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acpi_gbl_permanent_mmap
On x86, __acpi_map_table uses early_ioremap() to create the mapping,
replacing the previous mapping with a new one. Once enough of the
kernel is up an running it switches to using normal ioremap(). At
that point, we need to clean up the final mapping to avoid a warning
from the early_ioremap subsystem.
This can be removed after all the instances in the ACPI code are fixed
that rely on early-ioremap's implicit overmapping of previously
mapped tables.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Always map acpi tables, rather than assuming we can use the normal
linear mapping to access the acpi tables. This is necessary in a
virtual environment where the linear mappings are to pseudo-physical
memory, but the acpi tables exist at a real physical address. It
doesn't hurt to map in the normal non-virtual case, so just do it
unconditionally.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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__acpi_map_table() effectively reimplements early_ioremap(). Rather
than have that duplication, just implement it in terms of
early_ioremap().
However, unlike early_ioremap(), __acpi_map_table() just maintains a
single mapping which gets replaced each call, and has no corresponding
unmap function. Implement this by just removing the previous mapping
each time its called. Unfortunately, this will leave a stray mapping
at the end.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Commit 6194ba6ff6ccf8d5c54c857600843c67aa82c407 ("x86: don't special-case
pmd allocations as much") made changes to the way we handle pmd allocations,
and while doing that it dropped a call to paravirt_release_pd on the
pgd page from the pgd_dtor code path.
As a result of this missing release, the hypervisor is now unaware of the
pgd page being freed, and as a result it ends up tracking this page as a
page table page.
After this the guest may start using the same page for other purposes, and
depending on what use the page is put to, it may result in various performance
and/or functional issues ( hangs, reboots).
Since this release is only required for VMI, I now release the pgd page from
the (vmi)_pgd_free hook.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
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Impact: find right nr_irqs_gsi on some systems.
One test-system has gap between gsi's:
[ 0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
[ 0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
[ 0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
[ 0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
[ 0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
[ 0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
...
[ 0.000000] nr_irqs_gsi: 38
So nr_irqs_gsi is not right. some irq for MSI will overwrite with io_apic.
need to get that with acpi_probe_gsi when acpi io_apic is used
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Conflicts:
arch/x86/mach-voyager/voyager_smp.c
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With the differences in interrupt handling hoisted into handle_irq(),
do_IRQ is more or less identical between 32 and 64 bit, so unify it.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Xen uses a different interrupt path, so introduce handle_irq() to
allow interrupts to be inserted into the normal interrupt path. This
is handled slightly differently on 32 and 64-bit.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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arch/x86/kernel/early_printk.c: In function ‘early_dbgp_init’:
arch/x86/kernel/early_printk.c:827: error: ‘PAGE_KERNEL_NOCACHE’ undeclared (first use in this function)
arch/x86/kernel/early_printk.c:827: error: (Each undeclared identifier is reported only once
arch/x86/kernel/early_printk.c:827: error: for each function it appears in.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen into x86/headers
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For Intel 7400 series CPUs, the recommendation is to use a clflush on the
monitored address just before monitor and mwait pair [1].
This clflush makes sure that there are no false wakeups from mwait when the
monitored address was recently written to.
[1] "MONITOR/MWAIT Recommendations for Intel Xeon Processor 7400 series"
section in specification update document of 7400 series
http://download.intel.com/design/xeon/specupdt/32033601.pdf
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup and bug fix
Use the linker to create symbols for certain per-cpu variables
that are offset by __per_cpu_load. This allows the removal of
the runtime fixup of the GDT pointer, which fixes a bug with
resume reported by Jiri Slaby.
Reported-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Without frame pointers enabled, the x86 stack traces should not
pretend to be reliable; instead they should just be what they are:
unreliable.
The effect of this is that they have a '?' printed in the stacktrace,
to warn the reader that these entries are guesses rather than known
based on more reliable information.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: find right nr_irqs_gsi on some systems.
One test-system has gap between gsi's:
[ 0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
[ 0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
[ 0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
[ 0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
[ 0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
[ 0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
...
[ 0.000000] nr_irqs_gsi: 38
So nr_irqs_gsi is not right. some irq for MSI will overwrite with io_apic.
need to get that with acpi_probe_gsi when acpi io_apic is used
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: make check-timer more robust potentially solve boot fragility
For edge trigger io-apic routing, we already unmasked the pin via
setup_IO_APIC_irq(), so don't unmask it again.
