[S390] cleanup sysc_work and io_work code
Cleanup the #ifdef mess at io_work in entry[64].S and streamline the
TIF work code of the system call and io exit path.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 52106d5..ca02b10 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -291,38 +291,36 @@
#endif
#
-# recheck if there is more work to do
-#
-sysc_work_loop:
- tm __TI_flags+7(%r9),_TIF_WORK_SVC
- jz sysc_restore # there is no work to do
-#
-# One of the work bits is on. Find out which one.
+# 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_loop:
tm __TI_flags+7(%r9),_TIF_MCCK_PENDING
jo sysc_mcck_pending
tm __TI_flags+7(%r9),_TIF_NEED_RESCHED
jo sysc_reschedule
tm __TI_flags+7(%r9),_TIF_SIGPENDING
- jnz sysc_sigpending
+ jo sysc_sigpending
tm __TI_flags+7(%r9),_TIF_NOTIFY_RESUME
- jnz sysc_notify_resume
+ jo sysc_notify_resume
tm __TI_flags+7(%r9),_TIF_RESTART_SVC
jo sysc_restart
tm __TI_flags+7(%r9),_TIF_SINGLE_STEP
jo sysc_singlestep
- j sysc_restore
-sysc_work_done:
+ j sysc_return # beware of critical section cleanup
#
# _TIF_NEED_RESCHED is set, call schedule
#
sysc_reschedule:
larl %r14,sysc_work_loop
- jg schedule # return point is sysc_return
+ jg schedule # return point is sysc_work_loop
#
# _TIF_MCCK_PENDING is set, call handler
@@ -369,7 +367,7 @@
ni __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
xc SP_SVCNR(2,%r15),SP_SVCNR(%r15) # clear svc number
la %r2,SP_PTREGS(%r15) # address of register-save area
- larl %r14,sysc_return # load adr. of system return
+ larl %r14,sysc_work_loop # load adr. of system return
jg do_single_step # branch to do_sigtrap
#
@@ -605,37 +603,27 @@
#endif
#
-# There is work todo, we need to check if we return to userspace, then
-# check, if we are in SIE, if yes leave it
+# There is work todo, find out in which context we have been interrupted:
+# 1) if we return to user space we can do all _TIF_WORK_INT work
+# 2) if we return to kernel code and kvm is enabled check if we need to
+# modify the psw to leave SIE
+# 3) if we return to kernel code and preemptive scheduling is enabled check
+# the preemption counter and if it is zero call preempt_schedule_irq
+# Before any work can be done, a switch to the kernel stack is required.
#
io_work:
tm SP_PSW+1(%r15),0x01 # returning to user ?
-#ifndef CONFIG_PREEMPT
+ jo io_work_user # yes -> do resched & signal
#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
- jnz io_work_user # yes -> no need to check for SIE
- la %r1, BASED(sie_opcode) # we return to kernel here
- lg %r2, SP_PSW+8(%r15)
- clc 0(2,%r1), 0(%r2) # is current instruction = SIE?
- jne io_restore # no-> return to kernel
- lg %r1, SP_PSW+8(%r15) # yes-> add 4 bytes to leave SIE
- aghi %r1, 4
- stg %r1, SP_PSW+8(%r15)
- j io_restore # return to kernel
-#else
- jno io_restore # no-> skip resched & signal
-#endif
-#else
- jnz io_work_user # yes -> do resched & signal
-#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
- la %r1, BASED(sie_opcode)
- lg %r2, SP_PSW+8(%r15)
- clc 0(2,%r1), 0(%r2) # is current instruction = SIE?
