path: root/recipes/kexecboot/linux-kexecboot-2.6.29/0001-implement-TIF_RESTORE_SIGMASK-support-and-enable-the.patch

From 8a7643b09856f4f661403dcedbe0455b3cbeeea9 Mon Sep 17 00:00:00 2001
From: Steven Newbury <s_j_newbury@yahoo.co.uk>
Date: Fri, 22 May 2009 14:25:40 +0200
Subject: [PATCH] implement TIF_RESTORE_SIGMASK support and enable the related
 syscalls:

pselect6
ppoll
epoll_pwait

Based on http://www.spinics.net/lists/arm-kernel/msg38114.html
---
 arch/arm/include/asm/thread_info.h |    2 +
 arch/arm/include/asm/unistd.h      |    7 ++-
 arch/arm/kernel/calls.S            |    6 +-
 arch/arm/kernel/signal.c           |   90 +++++++++++++++---------------------
 4 files changed, 46 insertions(+), 59 deletions(-)

diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 4f88482..2cf0917 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -136,6 +136,7 @@ extern void vfp_sync_state(struct thread_info *thread);
 #define TIF_SIGPENDING		0
 #define TIF_NEED_RESCHED	1
 #define TIF_SYSCALL_TRACE	8
+#define TIF_RESTORE_SIGMASK	9       /* restore signal mask in do_signal */
 #define TIF_POLLING_NRFLAG	16
 #define TIF_USING_IWMMXT	17
 #define TIF_MEMDIE		18
@@ -144,6 +145,7 @@ extern void vfp_sync_state(struct thread_info *thread);
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
+#define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 #define _TIF_FREEZE		(1 << TIF_FREEZE)
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 94cc58e..cd1eaa0 100644
--- 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)
@@ -430,6 +430,7 @@
 #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
diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 1680e9e..534000d 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -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)
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 80b8b5c..7645048 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -47,57 +47,23 @@ 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);
+static void do_signal(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_thread_flag(TIF_RESTORE_SIGMASK);
+	return -ERESTARTNOHAND;
 }
 
 asmlinkage int 
@@ -290,7 +256,7 @@ asmlinkage int sys_sigreturn(struct pt_regs *regs)
 
 badframe:
 	force_sig(SIGSEGV, current);
-	return 0;
+	return -EFAULT;
 }
 
 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
@@ -325,7 +291,7 @@ asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 
 badframe:
 	force_sig(SIGSEGV, current);
-	return 0;
+	return -EFAULT;
 }
 
 static int
@@ -541,7 +507,7 @@ static inline void restart_syscall(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)
@@ -592,7 +558,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 
 	if (ret != 0) {
 		force_sigsegv(sig, tsk);
-		return;
+		return ret;
 	}
 
 	/*
@@ -606,6 +572,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	recalc_sigpending();
 	spin_unlock_irq(&tsk->sighand->siglock);
 
+	return ret;
 }
 
 /*
@@ -617,11 +584,12 @@ 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;
 	int signr;
+	sigset_t *oldset;
 
 	/*
 	 * We want the common case to go fast, which
@@ -630,18 +598,29 @@ 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;
 
 	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 */
+			clear_thread_flag(TIF_RESTORE_SIGMASK);
+		}
 		single_step_set(current);
-		return 1;
+		return;
 	}
 
  no_signal:
@@ -665,7 +644,7 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 				usp = (u32 __user *)regs->ARM_sp;
 
 				/*
-				 * Either we supports OABI only, or we have
+				 * Either we support OABI only, or we have
 				 * EABI with the OABI compat layer enabled.
 				 * In the later case we don't know if user
 				 * space is EABI or not, and if not we must
@@ -695,12 +674,17 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 		}
 	}
 	single_step_set(current);
-	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);
+		}
 }
 
 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);
+	if (thread_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
+		do_signal(regs, syscall);
 }
-- 
1.6.2.4