Also call local_irq_disable() between timer_irq_works(), because it
calls local_irq_enable() inside.
Also remove not needed apic version reading for 64-bit
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
also could kill platform_legacy_irq
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: make nr_irqs depend more on cards used in a system
depend on nr_irq_gsi more, and have a ratio for MSI.
v2: make nr_irqs less than NR_VECTORS * nr_cpu_ids
aka if only one cpu, we only can support nr_irqs = NR_VECTORS
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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'ec', 'misc', 'printk' and 'processor' into release
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Fix compile problem:
CC arch/x86/kernel/early_printk.o
In file included from /home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/early_printk.c:17:
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h: In function 'pmd_page':
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:516: error: implicit declaration of function '__pfn_to_section'
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:516: warning: initialization makes pointer from integer without a cast
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:516: error: implicit declaration of function '__section_mem_map_addr'
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:516: warning: return makes pointer from integer without a cast
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h: In function 'pud_page':
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:586: warning: initialization makes pointer from integer without a cast
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:586: warning: return makes pointer from integer without a cast
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h: In function 'pgd_page':
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:625: warning: initialization makes pointer from integer without a cast
/home/jeremy/hg/xen/paravirt/linux/arch/x86/include/asm/pgtable.h:625: warning: return makes pointer from integer without a cast
This is a cycling dependency between asm/pgtable.h and linux/mmzone.h
when using CONFIG_SPARSEMEM. Rather than hacking up the headers some
more, remove asm/pgtable.h, since early_printk.c doesn't actually need
it.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
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Implement Linus's suggestion: introduce the hpet_cnt_ahead()
helper function to compare hpet time values - like other
wrapping counter comparisons are abstracted away elsewhere.
(jiffies, ktime_t, etc.)
Reported-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Also move xquad_portio over to where it's allocated.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Conflicts:
arch/x86/mach-default/setup.c
Semantic merge:
arch/x86/kernel/irqinit_32.c
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
only leave _default_ipi_xx etc in .h
Beyond the cleanup factor, this saves a bit of code size as well:
text data bss dec hex filename
7281931 1630144 1463304 10375379 9e50d3 vmlinux.before
7281753 1630144 1463304 10375201 9e5021 vmlinux.after
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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disable_ioapic_setup()
Impact: cleanup
disable_ioapic_setup() in init/main.c is ugly as the function is
x86-specific. The #ifdef inline prototype there is ugly too.
Replace it with a generic arch_disable_smp_support() function - which
has a weak alias for non-x86 architectures and for non-ioapic x86 builds.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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At this time, the PowerNow! driver for K8 uses an experimentally
derived formula to calculate transition latency. The value it
provides is orders of magnitude too large on modern systems.
This patch replaces the formula with ACPI _PSS latency values
for more accuracy and better performance.
I've tested it on two 2nd generation Opteron systems, a 3rd
generation Operton system, and a Turion X2 without seeing any
stability problems.
Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>
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Fix user-visible grammo.
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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There's a small problem with hpet_rtc_reinit function - it checks
for the:
hpet_readl(HPET_COUNTER) - hpet_t1_cmp > 0
to continue increasing both the HPET_T1_CMP (register) and the
hpet_t1_cmp (variable).
But since the HPET_COUNTER is always 32-bit, if the hpet_t1_cmp
is 64-bit this condition will always be FALSE once the latter hits
the 32-bit boundary, and we can have a situation, when we don't
increase the HPET_T1_CMP register high enough.
The result - timer stops ticking, since HPET_T1_CMP becomes less,
than the COUNTER and never increased again.
The solution is (based on Linus's suggestion) to not compare 64-bits
(on 64-bit x86), but to do the comparison on 32-bit signed
integers.
Reported-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch echoes what we already do on 32-bit since
90f7d25c6b672137344f447a30a9159945ffea72, and prints the DMI
product name in show_regs, so that system specific problems can be
easily identified.
Signed-off-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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entries
They were long enough set deprecated...
Update Documentation/cpu-freq/users-guide.txt:
The deprecated files listed there seen not to exist for some time anymore
already.
