s390: system call path micro optimization
Add a pointer to the system call table to the thread_info structure.
The TIF_31BIT bit is set or cleared by SET_PERSONALITY exactly once
for the lifetime of a process. With the pointer to the correct system
call table in thread_info the system call code in entry64.S path can
drop the check for TIF_31BIT which saves a couple of instructions.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 72f230b..4c17eec 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -216,6 +216,7 @@
mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC
sysc_do_svc:
oi __TI_flags+7(%r12),_TIF_SYSCALL
+ lg %r10,__TI_sysc_table(%r12) # address of system call table
llgh %r8,__PT_INT_CODE+2(%r11)
slag %r8,%r8,2 # shift and test for svc 0
jnz sysc_nr_ok
@@ -226,13 +227,6 @@
sth %r1,__PT_INT_CODE+2(%r11)
slag %r8,%r1,2
sysc_nr_ok:
- larl %r10,sys_call_table # 64 bit system call table
-#ifdef CONFIG_COMPAT
- tm __TI_flags+5(%r12),(_TIF_31BIT>>16)
- jno sysc_noemu
- larl %r10,sys_call_table_emu # 31 bit system call table
-sysc_noemu:
-#endif
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
stg %r2,__PT_ORIG_GPR2(%r11)
stg %r7,STACK_FRAME_OVERHEAD(%r15)
@@ -1005,6 +999,7 @@
#ifdef CONFIG_COMPAT
#define SYSCALL(esa,esame,emu) .long emu
+ .globl sys_call_table_emu
sys_call_table_emu:
#include "syscalls.S"
#undef SYSCALL