[S390] add TIF_SYSCALL thread flag

Add an explicit TIF_SYSCALL bit that indicates if a task is inside
a system call. The svc_code in the pt_regs structure is now only
valid if TIF_SYSCALL is set. With this definition TIF_RESTART_SVC
can be replaced with TIF_SYSCALL. Overall do_signal is a bit more
readable and it saves a few lines of code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 26 insertions, 41 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 7ff07d3a29c1..e34907560c23 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -50,11 +50,11 @@ STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
 STACK_SIZE  = 1 << STACK_SHIFT
 
 _TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
-                 _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_PER_TRAP )
+                 _TIF_MCCK_PENDING | _TIF_PER_TRAP )
 _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
                  _TIF_MCCK_PENDING)
-_TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | \
-                _TIF_SECCOMP>>8 | _TIF_SYSCALL_TRACEPOINT>>8)
+_TIF_TRACE    = (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
+                 _TIF_SYSCALL_TRACEPOINT)
 _TIF_EXIT_SIE = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING)
 
 #define BASED(name) name-system_call(%r13)
@@ -248,9 +248,10 @@ ENTRY(system_call)
 sysc_saveall:
         SAVE_ALL_SVC __LC_SVC_OLD_PSW,__LC_SAVE_AREA
         CREATE_STACK_FRAME __LC_SAVE_AREA
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         mvc     SP_PSW(16,%r15),__LC_SVC_OLD_PSW
         mvc     SP_SVC_CODE(4,%r15),__LC_SVC_ILC
-        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
+        oi      __TI_flags+7(%r12),_TIF_SYSCALL
 sysc_vtime:
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
 sysc_stime:
@@ -276,7 +277,7 @@ sysc_nr_ok:
         larl    %r10,sys_call_table_emu  # use 31 bit emulation system calls
 sysc_noemu:
 #endif
-        tm      __TI_flags+6(%r12),_TIF_SYSCALL
+        tm      __TI_flags+6(%r12),_TIF_TRACE >> 8
         mvc     SP_ARGS(8,%r15),SP_R7(%r15)
         lgf     %r8,0(%r7,%r10) # load address of system call routine
         jnz     sysc_tracesys
@@ -286,23 +287,19 @@ sysc_noemu:
 sysc_return:
         LOCKDEP_SYS_EXIT
 sysc_tif:
+        tm      SP_PSW+1(%r15),0x01     # returning to user ?
+        jno     sysc_restore
         tm      __TI_flags+7(%r12),_TIF_WORK_SVC
         jnz     sysc_work       # there is work to do (signals etc.)
+        ni      __TI_flags+7(%r12),255-_TIF_SYSCALL
 sysc_restore:
         RESTORE_ALL __LC_RETURN_PSW,1
 sysc_done:
 
 #
-# There is work to do, but first we need to check if we return to userspace.
-#
-sysc_work:
-        tm      SP_PSW+1(%r15),0x01     # returning to user ?
-        jno     sysc_restore
-
-#
 # One of the work bits is on. Find out which one.
 #
-sysc_work_tif:
+sysc_work:
         tm      __TI_flags+7(%r12),_TIF_MCCK_PENDING
         jo      sysc_mcck_pending
         tm      __TI_flags+7(%r12),_TIF_NEED_RESCHED
@@ -311,8 +308,6 @@ sysc_work_tif:
         jo      sysc_sigpending
         tm      __TI_flags+7(%r12),_TIF_NOTIFY_RESUME
         jo      sysc_notify_resume
-        tm      __TI_flags+7(%r12),_TIF_RESTART_SVC
-        jo      sysc_restart
         tm      __TI_flags+7(%r12),_TIF_PER_TRAP
         jo      sysc_singlestep
         j       sysc_return             # beware of critical section cleanup
@@ -338,11 +333,15 @@ sysc_sigpending:
         ni      __TI_flags+7(%r12),255-_TIF_PER_TRAP # clear TIF_PER_TRAP
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         brasl   %r14,do_signal          # call do_signal
-        tm      __TI_flags+7(%r12),_TIF_RESTART_SVC
-        jo      sysc_restart
-        tm      __TI_flags+7(%r12),_TIF_PER_TRAP
-        jo      sysc_singlestep
-        j       sysc_return
+        tm      __TI_flags+7(%r12),_TIF_SYSCALL
+        jno     sysc_return
+        lmg     %r2,%r6,SP_R2(%r15)     # load svc arguments
+        lghi    %r7,0                   # svc 0 returns -ENOSYS
+        lh      %r1,SP_SVC_CODE+2(%r15) # load new svc number
+        cghi    %r1,NR_syscalls
+        jnl     sysc_nr_ok              # invalid svc number -> do svc 0
+        slag    %r7,%r1,2
+        j       sysc_nr_ok              # restart svc
 
