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>
This commit is contained in:
Martin Schwidefsky
parent
dc7ee00d47
commit
616498813b
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@ -120,6 +120,7 @@
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#include <asm/ptrace.h>
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#include <asm/compat.h>
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#include <asm/syscall.h>
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#include <asm/user.h>
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typedef s390_fp_regs elf_fpregset_t;
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@ -181,18 +182,31 @@ extern unsigned long elf_hwcap;
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extern char elf_platform[];
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#define ELF_PLATFORM (elf_platform)
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#ifdef CONFIG_64BIT
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#ifndef CONFIG_COMPAT
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#define SET_PERSONALITY(ex) \
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do { \
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set_personality(PER_LINUX | \
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(current->personality & (~PER_MASK))); \
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current_thread_info()->sys_call_table = \
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(unsigned long) &sys_call_table; \
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} while (0)
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#else /* CONFIG_COMPAT */
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#define SET_PERSONALITY(ex) \
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do { \
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if (personality(current->personality) != PER_LINUX32) \
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set_personality(PER_LINUX | \
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(current->personality & ~PER_MASK)); \
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if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
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if ((ex).e_ident[EI_CLASS] == ELFCLASS32) { \
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set_thread_flag(TIF_31BIT); \
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else \
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current_thread_info()->sys_call_table = \
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(unsigned long) &sys_call_table_emu; \
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} else { \
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clear_thread_flag(TIF_31BIT); \
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current_thread_info()->sys_call_table = \
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(unsigned long) &sys_call_table; \
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} \
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} while (0)
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#endif /* CONFIG_64BIT */
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#endif /* CONFIG_COMPAT */
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#define STACK_RND_MASK 0x7ffUL
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@ -23,6 +23,7 @@
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* type here is what we want [need] for both 32 bit and 64 bit systems.
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*/
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extern const unsigned int sys_call_table[];
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extern const unsigned int sys_call_table_emu[];
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static inline long syscall_get_nr(struct task_struct *task,
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struct pt_regs *regs)
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@ -41,6 +41,7 @@ struct thread_info {
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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unsigned long flags; /* low level flags */
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unsigned long sys_call_table; /* System call table address */
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unsigned int cpu; /* current CPU */
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int preempt_count; /* 0 => preemptable, <0 => BUG */
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struct restart_block restart_block;
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@ -35,6 +35,7 @@ int main(void)
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DEFINE(__TI_task, offsetof(struct thread_info, task));
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DEFINE(__TI_domain, offsetof(struct thread_info, exec_domain));
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DEFINE(__TI_flags, offsetof(struct thread_info, flags));
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DEFINE(__TI_sysc_table, offsetof(struct thread_info, sys_call_table));
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DEFINE(__TI_cpu, offsetof(struct thread_info, cpu));
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DEFINE(__TI_precount, offsetof(struct thread_info, preempt_count));
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DEFINE(__TI_user_timer, offsetof(struct thread_info, user_timer));
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@ -188,6 +188,7 @@ sysc_vtime:
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mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC
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sysc_do_svc:
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oi __TI_flags+3(%r12),_TIF_SYSCALL
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l %r10,__TI_sysc_table(%r12) # 31 bit system call table
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lh %r8,__PT_INT_CODE+2(%r11)
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sla %r8,2 # shift and test for svc0
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jnz sysc_nr_ok
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@ -198,7 +199,6 @@ sysc_do_svc:
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lr %r8,%r1
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sla %r8,2
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sysc_nr_ok:
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l %r10,BASED(.Lsys_call_table) # 31 bit system call table
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xc __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15)
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st %r2,__PT_ORIG_GPR2(%r11)
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st %r7,STACK_FRAME_OVERHEAD(%r15)
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@ -906,7 +906,6 @@ cleanup_idle_wait:
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.Ltrace_enter: .long do_syscall_trace_enter
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.Ltrace_exit: .long do_syscall_trace_exit
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.Lschedule_tail: .long schedule_tail
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.Lsys_call_table: .long sys_call_table
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.Lsysc_per: .long sysc_per + 0x80000000
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#ifdef CONFIG_TRACE_IRQFLAGS
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.Lhardirqs_on: .long trace_hardirqs_on_caller
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@ -216,6 +216,7 @@ sysc_vtime:
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mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC
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sysc_do_svc:
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oi __TI_flags+7(%r12),_TIF_SYSCALL
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lg %r10,__TI_sysc_table(%r12) # address of system call table
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llgh %r8,__PT_INT_CODE+2(%r11)
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slag %r8,%r8,2 # shift and test for svc 0
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jnz sysc_nr_ok
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@ -226,13 +227,6 @@ sysc_do_svc:
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sth %r1,__PT_INT_CODE+2(%r11)
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slag %r8,%r1,2
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sysc_nr_ok:
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larl %r10,sys_call_table # 64 bit system call table
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#ifdef CONFIG_COMPAT
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tm __TI_flags+5(%r12),(_TIF_31BIT>>16)
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jno sysc_noemu
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larl %r10,sys_call_table_emu # 31 bit system call table
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sysc_noemu:
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#endif
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xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
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stg %r2,__PT_ORIG_GPR2(%r11)
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stg %r7,STACK_FRAME_OVERHEAD(%r15)
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@ -1005,6 +999,7 @@ sys_call_table:
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#ifdef CONFIG_COMPAT
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#define SYSCALL(esa,esame,emu) .long emu
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.globl sys_call_table_emu
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sys_call_table_emu:
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#include "syscalls.S"
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#undef SYSCALL
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