Currently the size of the per-cpu region reserved to save crash notes is
set by the per-architecture value MAX_NOTE_BYTES. Which in turn is
currently set to 1024 on all supported architectures.
While testing ia64 I recently discovered that this value is in fact too
small. The particular setup I was using actually needs 1172 bytes. This
lead to very tedious failure mode where the tail of one elf note would
overwrite the head of another if they ended up being alocated sequentially
by kmalloc, which was often the case.
It seems to me that a far better approach is to caclculate the size that
the area needs to be. This patch does just that.
If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) is
needed then this should be as easy as making MAX_NOTE_BYTES larger in
arch/asm-ia64/kexec.h. Perhaps 2048 would be a good choice. However, I
think that the approach in this patch is a much more robust idea.
Acked-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch moves the die notifier handling to common code. Previous
various architectures had exactly the same code for it. Note that the new
code is compiled unconditionally, this should be understood as an appel to
the other architecture maintainer to implement support for it aswell (aka
sprinkling a notify_die or two in the proper place)
arm had a notifiy_die that did something totally different, I renamed it to
arm_notify_die as part of the patch and made it static to the file it's
declared and used at. avr32 used to pass slightly less information through
this interface and I brought it into line with the other architectures.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix vmalloc_sync_all bustage]
[bryan.wu@analog.com: fix vmalloc_sync_all in nommu]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: <linux-arch@vger.kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Adds the needed TCGETS2/TCSETS2 ioctl calls, structures, defines and the like.
Tested against the test suite and passes. Other platforms should need
roughly the same change.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert over to the new NMI handling for getting IPMI watchdog timeouts via an
NMI. This add config options to know if there is the ability to receive NMIs
and if it has an NMI post processing call. Then it modifies the IPMI watchdog
to take advantage of this so that it can know if an NMI comes in.
It also adds testing that the IPMI NMI watchdog works.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add safe (exception handled) variants of rdmsr_on_cpu and wrmsr_on_cpu.
You should use these when the target MSR may not actually exist, as
doing so could trigger an exception which the regular functions do not
handle. The safe variants are slower, though.
The upcoming coretemp hardware monitoring driver will need this.
Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Cc: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
i386 uses kmalloc to allocate the threadinfo structure assuming that the
allocations result in a page sized aligned allocation. That has worked so
far because SLAB exempts page sized slabs from debugging and aligns them in
special ways that goes beyond the restrictions imposed by
KMALLOC_ARCH_MINALIGN valid for other slabs in the kmalloc array.
SLUB also works fine without debugging since page sized allocations neatly
align at page boundaries. However, if debugging is switched on then SLUB
will extend the slab with debug information. The resulting slab is not
longer of page size. It will only be aligned following the requirements
imposed by KMALLOC_ARCH_MINALIGN. As a result the threadinfo structure may
not be page aligned which makes i386 fail to boot with SLUB debug on.
Replace the calls to kmalloc with calls into the page allocator.
An alternate solution may be to create a custom slab cache where the
alignment is set to PAGE_SIZE. That would allow slub debugging to be
applied to the threadinfo structure.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If you actually clear the bit, you need to:
+ pte_update_defer(vma->vm_mm, addr, ptep);
The reason is, when updating PTEs, the hypervisor must be notified. Using
atomic operations to do this is fine for all hypervisors I am aware of.
However, for hypervisors which shadow page tables, if these PTE
modifications are not trapped, you need a post-modification call to fulfill
the update of the shadow page table.
Acked-by: Zachary Amsden <zach@vmware.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add ptep_test_and_clear_{dirty,young} to i386. They advertise that they
have it and there is at least one place where it needs to be called without
the page table lock: to clear the accessed bit on write to
/proc/pid/clear_refs.
ptep_clear_flush_{dirty,young} are updated to use the new functions. The
overall net effect to current users of ptep_clear_flush_{dirty,young} is
that we introduce an additional branch.
