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=-17.3 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,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 AC163C48BD1 for ; Fri, 11 Jun 2021 10:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89EA4613DE for ; Fri, 11 Jun 2021 10:20:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231718AbhFKKW1 (ORCPT ); Fri, 11 Jun 2021 06:22:27 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:59338 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231655AbhFKKWX (ORCPT ); Fri, 11 Jun 2021 06:22:23 -0400 Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 478D91FD6C; Fri, 11 Jun 2021 10:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1623406825; 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=PxVK0K35pQZanZet6mzxQAOwPID5G7wB9PTtQWMWHKI=; b=cT1NR7aCEX3fBw33SzxKpP3CyxNUCV0oNJgoXp1gKAy4nP8ZtXYx01cSAYZ4fa7atfc1Z1 HgFH3f91tTcHd4iGYOyG9vBeMCC0icU5VswCAcE/zASrDfgrtLHTkkQHdiQbbR5+Sr2lEm oJcxmosZduOD3QZ7dn/lJt8L3v8OMp4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1623406825; 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=PxVK0K35pQZanZet6mzxQAOwPID5G7wB9PTtQWMWHKI=; b=a/soMZBUQOwdKcdjA0tTGCK+9u0PwngUVJFaXLAD/tar4tLefv9Oy10juz55l9mbbdik48 VqIitXUR+0hwZxDA== Received: from imap3-int (imap-alt.suse-dmz.suse.de [192.168.254.47]) by imap.suse.de (Postfix) with ESMTP id 2A3EE118DD; Fri, 11 Jun 2021 10:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1623406825; 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=PxVK0K35pQZanZet6mzxQAOwPID5G7wB9PTtQWMWHKI=; b=cT1NR7aCEX3fBw33SzxKpP3CyxNUCV0oNJgoXp1gKAy4nP8ZtXYx01cSAYZ4fa7atfc1Z1 HgFH3f91tTcHd4iGYOyG9vBeMCC0icU5VswCAcE/zASrDfgrtLHTkkQHdiQbbR5+Sr2lEm oJcxmosZduOD3QZ7dn/lJt8L3v8OMp4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1623406825; 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=PxVK0K35pQZanZet6mzxQAOwPID5G7wB9PTtQWMWHKI=; b=a/soMZBUQOwdKcdjA0tTGCK+9u0PwngUVJFaXLAD/tar4tLefv9Oy10juz55l9mbbdik48 VqIitXUR+0hwZxDA== Received: from director2.suse.de ([192.168.254.72]) by imap3-int with ESMTPSA id Pt5JCek4w2DxcgAALh3uQQ (envelope-from ); Fri, 11 Jun 2021 10:20:25 +0000 Date: Fri, 11 Jun 2021 12:20:23 +0200 From: Michal =?iso-8859-1?Q?Such=E1nek?= To: Nicholas Piggin Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Jessica Yu Subject: Re: [PATCH v4 2/2] powerpc/64: Option to use ELF V2 ABI for big-endian kernels Message-ID: <20210611102023.GB8544@kitsune.suse.cz> References: <20210611093959.821525-1-npiggin@gmail.com> <20210611093959.821525-3-npiggin@gmail.com> <20210611095819.GA8544@kitsune.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210611095819.GA8544@kitsune.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 11, 2021 at 11:58:19AM +0200, Michal Suchánek wrote: > On Fri, Jun 11, 2021 at 07:39:59PM +1000, Nicholas Piggin wrote: > > Provide an option to build big-endian kernels using the ELFv2 ABI. This > > works on GCC only so far, although it is rumored to work with clang > > that's not been tested yet. A new module version check ensures the > > module ELF ABI level matches the kernel build. > > > > This can give big-endian kernels some useful advantages of the ELFv2 ABI > > (e.g., less