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[23.128.96.18]) by mx.google.com with ESMTP id u15si7268553edx.51.2020.11.09.06.46.58; Mon, 09 Nov 2020 06:47:21 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2020-01-29 header.b=BOw2UsNL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731487AbgKIOoH (ORCPT + 99 others); Mon, 9 Nov 2020 09:44:07 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:35228 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730597AbgKIOoE (ORCPT ); Mon, 9 Nov 2020 09:44:04 -0500 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 0A9EZBJL084167; Mon, 9 Nov 2020 14:42:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2020-01-29; bh=4S8SgdDR3pFNDkoUDRIY1QDyIkmivlrOJFce4B1D2Gw=; b=BOw2UsNLZ/qUfJ+Evhp0zLlgVouu4AbwKc46Ay7g0Q1RCNG0shWexAynh2e8zO/MD4Mp HwQmsYuM3HhF86ez7adRfEeBrZPHHQ6Xycbken1ADHZ3li6koyMSM6iTQuJ8EcIftYmh cKBVoBZivtrsV2hwaiaY53qA+u5cl+9gy23q4lHjOHB2uV7Q7fN6t1P+Fy9l7Ic59dNb 3QShgZA1/+ivgW8ljbloE6RjPhK+RlCKnar5hvUDLYXwp/Xnc9oyw8MDMVWkEZHt4uk9 0CgmbGwW+1INrZHSLPDoBSSxOtNPjzHsGZnesvYdzBuSj06OJ785OVHuwc3DbSZBc+f5 mQ== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 34p72ecdw2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 09 Nov 2020 14:42:40 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0A9Ef2MX139201; Mon, 9 Nov 2020 14:42:39 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 34p5bqka6m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 09 Nov 2020 14:42:39 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 0A9Egccs031256; Mon, 9 Nov 2020 14:42:38 GMT Received: from linux.nl.oracle.com (/10.175.27.128) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 09 Nov 2020 06:42:37 -0800 From: Alexandre Chartre To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, thomas.lendacky@amd.com, jroedel@suse.de Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com, junaids@google.com, oweisse@google.com, rppt@linux.vnet.ibm.com, graf@amazon.de, mgross@linux.intel.com, kuzuno@gmail.com, alexandre.chartre@oracle.com Subject: [RFC][PATCH 05/24] x86/entry: Implement ret_from_fork body with C code Date: Mon, 9 Nov 2020 15:44:06 +0100 Message-Id: <20201109144425.270789-6-alexandre.chartre@oracle.com> X-Mailer: git-send-email 2.18.4 In-Reply-To: <20201109144425.270789-1-alexandre.chartre@oracle.com> References: <20201109144425.270789-1-alexandre.chartre@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9799 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 malwarescore=0 phishscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 suspectscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011090103 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9799 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxlogscore=999 mlxscore=0 malwarescore=0 suspectscore=0 lowpriorityscore=0 adultscore=0 phishscore=0 priorityscore=1501 spamscore=0 impostorscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011090102 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ret_from_fork is a mix of assembly code and calls to C functions. Re-implement ret_from_fork so that it calls a single C function. Signed-off-by: Alexandre Chartre --- arch/x86/entry/common.c | 18 ++++++++++++++++++ arch/x86/entry/entry_64.S | 28 +++++----------------------- 2 files changed, 23 insertions(+), 23 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index d222212908ad..7ee15a12c115 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -35,6 +35,24 @@ #include #include +__visible noinstr void return_from_fork(struct pt_regs *regs, + struct task_struct *prev, + void (*kfunc)(void *), void *kargs) +{ + schedule_tail(prev); + if (kfunc) { + /* kernel thread */ + kfunc(kargs); + /* + * A kernel thread is allowed to return here after + * successfully calling kernel_execve(). Exit to + * userspace to complete the execve() syscall. + */ + regs->ax = 0; + } + syscall_exit_to_user_mode(regs); +} + static __always_inline void run_syscall(sys_call_ptr_t sysfunc, struct pt_regs *regs) { diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 274384644b5e..73e9cd47dc83 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -276,31 +276,13 @@ SYM_FUNC_END(__switch_to_asm) */ .pushsection .text, "ax" SYM_CODE_START(ret_from_fork) - UNWIND_HINT_EMPTY - movq %rax, %rdi - call schedule_tail /* rdi: 'prev' task parameter */ - - testq %rbx, %rbx /* from kernel_thread? */ - jnz 1f /* kernel threads are uncommon */ - -2: UNWIND_HINT_REGS - movq %rsp, %rdi - call syscall_exit_to_user_mode /* returns with IRQs disabled */ + movq %rsp, %rdi /* pt_regs */ + movq %rax, %rsi /* 'prev' task parameter */ + movq %rbx, %rdx /* kernel thread func */ + movq %r12, %rcx /* kernel thread arg */ + call return_from_fork /* returns with IRQs disabled */ jmp swapgs_restore_regs_and_return_to_usermode - -1: - /* kernel thread */ - UNWIND_HINT_EMPTY - movq %r12, %rdi - CALL_NOSPEC rbx - /* - * A kernel thread is allowed to return here after successfully - * calling kernel_execve(). Exit to userspace to complete the execve() - * syscall. - */ - movq $0, RAX(%rsp) - jmp 2b SYM_CODE_END(ret_from_fork) .popsection -- 2.18.4