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wifipineapple-openwrt/target/linux/generic/patches-2.6.31/965-arm_restore_sigmask_v2....

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From: Mikael Pettersson <mikpe@it.uu.se>
Date: Sat, 15 Aug 2009 11:58:11 +0000 (+0100)
Subject: ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait
X-Git-Tag: next-20090817~86^2~1^6
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fnext%2Flinux-next.git;a=commitdiff_plain;h=369842658a36bcea28ecb643ba4bdb53919330dd
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: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -141,6 +141,7 @@
#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)
@@ -148,6 +149,7 @@
#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
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -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
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -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)
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -373,16 +373,6 @@
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
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -47,57 +47,22 @@
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;
- }
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ set_restore_sigmask();
+ return -ERESTARTNOHAND;
}
asmlinkage int
@@ -545,7 +510,7 @@
/*
* 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 @@
if (ret != 0) {
force_sigsegv(sig, tsk);
- return;
+ return ret;
}
/*
@@ -610,6 +575,7 @@
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
+ return 0;
}
/*
@@ -621,11 +587,12 @@
* 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;
int signr;
+ sigset_t *oldset;
/*
* We want the common case to go fast, which
@@ -634,18 +601,32 @@
* if so.
*/
if (!user_mode(regs))
- return 0;
+ return;
if (try_to_freeze())
goto no_signal;
single_step_clear(current);
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ oldset = &current->saved_sigmask;
+ else
+ oldset = &current->blocked;
+
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
- handle_signal(signr, &ka, &info, oldset, regs, syscall);
+ 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 @@
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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