# git rev-parse -q --verify 8d17c0c83c07bad137e2df3a45e9cd4e80d85418^{commit}
8d17c0c83c07bad137e2df3a45e9cd4e80d85418
already have revision, skipping fetch
# git checkout -q -f -B kisskb 8d17c0c83c07bad137e2df3a45e9cd4e80d85418
# git clean -qxdf
# < git log -1
# commit 8d17c0c83c07bad137e2df3a45e9cd4e80d85418
# Author: Ard Biesheuvel <ardb@kernel.org>
# Date:   Wed Oct 28 09:04:33 2020 +0100
# 
#     powerpc: Avoid broken GCC __attribute__((optimize))
#     
#     Commit 7053f80d9696 ("powerpc/64: Prevent stack protection in early
#     boot") introduced a couple of uses of __attribute__((optimize)) with
#     function scope, to disable the stack protector in some early boot
#     code.
#     
#     Unfortunately, and this is documented in the GCC man pages [0],
#     overriding function attributes for optimization is broken, and is only
#     supported for debug scenarios, not for production: the problem appears
#     to be that setting GCC -f flags using this method will cause it to
#     forget about some or all other optimization settings that have been
#     applied.
#     
#     So the only safe way to disable the stack protector is to disable it
#     for the entire source file.
#     
#     [0] https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
#     
#     Fixes: 7053f80d9696 ("powerpc/64: Prevent stack protection in early boot")
#     Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
#     [mpe: Drop one remaining use of __nostackprotector, reported by snowpatch]
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/20201028080433.26799-1-ardb@kernel.org
# < /opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 8d17c0c83c07bad137e2df3a45e9cd4e80d85418
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc64le_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  ppc64le_defconfig
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc64le_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc64le_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc64le_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
Completed OK
# rm -rf /kisskb/build/powerpc-next_ppc64le_defconfig_powerpc-gcc9
# Build took: 0:03:37.793790