# 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/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-ld --version
# < git log --format=%s --max-count=1 6e693b3ffecb0b478c7050b44a4842854154f715
# < make -s -j 120 ARCH=parisc O=/kisskb/build/linus_a500_defconfig_parisc64 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-  a500_defconfig
# make -s -j 120 ARCH=parisc O=/kisskb/build/linus_a500_defconfig_parisc64 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-  
<stdin>:1336:2: warning: #warning syscall rseq not implemented [-Wcpp]
In file included from /kisskb/src/arch/parisc/include/asm/atomic.h:10,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/arch/parisc/include/asm/bitops.h:13,
                 from /kisskb/src/include/linux/bitops.h:19,
                 from /kisskb/src/include/linux/kernel.h:11,
                 from /kisskb/src/include/linux/list.h:9,
                 from /kisskb/src/include/linux/module.h:9,
                 from /kisskb/src/drivers/scsi/scsi_debug.c:23:
/kisskb/src/drivers/scsi/scsi_debug.c: In function 'resp_start_stop':
/kisskb/src/arch/parisc/include/asm/cmpxchg.h:48:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
/kisskb/src/arch/parisc/include/asm/atomic.h:78:30: note: in expansion of macro 'xchg'
 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
                              ^~~~
/kisskb/src/drivers/scsi/scsi_debug.c:1624:2: note: in expansion of macro 'atomic_xchg'
  atomic_xchg(&devip->stopped, stop);
  ^~~~~~~~~~~
Completed OK
# rm -rf /kisskb/build/linus_a500_defconfig_parisc64
# Build took: 0:00:42.521505