ARM: 7474/1: get rid of TIF_SYSCALL_RESTARTSYS

just let do_work_pending() return 1 on normal local restarts and
-1 on those that had been caused by ERESTART_RESTARTBLOCK (and 0
is still "all done, sod off to userland now").  And let the asm
glue flip scno to restart_syscall(2) one if it got negative from
us...

[will: resolved conflicts with audit fixes]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/thread_info.h

@@ -148,7 +148,6 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
 #define TIF_NOTIFY_RESUME	2	/* callback before returning to user */
 #define TIF_SYSCALL_TRACE	8
 #define TIF_SYSCALL_AUDIT	9
-#define TIF_SYSCALL_RESTARTSYS	10
 #define TIF_POLLING_NRFLAG	16
 #define TIF_USING_IWMMXT	17
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
@@ -164,11 +163,9 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
-#define _TIF_SYSCALL_RESTARTSYS	(1 << TIF_SYSCALL_RESTARTSYS)
 
 /* Checks for any syscall work in entry-common.S */
-#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
-			   _TIF_SYSCALL_RESTARTSYS)
+#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
 
 /*
  * Change these and you break ASM code in entry-common.S

arch/arm/kernel/entry-common.S

@@ -54,8 +54,9 @@ work_pending:
 	mov	r0, sp				@ 'regs'
 	mov	r2, why				@ 'syscall'
 	bl	do_work_pending
-	tst	r0, #1
+	cmp	r0, #0
 	beq	no_work_pending
+	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
 	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6
 	b	local_restart			@ ... and off we go
 

arch/arm/kernel/ptrace.c

@@ -941,12 +941,7 @@ static int ptrace_syscall_trace(struct pt_regs *regs, int scno,
 
 asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
 {
-	int ret;
-
-	if (test_and_clear_thread_flag(TIF_SYSCALL_RESTARTSYS))
-		scno = __NR_restart_syscall - __NR_SYSCALL_BASE;
-
-	ret = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_ENTER);
+	int ret = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_ENTER);
 	audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0, regs->ARM_r1,
 			    regs->ARM_r2, regs->ARM_r3);
 	return ret;

arch/arm/kernel/signal.c

@@ -591,7 +591,7 @@ static int do_signal(struct pt_regs *regs, int syscall)
 		 */
 		switch (retval) {
 		case -ERESTART_RESTARTBLOCK:
-			restart++;
+			restart -= 2;
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
@@ -629,13 +629,9 @@ static int do_signal(struct pt_regs *regs, int syscall)
 		return 0;
 	}
 
-	if (unlikely(restart)) {
-		if (restart > 1)
-			set_thread_flag(TIF_SYSCALL_RESTARTSYS);
-		regs->ARM_pc = continue_addr;
-	}
-
 	restore_saved_sigmask();
+	if (unlikely(restart))
+		regs->ARM_pc = continue_addr;
 	return restart;
 }
 
@@ -650,13 +646,14 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 				return 0;
 			local_irq_enable();
 			if (thread_flags & _TIF_SIGPENDING) {
-				if (unlikely(do_signal(regs, syscall))) {
+				int restart = do_signal(regs, syscall);
+				if (unlikely(restart)) {
 					/*
 					 * Restart without handlers.
 					 * Deal with it without leaving
 					 * the kernel space.
 					 */
-					return 1;
+					return restart;
 				}
 				syscall = 0;
 			} else {