Commit 36984265 authored by Mikael Pettersson's avatar Mikael Pettersson Committed by Russell King

ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait

This patch adds support for TIF_RESTORE_SIGMASK to ARM's
signal handling, which allows to hook up the pselect6, ppoll,
and epoll_pwait syscalls on ARM.

Tested here with eabi userspace and a test program with a
deliberate race between a child's exit and the parent's
sigprocmask/select sequence. Using sys_pselect6() instead
of sigprocmask/select reliably prevents the race.

The other arch's support for TIF_RESTORE_SIGMASK has evolved
over time:

In 2.6.16:
- add TIF_RESTORE_SIGMASK which parallels TIF_SIGPENDING
- test both when checking for pending signal [changed later]
- reimplement sys_sigsuspend() to use current->saved_sigmask,
  TIF_RESTORE_SIGMASK [changed later], and -ERESTARTNOHAND;
  ditto for sys_rt_sigsuspend(), but drop private code and
  use common code via __ARCH_WANT_SYS_RT_SIGSUSPEND;
- there are now no "extra" calls to do_signal() so its oldset
  parameter is always &current->blocked so need not be passed,
  also its return value is changed to void
- change handle_signal() to return 0/-errno
- change do_signal() to honor TIF_RESTORE_SIGMASK:
  + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK
    is set
  + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
  + if no signal was delivered and TIF_RESTORE_SIGMASK is set then
    clear it and restore the sigmask
- hook up sys_pselect6() and sys_ppoll()

In 2.6.19:
- hook up sys_epoll_pwait()

In 2.6.26:
- allow archs to override how TIF_RESTORE_SIGMASK is implemented;
  default set_restore_sigmask() sets both TIF_RESTORE_SIGMASK and
  TIF_SIGPENDING; archs need now just test TIF_SIGPENDING again
  when checking for pending signal work; some archs now implement
  TIF_RESTORE_SIGMASK as a secondary/non-atomic thread flag bit
- call set_restore_sigmask() in sys_sigsuspend() instead of setting
  TIF_RESTORE_SIGMASK

