From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932766AbbCQQnh (ORCPT ); Tue, 17 Mar 2015 12:43:37 -0400 Received: from terminus.zytor.com ([198.137.202.10]:54677 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932151AbbCQQne (ORCPT ); Tue, 17 Mar 2015 12:43:34 -0400 Date: Tue, 17 Mar 2015 09:42:54 -0700 From: tip-bot for Ingo Molnar Message-ID: Cc: linux-kernel@vger.kernel.org, bp@alien8.de, hpa@zytor.com, luto@amacapital.net, oleg@redhat.com, dvlasenk@redhat.com, tglx@linutronix.de, fweisbec@gmail.com, mingo@kernel.org, ast@plumgrid.com, torvalds@linux-foundation.org, keescook@chromium.org, wad@chromium.org, rostedt@goodmis.org Reply-To: wad@chromium.org, keescook@chromium.org, rostedt@goodmis.org, dvlasenk@redhat.com, tglx@linutronix.de, fweisbec@gmail.com, mingo@kernel.org, ast@plumgrid.com, torvalds@linux-foundation.org, oleg@redhat.com, linux-kernel@vger.kernel.org, bp@alien8.de, hpa@zytor.com, luto@amacapital.net In-Reply-To: <1426599779-8010-2-git-send-email-dvlasenk@redhat.com> References: <1426599779-8010-2-git-send-email-dvlasenk@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/asm/entry/64: Simplify 'old_rsp' usage Git-Commit-ID: 9854dd74c3f6af8d9d527de86c6074b7ed0495f1 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: 9854dd74c3f6af8d9d527de86c6074b7ed0495f1 Gitweb: http://git.kernel.org/tip/9854dd74c3f6af8d9d527de86c6074b7ed0495f1 Author: Ingo Molnar AuthorDate: Tue, 17 Mar 2015 14:42:59 +0100 Committer: Ingo Molnar CommitDate: Tue, 17 Mar 2015 16:01:41 +0100 x86/asm/entry/64: Simplify 'old_rsp' usage Remove all manipulations of PER_CPU(old_rsp) in C code: - it is not used on SYSRET return anymore, and system entries are atomic, so updating it from the fork and context switch paths is pointless. - Tweak a few related comments as well: we no longer have a "partial stack frame" on entry, ever. Based on (split out of) patch from Denys Vlasenko. Originally-from: Denys Vlasenko Tested-by: Borislav Petkov Acked-by: Borislav Petkov Cc: Alexei Starovoitov Cc: Andy Lutomirski Cc: Denys Vlasenko 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/1426599779-8010-2-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/processor.h | 5 ----- arch/x86/kernel/process_64.c | 2 -- 2 files changed, 7 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 5abd9a5..3ac5092 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -905,11 +905,6 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk); #define task_pt_regs(tsk) ((struct pt_regs *)(tsk)->thread.sp0 - 1) extern unsigned long KSTK_ESP(struct task_struct *task); -/* - * User space RSP while inside the SYSCALL fast path - */ -DECLARE_PER_CPU(unsigned long, old_rsp); - #endif /* CONFIG_X86_64 */ extern void start_thread(struct pt_regs *regs, unsigned long new_ip, diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index e8c124a..59696d7 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -238,7 +238,6 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip, current->thread.usersp = new_sp; regs->ip = new_ip; regs->sp = new_sp; - this_cpu_write(old_rsp, new_sp); regs->cs = _cs; regs->ss = _ss; regs->flags = X86_EFLAGS_IF; @@ -399,7 +398,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) * Switch the PDA and FPU contexts. */ prev->usersp = this_cpu_read(old_rsp); - this_cpu_write(old_rsp, next->usersp); this_cpu_write(current_task, next_p); /*