From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 558A2C18E5B for ; Tue, 10 Mar 2020 14:04:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23AF324677 for ; Tue, 10 Mar 2020 14:04:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="T5C1pYb9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727229AbgCJOEa (ORCPT ); Tue, 10 Mar 2020 10:04:30 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:50070 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726390AbgCJOE2 (ORCPT ); Tue, 10 Mar 2020 10:04:28 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02AE3F7w007778; Tue, 10 Mar 2020 14:03:48 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=tmA+B5ZoHJ9yCSrn3VxvfaLD+xQtiRYNAjpJicXo2VE=; b=T5C1pYb9oHB3d8HnpM+s7BRNRyN6Z9wez8gPCX+mplF07jZppC9pZKpRG7Nx8OVIDEgb S5xI8e5QCD/8m/lTJlw/lqBSmH5GqtD5IR1ZLgpuJydUykS/n+Q+/Aj08yP/3RPLIBU4 opmZBoRZypciyo+Jt8UItwALSgJkKMU5Psa5Gfpm237LNAUSKK+q02ajvcRfZYTVV5GA jVLcWOyvjzygqw0lzH2hxTNHCbhcos9CMPCz9uW3Z/UlPXyCZTbvtsemIm4xIoOl8oJZ xAbscnUw7oayKFsuee3a0oJlgCcq2VZ6S8xB1fWnJll/9xqfZsiawF5yTQCXywVHf++O dg== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2120.oracle.com with ESMTP id 2yp7hm23d5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Mar 2020 14:03:47 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02AE2Qs5132062; Tue, 10 Mar 2020 14:03:46 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 2yp8nswtk4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Mar 2020 14:03:46 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 02AE3ii6024764; Tue, 10 Mar 2020 14:03:45 GMT Received: from [192.168.8.5] (/213.41.92.70) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 10 Mar 2020 07:03:44 -0700 Subject: Re: [patch part-II V2 12/13] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() To: Thomas Gleixner , LKML Cc: x86@kernel.org, Steven Rostedt , Brian Gerst , Juergen Gross , Frederic Weisbecker References: <20200308222359.370649591@linutronix.de> <20200308222610.150951641@linutronix.de> From: Alexandre Chartre Organization: Oracle Corporation Message-ID: Date: Tue, 10 Mar 2020 15:03:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20200308222610.150951641@linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9555 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxscore=0 phishscore=0 spamscore=0 malwarescore=0 adultscore=0 suspectscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003100095 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9555 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 spamscore=0 priorityscore=1501 clxscore=1015 mlxscore=0 impostorscore=0 mlxlogscore=999 suspectscore=0 phishscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003100095 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/8/20 11:24 PM, Thomas Gleixner wrote: > This is another step towards more C-code and less convoluted ASM. > > Note, that trace_hardirqs_on() is still incorrect vs. RCU idle when the > tracepoint is used by e.g. BPF. Will be addressed in the next step. > > Signed-off-by: Thomas Gleixner > --- > > V2: New patch simplifying the conversion and addressing Alex' review > comment of redundant tracing. > --- > arch/x86/entry/common.c | 1 + > arch/x86/entry/entry_32.S | 12 ++++-------- > arch/x86/entry/entry_64.S | 4 ---- > arch/x86/entry/entry_64_compat.S | 14 +++++--------- > 4 files changed, 10 insertions(+), 21 deletions(-) Reviewed-by: Alexandre Chartre alex. > --- a/arch/x86/entry/common.c > +++ b/arch/x86/entry/common.c > @@ -253,6 +253,7 @@ static noinline void __prepare_exit_to_u > > user_enter_irqoff(); > mds_user_clear_cpu_buffers(); > + trace_hardirqs_on(); > } > NOKPROBE_SYMBOL(prepare_exit_to_usermode); > > --- a/arch/x86/entry/entry_32.S > +++ b/arch/x86/entry/entry_32.S > @@ -811,8 +811,7 @@ SYM_CODE_START(ret_from_fork) > /* When we fork, we trace the syscall return in the child, too. */ > movl %esp, %eax > call syscall_return_slowpath > - STACKLEAK_ERASE > - jmp restore_all > + jmp .Lsyscall_32_done > > /* kernel thread */ > 1: movl %edi, %eax > @@ -855,7 +854,7 @@ SYM_CODE_START_LOCAL(ret_from_exception) > TRACE_IRQS_OFF > movl %esp, %eax > call prepare_exit_to_usermode > - jmp restore_all > + jmp restore_all_switch_stack > SYM_CODE_END(ret_from_exception) > > SYM_ENTRY(__begin_SYSENTER_singlestep_region, SYM_L_GLOBAL, SYM_A_NONE) > @@ -968,8 +967,7 @@ SYM_FUNC_START(entry_SYSENTER_32) > > STACKLEAK_ERASE > > -/* Opportunistic SYSEXIT */ > - TRACE_IRQS_ON /* User mode traces as IRQs on. */ > + /* Opportunistic SYSEXIT */ > > /* > * Setup entry stack - we keep the pointer in %eax and do the > @@ -1072,11 +1070,9 @@ SYM_FUNC_START(entry_INT80_32) > movl %esp, %eax > call do_int80_syscall_32 > .Lsyscall_32_done: > - > STACKLEAK_ERASE > > -restore_all: > - TRACE_IRQS_ON > +restore_all_switch_stack: > SWITCH_TO_ENTRY_STACK > CHECK_AND_APPLY_ESPFIX > > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -172,8 +172,6 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_h > movq %rsp, %rsi > call do_syscall_64 /* returns with IRQs disabled */ > > - TRACE_IRQS_ON /* return enables interrupts */ > - > /* > * Try to use SYSRET instead of IRET if we're returning to > * a completely clean 64-bit userspace context. If we're not, > @@ -340,7 +338,6 @@ SYM_CODE_START(ret_from_fork) > UNWIND_HINT_REGS > movq %rsp, %rdi > call syscall_return_slowpath /* returns with IRQs disabled */ > - TRACE_IRQS_ON /* user mode is traced as IRQS on */ > jmp swapgs_restore_regs_and_return_to_usermode > > 1: > @@ -617,7 +614,6 @@ SYM_CODE_START_LOCAL(common_interrupt) > .Lretint_user: > mov %rsp,%rdi > call prepare_exit_to_usermode > - TRACE_IRQS_ON > > SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL) > #ifdef CONFIG_DEBUG_ENTRY > --- a/arch/x86/entry/entry_64_compat.S > +++ b/arch/x86/entry/entry_64_compat.S > @@ -132,8 +132,8 @@ SYM_FUNC_START(entry_SYSENTER_compat) > movq %rsp, %rdi > call do_fast_syscall_32 > /* XEN PV guests always use IRET path */ > - ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \ > - "jmp .Lsyscall_32_done", X86_FEATURE_XENPV > + ALTERNATIVE "testl %eax, %eax; jz swapgs_restore_regs_and_return_to_usermode", \ > + "jmp swapgs_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV > jmp sysret32_from_system_call > > .Lsysenter_fix_flags: > @@ -244,8 +244,8 @@ SYM_INNER_LABEL(entry_SYSCALL_compat_aft > movq %rsp, %rdi > call do_fast_syscall_32 > /* XEN PV guests always use IRET path */ > - ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \ > - "jmp .Lsyscall_32_done", X86_FEATURE_XENPV > + ALTERNATIVE "testl %eax, %eax; jz swapgs_restore_regs_and_return_to_usermode", \ > + "jmp swapgs_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV > > /* Opportunistic SYSRET */ > sysret32_from_system_call: > @@ -254,7 +254,7 @@ SYM_INNER_LABEL(entry_SYSCALL_compat_aft > * stack. So let's erase the thread stack right now. > */ > STACKLEAK_ERASE > - TRACE_IRQS_ON /* User mode traces as IRQs on. */ > + > movq RBX(%rsp), %rbx /* pt_regs->rbx */ > movq RBP(%rsp), %rbp /* pt_regs->rbp */ > movq EFLAGS(%rsp), %r11 /* pt_regs->flags (in r11) */ > @@ -393,9 +393,5 @@ SYM_CODE_START(entry_INT80_compat) > > movq %rsp, %rdi > call do_int80_syscall_32 > -.Lsyscall_32_done: > - > - /* Go back to user mode. */ > - TRACE_IRQS_ON > jmp swapgs_restore_regs_and_return_to_usermode > SYM_CODE_END(entry_INT80_compat) >