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I figured out another ACPI related regression today.
randconfig testing triggered an early boot-time hang on a laptop of mine
(32-bit x86, config attached) - the screen was scrolling ACPI AML
exceptions [with no serial port and no early debugging available].
v2.6.24 works fine on that laptop with the same .config, so after a few
hours of bisection (had to restart it 3 times - other regressions
interacted), it honed in on this commit:
| 10270d4838bdc493781f5a1cf2e90e9c34c9142f is first bad commit
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| Author: Linus Torvalds <torvalds@woody.linux-foundation.org>
| Date: Wed Feb 13 09:56:14 2008 -0800
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| acpi: fix acpi_os_read_pci_configuration() misuse of raw_pci_read()
reverting this commit ontop of -rc5 gave a correctly booting kernel.
But this commit fixes a real bug so the real question is, why did it
break the bootup?
After quite some head-scratching, the following change stood out:
- pci_id->bus = tu8;
+ pci_id->bus = val;
pci_id->bus is defined as u16:
struct acpi_pci_id {
u16 segment;
u16 bus;
...
and 'tu8' changed from u8 to u32. So previously we'd unconditionally
mask the return value of acpi_os_read_pci_configuration()
(raw_pci_read()) to 8 bits, but now we just trust whatever comes back
from the PCI access routines and only crop it to 16 bits.
But if the high 8 bits of that result contains any noise then we'll
write that into ACPI's PCI ID descriptor and confuse the heck out of the
rest of ACPI.
So lets check the PCI-BIOS code on that theory. We have this codepath
for 8-bit accesses (arch/x86/pci/pcbios.c:pci_bios_read()):
switch (len) {
case 1:
__asm__("lcall *(%%esi); cld\n\t"
"jc 1f\n\t"
"xor %%ah, %%ah\n"
"1:"
: "=c" (*value),
"=a" (result)
: "1" (PCIBIOS_READ_CONFIG_BYTE),
"b" (bx),
"D" ((long)reg),
"S" (&pci_indirect));
Aha! The "=a" output constraint puts the full 32 bits of EAX into
*value. But if the BIOS's routines set any of the high bits to nonzero,
we'll return a value with more set in it than intended.
The other, more common PCI access methods (v1 and v2 PCI reads) clear
out the high bits already, for example pci_conf1_read() does:
switch (len) {
case 1:
*value = inb(0xCFC + (reg & 3));
which explicitly converts the return byte up to 32 bits and zero-extends
it.
So zero-extending the result in the PCI-BIOS read routine fixes the
regression on my laptop. ( It might fix some other long-standing issues
we had with PCI-BIOS during the past decade ... ) Both 8-bit and 16-bit
accesses were buggy.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Ahmed managed to crash the Host in release_pgd(), which cannot be a Guest
bug, and indeed it wasn't.
The bug was that handing a 0 as the address of the toplevel page table
being manipulated can cause the lookup code in find_pgdir() to return
an uninitialized cache entry (we shadow up to 4 top level page tables
for each Guest).
Commit 37cc8d7f963ba2deec29c9b68716944516a3244f introduced this
behaviour in the Guest, uncovering the bug.
The patch which he submitted (which removed the /4 from the index
calculation) simply ensured that these high-indexed entries hit the
early exit path of guest_set_pmd(). But you get lots of segfaults in
guest userspace as the PMDs aren't being updated.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Now the TSC code handles a zero return from calculate_cpu_khz(),
lguest can simply pass through the value it gets from the Host: if
non-zero, all the normal TSC code applies.
Otherwise (or if the Host really doesn't support TSC), the clocksource
code will fall back to the slower but reasonable lguest clock.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This makes 64-bit ptrace calls setting the 64-bit orig_ax field for a
32-bit task sign-extend the low 32 bits up to 64. This matches what a
64-bit debugger expects when tracing a 32-bit task.
This follows on my "x86_64 ia32 syscall restart fix". This didn't
matter until that was fixed.
The debugger ignores or zeros the high half of every register slot it
sets (including the orig_rax pseudo-register) uniformly. It expects
that the setting of the low 32 bits always has the same meaning as a
32-bit debugger setting those same 32 bits with native 32-bit
facilities.
This never arose before because the syscall restart check never
matched any -ERESTART* values due to lack of sign extension. Before
that fix, even 32-bit ptrace setting orig_eax to -1 failed to trigger
the restart check anyway. So this was never noticed as a regression
of 64-bit debuggers vs 32-bit debuggers on the same 64-bit kernel.
