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Commit 295286a8 authored by Jan Beulich's avatar Jan Beulich Committed by Ingo Molnar
Browse files

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: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9f8305fe

arch/x86/ia32/ia32entry.S

+10 −16
Original line number Original line Diff line number Diff line
@@ -39,11 +39,11 @@ 
	.endm 

	.endm 





	/* clobbers %eax */	

	/* clobbers %eax */	

	.macro  CLEAR_RREGS

	.macro  CLEAR_RREGS _r9=rax

	xorl 	%eax,%eax

	xorl 	%eax,%eax

	movq	%rax,R11(%rsp)

	movq	%rax,R11(%rsp)

	movq	%rax,R10(%rsp)

	movq	%rax,R10(%rsp)

	movq	%rax,R9(%rsp)

	movq	%\_r9,R9(%rsp)

	movq	%rax,R8(%rsp)

	movq	%rax,R8(%rsp)

	.endm

	.endm
@@ -52,11 +52,10 @@ 
	 * We don't reload %eax because syscall_trace_enter() returned

	 * We don't reload %eax because syscall_trace_enter() returned

	 * the value it wants us to use in the table lookup.

	 * the value it wants us to use in the table lookup.

	 */

	 */

	.macro LOAD_ARGS32 offset

	.macro LOAD_ARGS32 offset, _r9=0

	movl \offset(%rsp),%r11d

	.if \_r9

	movl \offset+8(%rsp),%r10d

	movl \offset+16(%rsp),%r9d

	movl \offset+16(%rsp),%r9d

	movl \offset+24(%rsp),%r8d

	.endif

	movl \offset+40(%rsp),%ecx

	movl \offset+40(%rsp),%ecx

	movl \offset+48(%rsp),%edx

	movl \offset+48(%rsp),%edx

	movl \offset+56(%rsp),%esi

	movl \offset+56(%rsp),%esi
@@ -145,7 +144,7 @@ ENTRY(ia32_sysenter_target) 
	SAVE_ARGS 0,0,1

	SAVE_ARGS 0,0,1

 	/* no need to do an access_ok check here because rbp has been

 	/* no need to do an access_ok check here because rbp has been

 	   32bit zero extended */ 

 	   32bit zero extended */ 

1:	movl	(%rbp),%r9d

1:	movl	(%rbp),%ebp

 	.section __ex_table,"a"

 	.section __ex_table,"a"

 	.quad 1b,ia32_badarg

 	.quad 1b,ia32_badarg

 	.previous	

 	.previous
@@ -157,7 +156,7 @@ ENTRY(ia32_sysenter_target) 
	cmpl	$(IA32_NR_syscalls-1),%eax

	cmpl	$(IA32_NR_syscalls-1),%eax

	ja	ia32_badsys

	ja	ia32_badsys

sysenter_do_call:

sysenter_do_call:

	IA32_ARG_FIXUP 1

	IA32_ARG_FIXUP

sysenter_dispatch:

sysenter_dispatch:

	call	*ia32_sys_call_table(,%rax,8)

	call	*ia32_sys_call_table(,%rax,8)

	movq	%rax,RAX-ARGOFFSET(%rsp)

	movq	%rax,RAX-ARGOFFSET(%rsp)
@@ -234,20 +233,17 @@ sysexit_audit: 
#endif

#endif





sysenter_tracesys:

sysenter_tracesys:

	xchgl	%r9d,%ebp

#ifdef CONFIG_AUDITSYSCALL

#ifdef CONFIG_AUDITSYSCALL

	testl	$(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)

	testl	$(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)

	jz	sysenter_auditsys

	jz	sysenter_auditsys

#endif

#endif

	SAVE_REST

	SAVE_REST

	CLEAR_RREGS

	CLEAR_RREGS

	movq	%r9,R9(%rsp)

	movq	$-ENOSYS,RAX(%rsp)/* ptrace can change this for a bad syscall */

	movq	$-ENOSYS,RAX(%rsp)/* ptrace can change this for a bad syscall */

	movq	%rsp,%rdi        /* &pt_regs -> arg1 */

	movq	%rsp,%rdi        /* &pt_regs -> arg1 */

	call	syscall_trace_enter

	call	syscall_trace_enter

	LOAD_ARGS32 ARGOFFSET  /* reload args from stack in case ptrace changed it */

	LOAD_ARGS32 ARGOFFSET  /* reload args from stack in case ptrace changed it */

	RESTORE_REST

	RESTORE_REST

	xchgl	%ebp,%r9d

	cmpl	$(IA32_NR_syscalls-1),%eax

	cmpl	$(IA32_NR_syscalls-1),%eax

	ja	int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */

	ja	int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */

	jmp	sysenter_do_call

	jmp	sysenter_do_call
@@ -314,9 +310,9 @@ ENTRY(ia32_cstar_target) 
	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)

	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)

	CFI_REMEMBER_STATE

	CFI_REMEMBER_STATE

	jnz   cstar_tracesys

	jnz   cstar_tracesys

cstar_do_call:	

	cmpl $IA32_NR_syscalls-1,%eax

	cmpl $IA32_NR_syscalls-1,%eax

	ja  ia32_badsys

	ja  ia32_badsys

cstar_do_call:

	IA32_ARG_FIXUP 1

	IA32_ARG_FIXUP 1

cstar_dispatch:

cstar_dispatch:

	call *ia32_sys_call_table(,%rax,8)

	call *ia32_sys_call_table(,%rax,8)
@@ -357,15 +353,13 @@ cstar_tracesys: 
#endif

#endif

	xchgl %r9d,%ebp

	xchgl %r9d,%ebp

	SAVE_REST

	SAVE_REST

	CLEAR_RREGS

	CLEAR_RREGS r9

	movq %r9,R9(%rsp)

	movq $-ENOSYS,RAX(%rsp)	/* ptrace can change this for a bad syscall */

	movq $-ENOSYS,RAX(%rsp)	/* ptrace can change this for a bad syscall */

	movq %rsp,%rdi        /* &pt_regs -> arg1 */

	movq %rsp,%rdi        /* &pt_regs -> arg1 */

	call syscall_trace_enter

	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

	RESTORE_REST

	xchgl %ebp,%r9d

	xchgl %ebp,%r9d

	movl RSP-ARGOFFSET(%rsp), %r8d

	cmpl $(IA32_NR_syscalls-1),%eax

	cmpl $(IA32_NR_syscalls-1),%eax

	ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */

	ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */

	jmp cstar_do_call

	jmp cstar_do_call