From: Nick Desaulniers <ndesaulniers@google.com> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org> Cc: 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>, "Nick Desaulniers" <ndesaulniers@google.com>, "kernelci . org bot" <bot@kernelci.org>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] arm64: link with -z norelro for LLD or aarch64-elf Date: Wed, 16 Dec 2020 16:40:51 -0800 [thread overview] Message-ID: <20201217004051.1247544-1-ndesaulniers@google.com> (raw) In-Reply-To: <CAKwvOdkP8vHidFPWczC24XwNHhQaXovQiQ43Yb6Csp_+kPR9XQ@mail.gmail.com> With newer GNU binutils, 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 relocation types, 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 relocation types 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: Ard Biesheuvel <ardb@kernel.org> 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> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- 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: Nick Desaulniers <ndesaulniers@google.com> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org> Cc: "kernelci . org bot" <bot@kernelci.org>, "Fāng-ruì Sòng" <maskray@google.com>, "Quentin Perret" <qperret@google.com>, "Alan Modra" <amodra@gmail.com>, "Nick Desaulniers" <ndesaulniers@google.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: [PATCH] arm64: link with -z norelro for LLD or aarch64-elf Date: Wed, 16 Dec 2020 16:40:51 -0800 [thread overview] Message-ID: <20201217004051.1247544-1-ndesaulniers@google.com> (raw) In-Reply-To: <CAKwvOdkP8vHidFPWczC24XwNHhQaXovQiQ43Yb6Csp_+kPR9XQ@mail.gmail.com> With newer GNU binutils, 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 relocation types, 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 relocation types 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: Ard Biesheuvel <ardb@kernel.org> 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> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- 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:[~2020-12-17 0:42 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 ` Nick Desaulniers [this message] 2020-12-17 0:40 ` [PATCH] arm64: link with -z norelro for LLD or aarch64-elf 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 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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