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most architectures' scatterlist.h use the type dma_addr_t, but omit to
include <asm/types.h> which defines it. This could lead to build failures,
so let's add the missing includes.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
There are two callers of __unlazy_fpu, unlazy_fpu and __switch_to, and
none of them appear to require additional preempt_disable/enable here.
Let's open-code save_init_fpu in __unlazy_fpu to save a few ops.
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Andi Kleen <ak@suse.de>
RDTSCP is already synchronous and doesn't need an explicit CPUID.
This is a little faster and more importantly avoids VMEXITs on Hypervisors.
Original patch from Joerg Roedel, but reworked by AK
Also includes miscompilation fix by Eric Biederman
Cc: "Joerg Roedel" <joerg.roedel@amd.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Redefine cpu_has() to evaluate cpu features already checked in early
boot at compile time. This way the compiler might eliminate some dead code.
Signed-off-by: Andi Kleen <ak@suse.de>
Check some CPUID bits that are needed for compiler generated early in boot.
When the system is still in real mode before changing the VESA BIOS mode
it is possible to still display an visible error message on the screen.
Similar to x86-64.
Includes cleanups from Eric Biederman
Signed-off-by: Andi Kleen <ak@suse.de>
- Introduce a wd_ops structure
- Convert the various nmi watchdogs over to it
- This allows to split the perfctr reservation from the watchdog
setup cleanly.
- Do perfctr reservation globally as it should have always been
- Remove dead code referenced only by unused EXPORT_SYMBOLs
Signed-off-by: Andi Kleen <ak@suse.de>
Add comment and condense code to make use of native_local_ptep_get_and_clear
function. Also, it turns out the 2-level and 3-level paging definitions were
identical, so move the common definition into pgtable.h
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
In situations where page table updates need only be made locally, and there is
no cross-processor A/D bit races involved, we need not use the heavyweight
xchg instruction to atomically fetch and clear page table entries. Instead,
we can just read and clear them directly.
This introduces a neat optimization for non-SMP kernels; drop the atomic xchg
operations from page table updates.
Thanks to Michel Lespinasse for noting this potential optimization.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
When exiting from an address space, no special hypervisor notification of page
table updates needs to occur; direct page table hypervisors, such as Xen,
switch to another address space first (init_mm) and unprotects the page tables
to avoid the cost of trapping to the hypervisor for each pte_clear. Shadow
mode hypervisors, such as VMI and lhype don't need to do the extra work of
calling through paravirt-ops, and can just directly clear the page table
entries without notifiying the hypervisor, since all the page tables are about
to be freed.
So introduce native_pte_clear functions which bypass any paravirt-ops
notification. This results in a significant performance win for VMI and
removes some indirect calls from zap_pte_range.
Note the 3-level paging already had a native_pte_clear function, thus
demanding argument conformance and extra args for the 2-level definition.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
apic_wait_icr_idle looks like this:
static __inline__ void apic_wait_icr_idle(void)
{
while (apic_read(APIC_ICR) & APIC_ICR_BUSY)
cpu_relax();
}
The busy loop in this function would not be problematic if the
corresponding status bit in the ICR were always updated, but that does
not seem to be the case under certain crash scenarios. Kdump uses an IPI
to stop the other CPUs in the event of a crash, but when any of the
other CPUs are locked-up inside the NMI handler the CPU that sends the
IPI will end up looping forever in the ICR check, effectively
hard-locking the whole system.
Quoting from Intel's "MultiProcessor Specification" (Version 1.4), B-3:
"A local APIC unit indicates successful dispatch of an IPI by
resetting the Delivery Status bit in the Interrupt Command
Register (ICR). The operating system polls the delivery status
bit after sending an INIT or STARTUP IPI until the command has
been dispatched.
A period of 20 microseconds should be sufficient for IPI dispatch
to complete under normal operating conditions. If the IPI is not
successfully dispatched, the operating system can abort the
command. Alternatively, the operating system can retry the IPI by
writing the lower 32-bit double word of the ICR. This “time-out”
mechanism can be implemented through an external interrupt, if
interrupts are enabled on the processor, or through execution of
an instruction or time-stamp counter spin loop."
