Re: [PATCH] BaseTools/tools_def IA32: disable PIE code generation explicitly

["Gao, Liming" <liming.gao@intel.com>]

Ard:
  GCC49 tool chain can be used by GCC4.9 and above compiler. It provides the GCC setting without LTO. GCC5 tool chain provides GCC setting with LTO. So, I suggest to disable it also in GCC49 tool chain. 

Thanks
Liming
> -----Original Message-----
> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> Sent: Tuesday, June 12, 2018 12:04 AM
> To: Gao, Liming <liming.gao@intel.com>
> Cc: edk2-devel@lists.01.org; lersek@redhat.com; zenith432@users.sourceforge.net
> Subject: Re: [edk2] [PATCH] BaseTools/tools_def IA32: disable PIE code generation explicitly
> 
> On 11 June 2018 at 18:00, Gao, Liming <liming.gao@intel.com> wrote:
> > Ard:
> >   Is this option required in GCC49 tool chain? Or, this option is only required when lto is enabled?
> >
> 
> It has nothing to do with LTO.
> 
> In theory, it could be required for any toolchain that supports -fpic
> and or -fpie. However, not all 4.x toolchains support -fpie and so
> they don't support -fno-pie either.
> 
> Given that the distros only changed this default recently (in the 5.x
> timeframe or later), it makes sense to only disable it for GCC5,
> although it is safe to disable it for GCC49 as well.
> 
> >> -----Original Message-----
> >> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Ard Biesheuvel
> >> Sent: Monday, June 11, 2018 4:53 PM
> >> To: Gao, Liming <liming.gao@intel.com>
> >> Cc: edk2-devel@lists.01.org; lersek@redhat.com; zenith432@users.sourceforge.net
> >> Subject: Re: [edk2] [PATCH] BaseTools/tools_def IA32: disable PIE code generation explicitly
> >>
> >> On 11 June 2018 at 10:38, Gao, Liming <liming.gao@intel.com> wrote:
> >> > Ard:
> >> >   Do you mean the default GCC compiler disables PIC and PIE for IA32 arch? But now, some distribution GCC compiler enables
> PIC
> >> and PIE by default. So, we have to obviously disable PIC and PIE in tools_def.txt.
> >> >
> >>
> >> Yes. On my x86 Ubuntu 18.04 LTS system:
> >>
> >> $ gcc -v
> >> Using built-in specs.
> >> COLLECT_GCC=gcc
> >> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
> >> OFFLOAD_TARGET_NAMES=nvptx-none
> >> OFFLOAD_TARGET_DEFAULT=1
> >> Target: x86_64-linux-gnu
> >> Configured with: ../src/configure -v --with-pkgversion='Ubuntu
> >> 7.3.0-16ubuntu3' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
> >> --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++
> >> --prefix=/usr --with-gcc-major-version-only
> >> --with-as=/usr/bin/x86_64-linux-gnu-as
> >> --with-ld=/usr/bin/x86_64-linux-gnu-ld --program-suffix=-7
> >> --program-prefix=x86_64-linux-gnu- --enable-shared
> >> --enable-linker-build-id --libexecdir=/usr/lib
> >> --without-included-gettext --enable-threads=posix --libdir=/usr/lib
> >> --enable-nls --with-sysroot=/ --enable-clocale=gnu
> >> --enable-libstdcxx-debug --enable-libstdcxx-time=yes
> >> --with-default-libstdcxx-abi=new --enable-gnu-unique-object
> >> --disable-vtable-verify --enable-libmpx --enable-plugin
> >> --enable-default-pie --with-system-zlib --with-target-system-zlib
> >> --enable-objc-gc=auto --enable-multiarch --disable-werror
> >> --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
> >> --enable-multilib --with-tune=generic
> >> --enable-offload-targets=nvptx-none --without-cuda-driver
> >> --enable-checking=release --build=x86_64-linux-gnu
> >> --host=x86_64-linux-gnu --target=x86_64-linux-gnu