+ lg %r2,SP_PSW+8(%r15) # check if current instruction is SIE
+ lh %r1,0(%r2)
+ chi %r1,-19948 # signed 16 bit compare with 0xb214
jne 0f # no -> leave PSW alone
- lg %r1, SP_PSW+8(%r15) # yes-> add 4 bytes to leave SIE
- aghi %r1, 4
- stg %r1, SP_PSW+8(%r15)
+ aghi %r2,4 # yes-> add 4 bytes to leave SIE
+ stg %r2,SP_PSW+8(%r15)
0:
#endif
+#ifdef CONFIG_PREEMPT
# check for preemptive scheduling
icm %r0,15,__TI_precount(%r9)
jnz io_restore # preemption is disabled
@@ -646,21 +634,25 @@
xc __SF_BACKCHAIN(8,%r1),__SF_BACKCHAIN(%r1) # clear back chain
lgr %r15,%r1
io_resume_loop:
- tm __TI_flags+7(%r9),_TIF_NEED_RESCHED
- jno io_restore
larl %r14,io_resume_loop
- jg preempt_schedule_irq
+ tm __TI_flags+7(%r12),_TIF_NEED_RESCHED
+ jgo preempt_schedule_irq
#endif
+ j io_restore
+#
+# Need to do work before returning to userspace, switch to kernel stack
+#
io_work_user:
lg %r1,__LC_KERNEL_STACK
aghi %r1,-SP_SIZE
mvc SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15)
xc __SF_BACKCHAIN(8,%r1),__SF_BACKCHAIN(%r1) # clear back chain
lgr %r15,%r1
+
#
# One of the work bits is on. Find out which one.
-# Checked are: _TIF_SIGPENDING, _TIF_RESTORE_SIGPENDING, _TIF_NEED_RESCHED
+# Checked are: _TIF_SIGPENDING, _TIF_NOTIFY_RESUME, _TIF_NEED_RESCHED
# and _TIF_MCCK_PENDING
#
io_work_loop:
@@ -669,16 +661,10 @@
tm __TI_flags+7(%r9),_TIF_NEED_RESCHED
jo io_reschedule
tm __TI_flags+7(%r9),_TIF_SIGPENDING
- jnz io_sigpending
+ jo io_sigpending
tm __TI_flags+7(%r9),_TIF_NOTIFY_RESUME
- jnz io_notify_resume
- j io_restore
-io_work_done:
-
-#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
-sie_opcode:
- .long 0xb2140000
-#endif
+ jo io_notify_resume
+ j io_return # beware of critical section cleanup
#
# _TIF_MCCK_PENDING is set, call handler
@@ -696,8 +682,6 @@
brasl %r14,schedule # call scheduler
stnsm __SF_EMPTY(%r15),0xfc # disable I/O and ext. interrupts
TRACE_IRQS_OFF
- tm __TI_flags+7(%r9),_TIF_WORK_INT
- jz io_restore # there is no work to do
j io_work_loop
#
@@ -903,14 +887,10 @@
.quad sysc_return, sysc_leave
cleanup_table_sysc_leave:
.quad sysc_leave, sysc_done
-cleanup_table_sysc_work_loop:
- .quad sysc_work_loop, sysc_work_done
cleanup_table_io_return:
.quad io_return, io_leave
cleanup_table_io_leave:
.quad io_leave, io_done
-cleanup_table_io_work_loop:
- .quad io_work_loop, io_work_done
cleanup_critical:
clc 8(8,%r12),BASED(cleanup_table_system_call)
@@ -928,11 +908,6 @@
clc 8(8,%r12),BASED(cleanup_table_sysc_leave+8)
jl cleanup_sysc_leave
0:
- clc 8(8,%r12),BASED(cleanup_table_sysc_work_loop)
- jl 0f
- clc 8(8,%r12),BASED(cleanup_table_sysc_work_loop+8)
- jl cleanup_sysc_return
-0:
clc 8(8,%r12),BASED(cleanup_table_io_return)
jl 0f
clc 8(8,%r12),BASED(cleanup_table_io_return+8)
@@ -943,11 +918,6 @@
clc 8(8,%r12),BASED(cleanup_table_io_leave+8)
jl cleanup_io_leave
0:
- clc 8(8,%r12),BASED(cleanup_table_io_work_loop)
- jl 0f
- clc 8(8,%r12),BASED(cleanup_table_io_work_loop+8)
- jl cleanup_io_work_loop
-0:
br %r14
cleanup_system_call:
@@ -1025,12 +995,6 @@
la %r12,__LC_RETURN_PSW
br %r14
-cleanup_io_work_loop:
- mvc __LC_RETURN_PSW(8),0(%r12)
- mvc __LC_RETURN_PSW+8(8),BASED(cleanup_table_io_work_loop)
- la %r12,__LC_RETURN_PSW
- br %r14
-
cleanup_io_leave:
clc 8(8,%r12),BASED(cleanup_io_leave_insn)
je 3f