Intel's documentation suggests the implementation of a time-out
mechanism, which, by the way, is already being open-coded in some parts
of the kernel that tinker with ICR.
Create a apic_wait_icr_idle replacement that implements the time-out
mechanism and that can be used to solve the aforementioned problem.
AK: moved both functions out of line
AK: added improved loop from Keith Owens
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
If our copy of the MTRRs of the BSP has RdMem or WrMem set, and
we are running on an AMD64/K8 system, the boot CPU must have had
MtrrFixDramEn and MtrrFixDramModEn set (otherwise our RDMSR would
have copied these bits cleared), so we set them on this CPU as well.
This allows us to keep the AMD64/K8 RdMem and WrMem bits in sync
across the CPUs of SMP systems in order to fullfill the duty of
system software to "initialize and maintain MTRR consistency
across all processors." as written in the AMD and Intel manuals.
If an WRMSR instruction fails because MtrrFixDramModEn is not
set, I expect that also the Intel-style MTRR bits are not updated.
AK: minor cleanup, moved MSR defines around
Signed-off-by: Bernhard Kaindl <bk@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
Applied fix by Andew Morton:
http://lkml.org/lkml/2007/4/8/88 - Fix `make headers_check'.
AMD and Intel x86 CPU manuals state that it is the responsibility of
system software to initialize and maintain MTRR consistency across
all processors in Multi-Processing Environments.
Quote from page 188 of the AMD64 System Programming manual (Volume 2):
7.6.5 MTRRs in Multi-Processing Environments
"In multi-processing environments, the MTRRs located in all processors must
characterize memory in the same way. Generally, this means that identical
values are written to the MTRRs used by the processors." (short omission here)
"Failure to do so may result in coherency violations or loss of atomicity.
Processor implementations do not check the MTRR settings in other processors
to ensure consistency. It is the responsibility of system software to
initialize and maintain MTRR consistency across all processors."
Current Linux MTRR code already implements the above in the case that the
BIOS does not properly initialize MTRRs on the secondary processors,
but the case where the fixed-range MTRRs of the boot processor are changed
after Linux started to boot, before the initialsation of a secondary
processor, is not handled yet.
In this case, secondary processors are currently initialized by Linux
with MTRRs which the boot processor had very early, when mtrr_bp_init()
did run, but not with the MTRRs which the boot processor uses at the
time when that secondary processors is actually booted,
causing differing MTRR contents on the secondary processors.
Such situation happens on Acer Ferrari 1000 and 5000 notebooks where the
BIOS enables and sets AMD-specific IORR bits in the fixed-range MTRRs
of the boot processor when it transitions the system into ACPI mode.
The SMI handler of the BIOS does this in SMM, entered while Linux ACPI
code runs acpi_enable().
Other occasions where the SMI handler of the BIOS may change bits in
the MTRRs could occur as well. To initialize newly booted secodary
processors with the fixed-range MTRRs which the boot processor uses
at that time, this patch saves the fixed-range MTRRs of the boot
processor before new secondary processors are started. When the
secondary processors run their Linux initialisation code, their
fixed-range MTRRs will be updated with the saved fixed-range MTRRs.
If CONFIG_MTRR is not set, we define mtrr_save_state
as an empty statement because there is nothing to do.
Possible TODOs:
*) CPU-hotplugging outside of SMP suspend/resume is not yet tested
with this patch.
*) If, even in this case, an AP never runs i386/do_boot_cpu or x86_64/cpu_up,
then the calls to mtrr_save_state() could be replaced by calls to
mtrr_save_fixed_ranges(NULL) and mtrr_save_state() would not be
needed.
That would need either verification of the CPU-hotplug code or
at least a test on a >2 CPU machine.
