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>

4 files changed, 10 insertions, 20 deletions

diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index b79f8e97f775..af7b0bda3355 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/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
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 8ae58c47dce6..2909bbcaa0d1 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/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
 
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index efd25d65ae13..3e0fc5f7ed4b 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/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;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 99851cb9591d..f27789e4e38a 100644
--- a/arch/arm/kernel/signal.c
+++ b/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 {