# git rev-parse -q --verify d0d283b05eee6a6c51df527e077d513ac2734d95^{commit}
d0d283b05eee6a6c51df527e077d513ac2734d95
already have revision, skipping fetch
# git checkout -q -f -B kisskb d0d283b05eee6a6c51df527e077d513ac2734d95
# git clean -qxdf
# < git log -1
# commit d0d283b05eee6a6c51df527e077d513ac2734d95
# Author: Naveen N Rao <naveen@kernel.org>
# Date:   Mon Jun 19 15:17:34 2023 +0530
# 
#     powerpc/ftrace: Add support for -fpatchable-function-entry
#     
#     GCC v13.1 updated support for -fpatchable-function-entry on ppc64le to
#     emit nops after the local entry point, rather than before it. This
#     allows us to use this in the kernel for ftrace purposes. A new script is
#     added under arch/powerpc/tools/ to help detect if nops are emitted after
#     the function local entry point, or before the global entry point.
#     
#     With -fpatchable-function-entry, we no longer have the profiling
#     instructions generated at function entry, so we only need to validate
#     the presence of two nops at the ftrace location in ftrace_init_nop(). We
#     patch the preceding instruction with 'mflr r0' to match the
#     -mprofile-kernel ABI for subsequent ftrace use.
#     
#     This changes the profiling instructions used on ppc32. The default -pg
#     option emits an additional 'stw' instruction after 'mflr r0' and before
#     the branch to _mcount 'bl _mcount'. This is very similar to the original
#     -mprofile-kernel implementation on ppc64le, where an additional 'std'
#     instruction was used to save LR to its save location in the caller's
#     stackframe. Subsequently, this additional store was removed in later
#     compiler versions for performance reasons. The same reasons apply for
#     ppc32 so we only patch in a 'mflr r0'.
#     
#     Signed-off-by: Naveen N Rao <naveen@kernel.org>
#     Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://msgid.link/68586d22981a2c3bb45f27a2b621173d10a7d092.1687166935.git.naveen@kernel.org
# < /opt/cross/kisskb/korg/gcc-12.2.0-nolibc/aarch64-linux/bin/aarch64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-12.2.0-nolibc/aarch64-linux/bin/aarch64-linux-ld --version
# < git log --format=%s --max-count=1 d0d283b05eee6a6c51df527e077d513ac2734d95
# make -s -j 160 ARCH=arm64 O=/kisskb/build/powerpc-next_defconfig_arm64-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/aarch64-linux/bin/aarch64-linux-  defconfig
# < make -s -j 160 ARCH=arm64 O=/kisskb/build/powerpc-next_defconfig_arm64-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/aarch64-linux/bin/aarch64-linux-  help
# make -s -j 160 ARCH=arm64 O=/kisskb/build/powerpc-next_defconfig_arm64-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/aarch64-linux/bin/aarch64-linux-  olddefconfig
# make -s -j 160 ARCH=arm64 O=/kisskb/build/powerpc-next_defconfig_arm64-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/aarch64-linux/bin/aarch64-linux-  
Completed OK
# rm -rf /kisskb/build/powerpc-next_defconfig_arm64-gcc12
# Build took: 0:03:45.357050