*) The MTRRs of other running processors are not yet checked at this
time but it might be interesting to syncronize the MTTRs of all
processors before booting. That would be an incremental patch,
but of rather low priority since there is no machine known so
far which would require this.
AK: moved prototypes on x86-64 around to fix warnings
Signed-off-by: Bernhard Kaindl <bk@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
In this current implementation which is used in other patches,
mtrr_save_fixed_ranges() accepts a dummy void pointer because
in the current implementation of one of these patches, this
function may be called from smp_call_function_single() which
requires that this function takes a void pointer argument.
This function calls get_fixed_ranges(), passing mtrr_state.fixed_ranges
which is the element of the static struct which stores our current
backup of the fixed-range MTRR values which all CPUs shall be
using.
Because mtrr_save_fixed_ranges calls get_fixed_ranges after
kernel initialisation time, __init needs to be removed from
the declaration of get_fixed_ranges().
If CONFIG_MTRR is not set, we define mtrr_save_fixed_ranges
as an empty statement because there is nothing to do.
AK: Moved prototypes for x86-64 around to fix warnings
Signed-off-by: Bernhard Kaindl <bk@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
The other symbols used to delineate the alt-instructions sections have the
form __foo/__foo_end. Rename parainstructions to match.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Convert VMI timer to use clock events, making it properly able to use the NO_HZ
infrastructure. On UP systems, with no local APIC, we just continue to route
these events through the PIT. On systems with a local APIC, or SMP, we provide
a single source interrupt chip which creates the local timer IRQ. It actually
gets delivered by the APIC hardware, but we don't want to use the same local
APIC clocksource processing, so we create our own handler here.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
CC: Dan Hecht <dhecht@vmware.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
Remove spurious comments, headers and keywords from x86-64 bugs.[ch].
Use identify_boot_cpu()
AK: merged with other patch
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Fixes two problems with the GDT when compiling for uniprocessor:
- There's no percpu segment, so trying to load its selector into %fs fails.
Use a null selector instead.
- The real gdt needs to be loaded at some point. Do it in cpu_init().
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Define per_cpu_offset in asm-i386/percpu.h when SMP defined, like
asm-generic/percpu.h does for UP.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
This patch does a few small cleanups:
- use PER_CPU_NAME to generate the names of per-cpu variables
- use lea to add the per_cpu offset in PER_CPU(), because it doesn't
affect condition flags
- add PER_CPU_VAR which allows direct access to pre-cpu variables
with the %fs: prefix on SMP.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Currently x86 (similar to x84-64) has a special per-cpu structure
called "i386_pda" which can be easily and efficiently referenced via
the %fs register. An ELF section is more flexible than a structure,
allowing any piece of code to use this area. Indeed, such a section
already exists: the per-cpu area.
So this patch:
(1) Removes the PDA and uses per-cpu variables for each current member.
(2) Replaces the __KERNEL_PDA segment with __KERNEL_PERCPU.
(3) Creates a per-cpu mirror of __per_cpu_offset called this_cpu_off, which
can be used to calculate addresses for this CPU's variables.
(4) Simplifies startup, because %fs doesn't need to be loaded with a
special segment at early boot; it can be deferred until the first
percpu area is allocated (or never for UP).
The result is less code and one less x86-specific concept.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Xen wants a dedicated page for the GDT. I believe VMI likes it too.
lguest, KVM and native don't care.
Simple transformation to page-aligned "struct gdt_page".
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>
In shadow mode hypervisors, ptep_get_and_clear achieves the desired
purpose of keeping the shadows in sync by issuing a native_get_and_clear,
followed by a call to pte_update, which indicates the PTE has been
modified.
Direct mode hypervisors (Xen) have no need for this anyway, and will trap
the update using writable pagetables.
This means no hypervisor makes use of ptep_get_and_clear; there is no
reason to have it in the paravirt-ops structure. Change confusing
terminology about raw vs. native functions into consistent use of
native_pte_xxx for operations which do not invoke paravirt-ops.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Replace all the open-coded macros for generating calls with a pair of
more general macros (__PVOP_CALL/VCALL), and redefine all the
PVOP_V?CALL[0-4] in terms of them.
