# git rev-parse -q --verify d02d2129641d6cd22492ddc85e11d112eb0d5a6f^{commit}
# git fetch -q -n -f git://gitlab.ozlabs.ibm.com/linuxppc/linux.git next-test
warning: The last gc run reported the following. Please correct the root cause
and remove .git/gc.log.
Automatic cleanup will not be performed until the file is removed.

warning: There are too many unreachable loose objects; run 'git prune' to remove them.

# git rev-parse -q --verify d02d2129641d6cd22492ddc85e11d112eb0d5a6f^{commit}
d02d2129641d6cd22492ddc85e11d112eb0d5a6f
# git checkout -q -f -B kisskb d02d2129641d6cd22492ddc85e11d112eb0d5a6f
# git clean -qxdf
# < git log -1
# commit d02d2129641d6cd22492ddc85e11d112eb0d5a6f
# Author: Russell Currey <ruscur@russell.cc>
# Date:   Fri Mar 1 01:49:17 2019 +1100
# 
#     powerpc/64s: Implement KUAP for Radix MMU
#     
#     Kernel Userspace Access Prevention utilises a feature of the Radix MMU
#     which disallows read and write access to userspace addresses. By
#     utilising this, the kernel is prevented from accessing user data from
#     outside of trusted paths that perform proper safety checks, such as
#     copy_{to/from}_user() and friends.
#     
#     Userspace access is disabled from early boot and is only enabled when
#     performing an operation like copy_{to/from}_user().  The register that
#     controls this (AMR) does not prevent userspace from accessing itself,
#     so there is no need to save and restore when entering and exiting
#     userspace.
#     
#     This feature has a slight performance impact which I roughly measured
#     to be 3% slower in the worst case (performing 1GB of 1 byte
#     read()/write() syscalls), and is gated behind the CONFIG_PPC_KUAP
#     option for performance-critical builds.
#     
#     This feature can be tested by using the lkdtm driver (CONFIG_LKDTM=y)
#     and performing the following:
#     
#       # (echo ACCESS_USERSPACE) > [debugfs]/provoke-crash/DIRECT
#     
#     If enabled, this should send SIGSEGV to the thread.
#     
#     mpe: Drop the unused paca flags. Zero the UAMOR to be safe. Save the
#     AMR when we enter the kernel from the kernel and then lock it again.
#     Restore on the way back to the kernel. This means we handle nesting of
#     interrupts properly, ie. we are protected inside the page fault
#     handler caused by a user access. Add paranoid checking of AMR in
#     switch and syscall return. Add an isync() to prevent_user_access()
#     
#     Signed-off-by: Russell Currey <ruscur@russell.cc>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/s390x-linux/bin/s390x-linux-gcc --version
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/s390x-linux/bin/s390x-linux-ld --version
# < git log --format=%s --max-count=1 d02d2129641d6cd22492ddc85e11d112eb0d5a6f
# < make -s -j 48 ARCH=s390 O=/kisskb/build/powerpc-next_s390-defconfig_s390x CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/s390x-linux/bin/s390x-linux-  defconfig
# make -s -j 48 ARCH=s390 O=/kisskb/build/powerpc-next_s390-defconfig_s390x CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/s390x-linux/bin/s390x-linux-  
/kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl':
/kisskb/src/kernel/printk/printk.c:186:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/cgroup/cgroup-v1.c: In function 'cgroup1_mount':
/kisskb/src/kernel/cgroup/cgroup-v1.c:1263:20: warning: 'root' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/mm/hugetlb.c: In function 'alloc_pool_huge_page':
/kisskb/src/mm/hugetlb.c:1434:5: warning: 'page' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/trace/trace_dynevent.c: In function 'create_dyn_event':
/kisskb/src/kernel/trace/trace_dynevent.c:89:5: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c: In function 'proc_reg_open':
/kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c:339:21: note: 'pdeo' was declared here
/kisskb/src/drivers/s390/scsi/zfcp_erp.c: In function 'zfcp_erp_setup_act':
/kisskb/src/drivers/s390/scsi/zfcp_erp.c:262:2: warning: 'erp_action' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/net/tun.c: In function 'tun_get_user':
/kisskb/src/drivers/net/tun.c:1843:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/net/tun.c:1753:46: warning: 'linear' may be used uninitialized in this function [-Wuninitialized]
Completed OK
# rm -rf /kisskb/build/powerpc-next_s390-defconfig_s390x
# Build took: 0:02:02.061014