# git rev-parse -q --verify af11dee4361b3519981fa04d014873f9d9edd6ac^{commit}
af11dee4361b3519981fa04d014873f9d9edd6ac
already have revision, skipping fetch
# git checkout -q -f -B kisskb af11dee4361b3519981fa04d014873f9d9edd6ac
# git clean -qxdf
# < git log -1
# commit af11dee4361b3519981fa04d014873f9d9edd6ac
# Author: Christophe Leroy <christophe.leroy@csgroup.eu>
# Date:   Tue Nov 30 09:42:37 2021 +0100
# 
#     powerpc/32s: Fix shift-out-of-bounds in KASAN init
#     
#     ================================================================================
#     UBSAN: shift-out-of-bounds in arch/powerpc/mm/kasan/book3s_32.c:22:23
#     shift exponent -1 is negative
#     CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.5-gentoo-PowerMacG4 #9
#     Call Trace:
#     [c214be60] [c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable)
#     [c214be80] [c0b99288] ubsan_epilogue+0x10/0x5c
#     [c214be90] [c0b98fe0] __ubsan_handle_shift_out_of_bounds+0x94/0x138
#     [c214bf00] [c1c0f010] kasan_init_region+0xd8/0x26c
#     [c214bf30] [c1c0ed84] kasan_init+0xc0/0x198
#     [c214bf70] [c1c08024] setup_arch+0x18/0x54c
#     [c214bfc0] [c1c037f0] start_kernel+0x90/0x33c
#     [c214bff0] [00003610] 0x3610
#     ================================================================================
#     
#     This happens when the directly mapped memory is a power of 2.
#     
#     Fix it by checking the shift and set the result to 0 when shift is -1
#     
#     Fixes: 7974c4732642 ("powerpc/32s: Implement dedicated kasan_init_region()")
#     Reported-by: Erhard Furtner <erhard_f@mailbox.org>
#     Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://bugzilla.kernel.org/show_bug.cgi?id=215169
#     Link: https://lore.kernel.org/r/15cbc3439d4ad988b225e2119ec99502a5cc6ad3.1638261744.git.christophe.leroy@csgroup.eu
# < /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 af11dee4361b3519981fa04d014873f9d9edd6ac
# < make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_40x_klondike_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  40x/klondike_defconfig
# < make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_40x_klondike_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_40x_klondike_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_40x_klondike_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
<stdin>:1559:2: warning: #warning syscall futex_waitv not implemented [-Wcpp]
Completed OK
# rm -rf /kisskb/build/powerpc-next_40x_klondike_defconfig_powerpc-gcc5
# Build took: 0:00:39.315149