From patchwork Wed Jun 24 20:31:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11624273 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6ECC660D for ; Wed, 24 Jun 2020 20:35:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E27920B80 for ; Wed, 24 Jun 2020 20:35:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vIahDq7a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406399AbgFXUdD (ORCPT ); Wed, 24 Jun 2020 16:33:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406336AbgFXUdB (ORCPT ); Wed, 24 Jun 2020 16:33:01 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A062CC061795 for ; Wed, 24 Jun 2020 13:33:00 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id e82so3495195ybh.12 for ; Wed, 24 Jun 2020 13:33:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=zJgCLl2NhOgZBqIPJZhtZ4TPiUfcQmmxIv/fzhpa6kU=; b=vIahDq7aqL96yiIpIepm/3ftBU8lrk2hUmV84VfhySVdQjCUeRR+npewyO02VLNg1H EKz3O7JTeZ12pduy22CiakNubOk5eUICY6CzRnZZ+sqjK5BZ+Ey/hYmxL252W/v3Vw3R QHQ+BsLn7Dhzl+5iipLN1+5H5sMa2z5svyVXJRQKvxVQctYxW6ebqQJ3ULghYqVLE/mE +epm6jN27/TjGyvgv03OaZPqY9SJiFtufPYwDQq2nbQ/suFkEhepQpQYZtjqOKH1NZDA RhrCSfZCiizO3jsUHNb/S1nkjOMbYcBzY5F4xXLc6roRSQybnwlsVEFxN2n39HcU9fzE 6+rw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=zJgCLl2NhOgZBqIPJZhtZ4TPiUfcQmmxIv/fzhpa6kU=; b=Epvm40xaOFwCpPkOyZQsbvbGDq2Ztt333Rpd6q1n0DdXX0IuIxcBoKJZY4Fto2pBTd Yrj3mT6G8cjjtdhJD5Iiu0LPrDN4bBAelVpW1JDv4a0hyp/B26IWK42bcVJIqjHqzXPR wrHDenhPxGMixtIU+q/JyKbewB0LaiMEvXcwQcOn+UCGQ8x1Q4igBYlz6tEh+BJ0BAL3 p1DVPkF0gk5GW8aC7DmZbBW1i9Pj1Puc9ZfIOXATE1gAKBqQglle+WG3MOID+ZKL+wJv mGpdFc0vcwP1KfrNABqjj4fZeDWqoovtSwlZDmTmJr/JyVj4CVeuy2IO0vzugxq0ts9Y MgCA== X-Gm-Message-State: AOAM53295xl/HXfpcC4gAnUpQPOH5RaqvpEtQe4KZDRDuu5j5i0HDP43 DtHyJGkpsglB/7W4zYFvxhLFI7Pxq4ngnfuN5HM= X-Google-Smtp-Source: ABdhPJwtupmBRpPe049uS/8X19V10xLMzevhQMzdrNMrqBVJvPzK6fkgs/2PZX+Qd9dpa9Rprg1LfaTpoC6sBdC1f/k= X-Received: by 2002:a25:7386:: with SMTP id o128mr46698757ybc.266.1593030779834; Wed, 24 Jun 2020 13:32:59 -0700 (PDT) Date: Wed, 24 Jun 2020 13:31:41 -0700 In-Reply-To: <20200624203200.78870-1-samitolvanen@google.com> Message-Id: <20200624203200.78870-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20200624203200.78870-1-samitolvanen@google.com> X-Mailer: git-send-email 2.27.0.212.ge8ba1cc988-goog Subject: [PATCH 03/22] kbuild: lto: fix module versioning From: Sami Tolvanen To: Masahiro Yamada , Will Deacon Cc: Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, Sami Tolvanen Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org With CONFIG_MODVERSIONS, version information is linked into each compilation unit that exports symbols. With LTO, we cannot use this method as all C code is compiled into LLVM bitcode instead. This change collects symbol versions into .symversions files and merges them in link-vmlinux.sh where they are all linked into vmlinux.o at the same time. Signed-off-by: Sami Tolvanen --- .gitignore | 1 + Makefile | 3 ++- arch/Kconfig | 1 - scripts/Makefile.build | 33 +++++++++++++++++++++++++++++++-- scripts/Makefile.modpost | 2 ++ scripts/link-vmlinux.sh | 25 ++++++++++++++++++++++++- 6 files changed, 60 insertions(+), 5 deletions(-) diff --git a/.gitignore b/.gitignore index 87b9dd8a163b..51b02c2f2826 100644 --- a/.gitignore +++ b/.gitignore @@ -41,6 +41,7 @@ *.so.dbg *.su *.symtypes +*.symversions *.tab.[ch] *.tar *.xz diff --git a/Makefile b/Makefile index 0c7fe6fb2143..161ad0d1f77f 100644 --- a/Makefile +++ b/Makefile @@ -1793,7 +1793,8 @@ clean: $(clean-dirs) -o -name '.tmp_*.o.*' \ -o -name '*.c.[012]*.*' \ -o -name '*.ll' \ - -o -name '*.gcno' \) -type f -print | xargs rm -f + -o -name '*.gcno' \ + -o -name '*.