From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753543AbbC0Lrh (ORCPT ); Fri, 27 Mar 2015 07:47:37 -0400 Received: from terminus.zytor.com ([198.137.202.10]:37342 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922AbbC0Lrd (ORCPT ); Fri, 27 Mar 2015 07:47:33 -0400 Date: Fri, 27 Mar 2015 04:46:44 -0700 From: tip-bot for Denys Vlasenko Message-ID: Cc: luto@amacapital.net, fweisbec@gmail.com, linux-kernel@vger.kernel.org, ast@plumgrid.com, dvlasenk@redhat.com, bp@alien8.de, mingo@kernel.org, wad@chromium.org, oleg@redhat.com, rostedt@goodmis.org, torvalds@linux-foundation.org, hpa@zytor.com, keescook@chromium.org, tglx@linutronix.de Reply-To: ast@plumgrid.com, dvlasenk@redhat.com, luto@amacapital.net, fweisbec@gmail.com, linux-kernel@vger.kernel.org, wad@chromium.org, rostedt@goodmis.org, oleg@redhat.com, bp@alien8.de, mingo@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com, keescook@chromium.org, tglx@linutronix.de In-Reply-To: <1427303896-24023-1-git-send-email-dvlasenk@redhat.com> References: <1427303896-24023-1-git-send-email-dvlasenk@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/asm/entry/64: Use better label name, fix comments Git-Commit-ID: 146b2b097d7a322b64b88a927fc5d870fc79a60b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 146b2b097d7a322b64b88a927fc5d870fc79a60b Gitweb: http://git.kernel.org/tip/146b2b097d7a322b64b88a927fc5d870fc79a60b Author: Denys Vlasenko AuthorDate: Wed, 25 Mar 2015 18:18:13 +0100 Committer: Ingo Molnar CommitDate: Fri, 27 Mar 2015 09:57:05 +0100 x86/asm/entry/64: Use better label name, fix comments A named label "ret_from_sys_call" implies that there are jumps to this location from elsewhere, as happens with many other labels in this file. But this label is used only by the JMP a few insns above. To make that obvious, use local numeric label instead. Improve comments: "and return regs->ax" isn't too informative. We always return regs->ax. The comment suggesting that it'd be cool to use rip relative addressing for CALL is deleted. It's unclear why that would be an improvement - we aren't striving to use position-independent code here. PIC code here would require something like LEA sys_call_table(%rip),reg + CALL *(reg,%rax*8)... "iret frame is also incomplete" is no longer true, fix that too. Also fix typo in comment. Signed-off-by: Denys Vlasenko Cc: Alexei Starovoitov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Steven Rostedt Cc: Will Drewry Link: http://lkml.kernel.org/r/1427303896-24023-1-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/entry_64.S | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index bf9afad..9988c4b 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -258,16 +258,15 @@ system_call_fastpath: andl $__SYSCALL_MASK,%eax cmpl $__NR_syscall_max,%eax #endif - ja ret_from_sys_call /* and return regs->ax */ + ja 1f /* return -ENOSYS (already in pt_regs->ax) */ movq %r10,%rcx - call *sys_call_table(,%rax,8) # XXX: rip relative + call *sys_call_table(,%rax,8) movq %rax,RAX(%rsp) +1: /* - * Syscall return path ending with SYSRET (fast path) - * Has incompletely filled pt_regs, iret frame is also incomplete. + * Syscall return path ending with SYSRET (fast path). + * Has incompletely filled pt_regs. */ -ret_from_sys_call: - LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF @@ -1407,7 +1406,7 @@ ENTRY(nmi) * NMI. */ - /* Use %rdx as out temp variable throughout */ + /* Use %rdx as our temp variable throughout */ pushq_cfi %rdx CFI_REL_OFFSET rdx, 0