[ Andrew, Andi: this should slot in immediately after "Document asm-i386/paravirt.h"
(paravirt_ops-document-asm-i386-paravirth.patch) ]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space. These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.
Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.
This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings. Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.
[ Zach - vmi.c will need some attention after this patch. It wasn't
immediately obvious to me what needs to be done. ]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Back out the map_pt_hook to clear the way for kmap_atomic_pte.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
This patch adds a pv_op for flush_tlb_others. Linux running on native
hardware uses cross-CPU IPIs to flush the TLB on any CPU which may
have a particular mm's pagetable entries cached in its TLB. This is
inefficient in a paravirtualized environment, since the hypervisor
knows which real CPUs actually contain cached mappings, which may be a
small subset of a guest's VCPUs.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Implement the actual patching machinery. paravirt_patch_default()
contains the logic to automatically patch a callsite based on a few
simple rules:
- if the paravirt_op function is paravirt_nop, then patch nops
- if the paravirt_op function is a jmp target, then jmp to it
- if the paravirt_op function is callable and doesn't clobber too much
for the callsite, call it directly
paravirt_patch_default is suitable as a default implementation of
paravirt_ops.patch, will remove most of the expensive indirect calls
in favour of either a direct call or a pile of nops.
Backends may implement their own patcher, however. There are several
helper functions to help with this:
paravirt_patch_nop nop out a callsite
paravirt_patch_ignore leave the callsite as-is
paravirt_patch_call patch a call if the caller and callee
have compatible clobbers
paravirt_patch_jmp patch in a jmp
paravirt_patch_insns patch some literal instructions over
the callsite, if they fit
This patch also implements more direct patches for the native case, so
that when running on native hardware many common operations are
implemented inline.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Acked-by: Ingo Molnar <mingo@elte.hu>
Clean things up, and broadly document:
- the paravirt_ops functions themselves
- the patching mechanism
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Wrap a set of interesting paravirt_ops calls in a wrapper which makes
the callsites available for patching. Unfortunately this is pretty
ugly because there's no way to get gcc to generate a function call,
but also wrap just the callsite itself with the necessary labels.
This patch supports functions with 0-4 arguments, and either void or
returning a value. 64-bit arguments must be split into a pair of
32-bit arguments (lower word first). Small structures are returned in
registers.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Fix a few clobbers to include the return register. The clobbers set
is the set of all registers modified (or may be modified) by the code
snippet, regardless of whether it was deliberate or accidental.
Also, make sure that callsites which are used in contexts which don't
allow clobbers actually save and restore all clobberable registers.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Use patch type identifiers derived from the offset of the operation in
the paravirt_ops structure. This avoids having to maintain a separate
enum for patch site types.
Also, since the identifier is derived from the offset into
paravirt_ops, the offset can be derived from the identifier. This is
used to remove replicated information in the various callsite macros,
which has been a source of bugs in the past.
This patch also drops the fused save_fl+cli operation, which doesn't
really add much and makes things more complex - specifically because
it breaks the 1:1 relationship between identifiers and offsets. If
this operation turns out to be particularly beneficial, then the right
answer is to define a new entrypoint for it.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Rename struct paravirt_patch to paravirt_patch_site, so that it
clearly refers to a callsite, and not the patch which may be applied
to that callsite.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Add hooks to allow a paravirt implementation to track the lifetime of
an mm. Paravirtualization requires three hooks, but only two are
needed in common code. They are:
arch_dup_mmap, which is called when a new mmap is created at fork
arch_exit_mmap, which is called when the last process reference to an
mm is dropped, which typically happens on exit and exec.
The third hook is activate_mm, which is called from the arch-specific
activate_mm() macro/function, and so doesn't need stub versions for
other architectures. It's called when an mm is first used.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: linux-arch@vger.kernel.org
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Normally when running in PAE mode, the 4th PMD maps the kernel address space,
which can be shared among all processes (since they all need the same kernel
mappings).
