# git rev-parse -q --verify c14cbef0319d21339a76247c3061230ae2950a7c^{commit}
c14cbef0319d21339a76247c3061230ae2950a7c
already have revision, skipping fetch
# git checkout -q -f -B kisskb c14cbef0319d21339a76247c3061230ae2950a7c
# git clean -qxdf
# < git log -1
# commit c14cbef0319d21339a76247c3061230ae2950a7c
# Author: Christophe Leroy <christophe.leroy@c-s.fr>
# Date:   Mon Jun 3 08:20:28 2019 +0000
# 
#     powerpc: fix kexec failure on book3s/32
#     
#     In the old days, _PAGE_EXEC didn't exist on 6xx aka book3s/32.
#     Therefore, allthough __mapin_ram_chunk() was already mapping kernel
#     text with PAGE_KERNEL_TEXT and the rest with PAGE_KERNEL, the entire
#     memory was executable. Part of the memory (first 512kbytes) was
#     mapped with BATs instead of page table, but it was also entirely
#     mapped as executable.
#     
#     In commit 385e89d5b20f ("powerpc/mm: add exec protection on
#     powerpc 603"), we started adding exec protection to some 6xx, namely
#     the 603, for pages mapped via pagetables.
#     
#     Then, in commit 63b2bc619565 ("powerpc/mm/32s: Use BATs for
#     STRICT_KERNEL_RWX"), the exec protection was extended to BAT mapped
#     memory, so that really only the kernel text could be executed.
#     
#     The problem here is that kexec is based on copying some code into
#     upper part of memory then executing it from there in order to install
#     a fresh new kernel at its definitive location.
#     
#     However, the code is position independant and first part of it is
#     just there to deactivate the MMU and jump to the second part. So it
#     is possible to run this first part inplace instead of running the
#     copy. Once the MMU is off, there is no protection anymore and the
#     second part of the code will just run as before.
#     
#     Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
#     Fixes: 63b2bc619565 ("powerpc/mm/32s: Use BATs for STRICT_KERNEL_RWX")
#     Cc: stable@vger.kernel.org
#     Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
#     Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
#     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 c14cbef0319d21339a76247c3061230ae2950a7c
# < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_85xx_ge_imp3a_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  85xx/ge_imp3a_defconfig
# make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_85xx_ge_imp3a_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:194:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/rcu/srcutree.c: In function 'init_srcu_struct_fields':
/kisskb/src/kernel/rcu/srcutree.c:140:32: warning: 'levelspread[<U 6e0>]' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/rcu/srcutree.c:88:6: note: 'levelspread[<U 6e0>]' was declared here
/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:331:21: note: 'pdeo' was declared here
/kisskb/src/drivers/base/regmap/regmap.c: In function 'regmap_raw_read':
/kisskb/src/drivers/base/regmap/regmap.c:2589:6: 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:1850:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/nfsd/nfs4xdr.c: In function 'nfsd4_encode_components_esc':
/kisskb/src/fs/nfsd/nfs4xdr.c:2077:9: warning: 'str' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char':
/kisskb/src/fs/udf/unicode.c:132:8: warning: 'c' 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
/kisskb/src/drivers/net/tun.c: In function 'tun_get_user':
/kisskb/src/drivers/net/tun.c:1851:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/net/tun.c:1764:46: warning: 'linear' may be used uninitialized in this function [-Wuninitialized]
INFO: Uncompressed kernel (size 0x84c25c) overlaps the address of the wrapper(0x400000)
INFO: Fixing the link_address of wrapper to (0x900000)
Image Name:   Linux-5.2.0-rc2-gc14cbef0319d
Created:      Fri Jun  7 01:42:49 2019
Image Type:   PowerPC Linux Kernel Image (gzip compressed)
Data Size:    4259556 Bytes = 4159.72 KiB = 4.06 MiB
Load Address: 00000000
Entry Point:  00000000
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_85xx_ge_imp3a_defconfig_powerpc-gcc4.6
# Build took: 0:01:13.062369