0200
 265 @@ -47,57 +47,22 @@ const unsigned long sigreturn_codes[7] =
 266         MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
 267  };
 268
 269 -static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
 270 -
 271  /*
 272   * atomically swap in the new signal mask, and wait for a signal.
 273   */
 274 -asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
 275 +asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
 276  {
 277 -       sigset_t saveset;
 278 -
 279         mask &= _BLOCKABLE;
 280         spin_lock_irq(&current->sighand->siglock);
 281 -       saveset = current->blocked;
 282 +       current->saved_sigmask = current->blocked;
 283         siginitset(&current->blocked, mask);
 284         recalc_sigpending();
 285         spin_unlock_irq(&current->sighand->siglock);
 286 -       regs->ARM_r0 = -EINTR;
 287 -
 288 -       while (1) {
 289 -               current->state = TASK_INTERRUPTIBLE;
 290 -               schedule();
 291 -               if (do_signal(&saveset, regs, 0))
 292 -                       return regs->ARM_r0;
 293 -       }
 294 -}
 295 -
 296 -asmlinkage int
 297 -sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
 298 -{
 299 -       sigset_t saveset, newset;
 300 -
 301 -       /* XXX: Don't preclude handling different sized sigset_t's. */
 302 -       if (sigsetsize != sizeof(sigset_t))
 303 -               return -EINVAL;
 304 -
 305 -       if (copy_from_user(&newset, unewset, sizeof(newset)))
 306 -               return -EFAULT;
 307 -       sigdelsetmask(&newset, ~_BLOCKABLE);
 308 -
 309 -       spin_lock_irq(&current->sighand->siglock);
 310 -       saveset = current->blocked;
 311 -       current->blocked = newset;
 312 -       recalc_sigpending();
 313 -       spin_unlock_irq(&current->sighand->siglock);
 314 -       regs->ARM_r0 = -EINTR;
 315
 316 -       while (1) {
 317 -               current->state = TASK_INTERRUPTIBLE;
 318 -               schedule();
 319 -               if (do_signal(&saveset, regs, 0))
 320 -                       return regs->ARM_r0;
 321 -       }
 322 +       current->state = TASK_INTERRUPTIBLE;
 323 +       schedule();
 324 +       set_restore_sigmask();
 325 +       return -ERESTARTNOHAND;
 326  }
 327
 328  asmlinkage int
 329 @@ -545,7 +510,7 @@ static inline void setup_syscall_restart
 330  /*
 331   * OK, we're invoking a handler
 332   */
 333 -static void
 334 +static int
 335  handle_signal(unsigned long sig, struct k_sigaction *ka,
 336               siginfo_t *info, sigset_t *oldset,
 337               struct pt_regs * regs, int syscall)
 338 @@ -596,7 +561,7 @@ handle_signal(unsigned long sig, struct
 339
 340         if (ret != 0) {
 341                 force_sigsegv(sig, tsk);
 342 -               return;
 343 +               return ret;
 344         }
 345
 346         /*
 347 @@ -610,6 +575,7 @@ handle_signal(unsigned long sig, struct
 348         recalc_sigpending();
 349         spin_unlock_irq(&tsk->sighand->siglock);
 350
 351 +       return 0;
 352  }
 353
 354  /*
 355 @@ -621,7 +587,7 @@ handle_signal(unsigned long sig, struct
 356   * the kernel can handle, and then we build all the user-level signal handling
 357   * stack-frames in one go after that.
 358   */
 359 -static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 360 +static void do_signal(struct pt_regs *regs, int syscall)
 361  {
 362         struct k_sigaction ka;
 363         siginfo_t info;
 364 @@ -634,7 +600,7 @@ static int do_signal(sigset_t *oldset, s
 365          * if so.
 366          */
 367         if (!user_mode(regs))
 368 -               return 0;
 369 +               return;
 370
 371         if (try_to_freeze())
 372                 goto no_signal;
 373 @@ -643,9 +609,24 @@ static int do_signal(sigset_t *oldset, s
 374
 375         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 376         if (signr > 0) {
 377 -               handle_signal(signr, &ka, &info, oldset, regs, syscall);
 378 +               sigset_t *oldset;
 379 +
 380 +               if (test_thread_flag(TIF_RESTORE_SIGMASK))
 381 +                       oldset = &current->saved_sigmask;
 382 +               else
 383 +                       oldset = &current->blocked;
 384 +               if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) {
 385 +                       /*
 386 +                        * A signal was successfully delivered; the saved
 387 +                        * sigmask will have been stored in the signal frame,
 388 +                        * and will be restored by sigreturn, so we can simply
 389 +                        * clear the TIF_RESTORE_SIGMASK flag.
 390 +                        */
 391 +                       if (test_thread_flag(TIF_RESTORE_SIGMASK))
 392 +                               clear_thread_flag(TIF_RESTORE_SIGMASK);
 393 +               }
 394                 single_step_set(current);
 395 -               return 1;
 396 +               return;
 397         }
 398
 399   no_signal:
 400 @@ -697,14 +678,21 @@ static int do_signal(sigset_t *oldset, s
 401                     regs->ARM_r0 == -ERESTARTNOINTR) {
 402                         setup_syscall_restart(regs);
 403                 }
 404 +
 405 +               /* If there's no signal to deliver, we just put the saved sigmask
 406 +                * back.
 407 +                */
 408 +               if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 409 +                       clear_thread_flag(TIF_RESTORE_SIGMASK);
 410 +                       sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 411 +               }
 412         }
 413         single_step_set(current);
 414 -       return 0;
 415  }
 416
 417  asmlinkage void
 418  do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 419  {
 420         if (thread_flags & _TIF_SIGPENDING)
 421 -               do_signal(&current->blocked, regs, syscall);
 422 +               do_signal(regs, syscall);
 423  }
 424
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 429