Commit 14f6e953 authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
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x86/asm/entry/64/compat: Fold the IA32_ARG_FIXUP macro into its callers 



Use of a small macro - one with conditional expansion - does
more harm than good. It obfuscates code, with minimal code
reuse.

For example, because of obfuscation it's not obvious that
in 'ia32_sysenter_target', we can optimize loading of r9 -
currently it is loaded with a detour through ebp.

This patch folds the IA32_ARG_FIXUP macro into its callers.

No code changes.

Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/4da092094cd78734384ac31e0d4ec1d8f69145a2.1424989793.git.luto@amacapital.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ebfc453e

arch/x86/ia32/ia32entry.S

+18 −14
Original line number Diff line number Diff line
@@ -30,17 +30,6 @@ 


	.section .entry.text, "ax"



	.macro IA32_ARG_FIXUP noebp=0

	movl	%edi,%r8d

	.if \noebp

	.else

	movl	%ebp,%r9d

	.endif

	xchg	%ecx,%esi

	movl	%ebx,%edi

	movl	%edx,%edx	/* zero extension */

	.endm 



	/* clobbers %rax */

	.macro  CLEAR_RREGS _r9=rax

	xorl 	%eax,%eax
@@ -178,7 +167,12 @@ sysenter_flags_fixed: 
	cmpq	$(IA32_NR_syscalls-1),%rax

	ja	ia32_badsys

sysenter_do_call:

	IA32_ARG_FIXUP

	/* 32bit syscall -> 64bit C ABI argument conversion */

	movl	%edi,%r8d	/* arg5 */

	movl	%ebp,%r9d	/* arg6 */

	xchg	%ecx,%esi	/* rsi:arg2, rcx:arg4 */

	movl	%ebx,%edi	/* arg1 */

	movl	%edx,%edx	/* arg3 (zero extension) */

sysenter_dispatch:

	call	*ia32_sys_call_table(,%rax,8)

	movq	%rax,RAX(%rsp)
@@ -360,7 +354,12 @@ ENTRY(ia32_cstar_target) 
	cmpq $IA32_NR_syscalls-1,%rax

	ja  ia32_badsys

cstar_do_call:

	IA32_ARG_FIXUP 1

	/* 32bit syscall -> 64bit C ABI argument conversion */

	movl	%edi,%r8d	/* arg5 */

	/* r9 already loaded */	/* arg6 */

	xchg	%ecx,%esi	/* rsi:arg2, rcx:arg4 */

	movl	%ebx,%edi	/* arg1 */

	movl	%edx,%edx	/* arg3 (zero extension) */

cstar_dispatch:

	call *ia32_sys_call_table(,%rax,8)

	movq %rax,RAX(%rsp)
@@ -477,7 +476,12 @@ ENTRY(ia32_syscall) 
	cmpq $(IA32_NR_syscalls-1),%rax

	ja ia32_badsys

ia32_do_call:

	IA32_ARG_FIXUP

	/* 32bit syscall -> 64bit C ABI argument conversion */

	movl %edi,%r8d	/* arg5 */

	movl %ebp,%r9d	/* arg6 */

	xchg %ecx,%esi	/* rsi:arg2, rcx:arg4 */

	movl %ebx,%edi	/* arg1 */

	movl %edx,%edx	/* arg3 (zero extension) */

	call *ia32_sys_call_table(,%rax,8) # xxx: rip relative

ia32_sysret:

	movq %rax,RAX(%rsp)

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