When a machine boots up, the TSC generally gets reset. However,
when kexec is used to boot into a kernel, the TSC value would be
carried over from the previous kernel. The computation of
cycns_offset in set_cyc2ns_scale is prone to an overflow, if the
machine has been up more than 208 days prior to the kexec. The
overflow happens when we multiply *scale, even though there is
enough room to store the final answer.
We fix this issue by decomposing tsc_now into the quotient and
remainder of division by CYC2NS_SCALE_FACTOR and then performing
the multiplication separately on the two components.
Refactor code to share the calculation with the previous
fix in __cycles_2_ns().
Signed-off-by: Salman Qazi <sqazi@google.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Turner <pjt@google.com>
Cc: john stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20120310004027.19291.88460.stgit@dungbeetle.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There are precedences of trap number being referred to as
trap_nr. However thread struct refers trap number as trap_no.
Change it to trap_nr.
Also use enum instead of left-over literals for trap values.
This is pure cleanup, no functional change intended.
Suggested-by: Ingo Molnar <mingo@eltu.hu>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120312092555.5379.942.sendpatchset@srdronam.in.ibm.com
[ Fixed the math-emu build ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
With the recent changes to clear_IO_APIC_pin() which tries to
clear remoteIRR bit explicitly, some of the users started to see
"Unable to reset IRR for apic .." messages.
Close look shows that these are related to bogus IO-APIC entries
which return's all 1's for their io-apic registers. And the
above mentioned error messages are benign. But kernel should
have ignored such io-apic's in the first place.
Check if register 0, 1, 2 of the listed io-apic are all 1's and
ignore such io-apic.
Reported-by: Álvaro Castillo <midgoon@gmail.com>
Tested-by: Jon Dufresne <jon@jondufresne.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: yinghai@kernel.org
Cc: kernel-team@fedoraproject.org
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/1331577393.31585.94.camel@sbsiddha-desk.sc.intel.com
[ Performed minor cleanup of affected code. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I got somewhat tired of having to decode hex numbers..
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Robert Richter <robert.richter@amd.com>
Link: http://lkml.kernel.org/n/tip-0vsy1sgywc4uar3mu1szm0rg@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Stepan found:
CPU0 CPUn
_cpu_up()
__cpu_up()
boostrap()
notify_cpu_starting()
set_cpu_online()
while (!cpu_active())
cpu_relax()
<PREEMPT-out>
smp_call_function(.wait=1)
/* we find cpu_online() is true */
arch_send_call_function_ipi_mask()
/* wait-forever-more */
<PREEMPT-in>
local_irq_enable()
cpu_notify(CPU_ONLINE)
sched_cpu_active()
set_cpu_active()
Now the purpose of cpu_active is mostly with bringing down a cpu, where
we mark it !active to avoid the load-balancer from moving tasks to it
while we tear down the cpu. This is required because we only update the
sched_domain tree after we brought the cpu-down. And this is needed so
that some tasks can still run while we bring it down, we just don't want
new tasks to appear.
On cpu-up however the sched_domain tree doesn't yet include the new cpu,
so its invisible to the load-balancer, regardless of the active state.
So instead of setting the active state after we boot the new cpu (and
consequently having to wait for it before enabling interrupts) set the
cpu active before we set it online and avoid the whole mess.
Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1323965362.18942.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For the hypervisor to take advantage of the MWAIT support it needs
to extract from the ACPI _CST the register address. But the
hypervisor does not have the support to parse DSDT so it relies on
the initial domain (dom0) to parse the ACPI Power Management information
and push it up to the hypervisor. The pushing of the data is done
by the processor_harveset_xen module which parses the information that
the ACPI parser has graciously exposed in 'struct acpi_processor'.
For the ACPI parser to also expose the Cx states for MWAIT, we need
to expose the MWAIT capability (leaf 1). Furthermore we also need to
expose the MWAIT_LEAF capability (leaf 5) for cstate.c to properly
function.
The hypervisor could expose these flags when it traps the XEN_EMULATE_PREFIX
operations, but it can't do it since it needs to be backwards compatible.
Instead we choose to use the native CPUID to figure out if the MWAIT
capability exists and use the XEN_SET_PDC query hypercall to figure out
if the hypervisor wants us to expose the MWAIT_LEAF capability or not.
Note: The XEN_SET_PDC query was implemented in c/s 23783:
"ACPI: add _PDC input override mechanism".
With this in place, instead of
C3 ACPI IOPORT 415
we get now
C3:ACPI FFH INTEL MWAIT 0x20
Note: The cpu_idle which would be calling the mwait variants for idling
never gets set b/c we set the default pm_idle to be the hypercall variant.
Acked-by: Jan Beulich <JBeulich@suse.com>
[v2: Fix missing header file include and #ifdef]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We needed that call in the past to force the kernel to use
default_idle (which called safe_halt, which called xen_safe_halt).
But set_pm_idle_to_default() does now that, so there is no need
to use this boot option operand.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We need to merge this ahead of some of the cleanup because a lot of needed
cleanup spans both new and old chips. If we try and clean up and the merge
we end up fighting ourselves.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[With a load of the cleanup stuff folded in, register stuff reworked sanely]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
The traps are referred to by their numbers and it can be difficult to
understand them while reading the code without context. This patch adds
enumeration of the trap numbers and replaces the numbers with the correct
enum for x86.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20120310000710.GA32667@www.outflux.net
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Commit f0fbf0abc0 ("x86: integrate delay functions") converted
delay_tsc() into a random delay generator for 64 bit. The reason is
that it merged the mostly identical versions of delay_32.c and
delay_64.c. Though the subtle difference of the result was:
static void delay_tsc(unsigned long loops)
{
- unsigned bclock, now;
+ unsigned long bclock, now;
Now the function uses rdtscl() which returns the lower 32bit of the
TSC. On 32bit that's not problematic as unsigned long is 32bit. On 64
bit this fails when the lower 32bit are close to wrap around when
bclock is read, because the following check
if ((now - bclock) >= loops)
break;
evaluated to true on 64bit for e.g. bclock = 0xffffffff and now = 0
because the unsigned long (now - bclock) of these values results in
0xffffffff00000001 which is definitely larger than the loops
value. That explains Tvortkos observation:
"Because I am seeing udelay(500) (_occasionally_) being short, and
that by delaying for some duration between 0us (yep) and 491us."
Make those variables explicitely u32 again, so this works for both 32
and 64 bit.
Reported-by: Tvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # >= 2.6.27
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ok, this is hacky, and only works on little-endian machines with goo
unaligned handling. And even then only with CONFIG_DEBUG_PAGEALLOC
disabled, since it can access up to 7 bytes after the pathname.
But it runs like a bat out of hell.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The code which checks whether to inject a pagefault to L1 or L2 (in
nested VMX) was wrong, incorrect in how it checked the PF_VECTOR bit.
Thanks to Dan Carpenter for spotting this.
Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
When CPUID Fn8000_0001_EAX reports 0x00100f22 Windows 7 x64 guest
tries to set bit 3 in MSRC001_0015 in nt!KiDisableCacheErrataSource
and fails. This patch will ignore this step and allow things to move
on without having to fake CPUID value.
Signed-off-by: Nicolae Mogoreanu <mogoreanu@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The reset_rsvds_bits_mask() function can use the guest walker's root level
number instead of using a separate 'level' variable.
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
Currently pmu emulation emulates fixed counter 2 as bus cycles
architectural counter, but since commit 9c1497ea59 perf has
pseudo encoding for it. Use it.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If eventsel has EDGE, INV or CMASK set we should create raw counter for
it, but the check is done on a wrong variable. Fix it.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Print warning once if pin control bit is set in eventsel msr since
emulation does not support it yet.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Shared MSRs (MSR_*STAR and related) are stored in both vmx->guest_msrs
and in the CPU registers, but vmx_set_msr() only updated memory. Prior
to 46199f33c2, this didn't matter, since we called vmx_load_host_state(),
which scheduled a vmx_save_host_state(), which re-synchronized the CPU
state, but now we don't, so the CPU state will not be synchronized until
the next exit to host userspace. This mostly affects nested vmx workloads,
which play with these MSRs a lot.