Signed-off-by: Roland McGrath <roland@redhat.com>
[ Changed to just do the sign-extension unconditionally on x86-64,
since orig_ax is always just a small integer and doesn't need
the full 64-bit range ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The new x86 setup code (4fd06960f120) broke booting on an old P3/500MHz
with an onboard Voodoo3 of mine. After debugging it, it turned out
to be caused by the fact that the vesa probing now asks for VBE2 data.
Disassembing the video BIOS shows that it overflows the vesa_general_info
structure when VBE2 data is requested because the source addresses for the
information strings which get strcpy'ed to the buffer lie outside the 32K
BIOS code (and hence contain long sequences of 0xff's).
E.G.:
get_vbe_controller_info:
00002A9C 60 pushaw
00002A9D 1E push ds
00002A9E 0E push cs
00002A9F 1F pop ds
00002AA0 2BC9 sub cx,cx
00002AA2 6626813D56424532 cmp dword [es:di],0x32454256 ; "VBE2"
00002AAA 7501 jnz .1
00002AAC 41 inc cx
.1:
00002AAD 51 push cx
00002AAE B91400 mov cx,0x14
00002AB1 BED47F mov si, controller_header
00002AB4 57 push di
00002AB5 F3A4 rep movsb ; copy vbe1.2 header
00002AB7 B9EC00 mov cx,0xec
00002ABA 2AC0 sub al,al
00002ABC F3AA rep stosb ; zero pad remainder
00002ABE 5F pop di
00002ABF E8EB0D call word get_memory
00002AC2 C1E002 shl ax,0x2
00002AC5 26894512 mov [es:di+0x12],ax ; total memory
00002AC9 26C745040003 mov word [es:di+0x4],0x300 ; VBE version
00002ACF 268C4D08 mov [es:di+0x8],cs
00002AD3 268C4D10 mov [es:di+0x10],cs
00002AD7 59 pop cx
00002AD8 E361 jcxz .done ; VBE2 requested?
00002ADA 8D9D0001 lea bx,[di+0x100]
00002ADE 53 push bx
00002ADF 87DF xchg bx,di ; di now points to 2nd half
00002AE1 26C747140001 mov word [es:bx+0x14],0x100 ; sw rev
00002AE7 26897F06 mov [es:bx+0x6],di ; oem string
00002AEB 268C4708 mov [es:bx+0x8],es
00002AEF BE5280 mov si,0x8052 ; oem string
00002AF2 E87A1B call word strcpy
00002AF5 26897F0E mov [es:bx+0xe],di ; video mode list
00002AF9 268C4710 mov [es:bx+0x10],es
00002AFD B91E00 mov cx,0x1e
00002B00 BEE87F mov si,vidmodes
00002B03 F3A5 rep movsw
00002B05 26897F16 mov [es:bx+0x16],di ; oem vendor
00002B09 268C4718 mov [es:bx+0x18],es
00002B0D BE2480 mov si,0x8024 ; oem vendor
00002B10 E85C1B call word strcpy
00002B13 26897F1A mov [es:bx+0x1a],di ; oem product
00002B17 268C471C mov [es:bx+0x1c],es
00002B1B BE3880 mov si,0x8038 ; oem product
00002B1E E84E1B call word strcpy
00002B21 26897F1E mov [es:bx+0x1e],di ; oem product rev
00002B25 268C4720 mov [es:bx+0x20],es
00002B29 BE4580 mov si,0x8045 ; oem product rev
00002B2C E8401B call word strcpy
00002B2F 58 pop ax
00002B30 B90001 mov cx,0x100
00002B33 2BCF sub cx,di
00002B35 03C8 add cx,ax
00002B37 2AC0 sub al,al
00002B39 F3AA rep stosb ; zero pad
.done:
00002B3B 1F pop ds
00002B3C 61 popaw
00002B3D B84F00 mov ax,0x4f
00002B40 C3 ret
(The full BIOS can be found at http://peter.korsgaard.com/vgabios.bin
if interested).
The old setup code didn't ask for VBE2 info, and the new code doesn't
actually do anything with the extra information, so the fix is to simply
not request it. Other BIOS'es might have the same problem.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Jan Beulich noticed that the reboot fixups went missing during
reboot.c unification.
