# git rev-parse -q --verify 34f0ee3c18c1ba6b31eea86c1e154ef1a7f31d56^{commit}
34f0ee3c18c1ba6b31eea86c1e154ef1a7f31d56
already have revision, skipping fetch
# git checkout -q -f -B kisskb 34f0ee3c18c1ba6b31eea86c1e154ef1a7f31d56
# git clean -qxdf
# < git log -1
# commit 34f0ee3c18c1ba6b31eea86c1e154ef1a7f31d56
# Author: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
# Date:   Tue Jul 17 16:57:29 2018 +0530
# 
#     powerpc/powernv: Save & Restore SPRG3 on entry/exit from stop (idle)
#     
#     On 64-bit Servers, SPRN_SPRG3 and its userspace read-only mirror
#     SPRN_USPRG3 are used as userspace VDSO write and read registers
#     respectively.
#     
#     SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
#     restored. As a result, any read from SPRN_USPRG3 returns zero on an
#     exit from stop4 and above. This affects Power9 only.
#     
#     Thus in this situation, any call from sched_getcpu() always returns
#     zero, as on powerpc, we call __kernel_getcpu() which relies upon
#     SPRN_USPRG3 to report the CPU and NUMA node information.
#     
#     Fix this by saving the SPRN_SPRG3 before entering a deep stop state,
#     and restoring it back on wakeup from the stop state.
#     
#     Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs for stop4 cpuidle")
#     Cc: stable@vger.kernel.org # v4.14+
#     Reported-by: Florian Weimer <fweimer@redhat.com>
#     Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-gcc --version
# < git log --format=%s --max-count=1 34f0ee3c18c1ba6b31eea86c1e154ef1a7f31d56
# < make -s -j 120 ARCH=arm64 O=/kisskb/build/powerpc-fixes_arm64-defconfig_arm64 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-  defconfig
# make -s -j 120 ARCH=arm64 O=/kisskb/build/powerpc-fixes_arm64-defconfig_arm64 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-  
arch/arm64/Makefile:27: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum
arch/arm64/Makefile:40: LSE atomics not supported by binutils
<stdin>:1335:2: warning: #warning syscall rseq not implemented [-Wcpp]
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_arm64-defconfig_arm64
# Build took: 0:01:33.349867