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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2013-04-24 12:58:39 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-04-26 09:07:05 +0200
commit616498813b11ffefe1ed36b9f2e4fd2cdbd22f15 (patch)
tree1748b3171ab5cf1ada0c0bbeef285352c37edfcd /arch/s390/kernel
parentdc7ee00d4771b3218b10e09e1071ee6eb176d381 (diff)
downloadop-kernel-dev-616498813b11ffefe1ed36b9f2e4fd2cdbd22f15.zip
op-kernel-dev-616498813b11ffefe1ed36b9f2e4fd2cdbd22f15.tar.gz
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>
Diffstat (limited to 'arch/s390/kernel')
-rw-r--r--arch/s390/kernel/asm-offsets.c1
-rw-r--r--arch/s390/kernel/entry.S3
-rw-r--r--arch/s390/kernel/entry64.S9
3 files changed, 4 insertions, 9 deletions
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index fface87..7a82f9f 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -35,6 +35,7 @@ int main(void)
DEFINE(__TI_task, offsetof(struct thread_info, task));
DEFINE(__TI_domain, offsetof(struct thread_info, exec_domain));
DEFINE(__TI_flags, offsetof(struct thread_info, flags));
+ DEFINE(__TI_sysc_table, offsetof(struct thread_info, sys_call_table));
DEFINE(__TI_cpu, offsetof(struct thread_info, cpu));
DEFINE(__TI_precount, offsetof(struct thread_info, preempt_count));
DEFINE(__TI_user_timer, offsetof(struct thread_info, user_timer));
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 17d5cc0..4d5e6f8 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -188,6 +188,7 @@ sysc_vtime:
mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC
sysc_do_svc:
oi __TI_flags+3(%r12),_TIF_SYSCALL
+ l %r10,__TI_sysc_table(%r12) # 31 bit system call table
lh %r8,__PT_INT_CODE+2(%r11)
sla %r8,2 # shift and test for svc0
jnz sysc_nr_ok
@@ -198,7 +199,6 @@ sysc_do_svc:
lr %r8,%r1
sla %r8,2
sysc_nr_ok:
- l %r10,BASED(.Lsys_call_table) # 31 bit system call table
xc __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15)
st %r2,__PT_ORIG_GPR2(%r11)
st %r7,STACK_FRAME_OVERHEAD(%r15)
@@ -906,7 +906,6 @@ cleanup_idle_wait:
.Ltrace_enter: .long do_syscall_trace_enter
.Ltrace_exit: .long do_syscall_trace_exit
.Lschedule_tail: .long schedule_tail
-.Lsys_call_table: .long sys_call_table
.Lsysc_per: .long sysc_per + 0x80000000
#ifdef CONFIG_TRACE_IRQFLAGS
.Lhardirqs_on: .long trace_hardirqs_on_caller
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 @@ sysc_vtime:
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 @@ sysc_do_svc:
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 @@ sys_call_table:
#ifdef CONFIG_COMPAT
#define SYSCALL(esa,esame,emu) .long emu
+ .globl sys_call_table_emu
sys_call_table_emu:
#include "syscalls.S"
#undef SYSCALL
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