Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754203AbbFISyk (ORCPT ); Tue, 9 Jun 2015 14:54:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58385 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754185AbbFISy1 (ORCPT ); Tue, 9 Jun 2015 14:54:27 -0400 From: Denys Vlasenko To: Ingo Molnar Cc: Denys Vlasenko , Linus Torvalds , Steven Rostedt , Borislav Petkov , "H. Peter Anvin" , Andy Lutomirski , Oleg Nesterov , Frederic Weisbecker , Alexei Starovoitov , Will Drewry , Kees Cook , x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/5] x86/asm/entry/32: Shorten __audit_syscall_entry args preparation Date: Tue, 9 Jun 2015 20:54:09 +0200 Message-Id: <1433876051-26604-3-git-send-email-dvlasenk@redhat.com> In-Reply-To: <1433876051-26604-1-git-send-email-dvlasenk@redhat.com> References: <1433876051-26604-1-git-send-email-dvlasenk@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2216 Lines: 58 We use three MOVs to swap edx and ecx. We can use one XCHG instead. Expand the comments. It's difficult to keep track which arg# every register corresponds to, so spell it out. Signed-off-by: Denys Vlasenko CC: Linus Torvalds CC: Steven Rostedt CC: Ingo Molnar CC: Borislav Petkov CC: "H. Peter Anvin" CC: Andy Lutomirski CC: Oleg Nesterov CC: Frederic Weisbecker CC: Alexei Starovoitov CC: Will Drewry CC: Kees Cook CC: x86@kernel.org CC: linux-kernel@vger.kernel.org --- arch/x86/entry/entry_64_compat.S | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 0fa108c..a0ddcb6 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -178,12 +178,16 @@ sysexit_from_sys_call: #ifdef CONFIG_AUDITSYSCALL .macro auditsys_entry_common - movl %esi, %r8d /* 5th arg: 4th syscall arg */ - movl %ecx, %r9d /* swap with edx */ - movl %edx, %ecx /* 4th arg: 3rd syscall arg */ - movl %r9d, %edx /* 3rd arg: 2nd syscall arg */ - movl %ebx, %esi /* 2nd arg: 1st syscall arg */ - movl %eax, %edi /* 1st arg: syscall number */ + /* + * At this point, registers hold syscall args in 32-bit ABI: + * eax is syscall#, args are in ebx,ecx,edx,esi,edi,ebp. + * Shuffle them to match what __audit_syscall_entry() wants. + */ + movl %esi, %r8d /* arg5 (r8): 4th syscall arg */ + xchg %ecx, %edx /* arg4 (rcx): 3rd syscall arg (edx) */ + /* arg3 (rdx): 2nd syscall arg (ecx) */ + movl %ebx, %esi /* arg2 (rsi): 1st syscall arg */ + movl %eax, %edi /* arg1 (rdi): syscall number */ call __audit_syscall_entry /* * We are going to jump back to syscall dispatch. -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/