Fix by loading the MSR eagerly.
Signed-off-by: Avi Kivity <avi@redhat.com>
PCI 2.3 allows to generically disable IRQ sources at device level. This
enables us to share legacy IRQs of such devices with other host devices
when passing them to a guest.
The new IRQ sharing feature introduced here is optional, user space has
to request it explicitly. Moreover, user space can inform us about its
view of PCI_COMMAND_INTX_DISABLE so that we can avoid unmasking the
interrupt and signaling it if the guest masked it via the virtualized
PCI config space.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If some vcpus are created before KVM_CREATE_IRQCHIP, then
irqchip_in_kernel() and vcpu->arch.apic will be inconsistent, leading
to potential NULL pointer dereferences.
Fix by:
- ensuring that no vcpus are installed when KVM_CREATE_IRQCHIP is called
- ensuring that a vcpu has an apic if it is installed after KVM_CREATE_IRQCHIP
This is somewhat long winded because vcpu->arch.apic is created without
kvm->lock held.
Based on earlier patch by Michael Ellerman.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Avi Kivity <avi@redhat.com>
Task switches can switch between Protected Mode and VM86. The current
mode must be updated during the task switch emulation so that the new
segment selectors are interpreted correctly.
In order to let privilege checks succeed, rflags needs to be updated in
the vcpu struct as this causes a CPL update.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Keep CPL at 0 in real mode and at 3 in VM86. In protected/long mode, use
RPL rather than DPL of the code segment.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Setting the segment DPL to 0 for at least the VM86 code segment makes
the VM entry fail on VMX.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Currently, all task switches check privileges against the DPL of the
TSS. This is only correct for jmp/call to a TSS. If a task gate is used,
the DPL of this take gate is used for the check instead. Exceptions,
external interrupts and iret shouldn't perform any check.
[avi: kill kvm-kmod remnants]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Some members of kvm_memory_slot are not used by every architecture.
This patch is the first step to make this difference clear by
introducing kvm_memory_slot::arch; lpage_info is moved into it.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch cleans up the code and removes the "(void)level;" warning
suppressor.
Note that we can also use this for PT_PAGE_TABLE_LEVEL to treat every
level uniformly later.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch fixes a race introduced by:
commit 95d4c16ce7
KVM: Optimize dirty logging by rmap_write_protect()
During protecting pages for dirty logging, other threads may also try
to protect a page in mmu_sync_children() or kvm_mmu_get_page().
In such a case, because get_dirty_log releases mmu_lock before flushing
TLB's, the following race condition can happen:
A (get_dirty_log) B (another thread)
lock(mmu_lock)
clear pte.w
unlock(mmu_lock)
lock(mmu_lock)
pte.w is already cleared
unlock(mmu_lock)
skip TLB flush
return
...
TLB flush
Though thread B assumes the page has already been protected when it
returns, the remaining TLB entry will break that assumption.
This patch fixes this problem by making get_dirty_log hold the mmu_lock
until it flushes the TLB's.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
yield_on_hlt was introduced for CPU bandwidth capping. Now it is
redundant with CFS hardlimit.
yield_on_hlt also complicates the scenario in paravirtual environment,
that needs to trap halt. for e.g. paravirtualized ticket spinlocks.
Acked-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This allows us to track the original nanosecond and counter values
at each phase of TSC writing by the guest. This gets us perfect
offset matching for stable TSC systems, and perfect software
computed TSC matching for machines with unstable TSC.
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
During a host suspend, TSC may go backwards, which KVM interprets
as an unstable TSC. Technically, KVM should not be marking the
TSC unstable, which causes the TSC clocksource to go bad, but we
need to be adjusting the TSC offsets in such a case.
Dealing with this issue is a little tricky as the only place we
can reliably do it is before much of the timekeeping infrastructure
is up and running. On top of this, we are not in a KVM thread
context, so we may not be able to safely access VCPU fields.
Instead, we compute our best known hardware offset at power-up and
stash it to be applied to all VCPUs when they actually start running.
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Redefine the API to take a parameter indicating whether an
adjustment is in host or guest cycles.
