From: Nathan Chancellor <natechancellor@gmail.com> To: Nick Desaulniers <ndesaulniers@google.com> Cc: "Catalin Marinas" <catalin.marinas@arm.com>, "Will Deacon" <will@kernel.org>, kernel-team <kernel-team@android.com>, "Peter Smith" <Peter.Smith@arm.com>, clang-built-linux <clang-built-linux@googlegroups.com>, stable <stable@vger.kernel.org>, "Ard Biesheuvel" <ardb@kernel.org>, "Fāng-ruì Sòng" <maskray@google.com>, "Quentin Perret" <qperret@google.com>, "Alan Modra" <amodra@gmail.com>, "kernelci . org bot" <bot@kernelci.org>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] arm64: link with -z norelro for LLD or aarch64-elf Date: Thu, 17 Dec 2020 19:36:58 -0700 [thread overview] Message-ID: <20201218023658.GA577188@ubuntu-m3-large-x86> (raw) In-Reply-To: <20201218002432.788499-1-ndesaulniers@google.com> On Thu, Dec 17, 2020 at 04:24:32PM -0800, 'Nick Desaulniers' via Clang Built Linux wrote: > With GNU binutils 2.35+, linking with BFD produces warnings for vmlinux: > aarch64-linux-gnu-ld: warning: -z norelro ignored > > BFD can produce this warning when the target emulation mode does not > support RELRO program headers, and -z relro or -z norelro is passed. > > Alan Modra clarifies: > The default linker emulation for an aarch64-linux ld.bfd is > -maarch64linux, the default for an aarch64-elf linker is > -maarch64elf. They are not equivalent. If you choose -maarch64elf > you get an emulation that doesn't support -z relro. > > The ARCH=arm64 kernel prefers -maarch64elf, but may fall back to > -maarch64linux based on the toolchain configuration. > > LLD will always create RELRO program header regardless of target > emulation. > > To avoid the above warning when linking with BFD, pass -z norelro only > when linking with LLD or with -maarch64linux. > > Cc: Alan Modra <amodra@gmail.com> > Cc: Fāng-ruì Sòng <maskray@google.com> > Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") > Reported-by: kernelci.org bot <bot@kernelci.org> > Reported-by: Quentin Perret <qperret@google.com> > Acked-by: Ard Biesheuvel <ardb@kernel.org> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > --- > Changes V1 -> V2: > * s/relocation types/program headers/ > * s/newer GNU binutils/GNU binutils 2.35+/ > * Pick up Ard's Ack. > > Note: maintainers may want to pick up the following tag: > > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") > > or drop the existing fixes tag (this patch is more so in response to > change to BFD to warn than fix a kernel regression, IMO, but I don't > care). Either way, it would be good to fix this for the newly minted > v5.10.y. Should probably have Cc: stable@vger.kernel.org then. > I'll probably be offline for the next two weeks for the holidays, so no > promises on quick replies. Happy holidays+new year! > > > arch/arm64/Makefile | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 6be9b3750250..90309208bb28 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -10,7 +10,7 @@ > # > # Copyright (C) 1995-2001 by Russell King > > -LDFLAGS_vmlinux :=--no-undefined -X -z norelro > +LDFLAGS_vmlinux :=--no-undefined -X > > ifeq ($(CONFIG_RELOCATABLE), y) > # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour > @@ -115,16 +115,20 @@ KBUILD_CPPFLAGS += -mbig-endian > CHECKFLAGS += -D__AARCH64EB__ > # Prefer the baremetal ELF build target, but not all toolchains include > # it so fall back to the standard linux version if needed. > -KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb) > +KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb -z norelro) > UTS_MACHINE := aarch64_be > else > KBUILD_CPPFLAGS += -mlittle-endian > CHECKFLAGS += -D__AARCH64EL__ > # Same as above, prefer ELF but fall back to linux target if needed. > -KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux) > +KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux -z norelro) > UTS_MACHINE := aarch64 > endif > > +ifeq ($(CONFIG_LD_IS_LLD), y) > +KBUILD_LDFLAGS += -z norelro > +endif > + > CHECKFLAGS += -D__aarch64__ > > ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y) > -- > 2.29.2.684.gfbc64c5ab5-goog >
