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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AF46ECDB482 for ; Mon, 16 Oct 2023 17:06:03 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.617899.960995 (Exim 4.92) (envelope-from ) id 1qsR2H-0002c3-FW; Mon, 16 Oct 2023 17:05:45 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 617899.960995; Mon, 16 Oct 2023 17:05:45 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qsR2H-0002bu-CM; Mon, 16 Oct 2023 17:05:45 +0000 Received: by outflank-mailman (input) for mailman id 617899; Mon, 16 Oct 2023 17:05:44 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qsR2G-0002bo-7B for xen-devel@lists.xenproject.org; Mon, 16 Oct 2023 17:05:44 +0000 Received: from support.bugseng.com (mail.bugseng.com [162.55.131.47]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 3c5a304f-6c46-11ee-9b0e-b553b5be7939; Mon, 16 Oct 2023 19:05:41 +0200 (CEST) Received: from support.bugseng.com (support.bugseng.com [162.55.131.47]) by support.bugseng.com (Postfix) with ESMTPA id ADA774EE0737; Mon, 16 Oct 2023 19:05:40 +0200 (CEST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 3c5a304f-6c46-11ee-9b0e-b553b5be7939 MIME-Version: 1.0 Date: Mon, 16 Oct 2023 19:05:40 +0200 From: Nicola Vetrini To: Jan Beulich Cc: sstabellini@kernel.org, michal.orzel@amd.com, xenia.ragiadakou@amd.com, ayan.kumar.halder@amd.com, consulting@bugseng.com, andrew.cooper3@citrix.com, roger.pau@citrix.com, Julien Grall , Bertrand Marquis , Volodymyr Babchuk , George Dunlap , Wei Liu , xen-devel@lists.xenproject.org Subject: Re: [XEN PATCH v2 1/7] xen: add declarations for variables where needed In-Reply-To: <2023f16b-46fb-2a19-9620-7872b3029b5f@suse.com> References: <002d58b1d15619a8c4b2ec6c2b5f20960ed0a428.1696833629.git.nicola.vetrini@bugseng.com> <2023f16b-46fb-2a19-9620-7872b3029b5f@suse.com> User-Agent: Roundcube Webmail/1.4.3 Message-ID: X-Sender: nicola.vetrini@bugseng.com Organization: BUGSENG s.r.l. Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit On 16/10/2023 16:50, Jan Beulich wrote: > On 09.10.2023 08:54, Nicola Vetrini wrote: >> Some variables with external linkage used in C code do not have >> a visible declaration where they are defined. Providing such >> declaration also resolves violations of MISRA C:2012 Rule 8.4. >> >> Signed-off-by: Nicola Vetrini > > This is a mix of different approaches to the same underlying issue. I > think respectively splitting would have helped. > >> --- a/xen/arch/x86/include/asm/compat.h >> +++ b/xen/arch/x86/include/asm/compat.h >> @@ -13,6 +13,7 @@ typedef unsigned long full_ptr_t; >> >> struct domain; >> #ifdef CONFIG_PV32 >> +extern unsigned long cr4_pv32_mask; > > Why is this needed? Didn't we say declarations aren't needed when the > only consumer is assembly code? (I also wonder how this header is any > more "appropriate" - see the changelog entry - than about any other > one.) > It was pointed out to me [1] that compat.h might be more appropriate than setup.h (probably because the asm code referencing it is under x86_64/compat). Further, while it's true that this variable is used in asm, it's also used in x86/setup.c, hence the need for a declaration. >> --- a/xen/arch/x86/include/asm/setup.h >> +++ b/xen/arch/x86/include/asm/setup.h >> @@ -13,6 +13,7 @@ extern char __2M_rwdata_start[], __2M_rwdata_end[]; >> extern unsigned long xenheap_initial_phys_start; >> extern uint64_t boot_tsc_stamp; >> >> +extern char cpu0_stack[STACK_SIZE]; > > Same question here. > This one is a bit more nuanced (I wouldn't oppose deviating this), but there is indeed one use. >> --- a/xen/common/symbols.c >> +++ b/xen/common/symbols.c >> @@ -21,23 +21,6 @@ >> #include >> #include >> >> -#ifdef SYMBOLS_ORIGIN >> -extern const unsigned int symbols_offsets[]; >> -#define symbols_address(n) (SYMBOLS_ORIGIN + symbols_offsets[n]) >> -#else >> -extern const unsigned long symbols_addresses[]; >> -#define symbols_address(n) symbols_addresses[n] >> -#endif >> -extern const unsigned int symbols_num_syms; >> -extern const u8 symbols_names[]; >> - >> -extern const struct symbol_offset symbols_sorted_offsets[]; >> - >> -extern const u8 symbols_token_table[]; >> -extern const u16 symbols_token_index[]; >> - >> -extern const unsigned int symbols_markers[]; >> - >> /* expand a compressed symbol data into the resulting uncompressed >> string, >> given the offset to where the symbol is in the compressed stream >> */ >> static unsigned int symbols_expand_symbol(unsigned int off, char >> *result) >> --- a/xen/include/xen/symbols.h >> +++ b/xen/include/xen/symbols.h >> @@ -33,4 +33,22 @@ struct symbol_offset { >> uint32_t stream; /* .. in the compressed stream.*/ >> uint32_t addr; /* .. and in the fixed size address array. */ >> }; >> + >> +#ifdef SYMBOLS_ORIGIN >> +extern const unsigned int symbols_offsets[]; >> +#define symbols_address(n) (SYMBOLS_ORIGIN + symbols_offsets[n]) >> +#else >> +extern const unsigned long symbols_addresses[]; >> +#define symbols_address(n) symbols_addresses[n] >> +#endif >> +extern const unsigned int symbols_num_syms; >> +extern const u8 symbols_names[]; >> + >> +extern const struct symbol_offset symbols_sorted_offsets[]; >> + >> +extern const u8 symbols_token_table[]; >> +extern const u16 symbols_token_index[]; >> + >> +extern const unsigned int symbols_markers[]; >> + >> #endif /*_XEN_SYMBOLS_H*/ > > This change is even less clear to me: The producer is assembly code, > and the consumer already had appropriate declarations. Why would we > want to increase the scope of their visibility? > > Jan The missing decls are about common/symbols-dummy.c. Xen can choose that this file does not need to conform (to this guideline or any guideline), in which case this change can be dropped. [1] https://lore.kernel.org/xen-devel/ZRqkbeVUZbjizjNv@MacBookPdeRoger/ -- Nicola Vetrini, BSc Software Engineer, BUGSENG srl (https://bugseng.com)