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
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Impact: reduce kernel BSS size by 7 pages, improve code readability
Two page tables are used in current x86_64 kexec implementation. One
is used to jump from kernel virtual address to identity map address,
the other is used to map all physical memory. In fact, on x86_64,
there is no conflict between kernel virtual address space and physical
memory space, so just one page table is sufficient. The page table
pages used to map control page are dynamically allocated to save
memory if kexec image is not loaded. ASM code used to map control page
is replaced by C code too.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Impact: fix to enable APIC for AMD Fam10h on chipsets with a missing/b0rked
ACPI MP table (MADT)
Booting a 32bit kernel on an AMD Fam10h CPU running on chipsets with
missing/b0rked MP table leads to a hang pretty early in the boot process
due to the APIC not being initialized. Fix that by falling back to the
default APIC base address in 32bit code, as it is done in the 64bit
codepath.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Impact: Fixes dumpstack and KDB on 64 bits
This re-adds the old stack pointer to the top of the irqstack to help
with unwinding. It was removed in commit d99015b1abbad743aa049b439c1e1dede6d0fa49
as part of the save_args out-of-line work.
Both dumpstack and KDB require this information.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Impact: fix regression with kexec with vmlinux
Split data.init into data.init, percpu, data.init2 sections
instead of let data.init wrap percpu secion.
Thus kexec loading will be happy, because sections will not
overlap.
Before the patch we have:
Elf file type is EXEC (Executable file)
Entry point 0x200000
There are 6 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000200000 0xffffffff80200000 0x0000000000200000
0x0000000000ca6000 0x0000000000ca6000 R E 200000
LOAD 0x0000000000ea6000 0xffffffff80ea6000 0x0000000000ea6000
0x000000000014dfe0 0x000000000014dfe0 RWE 200000
LOAD 0x0000000001000000 0xffffffffff600000 0x0000000000ff4000
0x0000000000000888 0x0000000000000888 RWE 200000
LOAD 0x00000000011f6000 0xffffffff80ff6000 0x0000000000ff6000
0x0000000000073086 0x0000000000a2d938 RWE 200000
LOAD 0x0000000001400000 0x0000000000000000 0x000000000106a000
0x00000000001d2ce0 0x00000000001d2ce0 RWE 200000
NOTE 0x00000000009e2c1c 0xffffffff809e2c1c 0x00000000009e2c1c
0x0000000000000024 0x0000000000000024 4
Section to Segment mapping:
Segment Sections...
00 .text .notes __ex_table .rodata __bug_table .pci_fixup .builtin_fw __ksymtab __ksymtab_gpl __ksymtab_strings __init_rodata __param
01 .data .init.rodata .data.cacheline_aligned .data.read_mostly
02 .vsyscall_0 .vsyscall_fn .vsyscall_gtod_data .vsyscall_1 .vsyscall_2 .vgetcpu_mode .jiffies
03 .data.init_task .smp_locks .init.text .init.data .init.setup .initcall.init .con_initcall.init .x86_cpu_dev.init .altinstructions .altinstr_replacement .exit.text .init.ramfs .bss
04 .data.percpu
05 .notes
After patch we've got:
Elf file type is EXEC (Executable file)
Entry point 0x200000
There are 7 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000200000 0xffffffff80200000 0x0000000000200000
0x0000000000ca6000 0x0000000000ca6000 R E 200000
LOAD 0x0000000000ea6000 0xffffffff80ea6000 0x0000000000ea6000
0x000000000014dfe0 0x000000000014dfe0 RWE 200000
LOAD 0x0000000001000000 0xffffffffff600000 0x0000000000ff4000
0x0000000000000888 0x0000000000000888 RWE 200000
LOAD 0x00000000011f6000 0xffffffff80ff6000 0x0000000000ff6000
0x0000000000073086 0x0000000000073086 RWE 200000
LOAD 0x0000000001400000 0x0000000000000000 0x000000000106a000
0x00000000001d2ce0 0x00000000001d2ce0 RWE 200000
LOAD 0x000000000163d000 0xffffffff8123d000 0x000000000123d000
0x0000000000000000 0x00000000007e6938 RWE 200000
NOTE 0x00000000009e2c1c 0xffffffff809e2c1c 0x00000000009e2c1c
0x0000000000000024 0x0000000000000024 4
Section to Segment mapping:
Segment Sections...
00 .text .notes __ex_table .rodata __bug_table .pci_fixup .builtin_fw __ksymtab __ksymtab_gpl __ksymtab_strings __init_rodata __param
01 .data .init.rodata .data.cacheline_aligned .data.read_mostly
02 .vsyscall_0 .vsyscall_fn .vsyscall_gtod_data .vsyscall_1 .vsyscall_2 .vgetcpu_mode .jiffies
03 .data.init_task .smp_locks .init.text .init.data .init.setup .initcall.init .con_initcall.init .x86_cpu_dev.init .altinstructions .altinstr_replacement .exit.text .init.ramfs
04 .data.percpu
05 .bss
06 .notes
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Zach says:
> Enable/Disable have no clobbers at all.
