[PATCH 1/2] Handle TIF_RESTORE_SIGMASK for FRV

David Howells
2005-11-29T21:18:41Z

The attached patch handles TIF_RESTORE_SIGMASK as added by David Woodhouse's
patch entitled:

[PATCH] 2/3 Add TIF_RESTORE_SIGMASK support for arch/powerpc
[PATCH] 3/3 Generic sys_rt_sigsuspend

It does the following:

(1) Declares TIF_RESTORE_SIGMASK for FRV.

(2) Invokes it over to do_signal() when TIF_RESTORE_SIGMASK is set.

(3) Makes do_signal() support TIF_RESTORE_SIGMASK, using the signal mask saved
in current->saved_sigmask.

(4) Discards sys_rt_sigsuspend() from the arch, using the generic one instead.

(5) Makes sys_sigsuspend() save the signal mask and set TIF_RESTORE_SIGMASK
rather than attempting to fudge the return registers.

(6) Makes sys_sigsuspend() return -ERESTARTNOHAND rather than looping
intrinsically.

(7) Makes setup_frame(), setup_rt_frame() and handle_signal() return 0 or
-EFAULT rather than true/false to be consistent with the rest of the
kernel.

Due to the fact do_signal() is then only called from one place:

(8) Make do_signal() no longer have a return value is it was just being
ignored; force_sig() takes care of this.

(9) Discards the old sigmask argument to do_signal() as it's no longer
necessary.

This patch depends on the FRV signalling patches as well as the
sys_rt_sigsuspend patch.

Signed-Off-By: David Howells <dhowells@redhat.com>
---
warthog>diffstat -p1 frv-tifrestore-2615rc2.diff
arch/frv/kernel/signal.c | 120 +++++++++++++++---------------------------
include/asm-frv/thread_info.h | 2
include/asm-frv/unistd.h | 1
3 files changed, 47 insertions(+), 76 deletions(-)

diff -uNrp linux-2.6.15-rc2-frv-dosignal/arch/frv/kernel/signal.c linux-2.6.15-rc2-frv-tifrestore/arch/frv/kernel/signal.c
--- linux-2.6.15-rc2-frv-dosignal/arch/frv/kernel/signal.c 2005-11-29 16:55:12.000000000 +0000
+++ linux-2.6.15-rc2-frv-tifrestore/arch/frv/kernel/signal.c 2005-11-29 18:54:24.000000000 +0000
@@ -35,74 +35,22 @@ struct fdpic_func_descriptor {
unsigned long GOT;
};

-static int do_signal(sigset_t *oldset);
-
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int sys_sigsuspend(int history0, int history1, 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);

- __frame->gr8 = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(&saveset))
- /* return the signal number as the return value of this function
- * - this is an utterly evil hack. syscalls should not invoke do_signal()
- * as entry.S sets regs->gr8 to the return value of the system call
- * - we can't just use sigpending() as we'd have to discard SIG_IGN signals
- * and call waitpid() if SIGCHLD needed discarding
- * - this only works on the i386 because it passes arguments to the signal
- * handler on the stack, and the return value in EAX is effectively
- * discarded
- */
- return __frame->gr8;
- }
-}
-
-asmlinkage int sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
-{
- 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);
-
- __frame->gr8 = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(&saveset))
- /* return the signal number as the return value of this function
- * - this is an utterly evil hack. syscalls should not invoke do_signal()
- * as entry.S sets regs->gr8 to the return value of the system call
- * - we can't just use sigpending() as we'd have to discard SIG_IGN signals
- * and call waitpid() if SIGCHLD needed discarding
- * - this only works on the i386 because it passes arguments to the signal
- * handler on the stack, and the return value in EAX is effectively
- * discarded
- */
- return __frame->gr8;
- }
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ return -ERESTARTNOHAND;
}

asmlinkage int sys_sigaction(int sig,
@@ -372,11 +320,11 @@ static int setup_frame(int sig, struct k
frame->pretcode);
#endif

- return 1;
+ return 0;

give_sigsegv:
force_sig(SIGSEGV, current);
- return 0;
+ return -EFAULT;

} /* end setup_frame() */

@@ -471,11 +419,11 @@ static int setup_rt_frame(int sig, struc
frame->pretcode);
#endif

- return 1;
+ return 0;

give_sigsegv:
force_sig(SIGSEGV, current);
- return 0;
+ return -EFAULT;

