# git rev-parse -q --verify d02d2129641d6cd22492ddc85e11d112eb0d5a6f^{commit}
d02d2129641d6cd22492ddc85e11d112eb0d5a6f
already have revision, skipping fetch
# 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/powerpc-linux/bin/powerpc-linux-gcc --version
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-ld --version
# < git log --format=%s --max-count=1 d02d2129641d6cd22492ddc85e11d112eb0d5a6f
# < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_85xx_socrates_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  85xx/socrates_defconfig
# make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_85xx_socrates_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-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/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/base/regmap/regmap.c: In function 'regmap_raw_read':
/kisskb/src/drivers/base/regmap/regmap.c:2594:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/base/regmap/regmap.c: In function '_regmap_raw_write':
/kisskb/src/drivers/base/regmap/regmap.c:1855:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/i2c/i2c-core-base.c: In function 'i2c_generic_scl_recovery':
/kisskb/src/drivers/i2c/i2c-core-base.c:235:5: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq':
/kisskb/src/drivers/tty/serial/8250/8250_core.c:247:18: warning: 'i' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/tty/serial/8250/8250_core.c:227:19: note: 'i' was declared here
INFO: Uncompressed kernel (size 0x5957c4) overlaps the address of the wrapper(0x400000)
INFO: Fixing the link_address of wrapper to (0x600000)
Image Name:   Linux-5.0.0-rc2-gd02d2129641d
Created:      Fri Mar  1 02:26:06 2019
Image Type:   PowerPC Linux Kernel Image (gzip compressed)
Data Size:    2832172 Bytes = 2765.79 KiB = 2.70 MiB
Load Address: 00000000
Entry Point:  00000000
Completed OK
# rm -rf /kisskb/build/powerpc-next_85xx_socrates_defconfig_powerpc-gcc4.6
# Build took: 0:00:22.842614