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/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 27ec2c3..78f4f87 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -120,6 +120,7 @@
#include <asm/ptrace.h>
#include <asm/compat.h>
+#include <asm/syscall.h>
#include <asm/user.h>
typedef s390_fp_regs elf_fpregset_t;
@@ -181,18 +182,31 @@
extern char elf_platform[];
#define ELF_PLATFORM (elf_platform)
-#ifdef CONFIG_64BIT
+#ifndef CONFIG_COMPAT
+#define SET_PERSONALITY(ex) \
+do { \
+ set_personality(PER_LINUX | \
+ (current->personality & (~PER_MASK))); \
+ current_thread_info()->sys_call_table = \
+ (unsigned long) &sys_call_table; \
+} while (0)
+#else /* CONFIG_COMPAT */
#define SET_PERSONALITY(ex) \
do { \
if (personality(current->personality) != PER_LINUX32) \
set_personality(PER_LINUX | \
(current->personality & ~PER_MASK)); \
- if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
+ if ((ex).e_ident[EI_CLASS] == ELFCLASS32) { \
set_thread_flag(TIF_31BIT); \
- else \
+ current_thread_info()->sys_call_table = \
+ (unsigned long) &sys_call_table_emu; \
+ } else { \
clear_thread_flag(TIF_31BIT); \
+ current_thread_info()->sys_call_table = \
+ (unsigned long) &sys_call_table; \
+ } \
} while (0)
-#endif /* CONFIG_64BIT */
+#endif /* CONFIG_COMPAT */
#define STACK_RND_MASK 0x7ffUL
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index fe7b997..cd29d2f 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -23,6 +23,7 @@
* type here is what we want [need] for both 32 bit and 64 bit systems.
*/
extern const unsigned int sys_call_table[];
+extern const unsigned int sys_call_table_emu[];
static inline long syscall_get_nr(struct task_struct *task,
struct pt_regs *regs)
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 9e2cfe0..51035e5 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -41,6 +41,7 @@
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
unsigned long flags; /* low level flags */
+ unsigned long sys_call_table; /* System call table address */
unsigned int cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
struct restart_block restart_block;
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 @@
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 @@
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 @@
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 @@
.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 @@
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