# git rev-parse -q --verify 9933819099c4600b41a042f27a074470a43cf6b9^{commit}
9933819099c4600b41a042f27a074470a43cf6b9
already have revision, skipping fetch
# git checkout -q -f -B kisskb 9933819099c4600b41a042f27a074470a43cf6b9
# git clean -qxdf
# < git log -1
# commit 9933819099c4600b41a042f27a074470a43cf6b9
# Author: Christophe Leroy <christophe.leroy@c-s.fr>
# Date:   Mon Jan 27 10:42:04 2020 +0000
# 
#     powerpc/32s: Fix CPU wake-up from sleep mode
#     
#     Commit f7354ccac844 ("powerpc/32: Remove CURRENT_THREAD_INFO and
#     rename TI_CPU") broke the CPU wake-up from sleep mode (i.e. when
#     _TLF_SLEEPING is set) by delaying the tovirt(r2, r2).
#     
#     This is because r2 is not restored by fast_exception_return. It used
#     to work (by chance ?) because CPU wake-up interrupt never comes from
#     user, so r2 is expected to point to 'current' on return.
#     
#     Commit e2fb9f544431 ("powerpc/32: Prepare for Kernel Userspace Access
#     Protection") broke it even more by clobbering r0 which is not
#     restored by fast_exception_return either.
#     
#     Use r6 instead of r0. This is possible because r3-r6 are restored by
#     fast_exception_return and only r3-r5 are used for exception arguments.
#     
#     For r2 it could be converted back to virtual address, but stay on the
#     safe side and restore it from the stack instead. It should be live
#     in the cache at that moment, so loading from the stack should make
#     no difference compared to converting it from phys to virt.
#     
#     Fixes: f7354ccac844 ("powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU")
#     Fixes: e2fb9f544431 ("powerpc/32: Prepare for Kernel Userspace Access Protection")
#     Cc: stable@vger.kernel.org
#     Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/6d02c3ae6ad77af34392e98117e44c2bf6d13ba1.1580121710.git.christophe.leroy@c-s.fr
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 9933819099c4600b41a042f27a074470a43cf6b9
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_powernv_defconfig+NO_PERF_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  powernv_defconfig
# Added to kconfig CONFIG_PERF_EVENTS=n
# yes \n | make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_powernv_defconfig+NO_PERF_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  oldconfig
yes: standard output: Broken pipe
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_powernv_defconfig+NO_PERF_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
WARNING: vmlinux.o(.text+0x2fc8): Section mismatch in reference from the variable start_here_common to the function .init.text:start_kernel()
The function start_here_common() references
the function __init start_kernel().
This is often because start_here_common lacks a __init 
annotation or the annotation of start_kernel is wrong.

Completed OK
# rm -rf /kisskb/build/powerpc-next_powernv_defconfig+NO_PERF_ppc64le-gcc5
# Build took: 0:03:03.384299