From patchwork Fri Apr 23 11:04:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12220117 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=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 5D2F0C433ED for ; Fri, 23 Apr 2021 11:04:21 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id EC90F61352 for ; Fri, 23 Apr 2021 11:04:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC90F61352 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.116196.221834 (Exim 4.92) (envelope-from ) id 1lZtbZ-0005v3-FI; Fri, 23 Apr 2021 11:04:13 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 116196.221834; Fri, 23 Apr 2021 11:04:13 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZtbZ-0005uw-CC; Fri, 23 Apr 2021 11:04:13 +0000 Received: by outflank-mailman (input) for mailman id 116196; Fri, 23 Apr 2021 11:04:12 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZtbY-0005uo-9E for xen-devel@lists.xenproject.org; Fri, 23 Apr 2021 11:04:12 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 60db8bb4-ba7b-4966-9e62-05e671b44324; Fri, 23 Apr 2021 11:04:11 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 7B153B0D0; Fri, 23 Apr 2021 11:04:10 +0000 (UTC) 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: 60db8bb4-ba7b-4966-9e62-05e671b44324 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1619175850; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3E4zY1ba3W2J+Wx0AnoEmzDCGCNqdtMSeVue/LO/Frk=; b=UXHKBV5YlqGmVQOdZENFX6MBQ856rFAbZRnaQUbP/FNzR8iDTyoqoTNWGPM9Htwx/RSp/d SrTV8qP2xIp8rk7koz0dD+aqRMRIt6nJ9WcD+w3b8XchenYvTCCzrt+KgaWgFbz1z4IwOi McaKmNytJ+3OREHdB2/pd4EeP27n9S0= Subject: [PATCH v2 2/3] x86/EFI: keep debug info in xen.efi From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Wei Liu , =?utf-8?q?Roger_Pau_Monn=C3=A9?= References: <89e97459-28fd-704f-d424-88afa3a2a4a5@suse.com> Message-ID: <084ef874-3ef2-cb52-bc4b-3b9d78c826ae@suse.com> Date: Fri, 23 Apr 2021 13:04:10 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <89e97459-28fd-704f-d424-88afa3a2a4a5@suse.com> Content-Language: en-US ... provided the linker supports it (which it does as of commit 2dfa8341e079 ["ELF DWARF in PE output"]). Without mentioning debugging sections, the linker would put them at VA 0, thus making them unreachable by 32-bit (relative or absolute) relocations. If relocations were resolvable (or absent) the resulting binary would have invalid section RVAs (0 - __image_base__, truncated to 32 bits). Mentioning debugging sections without specifying an address will result in the linker putting them all on the same RVA. A loader is, afaict, free to reject loading such an image, as sections shouldn't overlap. (The above describes GNU ld 2.36 behavior, which - if deemed buggy - could change.) Make sure our up-to-16Mb padding doesn't unnecessarily further extend the image. Take the opportunity and also switch to using $(call ld-option,...). Requested-by: Andrew Cooper Signed-off-by: Jan Beulich Acked-by: Roger Pau Monné --- v2: Add comment to linker script. --- This way we could also avoid discarding .comment for xen.efi. I'd like to point out that the linking of the debug info takes far longer than the linking of the "normal" parts of the image. The change therefore has the downside of slowing down debug builds. --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -129,8 +129,14 @@ export XEN_BUILD_EFI := $(shell $(CC) $( CFLAGS-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI # Check if the linker supports PE. -EFI_LDFLAGS = $(patsubst -m%,-mi386pep,$(XEN_LDFLAGS)) --subsystem=10 --strip-debug -XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) $(EFI_LDFLAGS) -o efi/check.efi efi/check.o 2>/dev/null && echo y)) +EFI_LDFLAGS = $(patsubst -m%,-mi386pep,$(XEN_LDFLAGS)) --subsystem=10 +XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(call ld-option,$(EFI_LDFLAGS) --image-base=0x100000000 -o efi/check.efi efi/check.o)) +# If the above failed, it may be merely because of the linker not dealing well +# with debug info. Try again with stripping it. +ifeq ($(CONFIG_DEBUG_INFO)-$(XEN_BUILD_PE),y-n) +EFI_LDFLAGS += --strip-debug +XEN_BUILD_PE := $(call ld-option,$(EFI_LDFLAGS) --image-base=0x100000000 -o efi/check.efi efi/check.o) +endif ifeq ($(XEN_BUILD_PE),y) @@ -235,6 +241,9 @@ note_file_option ?= $(note_file) ifeq ($(XEN_BUILD_PE),y) $(TARGET).efi: prelink.o $(note_file) efi.lds efi/relocs-dummy.o efi/mkreloc +ifeq ($(CONFIG_DEBUG_INFO),y) + $(if $(filter --strip-debug,$(EFI_LDFLAGS)),echo,:) "Will strip debug info from $(@F)" +endif $(foreach base, $(VIRT_BASE) $(ALT_BASE), \ $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< $(relocs-dummy) \ $(BASEDIR)/common/symbols-dummy.o $(note_file_option) -o $(@D)/.$(@F).$(base).0 &&) : --- a/xen/arch/x86/xen.lds.S +++ b/xen/arch/x86/xen.lds.S @@ -312,10 +312,70 @@ SECTIONS *(.reloc) __base_relocs_end = .; } - /* Trick the linker into setting the image size to exactly 16Mb. */ - . = ALIGN(__section_alignment__); - DECL_SECTION(.pad) { - . = ALIGN(MB(16)); + /* + * Explicitly list debug section for the PE output so that they don't end + * up at VA 0 which is below image base and thus invalid. Also use the + * NOLOAD directive, despite currently ignored by ld for PE output, in + * order to record that we'd prefer these sections to not be loaded into + * memory. + * + * Note that we're past _end here, so if these sections get loaded they'll + * be discarded at runtime anyway. + */ + .debug_abbrev ALIGN(1) (NOLOAD) : { + *(.debug_abbrev) + } + .debug_info ALIGN(1) (NOLOAD) : { + *(.debug_info) + *(.gnu.linkonce.wi.*) + } + .debug_types ALIGN(1) (NOLOAD) : { + *(.debug_types) + } + .debug_str ALIGN(1) (NOLOAD) : { + *(.debug_str) + } + .debug_line ALIGN(1) (NOLOAD) : { + *(.debug_line) + *(.debug_line.*) + } + .debug_line_str ALIGN(1) (NOLOAD) : { + *(.debug_line_str) + } + .debug_names ALIGN(4) (NOLOAD) : { + *(.debug_names) + } + .debug_frame ALIGN(4) (NOLOAD) : { + *(.debug_frame) + } + .debug_loc ALIGN(1) (NOLOAD) : { + *(.debug_loc) + } + .debug_loclists ALIGN(4) (NOLOAD) : { + *(.debug_loclists) + } + .debug_ranges ALIGN(8) (NOLOAD) : { + *(.debug_ranges) + } + .debug_rnglists ALIGN(4) (NOLOAD) : { + *(.debug_rnglists) + } + .debug_addr ALIGN(8) (NOLOAD) : { + *(.debug_addr) + } + .debug_aranges ALIGN(1) (NOLOAD) : { + *(.debug_aranges) + } + .debug_pubnames ALIGN(1) (NOLOAD) : { + *(.debug_pubnames) + } + .debug_pubtypes ALIGN(1) (NOLOAD) : { + *(.debug_pubtypes) + } + /* Trick the linker into setting the image size to no less than 16Mb. */ + __image_end__ = .; + .pad ALIGN(__section_alignment__) : { + . = __image_end__ < __image_base__ + MB(16) ? ALIGN(MB(16)) : .; } #elif defined(XEN_BUILD_EFI) /*