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The variable last_host_tsc was removed from upstream code. I am adding
it back for two reasons. First, it is unnecessary to use guest TSC
computation to conclude information about the host TSC. The guest may
set the TSC backwards (this case handled by the previous patch), but
the computation of guest TSC (and fetching an MSR) is significanlty more
work and complexity than simply reading the hardware counter. In addition,
we don't actually need the guest TSC for any part of the computation,
by always recomputing the offset, we can eliminate the need to deal with
the current offset and any scaling factors that may apply.
The second reason is that later on, we are going to be using the host
TSC value to restore TSC offsets after a host S4 suspend, so we need to
be reading the host values, not the guest values here.
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The variable last_guest_tsc was being used as an ad-hoc indicator
that guest TSC has been initialized and recorded correctly. However,
it may not have been, it could be that guest TSC has been set to some
large value, the back to a small value (by, say, a software reboot).
This defeats the logic and causes KVM to falsely assume that the
guest TSC has gone backwards, marking the host TSC unstable, which
is undesirable behavior.
In addition, rather than try to compute an offset adjustment for the
TSC on unstable platforms, just recompute the whole offset. This
allows us to get rid of one callsite for adjust_tsc_offset, which
is problematic because the units it takes are in guest units, but
here, the computation was originally being done in host units.
Doing this, and also recording last_guest_tsc when the TSC is written
allow us to remove the tricky logic which depended on last_guest_tsc
being zero to indicate a reset of uninitialized value.
Instead, we now have the guarantee that the guest TSC offset is
always at least something which will get us last_guest_tsc.
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Currently, when the TSC is written by the guest, the variable
ns is updated to force the current write to appear to have taken
place at the time of the first write in this sync phase. This
leaves a cliff at the end of the match window where updates will
fall of the end. There are two scenarios where this can be a
problem in practe - first, on a system with a large number of
VCPUs, the sync period may last for an extended period of time.
The second way this can happen is if the VM reboots very rapidly
and we catch a VCPU TSC synchronization just around the edge.
We may be unaware of the reboot, and thus the first VCPU might
synchronize with an old set of the timer (at, say 0.97 seconds
ago, when first powered on). The second VCPU can come in 0.04
seconds later to try to synchronize, but it misses the window
because it is just over the threshold.
Instead, stop doing this artificial setback of the ns variable
and just update it with every write of the TSC.
It may be observed that doing so causes values computed by
compute_guest_tsc to diverge slightly across CPUs - note that
the last_tsc_ns and last_tsc_write variable are used here, and
now they last_tsc_ns will be different for each VCPU, reflecting
the actual time of the update.
However, compute_guest_tsc is used only for guests which already
have TSC stability issues, and further, note that the previous
patch has caused last_tsc_write to be incremented by the difference
in nanoseconds, converted back into guest cycles. As such, only
boundary rounding errors should be visible, which given the
resolution in nanoseconds, is going to only be a few cycles and
only visible in cross-CPU consistency tests. The problem can be
fixed by adding a new set of variables to track the start offset
and start write value for the current sync cycle.
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
There are a few improvements that can be made to the TSC offset
matching code. First, we don't need to call the 128-bit multiply
(especially on a constant number), the code works much nicer to
do computation in nanosecond units.
Second, the way everything is setup with software TSC rate scaling,
we currently have per-cpu rates. Obviously this isn't too desirable
to use in practice, but if for some reason we do change the rate of
all VCPUs at runtime, then reset the TSCs, we will only want to
match offsets for VCPUs running at the same rate.
Finally, for the case where we have an unstable host TSC, but
rate scaling is being done in hardware, we should call the platform
code to compute the TSC offset, so the math is reorganized to recompute
the base instead, then transform the base into an offset using the
existing API.
[avi: fix 64-bit division on i386]
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
KVM: Fix 64-bit division in kvm_write_tsc()
Breaks i386 build.
