Peter Anvin says:
> 0xffff880000000000 is the lowest usable address because we have
> agreed to leave 0xffff800000000000-0xffff880000000000 for the
> hypervisor or other non-OS uses.
Let's call this out in the documentation.
This came up during the kernel address sanitizer discussions
where it was proposed to use this area for other kernel things.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Link: http://lkml.kernel.org/r/20140918195606.841389D2@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The IRET instruction, when returning to a 16-bit segment, only
restores the bottom 16 bits of the user space stack pointer. This
causes some 16-bit software to break, but it also leaks kernel state
to user space. We have a software workaround for that ("espfix") for
the 32-bit kernel, but it relies on a nonzero stack segment base which
is not available in 64-bit mode.
In checkin:
b3b42ac2cb x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels
we "solved" this by forbidding 16-bit segments on 64-bit kernels, with
the logic that 16-bit support is crippled on 64-bit kernels anyway (no
V86 support), but it turns out that people are doing stuff like
running old Win16 binaries under Wine and expect it to work.
This works around this by creating percpu "ministacks", each of which
is mapped 2^16 times 64K apart. When we detect that the return SS is
on the LDT, we copy the IRET frame to the ministack and use the
relevant alias to return to userspace. The ministacks are mapped
readonly, so if IRET faults we promote #GP to #DF which is an IST
vector and thus has its own stack; we then do the fixup in the #DF
handler.
(Making #GP an IST exception would make the msr_safe functions unsafe
in NMI/MC context, and quite possibly have other effects.)
Special thanks to:
- Andy Lutomirski, for the suggestion of using very small stack slots
and copy (as opposed to map) the IRET frame there, and for the
suggestion to mark them readonly and let the fault promote to #DF.
- Konrad Wilk for paravirt fixup and testing.
- Borislav Petkov for testing help and useful comments.
Reported-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Lutomriski <amluto@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dirk Hohndel <dirk@hohndel.org>
Cc: Arjan van de Ven <arjan.van.de.ven@intel.com>
Cc: comex <comexk@gmail.com>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <stable@vger.kernel.org> # consider after upstream merge
Pull trivial tree updates from Jiri Kosina:
"Usual rocket science stuff from trivial.git"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits)
neighbour.h: fix comment
sched: Fix warning on make htmldocs caused by wait.h
slab: struct kmem_cache is protected by slab_mutex
doc: Fix typo in USB Gadget Documentation
of/Kconfig: Spelling s/one/once/
mkregtable: Fix sscanf handling
lp5523, lp8501: comment improvements
thermal: rcar: comment spelling
treewide: fix comments and printk msgs
IXP4xx: remove '1 &&' from a condition check in ixp4xx_restart()
Documentation: update /proc/uptime field description
Documentation: Fix size parameter for snprintf
arm: fix comment header and macro name
asm-generic: uaccess: Spelling s/a ny/any/
mtd: onenand: fix comment header
doc: driver-model/platform.txt: fix a typo
drivers: fix typo in DEVTMPFS_MOUNT Kconfig help text
doc: Fix typo (acces_process_vm -> access_process_vm)
treewide: Fix typos in printk
drivers/gpu/drm/qxl/Kconfig: reformat the help text
...
Removed obsolte parameters from boot-options.txt.
Verified by grepping around in arch/x86/.
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
groundwork for kexec support on EFI - Borislav Petkov
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Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into x86/efi
Pull EFI virtual mapping changes from Matt Fleming:
* New static EFI runtime services virtual mapping layout which is
groundwork for kexec support on EFI. (Borislav Petkov)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We map the EFI regions needed for runtime services non-contiguously,
with preserved alignment on virtual addresses starting from -4G down
for a total max space of 64G. This way, we provide for stable runtime
services addresses across kernels so that a kexec'd kernel can still use
them.
Thus, they're mapped in a separate pagetable so that we don't pollute
the kernel namespace.
Add an efi= kernel command line parameter for passing miscellaneous
options and chicken bits from the command line.
While at it, add a chicken bit called "efi=old_map" which can be used as
a fallback to the old runtime services mapping method in case there's
some b0rkage with a particular EFI implementation (haha, it is hard to
hold up the sarcasm here...).
Also, add the UEFI RT VA space to Documentation/x86/x86_64/mm.txt.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Add a boot option to disable firmware first mode for corrected errors.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Pull x86 debug update from Ingo Molnar:
"Two small changes: a documentation update and a constification"
* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, early-printk: Update earlyprintk documentation (and kill x86 copy)
x86: Constify a few items
Documentation/kernel-parameters.txt and
Documentation/x86/x86_64/boot-options.txt contain virtually
identical text describing earlyprintk.
This consolidates the two copies and updates the documentation a
bit. No one ever documented the:
earlyprintk=serial,0x1008,115200
syntax, nor mentioned that ARM is now a supported earlyprintk
arch.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rob Landley <rob@landley.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20130410210338.E2930E98@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
'report_lost_ticks' parameter has been removed back in 2007 through
1489939f0a ("time: x86_64: convert x86_64 to use GENERIC_TIME").