 #
 # _TIF_NOTIFY_RESUME is set, call do_notify_resume
@@ -353,24 +352,10 @@ sysc_notify_resume:
         jg      do_notify_resume        # call do_notify_resume
 
 #
-# _TIF_RESTART_SVC is set, set up registers and restart svc
-#
-sysc_restart:
-        ni      __TI_flags+7(%r12),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
-        lmg     %r2,%r6,SP_R2(%r15)     # load svc arguments
-        lghi    %r7,0                   # svc 0 returns -ENOSYS
-        lh      %r1,SP_SVC_CODE+2(%r15) # load new svc number
-        cghi    %r1,NR_syscalls
-        jnl     sysc_nr_ok              # invalid svc number -> do svc 0
-        slag    %r7,%r1,2
-        j       sysc_nr_ok              # restart svc
-
-#
 # _TIF_PER_TRAP is set, call do_per_trap
 #
 sysc_singlestep:
-        ni      __TI_flags+7(%r12),255-_TIF_PER_TRAP    # clear TIF_PER_TRAP
-        xc      SP_SVC_CODE(4,%r15),SP_SVC_CODE(%r15)   # clear svc code
+        ni      __TI_flags+7(%r12),255-(_TIF_SYSCALL | _TIF_PER_TRAP)
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         larl    %r14,sysc_return        # load adr. of system return
         jg      do_per_trap
@@ -397,7 +382,7 @@ sysc_tracego:
         basr    %r14,%r8                # call sys_xxx
         stg     %r2,SP_R2(%r15)         # store return value
 sysc_tracenogo:
-        tm      __TI_flags+6(%r12),_TIF_SYSCALL
+        tm      __TI_flags+6(%r12),_TIF_TRACE >> 8
         jz      sysc_return
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         larl    %r14,sysc_return        # return point is sysc_return
@@ -470,7 +455,6 @@ ENTRY(pgm_check_handler)
         jnz     pgm_per                  # got per exception -> special case
         SAVE_ALL_PGM __LC_PGM_OLD_PSW,__LC_SAVE_AREA
         CREATE_STACK_FRAME __LC_SAVE_AREA
-        xc      SP_SVC_CODE(4,%r15),SP_SVC_CODE(%r15)
         mvc     SP_PSW(16,%r15),__LC_PGM_OLD_PSW
         lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         HANDLE_SIE_INTERCEPT
@@ -550,9 +534,10 @@ pgm_exit2:
 pgm_svcper:
         SAVE_ALL_PGM __LC_SVC_OLD_PSW,__LC_SAVE_AREA
         CREATE_STACK_FRAME __LC_SAVE_AREA
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         mvc     SP_PSW(16,%r15),__LC_SVC_OLD_PSW
         mvc     SP_SVC_CODE(4,%r15),__LC_SVC_ILC
-        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
+        oi      __TI_flags+7(%r12),(_TIF_SYSCALL | _TIF_PER_TRAP)
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
@@ -561,7 +546,6 @@ pgm_svcper:
         mvc     __THREAD_per_cause(2,%r8),__LC_PER_CAUSE
         mvc     __THREAD_per_address(8,%r8),__LC_PER_ADDRESS
         mvc     __THREAD_per_paid(1,%r8),__LC_PER_PAID
-        oi      __TI_flags+7(%r12),_TIF_PER_TRAP # set TIF_PER_TRAP
         stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
         lmg     %r2,%r6,SP_R2(%r15)     # load svc arguments
         j       sysc_do_svc
@@ -571,7 +555,6 @@ pgm_svcper:
 #
 kernel_per:
         REENABLE_IRQS
-        xc      SP_SVC_CODE(4,%r15),SP_SVC_CODE(%r15)   # clear svc number
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         brasl   %r14,do_per_trap
         j       pgm_exit
@@ -972,9 +955,11 @@ cleanup_system_call:
         stg     %r15,32(%r12)
         stg     %r11,0(%r12)
         CREATE_STACK_FRAME __LC_SAVE_AREA
+        mvc     8(8,%r12),__LC_THREAD_INFO
+        lg      %r12,__LC_THREAD_INFO
         mvc     SP_PSW(16,%r15),__LC_SVC_OLD_PSW
         mvc     SP_SVC_CODE(4,%r15),__LC_SVC_ILC
-        mvc     8(8,%r12),__LC_THREAD_INFO
+        oi      __TI_flags+7(%r12),_TIF_SYSCALL
 cleanup_vtime:
         clc     __LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn+24)
         jhe     cleanup_stime