Signed-off-by: Avi Kivity <avi@redhat.com>
This requires some restructuring; rather than use 'virtual_tsc_khz'
to indicate whether hardware rate scaling is in effect, we consider
each VCPU to always have a virtual TSC rate. Instead, there is new
logic above the vendor-specific hardware scaling that decides whether
it is even necessary to use and updates all rate variables used by
common code. This means we can simply query the virtual rate at
any point, which is needed for software rate scaling.
There is also now a threshold added to the TSC rate scaling; minor
differences and variations of measured TSC rate can accidentally
provoke rate scaling to be used when it is not needed. Instead,
we have a tolerance variable called tsc_tolerance_ppm, which is
the maximum variation from user requested rate at which scaling
will be used. The default is 250ppm, which is the half the
threshold for NTP adjustment, allowing for some hardware variation.
In the event that hardware rate scaling is not available, we can
kludge a bit by forcing TSC catchup to turn on when a faster than
hardware speed has been requested, but there is nothing available
yet for the reverse case; this requires a trap and emulate software
implementation for RDTSC, which is still forthcoming.
[avi: fix 64-bit division on i386]
Signed-off-by: Zachary Amsden <zamsden@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
While for a user mode register dump it may be reasonable to skip
those (albeit x86-64 doesn't do so), for kernel mode dumps these
should be printed to make sure all information possibly
necessary for analysis is available.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/4F58889202000078000770E7@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Building in support for either of these CPUs is pointless when
e.g. M686 was selected (since such a kernel would use cmov
instructions, which aren't available on these older CPUs).
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/4F58875A02000078000770E0@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It turns out that test-compiling this file on x86-64 doesn't really
help, because much of it is x86-32-specific. And so I hadn't noticed
the slightly over-eager removal of the 'r' from 'addr' variable despite
thinking I had tested it.
Signed-off-by: Linus "oopsie" Torvalds <torvalds@linux-foundation.org>
Several users of "find_vma_prev()" were not in fact interested in the
previous vma if there was no primary vma to be found either. And in
those cases, we're much better off just using the regular "find_vma()",
and then "prev" can be looked up by just checking vma->vm_prev.
The find_vma_prev() semantics are fairly subtle (see Mikulas' recent
commit 83cd904d271b: "mm: fix find_vma_prev"), and the whole "return
prev by reference" means that it generates worse code too.
Thus this "let's avoid using this inconvenient and clearly too subtle
interface when we don't really have to" patch.
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Like most systems, OLPC's ACPI LID switch wakes up the system
when the lid is opened, but not when it is closed.
Under OLPC's opportunistic suspend model, the lid may be closed
while the system was oportunistically suspended with the screen
running. In this event, we want to wake up to turn the screen
off.
Enable control of normal ACPI wakeups through lid close events
through a new sysfs attribute "lid_wake_on_closed". When set,
and when LID wakeups are enabled through ACPI, the system will
wake up on both open and close lid events.
Signed-off-by: Daniel Drake <dsd@laptop.org>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Matthew Garrett <mjg@redhat.com>
[ Fixed sscanf checking]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-bgt8hxu2wwe0x5p8edhogtf7@git.kernel.org
[ Did very minor readability tweaks ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix a bug in kprobes which can modify kernel code
permanently at run-time. In the result, kernel can
crash when it executes the modified code.
This bug can happen when we put two probes enough near
and the first probe is optimized. When the second probe
is set up, it copies a byte which is already modified
by the first probe, and executes it when the probe is hit.
Even worse, the first probe and the second probe are removed
respectively, the second probe writes back the copied
(modified) instruction.
To fix this bug, kprobes always recovers the original
code and copies the first byte from recovered instruction.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: systemtap@sourceware.org
Cc: anderson@redhat.com
Link: http://lkml.kernel.org/r/20120305133215.5982.31991.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Current probed-instruction recovery expects that only breakpoint
instruction modifies instruction. However, since kprobes jump
optimization can replace original instructions with a jump,
that expectation is not enough. And it may cause instruction
decoding failure on the function where an optimized probe
already exists.
This bug can reproduce easily as below:
1) find a target function address (any kprobe-able function is OK)
$ grep __secure_computing /proc/kallsyms
ffffffff810c19d0 T __secure_computing
2) decode the function
$ objdump -d vmlinux --start-address=0xffffffff810c19d0 --stop-address=0xffffffff810c19eb
vmlinux: file format elf64-x86-64
Disassembly of section .text:
ffffffff810c19d0 <__secure_computing>:
ffffffff810c19d0: 55 push %rbp
ffffffff810c19d1: 48 89 e5 mov %rsp,%rbp
ffffffff810c19d4: e8 67 8f 72 00 callq
ffffffff817ea940 <mcount>
ffffffff810c19d9: 65 48 8b 04 25 40 b8 mov %gs:0xb840,%rax
ffffffff810c19e0: 00 00
ffffffff810c19e2: 83 b8 88 05 00 00 01 cmpl $0x1,0x588(%rax)
ffffffff810c19e9: 74 05 je ffffffff810c19f0 <__secure_computing+0x20>
3) put a kprobe-event at an optimize-able place, where no
call/jump places within the 5 bytes.
$ su -
# cd /sys/kernel/debug/tracing
# echo p __secure_computing+0x9 > kprobe_events
4) enable it and check it is optimized.
# echo 1 > events/kprobes/p___secure_computing_9/enable
# cat ../kprobes/list
ffffffff810c19d9 k __secure_computing+0x9 [OPTIMIZED]
5) put another kprobe on an instruction after previous probe in
the same function.
# echo p __secure_computing+0x12 >> kprobe_events
bash: echo: write error: Invalid argument
# dmesg | tail -n 1
[ 1666.500016] Probing address(0xffffffff810c19e2) is not an instruction boundary.
6) however, if the kprobes optimization is disabled, it works.
# echo 0 > /proc/sys/debug/kprobes-optimization
# cat ../kprobes/list
ffffffff810c19d9 k __secure_computing+0x9
# echo p __secure_computing+0x12 >> kprobe_events
(no error)
This is because kprobes doesn't recover the instruction
which is overwritten with a relative jump by another kprobe
when finding instruction boundary.
It only recovers the breakpoint instruction.
This patch fixes kprobes to recover such instructions.
With this fix:
# echo p __secure_computing+0x9 > kprobe_events
# echo 1 > events/kprobes/p___secure_computing_9/enable
# cat ../kprobes/list
ffffffff810c1aa9 k __secure_computing+0x9 [OPTIMIZED]
# echo p __secure_computing+0x12 >> kprobe_events
# cat ../kprobes/list
ffffffff810c1aa9 k __secure_computing+0x9 [OPTIMIZED]
ffffffff810c1ab2 k __secure_computing+0x12 [DISABLED]
Changes in v4:
- Fix a bug to ensure optimized probe is really optimized
by jump.
- Remove kprobe_optready() dependency.
- Cleanup code for preparing optprobe separation.
Changes in v3:
- Fix a build error when CONFIG_OPTPROBE=n. (Thanks, Ingo!)
To fix the error, split optprobe instruction recovering
path from kprobes path.
- Cleanup comments/styles.
Changes in v2:
- Fix a bug to recover original instruction address in
RIP-relative instruction fixup.
- Moved on tip/master.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: systemtap@sourceware.org
Cc: anderson@redhat.com
Link: http://lkml.kernel.org/r/20120305133209.5982.36568.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add platform driver for the Soekris Engineering net5501 single-board
computer. Probes well-known locations in ROM for BIOS signature
to confirm correct platform. Registers 1 LED and 1 GPIO-based
button (typically used for soft reset).
Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Matthew Garrett <mjg@redhat.com>
[ Removed Kconfig and Makefile detritus from drivers/leds/]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-jv5uf34996juqh5syes8mn4h@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
GPIO 24 is used in reference designs as a soft-reset button, and
the alix2 is no exception. Add it as a gpio-button.
Use symbolic values to describe BIOS addresses.
Record the model number.
Signed-off-by: Philip A. Prindeville <philipp@redfish-solutions.com>
Acked-by: Ed Wildgoose <kernel@wildgooses.com>
Acked-by: Andres Salomon <dilinger@queued.net>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-sjp6k1rjksitx1pej0c0qxd1@git.kernel.org
[ tidied up the code a bit ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Salman Qazi