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The ACPI spec doesn't provide for a way for the bios to pass down
recommended thresholds to the OS on a _per-bank_ basis. This patch adds
a new boot option, which if passed, tells Linux to use CMCI thresholds
set by the bios.
As fail-safe, we initialize threshold to 1 if some banks have not been
initialized by the bios and warn the user.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This file only contains code relevant for the northbridge
gart in AMD processors. This patch renames the file to
represent this fact in the filename.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
The oops=panic cmdline option is not x86 specific, move it to generic code.
Update documentation.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
IRQ stacks provide much better safety against unexpected stack use from
interrupts, at the minimal downside of slightly higher memory usage.
Enable irq stacks also for the default 8k stack on 32-bit kernels to
minimize the problem of stack overflows through interrupt activity.
This is what the 64-bit kernel and various other architectures already do.
Signed-off-by: Christoph Hellwig <hch@lst.de>
LKML-Reference: <20100628121554.GA6605@lst.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that numa=fake=<size>[MG] is implemented, it is possible to remove
configurable node size support. The command-line parsing was already
broken (numa=fake=*128, for example, would not work) and since fake nodes
are now interleaved over physical nodes, this support is no longer
required.
Signed-off-by: David Rientjes <rientjes@google.com>
LKML-Reference: <alpine.DEB.2.00.1002151343080.26927@chino.kir.corp.google.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
numa=fake=N specifies the number of fake nodes, N, to partition the
system into and then allocates them by interleaving over physical nodes.
This requires knowledge of the system capacity when attempting to
allocate nodes of a certain size: either very large nodes to benchmark
scalability of code that operates on individual nodes, or very small
nodes to find bugs in the VM.
This patch introduces numa=fake=<size>[MG] so it is possible to specify
the size of each node to allocate. When used, nodes of the size
specified will be allocated and interleaved over the set of physical
nodes.
FAKE_NODE_MIN_SIZE was also moved to the more-appropriate
include/asm/numa_64.h.
Signed-off-by: David Rientjes <rientjes@google.com>
LKML-Reference: <alpine.DEB.2.00.1002151342510.26927@chino.kir.corp.google.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This patch introduces three boot options (no_cmci, dont_log_ce
and ignore_ce) to control handling for corrected errors.
The "mce=no_cmci" boot option disables the CMCI feature.
Since CMCI is a new feature so having boot controls to disable
it will be a help if the hardware is misbehaving.
The "mce=dont_log_ce" boot option disables logging for corrected
errors. All reported corrected errors will be cleared silently.
This option will be useful if you never care about corrected
errors.
The "mce=ignore_ce" boot option disables features for corrected
errors, i.e. polling timer and cmci. All corrected events are
not cleared and kept in bank MSRs.
Usually this disablement is not recommended, however it will be
a help if there are some conflict with the BIOS or hardware
monitoring applications etc., that clears corrected events in
banks instead of OS.
[ And trivial cleanup (space -> tab) for doc is included. ]
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <4A30ACDF.5030408@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
On Intel platforms machine check exceptions are always broadcast to
all CPUs. This patch makes the machine check handler synchronize all
these machine checks, elect a Monarch to handle the event and collect
the worst event from all CPUs and then process it first.
This has some advantages:
- When there is a truly data corrupting error the system panics as
quickly as possible. This improves containment of corrupted
data and makes sure the corrupted data never hits stable storage.
- The panics are synchronized and do not reenter the panic code
on multiple CPUs (which currently does not handle this well).
- All the errors are reported. Currently it often happens that
another CPU happens to do the panic first, but reports useless
information (empty machine check) because the real error
happened on another CPU which came in later.
This is a big advantage on Nehalem where the 8 threads per CPU
lead to often the wrong CPU winning the race and dumping
useless information on a machine check. The problem also occurs
in a less severe form on older CPUs.
- The system can detect when no CPUs detected a machine check
and shut down the system. This can happen when one CPU is so
badly hung that that it cannot process a machine check anymore
or when some external agent wants to stop the system by
asserting the machine check pin. This follows Intel hardware
recommendations.
- This matches the recommended error model by the CPU designers.
- The events can be output in true severity order
- When a panic happens on another CPU it makes sure to be actually
be able to process the stop IPI by enabling interrupts.
The code is extremly careful to handle timeouts while waiting
for other CPUs. It can't rely on the normal timing mechanisms
(jiffies, ktime_get) because of its asynchronous/lockless nature,
so it uses own timeouts using ndelay() and a "SPINUNIT"
The timeout is configurable. By default it waits for upto one
second for the other CPUs. This can be also disabled.
From some informal testing AMD systems do not see to broadcast
machine checks, so right now it's always disabled by default on
non Intel CPUs or also on very old Intel systems.
Includes fixes from Ying Huang
Fixed a "ecception" in a comment (H.Seto)
Moved global_nwo reset later based on suggestion from H.Seto
v2: Avoid duplicate messages
[ Impact: feature, fixes long standing problems. ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Document that check_interval set to 0 means no polling.
