[PATCH stable-v5.4 v2 0/2] properly cope with -z norelro

STALE1867d

6 messages, 2 authors, 2021-06-25 · open the first message on its own page

[PATCH stable-v5.4 v2 0/2] properly cope with -z norelro

From: Jisheng Zhang <hidden>
Date: 2021-06-25 07:57:35 

Fix below build warning:
aarch64-linux-gnu-ld: warning: -z norelro ignored

Since v1
  - Backport a preparation patch as pointed out by Nick Desaulniers

Nick Desaulniers (1):
  arm64: link with -z norelro for LLD or aarch64-elf

Sami Tolvanen (1):
  kbuild: add CONFIG_LD_IS_LLD

 arch/arm64/Makefile | 10 +++++++---
 init/Kconfig        |  3 +++
 2 files changed, 10 insertions(+), 3 deletions(-)

-- 
2.32.0


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[PATCH stable-v5.4 v2 2/2] arm64: link with -z norelro for LLD or aarch64-elf

From: Jisheng Zhang <hidden>
Date: 2021-06-25 07:57:20 

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: <redacted> # 5.0.x-
Reported-by: kernelci.org bot <redacted>
Reported-by: Quentin Perret <redacted>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <redacted>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Alan Modra <redacted>
Cc: Fāng-ruì Sòng <redacted>
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
+
 CHECKFLAGS	+= -D__aarch64__
 
 ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)
-- 
2.32.0


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[PATCH stable-v5.4 v2 1/2] kbuild: add CONFIG_LD_IS_LLD

From: Jisheng Zhang <hidden>
Date: 2021-06-25 07:57:27 

From: Sami Tolvanen <samitolvanen@google.com>

commit b744b43f79cc758127042e71f9ad7b1afda30f84 upstream.

Similarly to the CC_IS_CLANG config, add LD_IS_LLD to avoid GNU ld
specific logic such as ld-version or ld-ifversion and gain the
ability to select potential features that depend on the linker at
configuration time such as LTO.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
[nc: Reword commit message]
Signed-off-by: Nathan Chancellor <redacted>
Tested-by: Sedat Dilek <redacted>
Reviewed-by: Sedat Dilek <redacted>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
---
 init/Kconfig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index 4f9fd78e2200..f23e90d9935f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -20,6 +20,9 @@ config GCC_VERSION
 config CC_IS_CLANG
 	def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
 
+config LD_IS_LLD
+	def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
+
 config CLANG_VERSION
 	int
 	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
-- 
2.32.0


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Re: [PATCH stable-v5.4 v2 0/2] properly cope with -z norelro

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-06-25 10:16:30 

On Fri, Jun 25, 2021 at 03:47:37PM +0800, Jisheng Zhang wrote:
Fix below build warning:
aarch64-linux-gnu-ld: warning: -z norelro ignored

Since v1
  - Backport a preparation patch as pointed out by Nick Desaulniers

Nick Desaulniers (1):
  arm64: link with -z norelro for LLD or aarch64-elf

Sami Tolvanen (1):
  kbuild: add CONFIG_LD_IS_LLD

 arch/arm64/Makefile | 10 +++++++---
 init/Kconfig        |  3 +++
 2 files changed, 10 insertions(+), 3 deletions(-)

-- 
2.32.0
Took this series instead, thanks.

greg k-h

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Patch "arm64: link with -z norelro for LLD or aarch64-elf" has been added to the 5.4-stable tree

From: <gregkh@linuxfoundation.org>
Date: 2021-06-25 10:51:16 

This is a note to let you know that I've just added the patch titled

    arm64: link with -z norelro for LLD or aarch64-elf

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-link-with-z-norelro-for-lld-or-aarch64-elf.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let [off-list ref] know about it.


From foo@baz Fri Jun 25 12:15:34 PM CEST 2021
From: Jisheng Zhang <redacted>
Date: Fri, 25 Jun 2021 15:50:12 +0800
Subject: arm64: link with -z norelro for LLD or aarch64-elf
To: Nick Desaulniers <ndesaulniers@google.com>, stable@vger.kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Nathan Chancellor <redacted>, Ard Biesheuvel <ardb@kernel.org>, Sami Tolvanen <samitolvanen@google.com>, Masahiro Yamada <masahiroy@kernel.org>, Sedat Dilek <redacted>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "Catalin Marinas" <catalin.marinas@arm.com>, "Will Deacon" <will@kernel.org>, "Alan Modra" <redacted>, "Fāng-ruì Sòng" <redacted>, "Quentin Perret" <redacted>, linux-arm-kernel@lists.infradead.org
Message-ID: [off-list ref]

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: <redacted> # 5.0.x-
Reported-by: kernelci.org bot <redacted>
Reported-by: Quentin Perret <redacted>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <redacted>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Alan Modra <redacted>
Cc: Fāng-ruì Sòng <redacted>
Link: https://lore.kernel.org/r/20201218002432.788499-1-ndesaulniers@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/arm64/Makefile |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- 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)


Patches currently in stable-queue which might be from Jisheng.Zhang@synaptics.com are

queue-5.4/arm64-link-with-z-norelro-for-lld-or-aarch64-elf.patch
queue-5.4/kbuild-add-config_ld_is_lld.patch

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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Patch "kbuild: add CONFIG_LD_IS_LLD" has been added to the 5.4-stable tree

From: <gregkh@linuxfoundation.org>
Date: 2021-06-25 10:52:23 

This is a note to let you know that I've just added the patch titled

    kbuild: add CONFIG_LD_IS_LLD

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kbuild-add-config_ld_is_lld.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let [off-list ref] know about it.


From foo@baz Fri Jun 25 12:15:34 PM CEST 2021
From: Jisheng Zhang <redacted>
Date: Fri, 25 Jun 2021 15:48:35 +0800
Subject: kbuild: add CONFIG_LD_IS_LLD
To: Nick Desaulniers <ndesaulniers@google.com>, stable@vger.kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Nathan Chancellor <redacted>, Ard Biesheuvel <ardb@kernel.org>, Sami Tolvanen <samitolvanen@google.com>, Masahiro Yamada <masahiroy@kernel.org>, Sedat Dilek <redacted>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "Catalin Marinas" <catalin.marinas@arm.com>, "Will Deacon" <will@kernel.org>, "Alan Modra" <redacted>, "Fāng-ruì Sòng" <redacted>, "Quentin Perret" <redacted>, linux-arm-kernel@lists.infradead.org
Message-ID: [off-list ref]

From: Sami Tolvanen <samitolvanen@google.com>

commit b744b43f79cc758127042e71f9ad7b1afda30f84 upstream.

Similarly to the CC_IS_CLANG config, add LD_IS_LLD to avoid GNU ld
specific logic such as ld-version or ld-ifversion and gain the
ability to select potential features that depend on the linker at
configuration time such as LTO.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
[nc: Reword commit message]
Signed-off-by: Nathan Chancellor <redacted>
Tested-by: Sedat Dilek <redacted>
Reviewed-by: Sedat Dilek <redacted>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 init/Kconfig |    3 +++
 1 file changed, 3 insertions(+)

--- a/init/Kconfig
+++ b/init/Kconfig
@@ -20,6 +20,9 @@ config GCC_VERSION
 config CC_IS_CLANG
 	def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
 
+config LD_IS_LLD
+	def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
+
 config CLANG_VERSION
 	int
 	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))


Patches currently in stable-queue which might be from Jisheng.Zhang@synaptics.com are

queue-5.4/arm64-link-with-z-norelro-for-lld-or-aarch64-elf.patch
queue-5.4/kbuild-add-config_ld_is_lld.patch

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