> Save clobbers only return value, %eax
> Restore also clobbers nothing.
This is precisely compatible with the calling convention, so we can
just call them directly without wrapping.
(Compile tested only.)
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Eric Paris reported:
> I have an hp dl785g5 which is unable to successfully run
> 2.6.29-0.66.rc3.fc11.x86_64 or 2.6.29-rc2-next-20090126. During bootup
> (early in userspace daemons starting) I get the below BUG, which quickly
> renders the machine dead. I assume it is because sparse_irq_lock never
> gets released when the BUG kills that task.
Adjust lock sequence when migrating a descriptor with
CONFIG_NUMA_MIGRATE_IRQ_DESC enabled.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, ds, bts: cleanup/fix DS configuration
ring-buffer: reset timestamps when ring buffer is reset
trace: set max latency variable to zero on default
trace: stop all recording to ring buffer on ftrace_dump
trace: print ftrace_dump at KERN_EMERG log level
ring_buffer: reset write when reserve buffer fail
tracing/function-graph-tracer: fix a regression while suspend to disk
ring-buffer: fix alignment problem
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86 setup: fix asm constraints in vesa_store_edid
xen: make sysfs files behave as their names suggest
x86: tone down mtrr_trim_uncached_memory() warning
x86: correct the CPUID pattern for MSR_IA32_MISC_ENABLE availability
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[
mingo@elte.hu: these fixes are a subset of changes cherry-picked from:
git://git.kernel.org:/pub/scm/linux/kernel/git/jejb/voyager-2.6.git
They fix various problems that recent x86 changes caused in the Voyager
subarchitecture: both APIC changes and cpumask changes and certain
cleanups caused subarch assumptions to break.
Most of these changes are obsolete as the subarch code has been removed
from the x86 development tree - but we merge them upstream to make Voyager
build and boot.
]
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: split out a function, no functional change
Xen needs to be able to access percpu data from very early on. For
various reasons, it cannot also load the gdt at that time. It does,
however, have a pefectly functional gdt at that point, so there's no
pressing need to reload the gdt.
Split the function to load the segment registers off, so Xen can call
it directly.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: cleanup, prepare for xen boot fix.
Xen needs to call this function very early to setup the GDT and
per-cpu segments. Remove the call to smp_processor_id() and just
pass in the cpu number.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: fix possible tlb mis-flushing on UV
uv_flush_send_and_wait() should return a pointer if the broadcast
remote tlb shootdown requests fail. That causes the conventional IPI
method of shootdown to be used.
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Move the spurious vector sanity check to the place where it's
defined - out of a .c file.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: Optimization
In the native case, pte_val, make_pte, etc are all just identity
functions, so there's no need to clobber a lot of registers over them.
(This changes the 32-bit callee-save calling convention to return both
EAX and EDX so functions can return 64-bit values.)
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Impact: Optimization
One of the problems with inserting a pile of C calls where previously
there were none is that the register pressure is greatly increased.
The C calling convention says that the caller must expect a certain
set of registers may be trashed by the callee, and that the callee can
use those registers without restriction. This includes the function
argument registers, and several others.
This patch seeks to alleviate this pressure by introducing wrapper
thunks that will do the register saving/restoring, so that the
callsite doesn't need to worry about it, but the callee function can
be conventional compiler-generated code. In many cases (particularly
performance-sensitive cases) the callee will be in assembler anyway,
and need not use the compiler's calling convention.
Standard calling convention is:
arguments return scratch
x86-32 eax edx ecx eax ?
x86-64 rdi rsi rdx rcx rax r8 r9 r10 r11
The thunk preserves all argument and scratch registers. The return
register is not preserved, and is available as a scratch register for
unwrapped callee code (and of course the return value).
Wrapped function pointers are themselves wrapped in a struct
paravirt_callee_save structure, in order to get some warning from the
compiler when functions with mismatched calling conventions are used.
The most common paravirt ops, both statically and dynamically, are
interrupt enable/disable/save/restore, so handle them first. This is
particularly easy since their calls are handled specially anyway.
XXX Deal with VMI. What's their calling convention?
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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