From 616498813b11ffefe1ed36b9f2e4fd2cdbd22f15 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Wed, 24 Apr 2013 12:58:39 +0200 Subject: [PATCH] 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 --- arch/s390/include/asm/elf.h | 22 ++++++++++++++++++---- arch/s390/include/asm/syscall.h | 1 + arch/s390/include/asm/thread_info.h | 1 + arch/s390/kernel/asm-offsets.c | 1 + arch/s390/kernel/entry.S | 3 +-- arch/s390/kernel/entry64.S | 9 ++------- 6 files changed, 24 insertions(+), 13 deletions(-) diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h index 27ec2c3f95ac..78f4f8711d58 100644 --- a/arch/s390/include/asm/elf.h +++ b/arch/s390/include/asm/elf.h @@ -120,6 +120,7 @@ #include #include +#include #include 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 diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h index fe7b99759e12..cd29d2f4e4f3 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 9e2cfe0349c3..51035e5d86cb 100644 --- a/arch/s390/include/asm/thread_info.h +++ b/arch/s390/include/asm/thread_info.h @@ -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; diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c index fface87056eb..7a82f9f70100 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 17d5cc057893..4d5e6f8a7978 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 72f230baf5d1..4c17eece707e 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 -- 2.30.2