stack usage, -mprofile-kernel, better compatibility with eBPF > > tools). > > > > BE+ELFv2 is not officially supported by the GNU toolchain, but it works > > fine in testing and has been used by some userspace for some time (e.g., > > Void Linux). > > > > Tested-by: Michal Suchánek > > Reviewed-by: Segher Boessenkool > > Signed-off-by: Nicholas Piggin > > --- > > arch/powerpc/Kconfig | 22 ++++++++++++++++++++++ > > arch/powerpc/Makefile | 18 ++++++++++++------ > > arch/powerpc/boot/Makefile | 4 +++- > > arch/powerpc/include/asm/module.h | 24 ++++++++++++++++++++++++ > > arch/powerpc/kernel/vdso64/Makefile | 13 +++++++++++++ > > drivers/crypto/vmx/Makefile | 8 ++++++-- > > drivers/crypto/vmx/ppc-xlate.pl | 10 ++++++---- > > 7 files changed, 86 insertions(+), 13 deletions(-) > > > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > > index 088dd2afcfe4..093f973a28b9 100644 > > --- a/arch/powerpc/Kconfig > > +++ b/arch/powerpc/Kconfig > > @@ -163,6 +163,7 @@ config PPC > > select ARCH_WEAK_RELEASE_ACQUIRE > > select BINFMT_ELF > > select BUILDTIME_TABLE_SORT > > + select PPC64_BUILD_ELF_V2_ABI if PPC64 && CPU_LITTLE_ENDIAN > > select CLONE_BACKWARDS > > select DCACHE_WORD_ACCESS if PPC64 && CPU_LITTLE_ENDIAN > > select DMA_OPS_BYPASS if PPC64 > > @@ -561,6 +562,27 @@ config KEXEC_FILE > > config ARCH_HAS_KEXEC_PURGATORY > > def_bool KEXEC_FILE > > > > +config PPC64_BUILD_ELF_V2_ABI > > + bool > > + > > +config PPC64_BUILD_BIG_ENDIAN_ELF_V2_ABI > > + bool "Build big-endian kernel using ELF ABI V2 (EXPERIMENTAL)" > > + depends on PPC64 && CPU_BIG_ENDIAN && EXPERT > > + depends on CC_IS_GCC && LD_VERSION >= 22400 > > + default n > > + select PPC64_BUILD_ELF_V2_ABI > > + help > > + This builds the kernel image using the "Power Architecture 64-Bit ELF > > + V2 ABI Specification", which has a reduced stack overhead and faster > > + function calls. This internal kernel ABI option does not affect > > + userspace compatibility. > > + > > + The V2 ABI is standard for 64-bit little-endian, but for big-endian > > + it is less well tested by kernel and toolchain. However some distros > > + build userspace this way, and it can produce a functioning kernel. > > + > > + This requires GCC and binutils 2.24 or newer. > > + > > config RELOCATABLE > > bool "Build a relocatable kernel" > > depends on PPC64 || (FLATMEM && (44x || FSL_BOOKE)) > > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile > > index 3212d076ac6a..b90b5cb799aa 100644 > > --- a/arch/powerpc/Makefile > > +++ b/arch/powerpc/Makefile > > @@ -91,10 +91,14 @@ endif > > > > ifdef CONFIG_PPC64 > > ifndef CONFIG_CC_IS_CLANG > > -cflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mabi=elfv1) > > -cflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mcall-aixdesc) > > -aflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mabi=elfv1) > > -aflags-$(CONFIG_CPU_LITTLE_ENDIAN) += -mabi=elfv2 > > +ifdef CONFIG_PPC64_BUILD_ELF_V2_ABI > > +cflags-y += $(call cc-option,-mabi=elfv2) > > +aflags-y += $(call cc-option,-mabi=elfv2) > > +else > > +cflags-y += $(call cc-option,-mabi=elfv1) > > +cflags-y += $(call cc-option,-mcall-aixdesc) > > +aflags-y += $(call cc-option,-mabi=elfv1) > > +endif > > endif > > endif > > > > @@ -142,15 +146,17 @@ endif > > > > CFLAGS-$(CONFIG_PPC64) := $(call cc-option,-mtraceback=no) > > ifndef CONFIG_CC_IS_CLANG > > -ifdef CONFIG_CPU_LITTLE_ENDIAN > > -CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv2,$(call cc-option,-mcall-aixdesc)) > > +ifdef CONFIG_PPC64_BUILD_ELF_V2_ABI > > +CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv2) > > AFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv2) > > else > > +# Keep these in synch with arch/powerpc/kernel/vdso64/Makefile > > CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv1) > > CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcall-aixdesc) > > AFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv1) > > endif > > endif > > + > > CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcmodel=medium,$(call cc-option,-mminimal-toc)) > > CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mno-pointers-to-nested-functions) > > > > diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile > > index 2b8da923ceca..be84a72f8258 100644 > > --- a/arch/powerpc/boot/Makefile > > +++ b/arch/powerpc/boot/Makefile > > @@ -40,6 +40,9 @@ BOOTCFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ > > > > ifdef CONFIG_PPC64_BOOT_WRAPPER > > BOOTCFLAGS += -m64 > > +ifdef CONFIG_PPC64_BUILD_ELF_V2_ABI > > +BOOTCFLAGS += $(call cc-option,-mabi=elfv2) > > +endif > > else > > BOOTCFLAGS += -m32 > > endif > > @@ -50,7 +53,6 @@ ifdef CONFIG_CPU_BIG_ENDIAN > > BOOTCFLAGS += -mbig-endian > > else > > BOOTCFLAGS += -mlittle-endian > > -BOOTCFLAGS += $(call cc-option,-mabi=elfv2) > > endif > > > > BOOTAFLAGS := -D__ASSEMBLY__ $(BOOTCFLAGS) -nostdinc > > diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h > > index 857d9ff24295..043e11068ff4 100644 > > --- a/arch/powerpc/include/asm/module.h > > +++ b/arch/powerpc/include/asm/module.h > > @@ -52,6 +52,30 @@ struct mod_arch_specific { > > unsigned int num_bugs; > > }; > > > > +/* > > + * Check kernel module ELF header architecture specific compatibility. > > + */ > > +static inline bool elf_check_module_arch(Elf_Ehdr *hdr) > > +{ > > + if (!elf_check_arch(hdr)) > > + return false; > > + > > + if (IS_ENABLED(CONFIG_PPC64)) { > > + unsigned long abi_level = hdr->e_flags & 0x3; > > + > > + if (IS_ENABLED(CONFIG_PPC64_BUILD_ELF_V2_ABI)) { > > + if (abi_level != 2) > > + return false; > > + } else { > > + if (abi_level >= 2) > > + return false; > > + } > > + } > > + > > + return true; > > +} > > +#define elf_check_module_arch elf_check_module_arch > > + > > /* > > * Select ELF headers. > > * Make empty section for module_frob_arch_sections to expand. > Shouldn't this part go to the second patch? Nevermind, this is the second patch now. > > Thanks > > Michal > > diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile > > index 2813e3f98db6..d783c07e558f 100644 > > --- a/arch/powerpc/kernel/vdso64/Makefile > > +++ b/arch/powerpc/kernel/vdso64/Makefile > > @@ -25,6 +25,19 @@ KCOV_INSTRUMENT := n > > UBSAN_SANITIZE := n > > KASAN_SANITIZE := n > > > > +# Always build vdso64 with ELFv1 ABI for BE kernels > > +ifdef CONFIG_PPC64_BUILD_ELF_V2_ABI > > +ifdef CONFIG_CPU_BIG_ENDIAN > > +KBUILD_CFLAGS := $(filter-out -mabi=elfv2,$(KBUILD_CFLAGS)) > > +KBUILD_AFLAGS := $(filter-out -mabi=elfv2,$(KBUILD_AFLAGS)) > > + > > +# These are derived from arch/powerpc/Makefile > > +KBUILD_CFLAGS += $(call cc-option,-mabi=elfv1) > > +KBUILD_CFLAGS += $(call cc-option,-mcall-aixdesc) > > +KBUILD_AFLAGS += $(call cc-option,-mabi=elfv1) > > +endif > > +endif > > + > > ccflags-y := -shared -fno-common -fno-builtin -nostdlib \ > > -Wl,-soname=linux-vdso64.so.1 -Wl,--hash-style=both > > asflags-y := -D__VDSO64__ -s > > diff --git a/drivers/crypto/vmx/Makefile b/drivers/crypto/vmx/Makefile > > index 709670d2b553..d9ccf9fc3483 100644 > > --- a/drivers/crypto/vmx/Makefile > > +++ b/drivers/crypto/vmx/Makefile > > @@ -5,18 +5,22 @@ vmx-crypto-objs := vmx.o aesp8-ppc.o ghashp8-ppc.o aes.o aes_cbc.o aes_ctr.o aes > > ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y) > > override flavour := linux-ppc64le > > else > > +ifdef CONFIG_PPC64_BUILD_ELF_V2_ABI > > +override flavour := linux-ppc64-elfv2 > > +else > > override flavour := linux-ppc64 > > endif > > +endif > > > > quiet_cmd_perl = PERL $@ > > cmd_perl = $(PERL) $(<) $(flavour) > $(@) > > > > targets += aesp8-ppc.S ghashp8-ppc.S > > > > -$(obj)/aesp8-ppc.S: $(src)/aesp8-ppc.pl FORCE > > +$(obj)/aesp8-ppc.S: $(src)/aesp8-ppc.pl $(src)/ppc-xlate.pl FORCE > > $(call if_changed,perl) > > > > -$(obj)/ghashp8-ppc.S: $(src)/ghashp8-ppc.pl FORCE > > +$(obj)/ghashp8-ppc.S: $(src)/ghashp8-ppc.pl $(src)/ppc-xlate.pl FORCE > > $(call if_changed,perl) > > > > clean-files := aesp8-ppc.S ghashp8-ppc.S > > diff --git a/drivers/crypto/vmx/ppc-xlate.pl b/drivers/crypto/vmx/ppc-xlate.pl > > index 36db2ef09e5b..b583898c11ae 100644 > > --- a/drivers/crypto/vmx/ppc-xlate.pl > > +++ b/drivers/crypto/vmx/ppc-xlate.pl > > @@ -9,6 +9,8 @@ open STDOUT,">$output" || die "can't open $output: $!"; > > > > my %GLOBALS; > > my $dotinlocallabels=($flavour=~/linux/)?1:0; > > +my $elfv2abi=(($flavour =~ /linux-ppc64le/) or ($flavour =~ /linux-ppc64-elfv2/))?1:0; > > +my $dotfunctions=($elfv2abi=~1)?0:1; > > > > ################################################################ > > # directives which need special treatment on different platforms > > @@ -40,7 +42,7 @@ my $globl = sub { > > }; > > my $text = sub { > > my $ret = ($flavour =~ /aix/) ? ".csect\t.text[PR],7" : ".text"; > > - $ret = ".abiversion 2\n".$ret if ($flavour =~ /linux.*64le/); > > + $ret = ".abiversion 2\n".$ret if ($elfv2abi); > > $ret; > > }; > > my $machine = sub { > > @@ -56,8 +58,8 @@ my $size = sub { > > if ($flavour =~ /linux/) > > { shift; > > my $name = shift; $name =~ s|^[\.\_]||; > > - my $ret = ".size $name,.-".($flavour=~/64$/?".":"").$name; > > - $ret .= "\n.size .$name,.-.$name" if ($flavour=~/64$/); > > + my $ret = ".size $name,.-".($dotfunctions?".":"").$name; > > + $ret .= "\n.size .$name,.-.$name" if ($dotfunctions); > > $ret; > > } > > else > > @@ -142,7 +144,7 @@ my $vmr = sub { > > > > # Some ABIs specify vrsave, special-purpose register #256, as reserved > > # for system use. > > -my $no_vrsave = ($flavour =~ /linux-ppc64le/); > > +my $no_vrsave = ($elfv2abi); > > my $mtspr = sub { > > my ($f,$idx,$ra) = @_; > > if ($idx == 256 && $no_vrsave) { > > -- > > 2.23.0 > >