(commit 4d022e35fd7e07c522c7863fee6f07e53cf3fc14)
Geode and a few other rare boards with special reboot quirks are
affected.
Reported-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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TIF_DEBUGCTLMSR has no meaning in the actual MSR...
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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convert_fxsr_to_user() in 2.6.24's i387_32.c did this, and
convert_to_fxsr() also does the inverse, so I assume it's an oversight
that it is no longer being done.
[ mingo@elte.hu:
we encode it this way because there's no space for the 'FPU Last
Instruction Opcode' (->fop) field in the legacy user_i387_ia32_struct
that PTRACE_GETFPREGS/PTRACE_SETFPREGS uses.
it's probably pure legacy - i'd be surprised if any user-space relied on
the FPU Last Opcode in any way. But indeed we used to do it previously
so the most conservative thing is to preserve that piece of information.
]
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The Linux kernel currently does not clear the direction flag before
calling a signal handler, whereas the x86/x86-64 ABI requires that.
Linux had this behavior/bug forever, but this becomes a real problem
with gcc version 4.3, which assumes that the direction flag is
correctly cleared at the entry of a function.
This patches changes the setup_frame() functions to clear the
direction before entering the signal handler.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
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We don't need to printk a message every time we transition.
Leave the code there, but ifdef'd out, as it's useful when
adding support for new processors.
Reported-by: Petr Titěra <P.Titera@century.cz>
Signed-off-by: Dave Jones <davej@redhat.com>
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Add CONFIG_HAVE_KRETPROBES to the arch/<arch>/Kconfig file for relevant
architectures with kprobes support. This facilitates easy handling of
in-kernel modules (like samples/kprobes/kretprobe_example.c) that depend on
kretprobes being present in the kernel.
Thanks to Sam Ravnborg for helping make the patch more lean.
Per Mathieu's suggestion, added CONFIG_KRETPROBES and fixed up dependencies.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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P4 has been coming out as CPU_FAMILY=4 instead of 6: fix MPENTIUM4 typo.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86:
x86/xen: fix DomU boot problem
x86: not set node to cpu_to_node if the node is not online
x86, i387: fix ptrace leakage using init_fpu()
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git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm:
x86: disable KVM for Voyager and friends
KVM: VMX: Avoid rearranging switched guest msrs while they are loaded
KVM: MMU: Fix race when instantiating a shadow pte
KVM: Route irq 0 to vcpu 0 exclusively
KVM: Avoid infinite-frequency local apic timer
KVM: make MMU_DEBUG compile again
KVM: move alloc_apic_access_page() outside of non-preemptable region
KVM: SVM: fix Windows XP 64 bit installation crash
KVM: remove the usage of the mmap_sem for the protection of the memory slots.
KVM: emulate access to MSR_IA32_MCG_CTL
KVM: Make the supported cpuid list a host property rather than a vm property
KVM: Fix kvm_arch_vcpu_ioctl_set_sregs so that set_cr0 works properly
KVM: SVM: set NM intercept when enabling CR0.TS in the guest
KVM: SVM: Fix lazy FPU switching
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Construct Xen guest e820 map with a hole between 640K-1M.
It's pure luck that Xen kernels have gotten away with it in the past.
The patch below seems like the right thing to do. It certainly boots in
a domU without the DMI problem (without any of the other related patches
such as Alexander's).
Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Tested-by: Mark McLoughlin <markmc@redhat.com>
Acked-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
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resolve boot problem reported by Mel Gorman:
http://lkml.org/lkml/2008/2/13/404
init_cpu_to_node will use cpu->apic (from MADT or mptable) and
apic->node(from SRAT or AMD config space with k8_bus_64.c) to have
cpu->node mapping, and later identify_cpu will overwrite them
again...(with nearby_node...)
this patch checks if the node is online, otherwise it will not
update cpu_node map. so keep cpu_node map to online node before
identify_cpu..., to prevent possible error.
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
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This bug got introduced by the recent i387 merge:
commit 4421011120b2304e5c248ae4165a2704588aedf1
Author: Roland McGrath <roland@redhat.com>
Date: Wed Jan 30 13:31:50 2008 +0100
x86: x86 i387 user_regset
Current usage of unlazy_fpu() in ptrace specific routines is wrong.
unlazy_fpu() will not init fpu if the task never used math. So the
ptrace calls can expose the parent tasks FPU data in some cases.