} /* end setup_rt_frame() */

@@ -516,7 +464,7 @@ static int handle_signal(unsigned long s
else
ret = setup_frame(sig, ka, oldset);

- if (ret) {
+ if (ret == 0) {
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked, &current->blocked,
&ka->sa.sa_mask);
@@ -536,10 +484,11 @@ static int handle_signal(unsigned long s
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*/
-static int do_signal(sigset_t *oldset)
+static void do_signal(void)
{
struct k_sigaction ka;
siginfo_t info;
+ sigset_t *oldset;
int signr;

/*
@@ -549,43 +498,62 @@ static int do_signal(sigset_t *oldset)
* if so.
*/
if (!user_mode(__frame))
- return 1;
+ return;

if (try_to_freeze())
goto no_signal;

- if (!oldset)
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ oldset = &current->saved_sigmask;
+ else
oldset = &current->blocked;

signr = get_signal_to_deliver(&info, &ka, __frame, NULL);
- if (signr > 0)
- return handle_signal(signr, &info, &ka, oldset);
+ if (signr > 0) {
+ if (handle_signal(signr, &info, &ka, oldset) == 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);
+ }
+
+ return;
+ }

no_signal:
/* Did we come from a system call? */
if (__frame->syscallno >= 0) {
/* Restart the system call - no handlers present */
- if (__frame->gr8 == -ERESTARTNOHAND ||
- __frame->gr8 == -ERESTARTSYS ||
- __frame->gr8 == -ERESTARTNOINTR) {
+ switch (__frame->gr8) {
+ case -ERESTARTNOHAND:
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
__frame->gr8 = __frame->orig_gr8;
__frame->pc -= 4;
- }
+ break;

- if (__frame->gr8 == -ERESTART_RESTARTBLOCK){
+ case -ERESTART_RESTARTBLOCK:
__frame->gr8 = __NR_restart_syscall;
__frame->pc -= 4;
+ break;
}
}

- return 0;
+ /* 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);
+ }

} /* end do_signal() */

/*****************************************************************************/
/*
* notification of userspace execution resumption
- * - triggered by current->work.notify_resume
+ * - triggered by the TIF_WORK_MASK flags
*/
asmlinkage void do_notify_resume(__u32 thread_info_flags)
{
@@ -594,7 +562,7 @@ asmlinkage void do_notify_resume(__u32 t
clear_thread_flag(TIF_SINGLESTEP);

/* deal with pending signal delivery */
- if (thread_info_flags & _TIF_SIGPENDING)
- do_signal(NULL);
+ if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
+ do_signal();

} /* end do_notify_resume() */
diff -uNrp linux-2.6.15-rc2-frv-dosignal/include/asm-frv/thread_info.h linux-2.6.15-rc2-frv-tifrestore/include/asm-frv/thread_info.h
--- linux-2.6.15-rc2-frv-dosignal/include/asm-frv/thread_info.h 2005-11-29 16:41:11.000000000 +0000
+++ linux-2.6.15-rc2-frv-tifrestore/include/asm-frv/thread_info.h 2005-11-29 17:39:05.000000000 +0000
@@ -131,6 +131,7 @@ register struct thread_info *__current_t
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_IRET 5 /* return with iret */
+#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17 /* OOM killer killed process */

@@ -140,6 +141,7 @@ register struct thread_info *__current_t
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
#define _TIF_IRET (1 << TIF_IRET)
+#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)

#define _TIF_WORK_MASK 0x0000FFFE /* work to do on interrupt/exception return */
diff -uNrp linux-2.6.15-rc2-frv-dosignal/include/asm-frv/unistd.h linux-2.6.15-rc2-frv-tifrestore/include/asm-frv/unistd.h
--- linux-2.6.15-rc2-frv-dosignal/include/asm-frv/unistd.h 2005-06-22 13:52:26.000000000 +0100
+++ linux-2.6.15-rc2-frv-tifrestore/include/asm-frv/unistd.h 2005-11-29 18:02:04.000000000 +0000
@@ -486,6 +486,7 @@ static inline pid_t wait(int * wait_stat
/* #define __ARCH_WANT_SYS_SIGPENDING */
#define __ARCH_WANT_SYS_SIGPROCMASK
#define __ARCH_WANT_SYS_RT_SIGACTION
+#define __ARCH_WANT_SYS_RT_SIGSUSPEND
#endif

/*