Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753743AbbDBOgz (ORCPT ); Thu, 2 Apr 2015 10:36:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55640 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753660AbbDBOgw (ORCPT ); Thu, 2 Apr 2015 10:36:52 -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 5/9] x86/asm/entry/64: if execve fails, no need to use IRET return Date: Thu, 2 Apr 2015 16:36:14 +0200 Message-Id: <1427985378-4287-5-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: 2074 Lines: 76 This makes failed execve's faster. This also enables a future possible optimization: SAVE_EXTRA_REGS can be avoided in execve's. 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 | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 060cb2e..e8f2aeb 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -421,6 +421,11 @@ ENTRY(stub_execve) DEFAULT_FRAME 0, 8 SAVE_EXTRA_REGS 8 call sys_execve +return_from_exec: + testl %eax,%eax + jz return_from_stub + /* exec failed, can use fast SYSRET code path in this case */ + ret return_from_stub: addq $8, %rsp movq %rax,RAX(%rsp) @@ -434,7 +439,7 @@ ENTRY(stub_execveat) DEFAULT_FRAME 0, 8 SAVE_EXTRA_REGS 8 call sys_execveat - jmp return_from_stub + jmp return_from_exec CFI_ENDPROC END(stub_execveat) @@ -471,7 +476,7 @@ ENTRY(stub_x32_execve) DEFAULT_FRAME 0, 8 SAVE_EXTRA_REGS 8 call compat_sys_execve - jmp return_from_stub + jmp return_from_exec CFI_ENDPROC END(stub_x32_execve) @@ -480,7 +485,7 @@ ENTRY(stub_x32_execveat) DEFAULT_FRAME 0, 8 SAVE_EXTRA_REGS 8 call compat_sys_execveat - jmp return_from_stub + jmp return_from_exec CFI_ENDPROC END(stub_x32_execveat) -- 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/