Replace it with the init_fpu() which will init the math state, if the
task never used math before.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
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Most classic Pentiums don't have hardware virtualization extension,
and building kvm with Voyager, Visual Workstation, or NUMAQ
generates spurious failures.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
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KVM tries to run as much as possible with the guest msrs loaded instead of
host msrs, since switching msrs is very expensive. It also tries to minimize
the number of msrs switched according to the guest mode; for example,
MSR_LSTAR is needed only by long mode guests. This optimization is done by
setup_msrs().
However, we must not change which msrs are switched while we are running with
guest msr state:
- switch to guest msr state
- call setup_msrs(), removing some msrs from the list
- switch to host msr state, leaving a few guest msrs loaded
An easy way to trigger this is to kexec an x86_64 linux guest. Early during
setup, the guest will switch EFER to not include SCE. KVM will stop saving
MSR_LSTAR, and on the next msr switch it will leave the guest LSTAR loaded.
The next host syscall will end up in a random location in the kernel.
Fix by reloading the host msrs before changing the msr list.
Signed-off-by: Avi Kivity <avi@qumranet.com>
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For improved concurrency, the guest walk is performed concurrently with other
vcpus. This means that we need to revalidate the guest ptes once we have
write-protected the guest page tables, at which point they can no longer be
modified.
The current code attempts to avoid this check if the shadow page table is not
new, on the assumption that if it has existed before, the guest could not have
modified the pte without the shadow lock. However the assumption is incorrect,
as the racing vcpu could have modified the pte, then instantiated the shadow
page, before our vcpu regains control:
vcpu0 vcpu1
fault
walk pte
modify pte
fault in same pagetable
instantiate shadow page
lookup shadow page
conclude it is old
instantiate spte based on stale guest pte
We could do something clever with generation counters, but a test run by
Marcelo suggests this is unnecessary and we can just do the revalidation
unconditionally. The pte will be in the processor cache and the check can
be quite fast.
Signed-off-by: Avi Kivity <avi@qumranet.com>
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If the local apic initial count is zero, don't start a an hrtimer with infinite
frequency, locking up the host.
Signed-off-by: Avi Kivity <avi@qumranet.com>
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the cr3 variable is now inside the vcpu->arch structure.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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alloc_apic_access_page() can sleep, while vmx_vcpu_setup is called
inside a non preemptable region. Move it after put_cpu().
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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While installing Windows XP 64 bit wants to access the DEBUGCTL and the last
branch record (LBR) MSRs. Don't allowing this in KVM causes the installation to
crash. This patch allow the access to these MSRs and fixes the issue.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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This patch replaces the mmap_sem lock for the memory slots with a new
kvm private lock, it is needed beacuse untill now there were cases where
kvm accesses user memory while holding the mmap semaphore.
Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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Revert:
commit 8be8f54bae3453588011cad06363813a5293af53
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Sat Feb 23 20:43:21 2008 +0100
x86: CPA: avoid split of alias mappings
because it clearly mishandles the case when __change_page_attr(), called
from __change_page_attr_set_clr(), changes cpa->processed to 1 and
cpa_process_alias(cpa) is executed right after that.
This crashes my x86-64 test box early in the boot process
(ref. http://bugzilla.kernel.org/show_bug.cgi?id=10140#c4).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Injecting an GP when accessing this MSR lets Windows crash when running some
stress test tools in KVM. So this patch emulates access to this MSR.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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One of the use cases for the supported cpuid list is to create a "greatest
common denominator" of cpu capabilities in a server farm. As such, it is
useful to be able to get the list without creating a virtual machine first.
Since the code does not depend on the vm in any way, all that is needed is
to move it to the device ioctl handler. The capability identifier is also
changed so that binaries made against -rc1 will fail gracefully.
Signed-off-by: Avi Kivity <avi@qumranet.com>
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Whilst working on getting a VM to initialize in to IA32e mode I found
this issue. set_cr0 relies on comparing the old cr0 to the new one to
work correctly. Move the assignment below so the compare can work.
Signed-off-by: Paul Knowles <paul@transitive.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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Explicitly enable the NM intercept in svm_set_cr0 if we enable TS in the guest
copy of CR0 for lazy FPU switching. This fixes guest SMP with Linux under SVM.
