+++ /dev/null
-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 ¤t->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
-@@ -140,6 +140,7 @@ extern void vfp_sync_state(struct 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
- #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 @@ 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
---- a/arch/arm/kernel/signal.c
-+++ b/arch/arm/kernel/signal.c
-@@ -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(¤t->sighand->siglock);
-- saveset = current->blocked;
-+ current->saved_sigmask = current->blocked;
- siginitset(¤t->blocked, mask);
- recalc_sigpending();
- spin_unlock_irq(¤t->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(¤t->sighand->siglock);
-- saveset = current->blocked;
-- current->blocked = newset;
-- recalc_sigpending();
-- spin_unlock_irq(¤t->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 @@ static inline void setup_syscall_restart
- /*
- * 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
-
- if (ret != 0) {
- force_sigsegv(sig, tsk);
-- return;
-+ return ret;
- }
-
- /*
-@@ -610,6 +575,7 @@ handle_signal(unsigned long sig, struct
- recalc_sigpending();
- spin_unlock_irq(&tsk->sighand->siglock);
-
-+ return 0;
- }
-
- /*
-@@ -621,11 +587,12 @@ handle_signal(unsigned long sig, struct
- * 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 @@ static int do_signal(sigset_t *oldset, s
- * 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 = ¤t->saved_sigmask;
-+ else
-+ oldset = ¤t->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 @@ static int do_signal(sigset_t *oldset, s
- 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, ¤t->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(¤t->blocked, regs, syscall);
-+ do_signal(regs, syscall);
- }
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