# git rev-parse -q --verify 6e693b3ffecb0b478c7050b44a4842854154f715^{commit}
6e693b3ffecb0b478c7050b44a4842854154f715
already have revision, skipping fetch
# git checkout -q -f -B kisskb 6e693b3ffecb0b478c7050b44a4842854154f715
# git clean -qxdf
# < git log -1
# commit 6e693b3ffecb0b478c7050b44a4842854154f715
# Author: Will Deacon <will.deacon@arm.com>
# Date:   Sat Jan 19 21:56:05 2019 +0000
# 
#     x86: uaccess: Inhibit speculation past access_ok() in user_access_begin()
#     
#     Commit 594cc251fdd0 ("make 'user_access_begin()' do 'access_ok()'")
#     makes the access_ok() check part of the user_access_begin() preceding a
#     series of 'unsafe' accesses.  This has the desirable effect of ensuring
#     that all 'unsafe' accesses have been range-checked, without having to
#     pick through all of the callsites to verify whether the appropriate
#     checking has been made.
#     
#     However, the consolidated range check does not inhibit speculation, so
#     it is still up to the caller to ensure that they are not susceptible to
#     any speculative side-channel attacks for user addresses that ultimately
#     fail the access_ok() check.
#     
#     This is an oversight, so use __uaccess_begin_nospec() to ensure that
#     speculation is inhibited until the access_ok() check has passed.
#     
#     Reported-by: Julien Thierry <julien.thierry@arm.com>
#     Signed-off-by: Will Deacon <will.deacon@arm.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux-gcc --version
# < /opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux-ld --version
# < git log --format=%s --max-count=1 6e693b3ffecb0b478c7050b44a4842854154f715
# < make -s -j 48 ARCH=xtensa O=/kisskb/build/linus_xtensa-defconfig_xtensa CROSS_COMPILE=/opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux-  defconfig
drivers/staging/mt7621-dts/Kconfig:4:warning: 'BUILTIN_DTB' has wrong type. 'select' only accept arguments of bool and tristate type
# make -s -j 48 ARCH=xtensa O=/kisskb/build/linus_xtensa-defconfig_xtensa CROSS_COMPILE=/opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux-  
<stdin>:1333:2: warning: #warning syscall io_pgetevents not implemented [-Wcpp]
<stdin>:1336:2: warning: #warning syscall rseq not implemented [-Wcpp]
Completed OK
# rm -rf /kisskb/build/linus_xtensa-defconfig_xtensa
# Build took: 0:00:27.665193