Without that patch Linux deadlocks or panics right after trying to boot the
other CPUs.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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If the guest writes to cr0 and leaves the TS flag at 0 while vcpu->fpu_active
is also 0, the TS flag in the guest's cr0 gets lost. This leads to corrupt FPU
state an causes Windows Vista 64bit to crash very soon after boot. This patch
fixes this bug.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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Fix 32-on-64 pvops kernel:
we don't want userspace using syscall/sysenter, even if the hypervisor
supports it, so mask it out from CPUID.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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revert the BTS ptrace extension for now.
based on general objections from Roland McGrath:
http://lkml.org/lkml/2008/2/21/323
we'll let the BTS functionality cook some more and re-enable
it in v2.6.26. We'll leave the dead code around to help the
development of this code.
(X86_BTS is not defined at the moment)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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avoid over-eager large page splitup.
When the target area needs to be split or is split already (ioremap)
then the current code enforces the split of large mappings in the alias
regions even if we could avoid it.
Use a separate variable processed in the cpa_data structure to carry
the number of pages which have been processed instead of reusing the
numpages variable. This keeps numpages intact and gives the alias code
a chance to keep large mappings intact.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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delay the removal of this symbol export by one more kernel release,
giving external modules such as VirtualBox a chance to stop using it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Jan Beulich noticed it during code review that if a driver's ioremap()
fails (say due to -ENOMEM) then we might leak the struct vm_area.
Free it properly.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Priit Laes discovered that the sed command processing nm output was
sensitive to locale settings. This was addressed in commit
03994f01e8b72b3d01fd3d09d1cc7c9f421a727c by using [:alnum:] in place of
[a-zA-Z0-9].
But that solution too is locale-dependent and may not always match
the identifiers it needs to. The better fix is just to run sed et al
with a fixed locale setting in all builds.
Signed-off-by: Roland McGrath <roland@redhat.com>
CC: Priit Laes <plaes@plaes.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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a recent fix:
commit ce28b9864b853803320c3f1d8de1b81aa4120b14
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Wed Feb 20 23:57:30 2008 +0100
x86: fix vsyscall wreckage
removed the broken /kernel/vsyscall64 handler completely.
This triggers the following debug check:
sysctl table check failed: /kernel/vsyscall64 No proc_handler
Restore the sane part of the proc handler.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Fix a kernel bug (vmware boot problem) reported by Tomasz Grobelny,
which occurs with certain .config variants and gccs.
The x86 TLS cleanup in commit efd1ca52d04d2f6df337a3332cee56cd60e6d4c4
made the sys_set_thread_area and sys_get_thread_area functions ripe for
tail call optimization. If the compiler chooses to use it for them, it
can clobber the user trap frame because these are asmlinkage functions.
Reported-by: Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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> Diffing dmesg between git7 and git8 doesn't sched any light since
> git8 also removed the printouts of the x86 caps as they were being
> initialised and updated. I'm currently adding those printouts back
> in the hope of seeing where and when the caps get broken.
That turned out to be very illuminating:
--- dmesg-2.6.24-git7 2008-02-24 18:01:25.295851000 +0100
+++ dmesg-2.6.24-git8 2008-02-24 18:01:25.530358000 +0100
...
CPU: After generic identify, caps: 00000003 00000000 00000000 00000000 00000000 00000000 00000000 00000000
CPU: After all inits, caps: 00000003 00000000 00000000 00000000 00000000 00000000 00000000 00000000
+CPU: After applying cleared_cpu_caps, caps: 00000013 00000000 00000000 00000000 00000000 00000000 00000000 00000000
Notice how the TSC cap bit goes from Off to On.
(The first two lines are printout loops from -git7 forward-ported
to -git8, the third line is the same printout loop added just after
the xor-with-cleared_cpu_caps[] loop.)
Here's how the breakage occurs:
1. arch/x86/kernel/tsc_32.c:tsc_init() sees !cpu_has_tsc,
so bails and calls setup_clear_cpu_cap(X86_FEATURE_TSC).
2. include/asm-x86/cpufeature.h:setup_clear_cpu_cap(bit) clears
the bit in boot_cpu_data and sets it in cleared_cpu_caps
3. arch/x86/kernel/cpu/common.c:identify_cpu() XORs all caps
in with cleared_cpu_caps
HOWEVER, at this point c->x86_capability correctly has TSC
Off, cleared_cpu_caps has TSC On, so the XOR incorrectly
sets TSC to On in c->x86_capability, with disastrous results.