Xen, however, does not allow guests to have the kernel pmd shared between page
tables, so parameterize pgtable.c to allow both modes of operation.
There are several side-effects of this. One is that vmalloc will update the
kernel address space mappings, and those updates need to be propagated into
all processes if the kernel mappings are not intrinsically shared. In the
non-PAE case, this is done by maintaining a pgd_list of all processes; this
list is used when all process pagetables must be updated. pgd_list is
threaded via otherwise unused entries in the page structure for the pgd, which
means that the pgd must be page-sized for this to work.
Normally the PAE pgd is only 4x64 byte entries large, but Xen requires the PAE
pgd to page aligned anyway, so this patch forces the pgd to be page
aligned+sized when the kernel pmd is unshared, to accomodate both these
requirements.
Also, since there may be several distinct kernel pmds (if the user/kernel
split is below 3G), there's no point in allocating them from a slab cache;
they're just allocated with get_free_page and initialized appropriately. (Of
course the could be cached if there is just a single kernel pmd - which is the
default with a 3G user/kernel split - but it doesn't seem worthwhile to add
yet another case into this code).
[ Many thanks to wli for review comments. ]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Christoph Lameter <clameter@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Allocate a fixmap slot for use by a paravirt_ops implementation. This
is intended for early-boot bootstrap mappings. Once the zones and
allocator have been set up, it would be better to use get_vm_area() to
allocate some virtual space.
Xen uses this to map the hypervisor's shared info page, which doesn't
have a pseudo-physical page number, and therefore can't be mapped
ordinarily. It is needed early because it contains the vcpu state,
including the interrupt mask.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
This patch introduces paravirt_ops hooks to control how the kernel's
initial pagetable is set up.
In the case of a native boot, the very early bootstrap code creates a
simple non-PAE pagetable to map the kernel and physical memory. When
the VM subsystem is initialized, it creates a proper pagetable which
respects the PAE mode, large pages, etc.
When booting under a hypervisor, there are many possibilities for what
paging environment the hypervisor establishes for the guest kernel, so
the constructon of the kernel's pagetable depends on the hypervisor.
In the case of Xen, the hypervisor boots the kernel with a fully
constructed pagetable, which is already using PAE if necessary. Also,
Xen requires particular care when constructing pagetables to make sure
all pagetables are always mapped read-only.
In order to make this easier, kernel's initial pagetable construction
has been changed to only allocate and initialize a pagetable page if
there's no page already present in the pagetable. This allows the Xen
paravirt backend to make a copy of the hypervisor-provided pagetable,
allowing the kernel to establish any more mappings it needs while
keeping the existing ones.
A slightly subtle point which is worth highlighting here is that Xen
requires all kernel mappings to share the same pte_t pages between all
pagetables, so that updating a kernel page's mapping in one pagetable
is reflected in all other pagetables. This makes it possible to
allocate a page and attach it to a pagetable without having to
explicitly enumerate that page's mapping in all pagetables.
And:
+From: "Eric W. Biederman" <ebiederm@xmission.com>
If we don't set the leaf page table entries it is quite possible that
will inherit and incorrect page table entry from the initial boot
page table setup in head.S. So we need to redo the effort here,
so we pick up PSE, PGE and the like.
Hypervisors like Xen require that their page tables be read-only,
which is slightly incompatible with our low identity mappings, however
I discussed this with Jeremy he has modified the Xen early set_pte
function to avoid problems in this area.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: William Irwin <bill.irwin@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Add a set of accessors to pack, unpack and modify page table entries
(at all levels). This allows a paravirt implementation to control the
contents of pgd/pmd/pte entries. For example, Xen uses this to
convert the (pseudo-)physical address into a machine address when
populating a pagetable entry, and converting back to pphys address
when an entry is read.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Simon Horman