In 2.6.29-rc:
- kill sys_pselect7() which no arch wanted

So for 2.6.31-rc6/ARM this patch does the following:
- Add TIF_RESTORE_SIGMASK. Use the generic set_restore_sigmask()
  which sets both TIF_SIGPENDING and TIF_RESTORE_SIGMASK, so
  TIF_RESTORE_SIGMASK need not claim one of the scarce low thread
  flags, and existing TIF_SIGPENDING and _TIF_WORK_MASK tests need
  not be extended for TIF_RESTORE_SIGMASK.
- sys_sigsuspend() is reimplemented to use current->saved_sigmask
  and set_restore_sigmask(), making it identical to most other archs
- The private code for sys_rt_sigsuspend() is removed, instead
  generic code supplies it via __ARCH_WANT_SYS_RT_SIGSUSPEND.
- sys_sigsuspend() and sys_rt_sigsuspend() no longer need a pt_regs
  parameter, so their assembly code wrappers are removed.
- handle_signal() is changed to return 0 on success or -errno.
- The oldset parameter to do_signal() is now redundant and removed,
  and the return value is now also redundant and changed to void.
- do_signal() is changed to honor TIF_RESTORE_SIGMASK:
  + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK
    is set
  + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
  + if no signal was delivered and TIF_RESTORE_SIGMASK is set then
    clear it and restore the sigmask
- Hook up sys_pselect6, sys_ppoll, and sys_epoll_pwait.
Signed-off-by: default avatarMikael Pettersson <mikpe@it.uu.se>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 4bf1fa5a
......@@ -140,6 +140,7 @@ extern void vfp_sync_state(struct thread_info *thread);
#define TIF_USING_IWMMXT 17
#define TIF_MEMDIE 18
#define TIF_FREEZE 19
#define TIF_RESTORE_SIGMASK 20
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
......@@ -147,6 +148,7 @@ extern void vfp_sync_state(struct thread_info *thread);
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
#define _TIF_FREEZE (1 << TIF_FREEZE)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
/*
* Change these and you break ASM code in entry-common.S
......
......@@ -360,8 +360,8 @@
#define __NR_readlinkat (__NR_SYSCALL_BASE+332)
#define __NR_fchmodat (__NR_SYSCALL_BASE+333)
#define __NR_faccessat (__NR_SYSCALL_BASE+334)
/* 335 for pselect6 */
/* 336 for ppoll */
#define __NR_pselect6 (__NR_SYSCALL_BASE+335)
#define __NR_ppoll (__NR_SYSCALL_BASE+336)
#define __NR_unshare (__NR_SYSCALL_BASE+337)
#define __NR_set_robust_list (__NR_SYSCALL_BASE+338)
#define __NR_get_robust_list (__NR_SYSCALL_BASE+339)
......@@ -372,7 +372,7 @@
#define __NR_vmsplice (__NR_SYSCALL_BASE+343)
#define __NR_move_pages (__NR_SYSCALL_BASE+344)
#define __NR_getcpu (__NR_SYSCALL_BASE+345)
/* 346 for epoll_pwait */
#define __NR_epoll_pwait (__NR_SYSCALL_BASE+346)
#define __NR_kexec_load (__NR_SYSCALL_BASE+347)
#define __NR_utimensat (__NR_SYSCALL_BASE+348)
#define __NR_signalfd (__NR_SYSCALL_BASE+349)
......@@ -432,6 +432,7 @@
#define __ARCH_WANT_SYS_SIGPENDING
#define __ARCH_WANT_SYS_SIGPROCMASK
#define __ARCH_WANT_SYS_RT_SIGACTION
#define __ARCH_WANT_SYS_RT_SIGSUSPEND
#if !defined(CONFIG_AEABI) || defined(CONFIG_OABI_COMPAT)
#define __ARCH_WANT_SYS_TIME
......
......@@ -81,7 +81,7 @@
CALL(sys_ni_syscall) /* was sys_ssetmask */
/* 70 */ CALL(sys_setreuid16)
CALL(sys_setregid16)
CALL(sys_sigsuspend_wrapper)
CALL(sys_sigsuspend)
CALL(sys_sigpending)
CALL(sys_sethostname)
/* 75 */ CALL(sys_setrlimit)
......@@ -188,7 +188,7 @@
CALL(sys_rt_sigpending)
CALL(sys_rt_sigtimedwait)
CALL(sys_rt_sigqueueinfo)
CALL(sys_rt_sigsuspend_wrapper)
CALL(sys_rt_sigsuspend)
/* 180 */ CALL(ABI(sys_pread64, sys_oabi_pread64))
CALL(ABI(sys_pwrite64, sys_oabi_pwrite64))
CALL(sys_chown16)
......@@ -344,8 +344,8 @@
CALL(sys_readlinkat)
CALL(sys_fchmodat)
CALL(sys_faccessat)
/* 335 */ CALL(sys_ni_syscall) /* eventually pselect6 */
CALL(sys_ni_syscall) /* eventually ppoll */
/* 335 */ CALL(sys_pselect6)
CALL(sys_ppoll)
CALL(sys_unshare)
CALL(sys_set_robust_list)
CALL(sys_get_robust_list)
......@@ -355,7 +355,7 @@
CALL(sys_vmsplice)
CALL(sys_move_pages)
/* 345 */ CALL(sys_getcpu)
CALL(sys_ni_syscall) /* eventually epoll_pwait */
CALL(sys_epoll_pwait)
CALL(sys_kexec_load)
CALL(sys_utimensat)
CALL(sys_signalfd)
......
......@@ -373,16 +373,6 @@ sys_clone_wrapper:
b sys_clone
ENDPROC(sys_clone_wrapper)
sys_sigsuspend_wrapper:
add r3, sp, #S_OFF
b sys_sigsuspend
ENDPROC(sys_sigsuspend_wrapper)
sys_rt_sigsuspend_wrapper:
add r2, sp, #S_OFF
b sys_rt_sigsuspend
ENDPROC(sys_rt_sigsuspend_wrapper)
sys_sigreturn_wrapper:
add r0, sp, #S_OFF
b sys_sigreturn
......
......@@ -47,57 +47,22 @@ const unsigned long sigreturn_codes[7] = {
MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
};
static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
/*
* atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
{
sigset_t saveset;
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
current->saved_sigmask = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->ARM_r0 = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&saveset, regs, 0))
return regs->ARM_r0;
}
}
asmlinkage int
sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
{
sigset_t saveset, newset;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&newset, unewset, sizeof(newset)))
return -EFAULT;
sigdelsetmask(&newset, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
current->blocked = newset;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->ARM_r0 = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&saveset, regs, 0))
return regs->ARM_r0;
}
set_restore_sigmask();
return -ERESTARTNOHAND;
}
asmlinkage int
......@@ -545,7 +510,7 @@ static inline void setup_syscall_restart(struct pt_regs *regs)
/*
* OK, we're invoking a handler
*/
static void
static int
handle_signal(unsigned long sig, struct k_sigaction *ka,
siginfo_t *info, sigset_t *oldset,
struct pt_regs * regs, int syscall)
......@@ -596,7 +561,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
if (ret != 0) {
force_sigsegv(sig, tsk);
return;
return ret;
}
/*
......@@ -610,6 +575,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
return 0;
}
/*
......@@ -621,7 +587,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
static void do_signal(struct pt_regs *regs, int syscall)
{
struct k_sigaction ka;
siginfo_t info;
......@@ -634,7 +600,7 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
* if so.
*/
if (!user_mode(regs))
return 0;
return;
if (try_to_freeze())
goto no_signal;
......@@ -643,9 +609,24 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
handle_signal(signr, &ka, &info, oldset, regs, syscall);
sigset_t *oldset;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = &current->saved_sigmask;
else
oldset = &current->blocked;
if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) {
/*
* A signal was successfully delivered; the saved
* sigmask will have been stored in the signal frame,
* and will be restored by sigreturn, so we can simply
* clear the TIF_RESTORE_SIGMASK flag.
*/
if (test_thread_flag(TIF_RESTORE_SIGMASK))
clear_thread_flag(TIF_RESTORE_SIGMASK);
}
single_step_set(current);
return 1;
return;
}
no_signal:
......@@ -697,14 +678,21 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
regs->ARM_r0 == -ERESTARTNOINTR) {
setup_syscall_restart(regs);
}
/* If there's no signal to deliver, we just put the saved sigmask
* back.
*/
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
clear_thread_flag(TIF_RESTORE_SIGMASK);
sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
}
}
single_step_set(current);
return 0;
}
asmlinkage void
do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
if (thread_flags & _TIF_SIGPENDING)
do_signal(&current->blocked, regs, syscall);
do_signal(regs, syscall);
}
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