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;