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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F08AC433EF for ; Fri, 26 Nov 2021 10:24:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377043AbhKZK1o (ORCPT ); Fri, 26 Nov 2021 05:27:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232599AbhKZKZX (ORCPT ); Fri, 26 Nov 2021 05:25:23 -0500 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2C53C0613B6 for ; Fri, 26 Nov 2021 02:13:52 -0800 (PST) Received: by mail-pf1-x431.google.com with SMTP id z6so8478482pfe.7 for ; Fri, 26 Nov 2021 02:13:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=+8sSW0BteOPYD+HpYHPkb+QlFYOFvs+MADGM7L6C9w4=; b=lQCwAMdzpa2uNSpuCkBg0EaxkR7rl+xnc2HMHoQZ0JnLxIf620I8a0undGLLoF3/wh OLCGphcjMVbA7XTHYzvNlJBNDsF5Ls0iB6MSvn1zns3Pel5G3fNdBVIwug3yuAtc7OQW Nu5irRTn7YW00Zf3Eeug91pBBmXl6gDLXr0+Us8SG74ksiVltSgp8nyfN7Cv7z5MYPZf UGjrFgQU3Am+4axavVfhwhnsWTaBI3RcHv8HOSAOrNo3MPqfwQ21dYJOULXEaeJE/gkH rnqpIpvS/Ivv6c4SztEqsF6qtudK26BeEE9DL4tfWwmQd1RQgUkL5+nYif/Mhyv1VAfS bnZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=+8sSW0BteOPYD+HpYHPkb+QlFYOFvs+MADGM7L6C9w4=; b=NuujYLML8Xy94awi6EdIMlCVUpbU5aNKcpJpEHjT46WaU1cB0xGdsAmyESKq9RzEOI +JvysXKKzbM/SHB6KVIeXvOSttNpE3a1+ujGEboH+SDPy214GithNsbxrHLth35eZf/g OkmZfCwvMFOkN7meW9klv7VVrpbnhTC/1rsEzrDJpwXRHvH3+3U7MuUS0Ngkf0MguOqW qCw52NSdcmC71d2FmQFdrdy9nJaaOsBjyNL4FE8AE+GUMefeGDwMvzQ3P6ZZbu/WqDdW bY36k6YovY7W6t/NBcwvjgbw794XF+FLRUo+h9gWKqb0ojzeTWL6gzoOo+Bx633GxeWq iL3A== X-Gm-Message-State: AOAM531i7HFfxsyQad4h49HMwbf73iBlG7P+NUuEQBBtj0m6uDSxSYTg k8WmbdlRe+XCdQcQ8tPQe5jSnRMovBI= X-Google-Smtp-Source: ABdhPJyHJSmHqag8cZF/glSYAIu/6njOmMZzg+dYcVep0YXTf3rves7Kj+TPfQ1+lgIiSK7hqSbIRg== X-Received: by 2002:a05:6a00:1741:b0:4a6:3de7:a816 with SMTP id j1-20020a056a00174100b004a63de7a816mr20427019pfc.29.1637921632319; Fri, 26 Nov 2021 02:13:52 -0800 (PST) Received: from localhost ([47.251.3.230]) by smtp.gmail.com with ESMTPSA id k26sm5924270pfe.78.2021.11.26.02.13.51 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Nov 2021 02:13:52 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Lai Jiangshan , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH V6 18/49] x86/entry: Switch the stack after error_entry() returns Date: Fri, 26 Nov 2021 18:11:38 +0800 Message-Id: <20211126101209.8613-19-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211126101209.8613-1-jiangshanlai@gmail.com> References: <20211126101209.8613-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan error_entry() calls sync_regs() to settle/copy the pt_regs and switches the stack directly after sync_regs(). But because error_entry() is also called from entry, the switching has to handle the return address together, which causes the behavior tangly. Switching to the stack after error_entry() makes the code simpler and intuitive. Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry_64.S | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 0d81f9b77367..e5d69604322d 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -323,6 +323,8 @@ SYM_CODE_END(ret_from_fork) .macro idtentry_body cfunc has_error_code:req call error_entry + movq %rax, %rsp /* switch stack settled by sync_regs() */ + ENCODE_FRAME_POINTER UNWIND_HINT_REGS movq %rsp, %rdi /* pt_regs pointer into 1st argument*/ @@ -985,14 +987,10 @@ SYM_CODE_START_LOCAL(error_entry) /* We have user CR3. Change to kernel CR3. */ SWITCH_TO_KERNEL_CR3 scratch_reg=%rax + leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ .Lerror_entry_from_usermode_after_swapgs: /* Put us onto the real thread stack. */ - popq %r12 /* save return addr in %12 */ - movq %rsp, %rdi /* arg0 = pt_regs pointer */ call sync_regs - movq %rax, %rsp /* switch stack */ - ENCODE_FRAME_POINTER - pushq %r12 ret /* @@ -1025,6 +1023,7 @@ SYM_CODE_START_LOCAL(error_entry) */ .Lerror_entry_done_lfence: FENCE_SWAPGS_KERNEL_ENTRY + leaq 8(%rsp), %rax /* return pt_regs pointer */ ret .Lbstep_iret: @@ -1045,12 +1044,9 @@ SYM_CODE_START_LOCAL(error_entry) * Pretend that the exception came from user mode: set up pt_regs * as if we faulted immediately after IRET. */ - popq %r12 /* save return addr in %12 */ - movq %rsp, %rdi /* arg0 = pt_regs pointer */ + leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ call fixup_bad_iret - mov %rax, %rsp - ENCODE_FRAME_POINTER - pushq %r12 + mov %rax, %rdi jmp .Lerror_entry_from_usermode_after_swapgs SYM_CODE_END(error_entry) -- 2.19.1.6.gb485710b