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x86-64: slightly stream-line 32-bit syscall entry code 

Avoid updating registers or memory twice as well as needlessly loading
or copying registers.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jan Beulich 2008-08-29 13:21:11 +01:00 committed by Ingo Molnar
parent 9f8305fe16
commit 295286a891
1 changed files with 10 additions and 16 deletions
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26
arch/x86/ia32/ia32entry.S
View File

@ -39,11 +39,11 @@
.endm
/* clobbers %eax */
.macro CLEAR_RREGS
.macro CLEAR_RREGS _r9=rax
xorl %eax,%eax
movq %rax,R11(%rsp)
movq %rax,R10(%rsp)
movq %rax,R9(%rsp)
movq %\_r9,R9(%rsp)
movq %rax,R8(%rsp)
.endm
@ -52,11 +52,10 @@
* We don't reload %eax because syscall_trace_enter() returned
* the value it wants us to use in the table lookup.
*/
.macro LOAD_ARGS32 offset
movl \offset(%rsp),%r11d
movl \offset+8(%rsp),%r10d
.macro LOAD_ARGS32 offset, _r9=0
.if \_r9
movl \offset+16(%rsp),%r9d
movl \offset+24(%rsp),%r8d
.endif
movl \offset+40(%rsp),%ecx
movl \offset+48(%rsp),%edx
movl \offset+56(%rsp),%esi
@ -145,7 +144,7 @@ ENTRY(ia32_sysenter_target)
SAVE_ARGS 0,0,1
/* no need to do an access_ok check here because rbp has been
32bit zero extended */
1: movl (%rbp),%r9d
1: movl (%rbp),%ebp
.section __ex_table,"a"
.quad 1b,ia32_badarg
.previous
@ -157,7 +156,7 @@ ENTRY(ia32_sysenter_target)
cmpl $(IA32_NR_syscalls-1),%eax
ja ia32_badsys
sysenter_do_call:
IA32_ARG_FIXUP 1
IA32_ARG_FIXUP
sysenter_dispatch:
call *ia32_sys_call_table(,%rax,8)
movq %rax,RAX-ARGOFFSET(%rsp)
@ -234,20 +233,17 @@ sysexit_audit:
#endif
sysenter_tracesys:
xchgl %r9d,%ebp
#ifdef CONFIG_AUDITSYSCALL
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)
jz sysenter_auditsys
#endif
SAVE_REST
CLEAR_RREGS
movq %r9,R9(%rsp)
movq $-ENOSYS,RAX(%rsp)/* ptrace can change this for a bad syscall */
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
RESTORE_REST
xchgl %ebp,%r9d
cmpl $(IA32_NR_syscalls-1),%eax
ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */
jmp sysenter_do_call
@ -314,9 +310,9 @@ ENTRY(ia32_cstar_target)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
CFI_REMEMBER_STATE
jnz cstar_tracesys
cstar_do_call:
cmpl $IA32_NR_syscalls-1,%eax
ja ia32_badsys
cstar_do_call:
IA32_ARG_FIXUP 1
cstar_dispatch:
call *ia32_sys_call_table(,%rax,8)
@ -357,15 +353,13 @@ cstar_tracesys:
#endif
xchgl %r9d,%ebp
SAVE_REST
CLEAR_RREGS
movq %r9,R9(%rsp)
CLEAR_RREGS r9
movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
LOAD_ARGS32 ARGOFFSET, 1 /* reload args from stack in case ptrace changed it */
RESTORE_REST
xchgl %ebp,%r9d
movl RSP-ARGOFFSET(%rsp), %r8d
cmpl $(IA32_NR_syscalls-1),%eax
ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */
jmp cstar_do_call