Noticed by Hidetoshi Seto
Also add a reference from boot options to the sysfs tunables
Acked-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
after:
| commit b263295dbf
| Author: Christoph Lameter <clameter@sgi.com>
| Date: Wed Jan 30 13:30:47 2008 +0100
|
| x86: 64-bit, make sparsemem vmemmap the only memory model
we don't have MEMORY_HOTPLUG_RESERVE anymore.
Historically, x86-64 had an architecture-specific method for memory hotplug
whereby it scanned the SRAT for physical memory ranges that could be
potentially used for memory hot-add later. By reserving those ranges
without physical memory, the memmap would be allocated and left dormant
until needed. This depended on the DISCONTIG memory model which has been
removed so the code implementing HOTPLUG_RESERVE is now dead.
This patch removes the dead code used by MEMORY_HOTPLUG_RESERVE.
(Changelog authored by Mel.)
v2: updated changelog, and remove hotadd= in doc
[ Impact: remove dead code ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Workflow-found-OK-by: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A0C4910.7090508@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix a trivial typo in Documentation/x86/x86_64/mm.txt.
[ Impact: documentation only ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Rik van Riel <riel@redhat.com>
Extend the maximum addressable memory on x86-64 from 2^44 to
2^46 bytes. This requires some shuffling around of the vmalloc
and virtual memmap memory areas, to keep them away from the
direct mapping of up to 64TB of physical memory.
This patch also introduces a guard hole between the vmalloc
area and the virtual memory map space. There's really no
good reason why we wouldn't have a guard hole there.
[ Impact: future hardware enablement ]
Signed-off-by: Rik van Riel <riel@redhat.com>
LKML-Reference: <20090505172856.6820db22@cuia.bos.redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
cgroup documentation was moved to Documentation/cgroups/. There are some
places that still refer to Documentation/controllers/,
Documentation/cgroups.txt and Documentation/cpusets.txt. Fix those.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Impact: documentation update
Commit a6523748bd
(paravirt/x86, 64-bit: move __PAGE_OFFSET to leave a space for hypervisor)
changed address space without changing the documentation.
Change it according to the code change -- direct mapping start:
ffff810000000000 => ffff880000000000 which gives 57 TiB, something
between 45 and 46 bits.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: documentation update
1) nmi_watchdog boot parameter is common to 32/64 bit modes. So
move it from Documentation/x86/x86_64/boot-options.txt to
Documentation/kernel-parameters.txt and integrate with.
2) Also fix [panic] keyword placement -- it ought to be at first
position otherwise it will not be recognized.
3) Document lapic and ioapic keywords.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The Documentation/i386 and Documentation/x86_64 directories and their
contents have been moved into Documentation/x86. Fix references to
those files accordingly.
Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit ecd29476ae removed the
"disable_8254_timer" and "enable_8254_timer" kernel parameters from
the kernel but did not remove the references to them from two
files in the Documentation directory: kernel-parameters.txt and
x86/x86_64/boot-options.txt.
This change completes the removal.
Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Applies on top of the previous patch:
x86 boot: add code to add BIOS provided EFI memory entries to kernel
Instead of always adding EFI memory map entries (if present) to the
memory map after initially finding either E820 BIOS memory map entries
and/or kernel command line memmap entries, -instead- only add such
additional EFI memory map entries if the kernel boot option:
add_efi_memmap
is specified.
Requiring this 'add_efi_memmap' option is backward compatible with
kernels that didn't load such additional EFI memory map entries in
the first place, and it doesn't override a configuration that tries
to replace all E820 or EFI BIOS memory map entries with ones given
entirely on the kernel command line.
Signed-off-by: Paul Jackson <pj@sgi.com>
Cc: "Yinghai Lu" <yhlu.kernel@gmail.com>
Cc: "Jack Steiner" <steiner@sgi.com>
Cc: "Mike Travis" <travis@sgi.com>
Cc: "Huang
Cc: Ying" <ying.huang@intel.com>
Cc: "Andi Kleen" <andi@firstfloor.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The current organization of the x86 documentation makes it appear as
if the "i386" documentation doesn't apply to x86-64, which is does.
Thus, move that documentation into Documentation/x86, and move the
x86-64-specific stuff into Documentation/x86/x86_64 with the eventual
goal to move stuff that isn't actually 64-bit specific back into
Documentation/x86.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Dave Hansen
H. Peter Anvin
Linus Torvalds
Richard Weinberger
Ingo Molnar
Borislav Petkov
Naveen N. Rao
Dave Hansen
Borislav Petkov
Jiri Kosina
Joerg Roedel
Olaf Hering
Lucas De Marchi
Christoph Hellwig
David Rientjes
Ingo Molnar
Hidetoshi Seto
Andi Kleen
Yinghai Lu
H. Peter Anvin
Rik van Riel
Thadeu Lima de Souza Cascardo
Jiri Slaby
Cyrill Gorcunov
Uwe Hermann
Luiz Fernando N. Capitulino
Paul Jackson