> >> Thread model: posix
> >> gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)
> >>
> >>
> >> Notice the '--enable-default-pie' 4 lines from the bottom.
> >>
> >>
> >>
> >> >>-----Original Message-----
> >> >>From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> >> >>Sent: Monday, June 11, 2018 3:42 PM
> >> >>To: edk2-devel@lists.01.org
> >> >>Cc: Zhu, Yonghong <yonghong.zhu@intel.com>; Gao, Liming
> >> >><liming.gao@intel.com>; lersek@redhat.com; Shi, Steven
> >> >><steven.shi@intel.com>; zenith432@users.sourceforge.net; Ard Biesheuvel
> >> >><ard.biesheuvel@linaro.org>
> >> >>Subject: [PATCH] BaseTools/tools_def IA32: disable PIE code generation
> >> >>explicitly
> >> >>
> >> >>As a security measure, some distros now build their GCC toolchains with
> >> >>PIE code generation enabled by default, because it is a prerequisite
> >> >>for ASLR to be enabled when running the executable.
> >> >>
> >> >>This typically results in slightly larger code, but it also generates
> >> >>ELF relocations that our tooling cannot deal with, so let's disable it
> >> >>explicitly when using GCC5 for IA32. (Note that this does not apply to
> >> >>X64: it uses PIE code deliberately in some cases, and our tooling does
> >> >>deal with the resuling relocations)
> >> >>
> >> >>Contributed-under: TianoCore Contribution Agreement 1.1
> >> >>Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >> >>---
> >> >> BaseTools/Conf/tools_def.template | 6 +++---
> >> >> 1 file changed, 3 insertions(+), 3 deletions(-)
> >> >>
> >> >>diff --git a/BaseTools/Conf/tools_def.template
> >> >>b/BaseTools/Conf/tools_def.template
> >> >>index 7e9c915755ed..ab57f9c706e3 100755
> >> >>--- a/BaseTools/Conf/tools_def.template
> >> >>+++ b/BaseTools/Conf/tools_def.template
> >> >>@@ -4670,7 +4670,7 @@ DEFINE GCC49_AARCH64_DLINK2_FLAGS    =
> >> >>DEF(GCC48_AARCH64_DLINK2_FLAGS)
> >> >> DEFINE GCC49_ARM_ASLDLINK_FLAGS      =
> >> >>DEF(GCC48_ARM_ASLDLINK_FLAGS)
> >> >> DEFINE GCC49_AARCH64_ASLDLINK_FLAGS  =
> >> >>DEF(GCC48_AARCH64_ASLDLINK_FLAGS)
> >> >>
> >> >>-DEFINE GCC5_IA32_CC_FLAGS            = DEF(GCC49_IA32_CC_FLAGS)
> >> >>+DEFINE GCC5_IA32_CC_FLAGS            = DEF(GCC49_IA32_CC_FLAGS) -fno-pic
> >> >>-fno-pie
> >> >> DEFINE GCC5_X64_CC_FLAGS             = DEF(GCC49_X64_CC_FLAGS)
> >> >> DEFINE GCC5_IA32_X64_DLINK_COMMON    =
> >> >>DEF(GCC49_IA32_X64_DLINK_COMMON)
> >> >> DEFINE GCC5_IA32_X64_ASLDLINK_FLAGS  =
> >> >>DEF(GCC49_IA32_X64_ASLDLINK_FLAGS)
> >> >>@@ -5502,9 +5502,9 @@ RELEASE_GCC49_AARCH64_DLINK_FLAGS  =
> >> >>DEF(GCC49_AARCH64_DLINK_FLAGS)
> >> >> *_GCC5_IA32_RC_PATH              = DEF(GCC5_IA32_PREFIX)objcopy
> >> >>
> >> >> *_GCC5_IA32_ASLCC_FLAGS          = DEF(GCC_ASLCC_FLAGS) -m32 -fno-lto
> >> >>-*_GCC5_IA32_ASLDLINK_FLAGS       = DEF(GCC5_IA32_X64_ASLDLINK_FLAGS)
> >> >>-Wl,-m,elf_i386
> >> >>+*_GCC5_IA32_ASLDLINK_FLAGS       =
> >> >>DEF(GCC5_IA32_X64_ASLDLINK_FLAGS) -Wl,-m,elf_i386 -no-pie
> >> >> *_GCC5_IA32_ASM_FLAGS            = DEF(GCC5_ASM_FLAGS) -m32 -
> >> >>march=i386
> >> >>-*_GCC5_IA32_DLINK2_FLAGS         = DEF(GCC5_IA32_DLINK2_FLAGS)
> >> >>+*_GCC5_IA32_DLINK2_FLAGS         = DEF(GCC5_IA32_DLINK2_FLAGS) -no-
> >> >>pie
> >> >> *_GCC5_IA32_RC_FLAGS             = DEF(GCC_IA32_RC_FLAGS)
> >> >> *_GCC5_IA32_OBJCOPY_FLAGS        =
> >> >> *_GCC5_IA32_NASM_FLAGS           = -f elf32
> >> >>--
> >> >>2.17.1
> >> >
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