Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753862AbbDBOhP (ORCPT ); Thu, 2 Apr 2015 10:37:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43931 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753842AbbDBOhM (ORCPT ); Thu, 2 Apr 2015 10:37:12 -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 4/9] x86/asm/entry/64: delay popping return address in stubs Date: Thu, 2 Apr 2015 16:36:13 +0200 Message-Id: <1427985378-4287-4-git-send-email-dvlasenk@redhat.com> In-Reply-To: <1427985378-4287-1-git-send-email-dvlasenk@redhat.com> References: <1427985378-4287-1-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: 2766 Lines: 107 This allows to remove "addq $8, %rsp" from five of six execve and sigreturn stubs. More importantly, it enables next optimization: faster return on execve failure. Run-tested. 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/kernel/entry_64.S | 27 +++++++++++---------------- 1 file changed, 11 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 1cf245d..060cb2e 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -418,11 +418,11 @@ END(stub_\func) ENTRY(stub_execve) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS + DEFAULT_FRAME 0, 8 + SAVE_EXTRA_REGS 8 call sys_execve return_from_stub: + addq $8, %rsp movq %rax,RAX(%rsp) RESTORE_EXTRA_REGS jmp int_ret_from_sys_call @@ -431,9 +431,8 @@ END(stub_execve) ENTRY(stub_execveat) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS + DEFAULT_FRAME 0, 8 + SAVE_EXTRA_REGS 8 call sys_execveat jmp return_from_stub CFI_ENDPROC @@ -445,8 +444,7 @@ END(stub_execveat) */ ENTRY(stub_rt_sigreturn) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 + DEFAULT_FRAME 0, 8 /* * Despite RESTORE_EXTRA_REGS in return_from_stub, * no need to SAVE_EXTRA_REGS here: @@ -461,8 +459,7 @@ END(stub_rt_sigreturn) #ifdef CONFIG_X86_X32_ABI ENTRY(stub_x32_rt_sigreturn) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 + DEFAULT_FRAME 0, 8 /* No need to SAVE_EXTRA_REGS */ call sys32_x32_rt_sigreturn jmp return_from_stub @@ -471,9 +468,8 @@ END(stub_x32_rt_sigreturn) ENTRY(stub_x32_execve) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS + DEFAULT_FRAME 0, 8 + SAVE_EXTRA_REGS 8 call compat_sys_execve jmp return_from_stub CFI_ENDPROC @@ -481,9 +477,8 @@ END(stub_x32_execve) ENTRY(stub_x32_execveat) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS + DEFAULT_FRAME 0, 8 + SAVE_EXTRA_REGS 8 call compat_sys_execveat jmp return_from_stub CFI_ENDPROC -- 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/