AuxXxilium/linux_dsm_epyc7002
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linux_dsm_epyc7002/arch/x86/entry
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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
..
syscalls uapi, x86: Fix the syscall numbering of the mount API syscalls [ver #2] 2019-05-16 12:23:45 -04:00
vdso x86/vdso: Prevent segfaults due to hoisted vclock reads 2019-06-21 13:31:52 -07:00
vsyscall treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 180 2019-05-30 11:29:20 -07:00
calling.h jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
common.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 257 2019-06-05 17:30:27 +02:00
entry_32.S Merge branch 'x86-entry-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 15:55:15 -07:00
entry_64_compat.S x86/entry/64/compat: Fix stack switching for XEN PV 2019-01-18 00:39:33 +01:00
entry_64.S The major changes in this tracing update includes: 2019-05-15 16:05:47 -07:00
Makefile
syscall_32.c syscalls/x86: Unconditionally enable 'struct pt_regs' based syscalls on x86_64 2018-04-05 16:59:38 +02:00
syscall_64.c syscalls/x86: Unconditionally enable 'struct pt_regs' based syscalls on x86_64 2018-04-05 16:59:38 +02:00
thunk_32.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 474 2019-06-19 17:09:11 +02:00
thunk_64.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 474 2019-06-19 17:09:11 +02:00