The real bug is that clearing bits with XOR only works if the
bits are known to be 1 prior to the XOR, and that's not true here.
A simple fix is to convert the XOR to AND-NOT instead. The following
patch does that, and allows my 486 to boot 2.6.25-rc kernels again.
[ mingo@elte.hu: fixed a similar bug in setup_64.c as well. ]
The breakage was introduced via commit 7d851c8d3db0.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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For some locales regex range [a-zA-Z] does not work as it is supposed to.
so we have to use [:alnum:] and [:xdigit:] to make it work as intended.
[1] http://en.wikipedia.org/wiki/Estonian_alphabet
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Currently, c_idle is declared in the stack, and thus, have no static address.
Peter Zijlstra points out this simple solution, in which c_idle.work
is initializated separatedly. Note that the INIT_WORK macro has a static
declaration of a key inside.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Acked-by: Peter Zijlstra <pzijlstr@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Currently, there is no way for print_stack_trace() to determine whether
a given stack trace entry was deemed reliable or not, simply because
save_stack_trace() does not record this information. (Perhaps needless
to say, this makes the saved stack traces A LOT harder to read, and
probably with no other benefits, since debugging features that use
save_stack_trace() most likely also require frame pointers, etc.)
This patch reverts to the old behaviour of only recording the reliable trace
entries for saved stack traces.
Signed-off-by: Vegard Nossum <vegardno@ifi.uio.no>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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There doesn't seem to be any reason for swapper_pg_pmd being global.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Inside a KVM virtual machine the MTRRs are usually blank. This confuses Linux
and causes a warning message at boot. This patch removes that warning message
when running Linux as a KVM guest.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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pointed out by pageexec@freemail.hu:
> what happens here is that gcc treats the argument area as owned by the
> callee, not the caller and is allowed to do certain tricks. for ssp it
> will make a copy of the struct passed by value into the local variable
> area and pass *its* address down, and it won't copy it back into the
> original instance stored in the argument area.
>
> so once sys_execve returns, the pt_regs passed by value hasn't at all
> changed and its default content will cause a nice double fault (FWIW,
> this part took me the longest to debug, being down with cold didn't
> help it either ;).
To fix this we pass in pt_regs by pointer.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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based on a report from Arne Georg Gleditsch about user-space apps
misbehaving after toggling /proc/sys/kernel/vsyscall64, a review
of the code revealed that the "NOP patching" done there is
fundamentally unsafe for a number of reasons:
1) the patching code runs without synchronizing other CPUs
2) it inserts NOPs even if there is no clock source which provides vread
3) when the clock source changes to one without vread we run in
exactly the same problem as in #2
4) if nobody toggles the proc entry from 1 to 0 and to 1 again, then
the syscall is not patched out
as a result it is possible to break user-space via this patching.
The only safe thing for now is to remove the patching.
This code was broken since v2.6.21.
Reported-by: Arne Georg Gleditsch <arne.gleditsch@dolphinics.no>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The KERNEL_TEXT_SIZE constant was mis-named, as we not only map the kernel
text but data, bss and init sections as well.
That name led me on the wrong path with the KERNEL_TEXT_SIZE regression,
because i knew how big of _text_ my images have and i knew about the 40 MB
"text" limit so i wrongly thought to be on the safe side of the 40 MB limit
with my 29 MB of text, while the total image size was slightly above 40 MB.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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recently the 64-bit allyesconfig bzImage kernel started spontaneously
rebooting during early bootup.
after a few fun hours spent with early init debugging, it turns out
that we've got this rather annoying limit on the size of the kernel
image:
#define KERNEL_TEXT_SIZE (40*1024*1024)
which limit my vmlinux just happened to pass:
text data bss dec hex filename
29703744 4222751 8646224 42572719 2899baf vmlinux
40 MB is 42572719 bytes, so my vmlinux was just 1.5% above this limit :-/
So it happily crashed right in head_64.S, which - as we all know - is
the most debuggable code in the whole architecture ;-)
So increase the limit to allow an up to 128MB kernel image to be mapped.
(should anyone be that crazy or lazy)
We have a full 4K of pagetable (level2_kernel_pgt) allocated for these
mappings already, so there's no RAM overhead and the limit was rather
pointless and arbitrary.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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so far no one complained about that.
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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