This erratum essentially causes the CPU to forget which privilege
level it is operating on (kernel vs. user) for the purposes of MPX.
This erratum can only be triggered when a system is not using
Supervisor Mode Execution Prevention (SMEP). Our workaround for
the erratum is to ensure that MPX can only be used in cases where
SMEP is present in the processor and is enabled.
This erratum only affects Core processors. Atom is unaffected.
But, there is no architectural way to determine Atom vs. Core.
So, we just apply this workaround to all processors. It's
possible that it will mistakenly disable MPX on some Atom
processsors or future unaffected Core processors. There are
currently no processors that have MPX and not SMEP. It would
take something akin to a hypervisor masking SMEP out on an Atom
processor for this to present itself on current hardware.
More details can be found at:
http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/desktop-6th-gen-core-family-spec-update.pdf
"
SKD046 Branch Instructions May Initialize MPX Bound Registers Incorrectly
Problem:
Depending on the current Intel MPX (Memory Protection
Extensions) configuration, execution of certain branch
instructions (near CALL, near RET, near JMP, and Jcc
instructions) without a BND prefix (F2H) initialize the MPX bound
registers. Due to this erratum, such a branch instruction that is
executed both with CPL = 3 and with CPL < 3 may not use the
correct MPX configuration register (BNDCFGU or BNDCFGS,
respectively) for determining whether to initialize the bound
registers; it may thus initialize the bound registers when it
should not, or fail to initialize them when it should.
Implication:
A branch instruction that has executed both in user mode and in
supervisor mode (from the same linear address) may cause a #BR
(bound range fault) when it should not have or may not cause a
#BR when it should have. Workaround An operating system can
avoid this erratum by setting CR4.SMEP[bit 20] to enable
supervisor-mode execution prevention (SMEP). When SMEP is
enabled, no code can be executed both with CPL = 3 and with CPL < 3.
"
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160512220400.3B35F1BC@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:
User visible changes:
- Honour the kernel.perf_event_max_stack knob more precisely by not counting
PERF_CONTEXT_{KERNEL,USER} when deciding when to stop adding entries to
the perf_sample->ip_callchain[] array (Arnaldo Carvalho de Melo)
- Fix identation of 'stalled-backend-cycles' in 'perf stat' (Namhyung Kim)
- Update runtime using 'cpu-clock' event in 'perf stat' (Namhyung Kim)
- Use 'cpu-clock' for cpu targets in 'perf stat' (Namhyung Kim)
- Avoid fractional digits for integer scales in 'perf stat' (Andi Kleen)
- Store vdso buildid unconditionally, as it appears in callchains and
we're not checking those when creating the build-id table, so we
end up not being able to resolve VDSO symbols when doing analysis
on a different machine than the one where recording was done, possibly
of a different arch even (arm -> x86_64) (He Kuang)
Infrastructure changes:
- Generalize max_stack sysctl handler, will be used for configuring
multiple kernel knobs related to callchains (Arnaldo Carvalho de Melo)
Cleanups:
- Introduce DSO__NAME_KALLSYMS and DSO__NAME_KCORE, to stop using
open coded strings (Masami Hiramatsu)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is a simplied version of the fix by Roy in fdo#93629. While this
doesn't appear to fix the issues for the users in that report, it's a
real issue that deserves to be resolved.
Reported-by: Roy Spliet <rspliet@eclipso.eu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Also removes an XXX; according to nvgpu headers the field is called
NV_PGRAPH_GPCS_SWDX_TC_BETA_CB_SIZE_DIV3, so, apparently not some
magic we need to figure out :)
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This was really inconsistent, some implementations could touch PPCs
that didn't exist, others neglected to touch ones that did.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
We always want a equal or higher voltage than the requested ones, otherwise
nouveau undervolts.
Signed-off-by: Karol Herbst <nouveau@karolherbst.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Appears to more closely match what RM does.
For GM20B, now also copying bit 12 from NV_PFB_MMU_CTRL as upcoming
changes will require it.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
It appears these don't map to PBDMAs (at least on Kepler, it may or may
be valid for Fermi - this hasn't been checked), but to runlists.
This drops the NVKM_ENGINE_FIFO data from the entries too, as resetting
all of PFIFO is *not* the way to handle such faults.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
With the addition of PTOP-specified reset bits, it makes more sense to
move the definitions here rather than in individual subdev
implementations.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
