| Message ID | 20210624170919.3d018a1a@xhacker.debian |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v5.4] arm64: link with -z norelro for LLD or aarch64-elf | expand |
On Thu, Jun 24, 2021 at 2:09 AM Jisheng Zhang <Jisheng.Zhang@synaptics.com> wrote: > > From: Nick Desaulniers <ndesaulniers@google.com> > > commit 311bea3cb9ee20ef150ca76fc60a592bf6b159f5 upstream. > > 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. > > Fixes: 3b92fa7485eb ("arm64: link with -z norelro thank you regardless of CONFIG_RELOCATABLE") ^ exists in 5.4 as 57a88e44b512 > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") ^ landed in v5.0-rc1 > Cc: <stable@vger.kernel.org> # 5.0.x- > Reported-by: kernelci.org bot <bot@kernelci.org> > Reported-by: Quentin Perret <qperret@google.com> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > Acked-by: Ard Biesheuvel <ardb@kernel.org> > Cc: Alan Modra <amodra@gmail.com> > Cc: Fāng-ruì Sòng <maskray@google.com> > Link: https://lore.kernel.org/r/20201218002432.788499-1-ndesaulniers@google.com > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > --- > arch/arm64/Makefile | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index cd8f3cdabfd0..d227cf87c48f 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 > CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET) > GZFLAGS :=-9 > > @@ -82,17 +82,21 @@ CHECKFLAGS += -D__AARCH64EB__ > AS += -EB > # 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__ > AS += -EL > # 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 ^ ah but 5.4 doesn't have commit b744b43f79cc ("kbuild: add CONFIG_LD_IS_LLD") which landed in v5.8-rc1. So this patch will break LLD on 5.4. That should be trivial to backport, but would you please send that first, then this? > + > CHECKFLAGS += -D__aarch64__ > > ifeq ($(CONFIG_ARM64_MODULE_PLTS),y) > -- > 2.32.0 > -- Thanks, ~Nick Desaulniers
On Thu, Jun 24, 2021 at 05:09:19PM +0800, Jisheng Zhang wrote: > From: Nick Desaulniers <ndesaulniers@google.com> > > commit 311bea3cb9ee20ef150ca76fc60a592bf6b159f5 upstream. > > 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. > > Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") > Cc: <stable@vger.kernel.org> # 5.0.x- > Reported-by: kernelci.org bot <bot@kernelci.org> > Reported-by: Quentin Perret <qperret@google.com> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > Acked-by: Ard Biesheuvel <ardb@kernel.org> > Cc: Alan Modra <amodra@gmail.com> > Cc: Fāng-ruì Sòng <maskray@google.com> > Link: https://lore.kernel.org/r/20201218002432.788499-1-ndesaulniers@google.com > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > --- > arch/arm64/Makefile | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) Now queued up, thanks. greg k-h
Hi Greg, On Fri, 25 Jun 2021 12:09:33 +0200 Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Thu, Jun 24, 2021 at 05:09:19PM +0800, Jisheng Zhang wrote: > > From: Nick Desaulniers <ndesaulniers@google.com> > > > > commit 311bea3cb9ee20ef150ca76fc60a592bf6b159f5 upstream. > > > > 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. > > > > Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") > > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") > > Cc: <stable@vger.kernel.org> # 5.0.x- > > Reported-by: kernelci.org bot <bot@kernelci.org> > > Reported-by: Quentin Perret <qperret@google.com> > > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > > Acked-by: Ard Biesheuvel <ardb@kernel.org> > > Cc: Alan Modra <amodra@gmail.com> > > Cc: Fāng-ruì Sòng <maskray@google.com> > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > > --- > > arch/arm64/Makefile | 10 +++++++--- > > 1 file changed, 7 insertions(+), 3 deletions(-) > > Now queued up, thanks. > I assume the two patches in v2 series are queued up. Nick pointed out applying only this patch can break kernel building with lld. Thanks
On Fri, Jun 25, 2021 at 06:12:30PM +0800, Jisheng Zhang wrote: > Hi Greg, > > On Fri, 25 Jun 2021 12:09:33 +0200 > Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > > > > > On Thu, Jun 24, 2021 at 05:09:19PM +0800, Jisheng Zhang wrote: > > > From: Nick Desaulniers <ndesaulniers@google.com> > > > > > > commit 311bea3cb9ee20ef150ca76fc60a592bf6b159f5 upstream. > > > > > > 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. > > > > > > Fixes: 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") > > > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") > > > Cc: <stable@vger.kernel.org> # 5.0.x- > > > Reported-by: kernelci.org bot <bot@kernelci.org> > > > Reported-by: Quentin Perret <qperret@google.com> > > > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > > > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > > > Acked-by: Ard Biesheuvel <ardb@kernel.org> > > > Cc: Alan Modra <amodra@gmail.com> > > > Cc: Fāng-ruì Sòng <maskray@google.com> > > > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > > > --- > > > arch/arm64/Makefile | 10 +++++++--- > > > 1 file changed, 7 insertions(+), 3 deletions(-) > > > > Now queued up, thanks. > > > > I assume the two patches in v2 series are queued up. Nick pointed out > applying only this patch can break kernel building with lld. Yes, I now took those instead, thanks. greg k-h
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index cd8f3cdabfd0..d227cf87c48f 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 CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET) GZFLAGS :=-9 @@ -82,17 +82,21 @@ CHECKFLAGS += -D__AARCH64EB__ AS += -EB # 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__ AS += -EL # 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_ARM64_MODULE_PLTS),y)