*.symversions' \) -type f -print | xargs rm -f # Generate tags for editors # --------------------------------------------------------------------------- diff --git a/arch/Kconfig b/arch/Kconfig index e00b122293f8..87488fe1e6b8 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -600,7 +600,6 @@ config LTO_CLANG depends on ARCH_SUPPORTS_LTO_CLANG depends on !FTRACE_MCOUNT_RECORD depends on !KASAN - depends on !MODVERSIONS select LTO help This option enables Clang's Link Time Optimization (LTO), which diff --git a/scripts/Makefile.build b/scripts/Makefile.build index f307e708a1b7..5c0bbb6ddfcf 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -163,6 +163,15 @@ ifdef CONFIG_MODVERSIONS # the actual value of the checksum generated by genksyms # o remove .tmp_.o to .o +ifdef CONFIG_LTO_CLANG +# Generate .o.symversions files for each .o with exported symbols, and link these +# to the kernel and/or modules at the end. +cmd_modversions_c = \ + if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \ + $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ + > $@.symversions; \ + fi; +else cmd_modversions_c = \ if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \ $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ @@ -174,6 +183,7 @@ cmd_modversions_c = \ rm -f $(@D)/.tmp_$(@F:.o=.ver); \ fi endif +endif ifdef CONFIG_FTRACE_MCOUNT_RECORD ifndef CC_USING_RECORD_MCOUNT @@ -389,6 +399,18 @@ $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler $(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ; $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ; +# combine symversions for later processing +quiet_cmd_update_lto_symversions = SYMVER $@ +ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y) + cmd_update_lto_symversions = \ + rm -f $@.symversions \ + $(foreach n, $(filter-out FORCE,$^), \ + $(if $(wildcard $(n).symversions), \ + ; cat $(n).symversions >> $@.symversions)) +else + cmd_update_lto_symversions = echo >/dev/null +endif + # # Rule to compile a set of .o files into one .a file (without symbol table) # @@ -396,8 +418,11 @@ $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ; quiet_cmd_ar_builtin = AR $@ cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs) +quiet_cmd_ar_and_symver = AR $@ + cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin) + $(obj)/built-in.a: $(real-obj-y) FORCE - $(call if_changed,ar_builtin) + $(call if_changed,ar_and_symver) # # Rule to create modules.order file @@ -417,8 +442,11 @@ $(obj)/modules.order: $(obj-m) FORCE # # Rule to compile a set of .o files into one .a file (with symbol table) # +quiet_cmd_ar_lib = AR $@ + cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar) + $(obj)/lib.a: $(lib-y) FORCE - $(call if_changed,ar) + $(call if_changed,ar_lib) # NOTE: # Do not replace $(filter %.o,^) with $(real-prereqs). When a single object @@ -427,6 +455,7 @@ $(obj)/lib.a: $(lib-y) FORCE ifdef CONFIG_LTO_CLANG quiet_cmd_link_multi-m = AR [M] $@ cmd_link_multi-m = \ + $(cmd_update_lto_symversions); \ rm -f $@; \ $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(filter %.o,$^) else diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost index 9ced8aecd579..42dbdc2bbf73 100644 --- a/scripts/Makefile.modpost +++ b/scripts/Makefile.modpost @@ -110,6 +110,8 @@ prelink-ext = .lto quiet_cmd_cc_lto_link_modules = LTO [M] $@ cmd_cc_lto_link_modules = \ $(LD) $(ld_flags) -r -o $@ \ + $(shell [ -s $(@:.lto.o=.o.symversions) ] && \ + echo -T $(@:.lto.o=.o.symversions)) \ --whole-archive $(filter-out FORCE,$^) %.lto.o: %.o FORCE diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index a681b3b6722e..69a6d7254e28 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -39,11 +39,28 @@ info() fi } +# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into +# .tmp_symversions.lds +gen_symversions() +{ + info GEN .tmp_symversions.lds + rm -f .tmp_symversions.lds + + for a in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do + for o in $(${AR} t $a 2>/dev/null); do + if [ -f ${o}.symversions ]; then + cat ${o}.symversions >> .tmp_symversions.lds + fi + done + done +} + # Link of vmlinux.o used for section mismatch analysis # ${1} output file modpost_link() { local objects + local lds="" objects="--whole-archive \ ${KBUILD_VMLINUX_OBJS} \ @@ -53,6 +70,11 @@ modpost_link() --end-group" if [ -n "${CONFIG_LTO_CLANG}" ]; then + if [ -n "${CONFIG_MODVERSIONS}" ]; then + gen_symversions + lds="${lds} -T .tmp_symversions.lds" + fi + # This might take a while, so indicate that we're doing # an LTO link info LTO ${1} @@ -60,7 +82,7 @@ modpost_link() info LD ${1} fi - ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects} + ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects} } objtool_link() @@ -238,6 +260,7 @@ cleanup() { rm -f .btf.* rm -f .tmp_System.map + rm -f .tmp_symversions.lds rm -f .tmp_vmlinux* rm -f System.map rm -f vmlinux