From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758885AbbJINNS (ORCPT ); Fri, 9 Oct 2015 09:13:18 -0400 Received: from terminus.zytor.com ([198.137.202.10]:46112 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751231AbbJINNO (ORCPT ); Fri, 9 Oct 2015 09:13:14 -0400 Date: Fri, 9 Oct 2015 06:12:24 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: tglx@linutronix.de, luto@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, brgerst@gmail.com, luto@amacapital.net, bp@alien8.de, dvlasenk@redhat.com, peterz@infradead.org, mingo@kernel.org, torvalds@linux-foundation.org Reply-To: hpa@zytor.com, brgerst@gmail.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, luto@kernel.org, peterz@infradead.org, mingo@kernel.org, dvlasenk@redhat.com, torvalds@linux-foundation.org, luto@amacapital.net, bp@alien8.de In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/entry/32: Open-code return tracking from fork and kthreads Git-Commit-ID: 39e8701f33d65c7f51d749a5d12a1379065e0926 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: 39e8701f33d65c7f51d749a5d12a1379065e0926 Gitweb: http://git.kernel.org/tip/39e8701f33d65c7f51d749a5d12a1379065e0926 Author: Andy Lutomirski AuthorDate: Mon, 5 Oct 2015 17:48:13 -0700 Committer: Ingo Molnar CommitDate: Fri, 9 Oct 2015 09:41:10 +0200 x86/entry/32: Open-code return tracking from fork and kthreads syscall_exit is going away, and return tracing is just a function call now, so open-code the two non-syscall 32-bit users. While we're at it, update the big register layout comment. Signed-off-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/a6b3c472fda7cda0e368c3ccd553dea7447dfdd2.1444091585.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/entry_32.S | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index a08ded4..36b6beb 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -3,7 +3,7 @@ * * entry_32.S contains the system-call and low-level fault and trap handling routines. * - * Stack layout in 'syscall_exit': + * Stack layout while running C code: * ptrace needs to have all registers on the stack. * If the order here is changed, it needs to be * updated in fork.c:copy_process(), signal.c:do_signal(), @@ -211,7 +211,11 @@ ENTRY(ret_from_fork) popl %eax pushl $0x0202 # Reset kernel eflags popfl - jmp syscall_exit + + /* When we fork, we trace the syscall return in the child, too. */ + movl %esp, %eax + call syscall_return_slowpath + jmp restore_all END(ret_from_fork) ENTRY(ret_from_kernel_thread) @@ -224,7 +228,15 @@ ENTRY(ret_from_kernel_thread) movl PT_EBP(%esp), %eax call *PT_EBX(%esp) movl $0, PT_EAX(%esp) - jmp syscall_exit + + /* + * Kernel threads return to userspace as if returning from a syscall. + * We should check whether anything actually uses this path and, if so, + * consider switching it over to ret_from_fork. + */ + movl %esp, %eax + call syscall_return_slowpath + jmp restore_all ENDPROC(ret_from_kernel_thread) /*