linux/arch/x86
Andy Lutomirski ff17bbe0bb x86/vdso: Prevent segfaults due to hoisted vclock reads
GCC 5.5.0 sometimes cleverly hoists reads of the pvclock and/or hvclock
pages before the vclock mode checks.  This creates a path through
vclock_gettime() in which no vclock is enabled at all (due to disabled
TSC on old CPUs, for example) but the pvclock or hvclock page
nevertheless read.  This will segfault on bare metal.

This fixes commit 459e3a2153 ("gcc-9: properly declare the
{pv,hv}clock_page storage") in the sense that, before that commit, GCC
didn't seem to generate the offending code.  There was nothing wrong
with that commit per se, and -stable maintainers should backport this to
all supported kernels regardless of whether the offending commit was
present, since the same crash could just as easily be triggered by the
phase of the moon.

On GCC 9.1.1, this doesn't seem to affect the generated code at all, so
I'm not too concerned about performance regressions from this fix.

Cc: stable@vger.kernel.org
Cc: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Reported-by: Duncan Roe <duncan_roe@optusnet.com.au>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-21 13:31:52 -07:00
..
boot treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
configs x86/defconfig: Remove archaic partition tables support 2019-04-19 12:29:48 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
entry x86/vdso: Prevent segfaults due to hoisted vclock reads 2019-06-21 13:31:52 -07:00
events treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
hyperv treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 280 2019-06-05 17:36:36 +02:00
ia32 treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
include SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
kernel treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
kvm SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
lib treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 504 2019-06-19 17:09:56 +02:00
math-emu x86/fpu: Always init the state in fpu__clear() 2019-04-09 19:28:06 +02:00
mm treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-17 15:55:34 -07:00
oprofile x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() 2018-02-21 09:54:17 +01:00
pci treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 387 2019-06-05 17:37:11 +02:00
platform treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
power SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
purgatory treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230 2019-06-19 17:09:06 +02:00
ras
realmode x86/realmode: Make set_real_mode_mem() static inline 2019-03-29 10:16:27 +01:00
tools treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
um treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
video treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
xen xen: fixes and features for 5.2-rc1 2019-05-15 18:44:52 -07:00
.gitignore x86/build: Add arch/x86/tools/insn_decoder_test to .gitignore 2018-02-13 14:10:29 +01:00
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-16 11:02:27 -07:00
Kconfig.cpu x86/cpu: Create Hygon Dhyana architecture support file 2018-09-27 16:14:05 +02:00
Kconfig.debug compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING 2019-05-14 19:52:48 -07:00
Makefile x86/build: Keep local relocations with ld.lld 2019-04-05 12:34:35 +02:00
Makefile_32.cpu
Makefile.um x86, powerpc: Remove -funit-at-a-time compiler option entirely 2018-12-09 11:55:32 +01:00