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s390: system call path micro optimization

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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>
This commit is contained in:
Martin Schwidefsky
2013-04-24 12:58:39 +02:00
parent dc7ee00d47
commit 616498813b
6 changed files with 24 additions and 13 deletions
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22
arch/s390/include/asm/elf.h
View File

@@ -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 unsigned long elf_hwcap;
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

1
arch/s390/include/asm/syscall.h
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@@ -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)

1
arch/s390/include/asm/thread_info.h
View File

@@ -41,6 +41,7 @@ struct thread_info {
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;