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <natechancellor@gmail.com> To: Nick Desaulniers <ndesaulniers@google.com> Cc: "kernelci . org bot" <bot@kernelci.org>, "Fāng-ruì Sòng" <maskray@google.com>, "Will Deacon" <will@kernel.org>, "Quentin Perret" <qperret@google.com>, "Catalin Marinas" <catalin.marinas@arm.com>, "Alan Modra" <amodra@gmail.com>, "Peter Smith" <Peter.Smith@arm.com>, stable <stable@vger.kernel.org>, linux-kernel@vger.kernel.org, clang-built-linux <clang-built-linux@googlegroups.com>, kernel-team <kernel-team@android.com>, "Ard Biesheuvel" <ardb@kernel.org>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2] arm64: link with -z norelro for LLD or aarch64-elf Date: Thu, 17 Dec 2020 19:36:58 -0700 [thread overview] Message-ID: <20201218023658.GA577188@ubuntu-m3-large-x86> (raw) In-Reply-To: <20201218002432.788499-1-ndesaulniers@google.com> On Thu, Dec 17, 2020 at 04:24:32PM -0800, 'Nick Desaulniers' via Clang Built Linux wrote: > With GNU binutils 2.35+, linking with BFD produces warnings for vmlinux: > aarch64-linux-gnu-ld: warning: -z norelro ignored > > BFD can produce this warning when the target emulation mode does not > support RELRO program headers, and -z relro or -z norelro is passed. > > Alan Modra clarifies: > The default linker emulation for an aarch64-linux ld.bfd is > -maarch64linux, the default for an aarch64-elf linker is > -maarch64elf. They are not equivalent. If you choose -maarch64elf > you get an emulation that doesn't support -z relro. > > The ARCH=arm64 kernel prefers -maarch64elf, but may fall back to > -maarch64linux based on the toolchain configuration. > > LLD will always create RELRO program header regardless of target > emulation. > > To avoid the above warning when linking with BFD, pass -z norelro only > when linking with LLD or with -maarch64linux. > > Cc: Alan Modra <amodra@gmail.com> > Cc: Fāng-ruì Sòng <maskray@google.com> > Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") > Reported-by: kernelci.org bot <bot@kernelci.org> > Reported-by: Quentin Perret <qperret@google.com> > Acked-by: Ard Biesheuvel <ardb@kernel.org> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > --- > Changes V1 -> V2: > * s/relocation types/program headers/ > * s/newer GNU binutils/GNU binutils 2.35+/ > * Pick up Ard's Ack. > > Note: maintainers may want to pick up the following tag: > > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") > > or drop the existing fixes tag (this patch is more so in response to > change to BFD to warn than fix a kernel regression, IMO, but I don't > care). Either way, it would be good to fix this for the newly minted > v5.10.y. Should probably have Cc: stable@vger.kernel.org then. > I'll probably be offline for the next two weeks for the holidays, so no > promises on quick replies. Happy holidays+new year! > > > arch/arm64/Makefile | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 6be9b3750250..90309208bb28 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -10,7 +10,7 @@ > # > # Copyright (C) 1995-2001 by Russell King > > -LDFLAGS_vmlinux :=--no-undefined -X -z norelro > +LDFLAGS_vmlinux :=--no-undefined -X > > ifeq ($(CONFIG_RELOCATABLE), y) > # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour > @@ -115,16 +115,20 @@ KBUILD_CPPFLAGS += -mbig-endian > CHECKFLAGS += -D__AARCH64EB__ > # Prefer the baremetal ELF build target, but not all toolchains include > # it so fall back to the standard linux version if needed. > -KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb) > +KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb -z norelro) > UTS_MACHINE := aarch64_be > else > KBUILD_CPPFLAGS += -mlittle-endian > CHECKFLAGS += -D__AARCH64EL__ > # Same as above, prefer ELF but fall back to linux target if needed. > -KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux) > +KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux -z norelro) > UTS_MACHINE := aarch64 > endif > > +ifeq ($(CONFIG_LD_IS_LLD), y) > +KBUILD_LDFLAGS += -z norelro > +endif > + > CHECKFLAGS += -D__aarch64__ > > ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y) > -- > 2.29.2.684.gfbc64c5ab5-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-12-18 2:37 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-16 17:53 [PATCH] arm64: link with -z norelro regardless of CONFIG_RELOCATABLE Nick Desaulniers 2020-10-16 17:53 ` Nick Desaulniers 2020-10-20 17:57 ` Will Deacon 2020-10-20 17:57 ` Will Deacon 2020-10-20 20:16 ` Nick Desaulniers 2020-10-20 20:16 ` Nick Desaulniers 2020-10-21 6:58 ` Ard Biesheuvel 2020-10-21 6:58 ` Ard Biesheuvel 2020-12-14 21:44 ` Nick Desaulniers 2020-12-14 21:44 ` Nick Desaulniers 2020-12-14 23:18 ` Alan Modra 2020-12-14 23:18 ` Alan Modra 2020-12-14 23:33 ` Nick Desaulniers 2020-12-14 23:33 ` Nick Desaulniers 2020-12-17 0:40 ` [PATCH] arm64: link with -z norelro for LLD or aarch64-elf Nick Desaulniers 2020-12-17 0:40 ` Nick Desaulniers 2020-12-17 12:01 ` Will Deacon 2020-12-17 12:01 ` Will Deacon 2020-12-17 21:07 ` Nick Desaulniers 2020-12-17 21:07 ` Nick Desaulniers 2020-12-18 0:24 ` [PATCH v2] " Nick Desaulniers 2020-12-18 0:24 ` Nick Desaulniers 2020-12-18 2:36 ` Nathan Chancellor [this message] 2020-12-18 2:36 ` Nathan Chancellor 2021-01-05 12:26 ` Catalin Marinas 2021-01-05 12:26 ` Catalin Marinas 2020-12-17 19:29 ` [PATCH] " Ard Biesheuvel 2020-12-17 19:29 ` Ard Biesheuvel
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