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=-2.0 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 96F8AC433ED for ; Wed, 14 Apr 2021 14:56:31 +0000 (UTC) Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 077ED613D1 for ; Wed, 14 Apr 2021 14:56:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 077ED613D1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernelnewbies-bounces+kernelnewbies=archiver.kernel.org@kernelnewbies.org Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.94) (envelope-from ) id 1lWgwN-0005vg-UJ for kernelnewbies@archiver.kernel.org; Wed, 14 Apr 2021 10:56:27 -0400 Received: from mail-pf1-x42c.google.com ([2607:f8b0:4864:20::42c]) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1lWgui-0004Y3-BU for kernelnewbies@kernelnewbies.org; Wed, 14 Apr 2021 10:54:44 -0400 Received: by mail-pf1-x42c.google.com with SMTP id c17so13914424pfn.6 for ; Wed, 14 Apr 2021 07:54:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:subject:message-id:mime-version:content-disposition :user-agent; bh=L1KcWv75kyqwEhjN5fgdjA1jaLgeFpmGHH4h4QJeHdo=; b=iNScNEwocHKy5uU1YoaYkXhVODDzphs10OhXX6SzCZTssAB6eezw7W1jHeNApsiZkN HLNmdBeyztP5TKuDZ2s5el8aYpbJth2B3TCg9LYj4bUnlWsnFrhcknxeRgdop4xzzV8I S0tCcpcJejp/mXngU9lvoOTVJczXBmXdP77fBjTLSfdjUkEZbV+zjVoSZOniuHX/G6Gv OgLlCG0dHjgMDMB3vkFXG42+CwntTjK/1IG3qDjpnTOmYMQRyW0ifZjSvWh2m4KGiVz/ 8cqG9jTbQ7K1VrdRqVp+QfYvFAUCL57BtImAOgUhXgS2ScG3JMcE2zTAb52uh8PzlWyd FPnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:mime-version :content-disposition:user-agent; bh=L1KcWv75kyqwEhjN5fgdjA1jaLgeFpmGHH4h4QJeHdo=; b=DbSHOTHG30nUiZ+20jUvITTqY+xFHdhTuhgHyHrL9kbzwPpyMMkpOG2FWFCoi6CRn0 P5/JKENNAMrbds3q9+dhJEZF5jlV0EpGV0Lr7SUzLThBqfKtd5pi4z7zlve8j+dGZRZU oLS3M2J9ym8KC9e39Ltlt+2JkzL5DURsQSGL9iF6BHfUVlgYXDELER/DWvc7ru0FpdKu x1T09u5V/ng9/dCbO/hzd+S87BZu55a8dCHrRmCuNNGTrQKRlMUSRY0J0hXovukl0WPd cVbP1XqJSqcnN9LDDti1CbzaOE0MOUnDsHoC6T9OSdkbCenO4aEx8bP1bFSR1fJZkfJ0 0AUw== X-Gm-Message-State: AOAM5333QxWS4fNw86m5QA9QmkDj2wYz/nH1OhNm8B+cnP7b4zVDoyu8 Ax/TY7zO+pBY+WgXAa4xKXphpK1hSKDVpq0a X-Google-Smtp-Source: ABdhPJydx0SlldaM+iCzZwInwPXpZ0pBv82v3bCI9bXnu//A0RR9eDqIzP/xQvr7fwi+2smyRXhLQQ== X-Received: by 2002:a62:187:0:b029:241:fc67:d41f with SMTP id 129-20020a6201870000b0290241fc67d41fmr34998853pfb.55.1618412082734; Wed, 14 Apr 2021 07:54:42 -0700 (PDT) Received: from localhost.localdomain (42-98-49-250.static.netvigator.com. [42.98.49.250]) by smtp.gmail.com with ESMTPSA id x11sm2745791pfr.7.2021.04.14.07.54.41 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Apr 2021 07:54:42 -0700 (PDT) Date: Wed, 14 Apr 2021 07:54:35 -0700 From: Lv Ying To: kernelnewbies@kernelnewbies.org Subject: Why does dump_stack need asmlinkage? Message-ID: <20210414145422.GA33226@localhost.localdomain> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kernelnewbies-bounces+kernelnewbies=archiver.kernel.org@kernelnewbies.org Hi all: asmlinkage is only defined in arch ia64 and x86_32: 1. arch/x86/include/asm/linkage.h: #ifdef CONFIG_X86_32 #define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0))) #endif /* CONFIG_X86_32 */ 2. arch/ia64/include/asm/linkage.h: #define asmlinkage CPP_ASMLINKAGE __attribute__((syscall_linkage)) 3. arch independent include/linux/linkage.h: #ifdef __cplusplus #define CPP_ASMLINKAGE extern "C" #else #define CPP_ASMLINKAGE #endif #ifndef asmlinkage #define asmlinkage CPP_ASMLINKAGE #endif As kernelnewbies FAQ(https://kernelnewbies.org/FAQ/asmlinkage) said, in short, asmlinkage tells your compiler to look on the CPU stack for the function parameters, instead of registers. So, there are two questions: 1. asmlinkage is only defined in x86_32 and ia64, what about other archs? How do they achieve the same effect as mentioned above? 2. "asmlinkage __visible void dump_stack(void)", dump_stack does not have any parameter, so why do it need asmlinkage? Thanks! Lv Ying _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies