fix:
arch/x86/kernel/ftrace.c: Assembler messages:
arch/x86/kernel/ftrace.c:140: Error: missing ')'
arch/x86/kernel/ftrace.c:140: Error: junk `(%ebp))' after expression
arch/x86/kernel/ftrace.c:141: Error: missing ')'
arch/x86/kernel/ftrace.c:141: Error: junk `(%ebp))' after expression
the [parent_replaced] is used in an =rm fashion, so that constraint
is correct in isolation - but [parent_old] aliases register %0 and uses
it in an addressing mode that is only valid with registers - so change
the constraint from =rm to =r.
This fixes the build failure.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add infrastructure for function-return tracing
Add low level support for ftrace return tracing.
This plug-in stores return addresses on the thread_info structure of
the current task.
The index of the current return address is initialized when the task
is the first one (init) and when a process forks (the child). It is
not needed when a task does a sys_execve because after this syscall,
it still needs to return on the kernel functions it called.
Note that the code of return_to_handler has been suggested by Steven
Rostedt as almost all of the ideas of improvements in this V3.
For purpose of security, arch/x86/kernel/process_32.c is not traced
because __switch_to() changes the current task during its execution.
That could cause inconsistency in the stored return address of this
function even if I didn't have any crash after testing with tracing on
this function enabled.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: optimize sched_clock() a bit
sched: improve sched_clock() performance
sched_clock() uses cycles_2_ns() needlessly - which is an irq-disabling
variant of __cycles_2_ns().
Most of the time sched_clock() is called with irqs disabled already.
The few places that call it with irqs enabled need to be updated.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
in scheduler-intense workloads native_read_tsc() overhead accounts for
20% of the system overhead:
659567 system_call 41222.9375
686796 schedule 435.7843
718382 __switch_to 665.1685
823875 switch_mm 4526.7857
1883122 native_read_tsc 55385.9412
9761990 total 2.8468
this is large part due to the rdtsc_barrier() that is done before
and after reading the TSC.
But sched_clock() is not a precise clock in the GTOD sense, using such
barriers is completely pointless. So remove the barriers and only use
them in vget_cycles().
This improves lat_ctx performance by about 5%.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, xen: fix use of pgd_page now that it really does return a page
Fix the counter overflow check for CPUs with counter width > 32
I had a similar change in a different patch that I didn't submit
and I didn't notice the problem earlier because it was always
tested together.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
Xen requires that all mappings of pagetable pages are read-only, so
that they can't be updated illegally. As a result, if a page is being
turned into a pagetable page, we need to make sure all its mappings
are RO.
If the page had been used for ioremap or vmalloc, it may still have
left over mappings as a result of not having been lazily unmapped.
This change makes sure we explicitly mop them all up before pinning
the page.
Unlike aliases created by kmap, the there can be vmalloc aliases even
for non-high pages, so we must do the flush unconditionally.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
Revert "x86: default to reboot via ACPI"
x86: align DirectMap in /proc/meminfo
AMD IOMMU: fix lazy IO/TLB flushing in unmap path
x86: add smp_mb() before sending INVALIDATE_TLB_VECTOR
x86: remove VISWS and PARAVIRT around NR_IRQS puzzle
x86: mention ACPI in top-level Kconfig menu
x86: size NR_IRQS on 32-bit systems the same way as 64-bit
x86: don't allow nr_irqs > NR_IRQS
x86/docs: remove noirqbalance param docs
x86: don't use tsc_khz to calculate lpj if notsc is passed
x86, voyager: fix smp_intr_init() compile breakage
AMD IOMMU: fix detection of NP capable IOMMUs
Impact: fix 32-bit Xen guest boot crash
On 32-bit PAE, pud_page, for no good reason, didn't really return a
struct page *. Since Jan Beulich's fix "i386/PAE: fix pud_page()",
pud_page does return a struct page *.
Because PAE has 3 pagetable levels, the pud level is folded into the
pgd level, so pgd_page() is the same as pud_page(), and now returns
a struct page *. Update the xen/mmu.c code which uses pgd_page()
accordingly.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This reverts commit c7ffa6c262.
the assumptio of this change was that this would not break
any existing machine. Andrey Borzenkov reported troubles with
the ACPI reboot method: the system would hang on reboot, necessiating
a power cycle. Probably more systems are affected as well.
Also, there are patches queued up for v2.6.29 to disable virtualization
on emergency_restart() - which was the original motivation of
this change.
Reported-by: Andrey Borzenkov <arvidjaar@mail.ru>
Bisected-by: Andrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Acked-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: right-align /proc/meminfo consistent with other fields
When the split-LRU patches added Inactive(anon) and Inactive(file) lines
to /proc/meminfo, all counts were moved two columns rightwards to fit in.
Now move x86's DirectMap lines two columns rightwards to line up.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lazy flushing needs to take care of the unmap path too which is not yet
implemented and leads to stale IO/TLB entries. This is fixed by this
patch.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Impact: fix rare x2apic hang
On x86, x2apic mode accesses for sending IPI's don't have serializing
semantics. If the IPI receivner refers(in lock-free fashion) to some
memory setup by the sender, the need for smp_mb() before sending the
IPI becomes critical in x2apic mode.
Add the smp_mb() in native_flush_tlb_others() before sending the IPI.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix warning message when PARAVIRT is set in config
Remove stale #ifdef components from our IRQ sizing logic.
x86/Voyager is the only holdout.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clarify menuconfig text
Mention ACPI in the top-level menu to give a clue as to where
it lives. This matches what ia64 does.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: quick start and stop of function tracer
This patch adds a way to disable the function tracer quickly without
the need to run kstop_machine. It adds a new variable called
function_trace_stop which will stop the calls to functions from mcount
when set. This is just an on/off switch and does not handle recursion
like preempt_disable().
It's main purpose is to help other tracers/debuggers start and stop tracing
fuctions without the need to call kstop_machine.
The config option HAVE_FUNCTION_TRACE_MCOUNT_TEST is added for archs
that implement the testing of the function_trace_stop in the mcount
arch dependent code. Otherwise, the test is done in the C code.
x86 is the only arch at the moment that supports this.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: make NR_IRQS big enough for system with lots of apic/pins
If lots of IO_APIC's are there (or can be there), size the same way
as 64-bit, depending on MAX_IO_APICS and NR_CPUS.
This fixes the boot problem reported by Ben Hutchings on a 32-bit
server with 5 IO-APICs and 240 IO-APIC pins.
Signed-off-by: Yinghai <yinghai@kernel.org>
Tested-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix boot hang on 32-bit systems with more than 224 IO-APIC pins
On some 32-bit systems with a lot of IO-APICs probe_nr_irqs() can
return a value larger than NR_IRQS. This will lead to probe_irq_on()
overrunning the irq_desc array.
I hit this when running net-next-2.6 (close to 2.6.28-rc3) on a
Supermicro dual Xeon system. NR_IRQS is 224 but probe_nr_irqs() detects
5 IOAPICs and returns 240. Here are the log messages:
Tue Nov 4 16:53:47 2008 ACPI: IOAPIC (id[0x01] address[0xfec00000] gsi_base[0])
Tue Nov 4 16:53:47 2008 IOAPIC[0]: apic_id 1, version 32, address 0xfec00000, GSI 0-23
Tue Nov 4 16:53:47 2008 ACPI: IOAPIC (id[0x02] address[0xfec81000] gsi_base[24])
Tue Nov 4 16:53:47 2008 IOAPIC[1]: apic_id 2, version 32, address 0xfec81000, GSI 24-47
Tue Nov 4 16:53:47 2008 ACPI: IOAPIC (id[0x03] address[0xfec81400] gsi_base[48])
Tue Nov 4 16:53:47 2008 IOAPIC[2]: apic_id 3, version 32, address 0xfec81400, GSI 48-71
Tue Nov 4 16:53:47 2008 ACPI: IOAPIC (id[0x04] address[0xfec82000] gsi_base[72])
Tue Nov 4 16:53:47 2008 IOAPIC[3]: apic_id 4, version 32, address 0xfec82000, GSI 72-95
Tue Nov 4 16:53:47 2008 ACPI: IOAPIC (id[0x05] address[0xfec82400] gsi_base[96])
Tue Nov 4 16:53:47 2008 IOAPIC[4]: apic_id 5, version 32, address 0xfec82400, GSI 96-119
Tue Nov 4 16:53:47 2008 ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 high edge)
Tue Nov 4 16:53:47 2008 ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
Tue Nov 4 16:53:47 2008 Enabling APIC mode: Flat. Using 5 I/O APICs
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: improve wakeup affinity on NUMA systems, tweak SMP systems
Given the fixes+tweaks to the wakeup-buddy code, re-tweak the domain
balancing defaults on NUMA and SMP systems.
Turn on SD_WAKE_AFFINE which was off on x86 NUMA - there's no reason
why we would not want to have wakeup affinity across nodes as well.
(we already do this in the standard NUMA template.)
lat_ctx on a NUMA box is particularly happy about this change:
before:
| phoenix:~/l> ./lat_ctx -s 0 2
| "size=0k ovr=2.60
| 2 5.70
after:
| phoenix:~/l> ./lat_ctx -s 0 2
| "size=0k ovr=2.65
| 2 2.07
a 2.75x speedup.
pipe-test is similarly happy about it too:
| phoenix:~/sched-tests> ./pipe-test
| 18.26 usecs/loop.
| 14.70 usecs/loop.
| 14.38 usecs/loop.
| 10.55 usecs/loop. # +WAKE_AFFINE on domain0+domain1
| 8.63 usecs/loop.
| 8.59 usecs/loop.
| 9.03 usecs/loop.
| 8.94 usecs/loop.
| 8.96 usecs/loop.
| 8.63 usecs/loop.
Also:
- disable SD_BALANCE_NEWIDLE on NUMA and SMP domains (keep it for siblings)
- enable SD_WAKE_BALANCE on SMP domains
Sysbench+postgresql improves all around the board, quite significantly:
.28-rc3-11474e2c .28-rc3-11474e2c-tune
-------------------------------------------------
1: 571 688 +17.08%
2: 1236 1206 -2.55%
4: 2381 2642 +9.89%
8: 4958 5164 +3.99%
16: 9580 9574 -0.07%
32: 7128 8118 +12.20%
64: 7342 8266 +11.18%
128: 7342 8064 +8.95%
256: 7519 7884 +4.62%
512: 7350 7731 +4.93%
-------------------------------------------------
SUM: 55412 59341 +6.62%
So it's a win both for the runup portion, the peak area and the tail.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix udelay when "notsc" boot parameter is passed
With notsc passed on commandline, tsc may not be used for
udelays, make sure that we do not use tsc_khz to calculate
the lpj value in such cases.
Reported-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'io-mappings-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
io mapping: clean up #ifdefs
io mapping: improve documentation
i915: use io-mapping interfaces instead of a variety of mapping kludges
resources: add io-mapping functions to dynamically map large device apertures
x86: add iomap_atomic*()/iounmap_atomic() on 32-bit using fixmaps
Impact: cleanup
clean up ifdefs: change #ifdef CONFIG_X86_32/64 to
CONFIG_HAVE_ATOMIC_IOMAP.
flip around the #ifdef sections to clean up the structure.
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix for non-ftrace architectures
Not all archs implement ftrace, and therefore do not have an asm/ftrace.h.
This patch corrects the problem.
The ftrace_nmi_enter/exit now must be defined for all archs that implement
dynamic ftrace. Currently, only x86 does.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix x86/Voyager build
Looks like this became static on the rest of x86. Fix it up by adding
an external definition to mach-voyager/setup.c
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: fix AMDC1E and XTOPOLOGY conflict in cpufeature
x86: build fix
This makes the late e820 resources use 'insert_resource_expand_to_fit()'
instead of doing a 'reserve_region_with_split()', and also avoids
marking them as IORESOURCE_BUSY.
This results in us being perfectly happy to use pre-existing PCI
resources even if they were marked as being in a reserved region, while
still avoiding any _new_ allocations in the reserved regions. It also
makes for a simpler and more accurate resource tree.
Example resource allocation from Jonathan Corbet, who has firmware that
has an e820 reserved entry that covered a big range (e0000000-fed003ff),
and that had various PCI resources in it set up by firmware.
With old kernels, the reserved range would force us to re-allocate all
pre-existing PCI resources, and his reserved range would end up looking
like this:
e0000000-fed003ff : reserved
fec00000-fec00fff : IOAPIC 0
fed00000-fed003ff : HPET 0
where only the pre-allocated special regions (IOAPIC and HPET) were kept
around.
With 2.6.28-rc2, which uses 'reserve_region_with_split()', Jonathan's
resource tree looked like this:
e0000000-fe7fffff : reserved
fe800000-fe8fffff : PCI Bus 0000:01
fe800000-fe8fffff : reserved
fe900000-fe9d9aff : reserved
fe9d9b00-fe9d9bff : 0000:00:1f.3
fe9d9b00-fe9d9bff : reserved
fe9d9c00-fe9d9fff : 0000:00:1a.7
fe9d9c00-fe9d9fff : reserved
fe9da000-fe9dafff : 0000:00:03.3
fe9da000-fe9dafff : reserved
fe9db000-fe9dbfff : 0000:00:19.0
fe9db000-fe9dbfff : reserved
fe9dc000-fe9dffff : 0000:00:1b.0
fe9dc000-fe9dffff : reserved
fe9e0000-fe9fffff : 0000:00:19.0
fe9e0000-fe9fffff : reserved
fea00000-fea7ffff : 0000:00:02.0
fea00000-fea7ffff : reserved
fea80000-feafffff : 0000:00:02.1
fea80000-feafffff : reserved
feb00000-febfffff : 0000:00:02.0
feb00000-febfffff : reserved
fec00000-fed003ff : reserved
fec00000-fec00fff : IOAPIC 0
fed00000-fed003ff : HPET 0
and because the reserved entry had been split and moved into the
individual resources, and because it used the IORESOURCE_BUSY flag, the
drivers that actually wanted to _use_ those resources couldn't actually
attach to them:
e1000e 0000:00:19.0: BAR 0: can't reserve mem region [0xfe9e0000-0xfe9fffff]
HDA Intel 0000:00:1b.0: BAR 0: can't reserve mem region [0xfe9dc000-0xfe9dffff]
with this patch, the resource tree instead becomes
e0000000-fed003ff : reserved
fe800000-fe8fffff : PCI Bus 0000:01
fe9d9b00-fe9d9bff : 0000:00:1f.3
fe9d9c00-fe9d9fff : 0000:00:1a.7
fe9d9c00-fe9d9fff : ehci_hcd
fe9da000-fe9dafff : 0000:00:03.3
fe9db000-fe9dbfff : 0000:00:19.0
fe9db000-fe9dbfff : e1000e
fe9dc000-fe9dffff : 0000:00:1b.0
fe9dc000-fe9dffff : ICH HD audio
fe9e0000-fe9fffff : 0000:00:19.0
fe9e0000-fe9fffff : e1000e
fea00000-fea7ffff : 0000:00:02.0
fea80000-feafffff : 0000:00:02.1
feb00000-febfffff : 0000:00:02.0
fec00000-fec00fff : IOAPIC 0
fed00000-fed003ff : HPET 0
ie the one reserved region now ends up surrounding all the PCI resources
that were allocated inside of it by firmware, and because it is not
marked BUSY, drivers have no problem attaching to the pre-allocated
resources.
Reported-and-tested-by: Jonathan Corbet <corbet@lwn.net>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: cleanup
This patch cleans up the NMI safe code for dynamic ftrace as suggested
by Andrew Morton.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: introduce new APIs, separate kmap code from CONFIG_HIGHMEM
This takes the code used for CONFIG_HIGHMEM memory mappings except that
it's designed for dynamic IO resource mapping.
These fixmaps are available even with CONFIG_HIGHMEM turned off.
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix on certain UP configs
fix:
arch/x86/kernel/cpu/common.c: In function 'cpu_init':
arch/x86/kernel/cpu/common.c:1141: error: 'boot_cpu_id' undeclared (first use in this function)
arch/x86/kernel/cpu/common.c:1141: error: (Each undeclared identifier is reported only once
arch/x86/kernel/cpu/common.c:1141: error: for each function it appears in.)
Pull in asm/smp.h on UP, so that we get the definition of
boot_cpu_id.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
lguest: fix irq vectors.
lguest: fix early_ioremap.
lguest: fix example launcher compile after moved asm-x86 dir.
do_IRQ: cannot handle IRQ -1 vector 0x20 cpu 0
------------[ cut here ]------------
kernel BUG at arch/x86/kernel/irq_32.c:219!
We're not ISA: we have a 1:1 mapping from vectors to irqs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
dmi_scan_machine breaks under lguest:
lguest: unhandled trap 14 at 0xc04edeae (0xffa00000)
This is because we use current_cr3 for the read_cr3() paravirt
function, and it isn't set until the first cr3 change. We got away
with it until this happened.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
fix:
arch/x86/kernel/cpu/common.c: In function 'early_identify_cpu':
arch/x86/kernel/cpu/common.c:553: error: 'struct cpuinfo_x86' has no member named 'cpu_index'
as cpu_index is only available on SMP.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix /proc/cpuinfo output on x86/Voyager
Ever since
| commit 92cb7612ae
| Author: Mike Travis <travis@sgi.com>
| Date: Fri Oct 19 20:35:04 2007 +0200
|
| x86: convert cpuinfo_x86 array to a per_cpu array
We've had an extra field in cpuinfo_x86 which is cpu_index.
Unfortunately, voyager has never initialised this, although the only
noticeable impact seems to be that /proc/cpuinfo shows all zeros for
the processor ids.
Anyway, fix this by initialising the boot CPU properly and setting the
index when the secondaries update.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix on x86/Voyager
Given commits like this:
| Author: Suresh Siddha <suresh.b.siddha@intel.com>
| Date: Tue Jul 29 10:29:19 2008 -0700
|
| x86, xsave: enable xsave/xrstor on cpus with xsave support
Which deliberately expose boot cpu dependence to pieces of the system,
I think it's time to explicitly have a variable for it to prevent this
continual misassumption that the boot CPU is zero.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: allow /dev/mem mmaps on non-PAT CPUs/platforms
Fix mmap to /dev/mem when CONFIG_X86_PAT is off and CONFIG_STRICT_DEVMEM is
off
mmap to /dev/mem on kernel memory has been failing since the
introduction of PAT (CONFIG_STRICT_DEVMEM=n case). Seems like
the check to avoid cache aliasing with PAT is kicking in even
when PAT is disabled. The bug seems to have crept in 2.6.26.
This patch makes sure that the mmap to regular
kernel memory succeeds if CONFIG_STRICT_DEVMEM=n and
PAT is disabled, and the checks to avoid cache aliasing
still happens if PAT is enabled.
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Tested-by: Tim Sirianni <tim@scalemp.com>
Cc: <stable@kernel.org>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix build failure on x86/Voyager
Before:
| commit 329513a35d
| Author: Yinghai Lu <yhlu.kernel@gmail.com>
| Date: Wed Jul 2 18:54:40 2008 -0700
|
| x86: move prefill_possible_map calling early
prefill_possible_mask() was hidden under CONFIG_HOTPLUG_CPU rendering
it invisitble to voyager. Since this commit it's exposed, but not
provided by the voyager subarch, so add a dummy stub to fix the link
breakage.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix x86/Voyager boot
CONFIG_SMP is used for features which work on *all* x86 boxes.
CONFIG_X86_SMP is used for standard PC like x86 boxes (for things like
multi core and apics)
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: boot up secondary CPUs as well on x86/Voyager systems
This commit:
| commit 3e9704739d
| Author: Glauber Costa <gcosta@redhat.com>
| Date: Wed May 28 13:01:54 2008 -0300
|
| x86: boot secondary cpus through initial_code
removed the use of initialize_secondary. However, it didn't update
voyager, so the secondary cpus no longer boot. Fix this by adding the
initial_code switch to voyager as well.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add more debug info to /debugfs/tracing/dyn_ftrace_total_info
This patch adds dynamic ftrace NMI update statistics to the
/debugfs/tracing/dyn_ftrace_total_info stat file.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix crashes that can occur in NMI handlers, if their code is modified
Modifying code is something that needs special care. On SMP boxes,
if code that is being modified is also being executed on another CPU,
that CPU will have undefined results.
The dynamic ftrace uses kstop_machine to make the system act like a
uniprocessor system. But this does not address NMIs, that can still
run on other CPUs.
One approach to handle this is to make all code that are used by NMIs
not be traced. But NMIs can call notifiers that spread throughout the
kernel and this will be very hard to maintain, and the chance of missing
a function is very high.
The approach that this patch takes is to have the NMIs modify the code
if the modification is taking place. The way this works is that just
writing to code executing on another CPU is not harmful if what is
written is the same as what exists.
Two buffers are used: an IP buffer and a "code" buffer.
The steps that the patcher takes are:
1) Put in the instruction pointer into the IP buffer
and the new code into the "code" buffer.
2) Set a flag that says we are modifying code
3) Wait for any running NMIs to finish.
4) Write the code
5) clear the flag.
6) Wait for any running NMIs to finish.
If an NMI is executed, it will also write the pending code.
Multiple writes are OK, because what is being written is the same.
Then the patcher must wait for all running NMIs to finish before
going to the next line that must be patched.
This is basically the RCU approach to code modification.
Thanks to Ingo Molnar for suggesting the idea, and to Arjan van de Ven
for his guidence on what is safe and what is not.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Ingo Molnar