From patchwork Fri Nov 24 13:59:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 13467689 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 379B7C61DF4 for ; Fri, 24 Nov 2023 13:59:26 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.640725.999354 (Exim 4.92) (envelope-from ) id 1r6Wi7-0002tB-DD; Fri, 24 Nov 2023 13:59:11 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 640725.999354; Fri, 24 Nov 2023 13:59:11 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1r6Wi7-0002t4-Ai; Fri, 24 Nov 2023 13:59:11 +0000 Received: by outflank-mailman (input) for mailman id 640725; Fri, 24 Nov 2023 13:59:10 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1r6Wi6-0002rA-6T for xen-devel@lists.xenproject.org; Fri, 24 Nov 2023 13:59:10 +0000 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id a3039d44-8ad1-11ee-98e2-6d05b1d4d9a1; Fri, 24 Nov 2023 14:59:08 +0100 (CET) Received: from imap2.dmz-prg2.suse.org (imap2.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id E45861FDD9; Fri, 24 Nov 2023 13:59:06 +0000 (UTC) Received: from imap2.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap2.dmz-prg2.suse.org (Postfix) with ESMTPS id BBF50139E8; Fri, 24 Nov 2023 13:59:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap2.dmz-prg2.suse.org with ESMTPSA id TSCSLCqsYGURGwAAn2gu4w (envelope-from ); Fri, 24 Nov 2023 13:59:06 +0000 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: a3039d44-8ad1-11ee-98e2-6d05b1d4d9a1 From: Juergen Gross To: minios-devel@lists.xenproject.org, xen-devel@lists.xenproject.org Cc: samuel.thibault@ens-lyon.org, wl@xen.org, Juergen Gross Subject: [RFC PATCH] Mini-OS: explicitly mark symbols to be visible for apps Date: Fri, 24 Nov 2023 14:59:03 +0100 Message-Id: <20231124135903.16621-1-jgross@suse.com> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 X-Spamd-Bar: +++++++++++++++++++++ Authentication-Results: smtp-out2.suse.de; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=suse.com (policy=quarantine); spf=fail (smtp-out2.suse.de: domain of jgross@suse.com does not designate 2a07:de40:b281:104:10:150:64:98 as permitted sender) smtp.mailfrom=jgross@suse.com X-Rspamd-Server: rspamd2 X-Spamd-Result: default: False [21.50 / 50.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:98:from]; TO_DN_SOME(0.00)[]; R_MISSING_CHARSET(2.50)[]; BROKEN_CONTENT_TYPE(1.50)[]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_THREE(0.00)[3]; MX_GOOD(-0.01)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(2.20)[]; MIME_TRACE(0.00)[0:+]; BAYES_HAM(-3.00)[100.00%]; ARC_NA(0.00)[]; R_SPF_FAIL(1.00)[-all]; FROM_HAS_DN(0.00)[]; DMARC_POLICY_QUARANTINE(1.50)[suse.com : No valid SPF, No valid DKIM,quarantine]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_SPAM_SHORT(3.00)[1.000]; MIME_GOOD(-0.10)[text/plain]; NEURAL_SPAM_LONG(3.50)[1.000]; MID_CONTAINS_FROM(1.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,mini-os.map:url]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[] X-Rspamd-Queue-Id: E45861FDD9 Add an EXPORT_SYMBOL() macro to explicitly mark a symbol to be visible for an app or library linked with Mini-OS. This enables to hide all other symbols from external components, avoiding any problems with duplicate symbol names. Signed-off-by: Juergen Gross Reviewed-by: Samuel Thibault --- Based on top of my previous series "Mini-OS: hide mini-os internal symbols". This is a RFC as an alternative to the map file containing all visible symbol names. It would add more code churn, but it has the large benefit of declaring visibility of a symbol at the place where it is defined, reducing the chance to miss a proper symbol visibility definition. This patch is including an example for the do_exit() function in order to prove the viability of the approach. In case this idea is approved, I'd setup a patch series replacing the second patch of above series with this patch (minus the do_exit() example) and the scattered EXPORT_SYMBOL() instances. Signed-off-by: Juergen Gross --- Makefile | 3 ++- include/lib.h | 6 ++++++ kernel.c | 1 + mini-os.map | 1 - 4 files changed, 9 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index d4768110..5dbad8ce 100644 --- a/Makefile +++ b/Makefile @@ -166,7 +166,8 @@ $(OBJ_DIR)/arch/x86/minios-x86%.lds: arch/x86/minios-x86.lds.S $(OBJ_DIR)/$(TARGET)-kern.o: $(OBJS) arch_lib $(OBJ_DIR)/$(TARGET_ARCH_DIR)/minios-$(MINIOS_TARGET_ARCH).lds mini-os.map $(LD) -r $(LDFLAGS) $(HEAD_OBJ) $(OBJS) $(LDARCHLIB) -o $@ - $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* --keep-global-symbols=mini-os.map $@ $@ + $(OBJCOPY) --dump-section .export_symbol=syms mini-os-kern.o + $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* --keep-global-symbols=mini-os.map --keep-global-symbols=syms --remove-section=.export_symbol $@ $@ $(OBJ_DIR)/$(TARGET): $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) $(LD) -r $(LDFLAGS) $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) $(LDLIBS) -o $@.o diff --git a/include/lib.h b/include/lib.h index dd68985a..24fd0186 100644 --- a/include/lib.h +++ b/include/lib.h @@ -64,6 +64,12 @@ #define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond)) #endif +#define EXPORT_SYMBOL(sym) \ + extern typeof(sym) sym; \ + asm(".section \".export_symbol\",\"a\"\n" \ + "\t.ascii \""#sym"\n\"\n" \ + ".previous") + #ifdef HAVE_LIBC #include #include diff --git a/kernel.c b/kernel.c index 1f97d8dd..29eed535 100644 --- a/kernel.c +++ b/kernel.c @@ -199,3 +199,4 @@ void do_exit(void) HYPERVISOR_sched_op(SCHEDOP_shutdown, &sched_shutdown); } } +EXPORT_SYMBOL(do_exit); diff --git a/mini-os.map b/mini-os.map index 58a3a0ee..90f02edf 100644 --- a/mini-os.map +++ b/mini-os.map @@ -69,7 +69,6 @@ close closedir closelog connect -do_exit dup dup2 err