In some cases it may happen that pmd_none_or_clear_bad() is called with
the mmap_sem hold in read mode. In those cases the huge page faults can
allocate hugepmds under pmd_none_or_clear_bad() and that can trigger a
false positive from pmd_bad() that will not like to see a pmd
materializing as trans huge.
It's not khugepaged causing the problem, khugepaged holds the mmap_sem
in write mode (and all those sites must hold the mmap_sem in read mode
to prevent pagetables to go away from under them, during code review it
seems vm86 mode on 32bit kernels requires that too unless it's
restricted to 1 thread per process or UP builds). The race is only with
the huge pagefaults that can convert a pmd_none() into a
pmd_trans_huge().
Effectively all these pmd_none_or_clear_bad() sites running with
mmap_sem in read mode are somewhat speculative with the page faults, and
the result is always undefined when they run simultaneously. This is
probably why it wasn't common to run into this. For example if the
madvise(MADV_DONTNEED) runs zap_page_range() shortly before the page
fault, the hugepage will not be zapped, if the page fault runs first it
will be zapped.
Altering pmd_bad() not to error out if it finds hugepmds won't be enough
to fix this, because zap_pmd_range would then proceed to call
zap_pte_range (which would be incorrect if the pmd become a
pmd_trans_huge()).
The simplest way to fix this is to read the pmd in the local stack
(regardless of what we read, no need of actual CPU barriers, only
compiler barrier needed), and be sure it is not changing under the code
that computes its value. Even if the real pmd is changing under the
value we hold on the stack, we don't care. If we actually end up in
zap_pte_range it means the pmd was not none already and it was not huge,
and it can't become huge from under us (khugepaged locking explained
above).
All we need is to enforce that there is no way anymore that in a code
path like below, pmd_trans_huge can be false, but pmd_none_or_clear_bad
can run into a hugepmd. The overhead of a barrier() is just a compiler
tweak and should not be measurable (I only added it for THP builds). I
don't exclude different compiler versions may have prevented the race
too by caching the value of *pmd on the stack (that hasn't been
verified, but it wouldn't be impossible considering
pmd_none_or_clear_bad, pmd_bad, pmd_trans_huge, pmd_none are all inlines
and there's no external function called in between pmd_trans_huge and
pmd_none_or_clear_bad).
if (pmd_trans_huge(*pmd)) {
if (next-addr != HPAGE_PMD_SIZE) {
VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
split_huge_page_pmd(vma->vm_mm, pmd);
} else if (zap_huge_pmd(tlb, vma, pmd, addr))
continue;
/* fall through */
}
if (pmd_none_or_clear_bad(pmd))
Because this race condition could be exercised without special
privileges this was reported in CVE-2012-1179.
The race was identified and fully explained by Ulrich who debugged it.
I'm quoting his accurate explanation below, for reference.
====== start quote =======
mapcount 0 page_mapcount 1
kernel BUG at mm/huge_memory.c:1384!
At some point prior to the panic, a "bad pmd ..." message similar to the
following is logged on the console:
mm/memory.c:145: bad pmd ffff8800376e1f98(80000000314000e7).
The "bad pmd ..." message is logged by pmd_clear_bad() before it clears
the page's PMD table entry.
143 void pmd_clear_bad(pmd_t *pmd)
144 {
-> 145 pmd_ERROR(*pmd);
146 pmd_clear(pmd);
147 }
After the PMD table entry has been cleared, there is an inconsistency
between the actual number of PMD table entries that are mapping the page
and the page's map count (_mapcount field in struct page). When the page
is subsequently reclaimed, __split_huge_page() detects this inconsistency.
1381 if (mapcount != page_mapcount(page))
1382 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1383 mapcount, page_mapcount(page));
-> 1384 BUG_ON(mapcount != page_mapcount(page));
The root cause of the problem is a race of two threads in a multithreaded
process. Thread B incurs a page fault on a virtual address that has never
been accessed (PMD entry is zero) while Thread A is executing an madvise()
system call on a virtual address within the same 2 MB (huge page) range.
virtual address space
.---------------------.
| |
| |
.-|---------------------|
| | |
| | |<-- B(fault)
| | |
2 MB | |/////////////////////|-.
huge < |/////////////////////| > A(range)
page | |/////////////////////|-'
| | |
| | |
'-|---------------------|
| |
| |
'---------------------'
- Thread A is executing an madvise(..., MADV_DONTNEED) system call
on the virtual address range "A(range)" shown in the picture.
sys_madvise
// Acquire the semaphore in shared mode.
down_read(¤t->mm->mmap_sem)
...
madvise_vma
switch (behavior)
case MADV_DONTNEED:
madvise_dontneed
zap_page_range
unmap_vmas
unmap_page_range
zap_pud_range
zap_pmd_range
//
// Assume that this huge page has never been accessed.
// I.e. content of the PMD entry is zero (not mapped).
//
if (pmd_trans_huge(*pmd)) {
// We don't get here due to the above assumption.
}
//
// Assume that Thread B incurred a page fault and
.---------> // sneaks in here as shown below.
| //
| if (pmd_none_or_clear_bad(pmd))
| {
| if (unlikely(pmd_bad(*pmd)))
| pmd_clear_bad
| {
| pmd_ERROR
| // Log "bad pmd ..." message here.
| pmd_clear
| // Clear the page's PMD entry.
| // Thread B incremented the map count
| // in page_add_new_anon_rmap(), but
| // now the page is no longer mapped
| // by a PMD entry (-> inconsistency).
| }
| }
|
v
- Thread B is handling a page fault on virtual address "B(fault)" shown
in the picture.
...
do_page_fault
__do_page_fault
// Acquire the semaphore in shared mode.
down_read_trylock(&mm->mmap_sem)
...
handle_mm_fault
if (pmd_none(*pmd) && transparent_hugepage_enabled(vma))
// We get here due to the above assumption (PMD entry is zero).
do_huge_pmd_anonymous_page
alloc_hugepage_vma
// Allocate a new transparent huge page here.
...
__do_huge_pmd_anonymous_page
...
spin_lock(&mm->page_table_lock)
...
page_add_new_anon_rmap
// Here we increment the page's map count (starts at -1).
atomic_set(&page->_mapcount, 0)
set_pmd_at
// Here we set the page's PMD entry which will be cleared
// when Thread A calls pmd_clear_bad().
...
spin_unlock(&mm->page_table_lock)
The mmap_sem does not prevent the race because both threads are acquiring
it in shared mode (down_read). Thread B holds the page_table_lock while
the page's map count and PMD table entry are updated. However, Thread A
does not synchronize on that lock.
====== end quote =======
[akpm@linux-foundation.org: checkpatch fixes]
Reported-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Jones <davej@redhat.com>
Acked-by: Larry Woodman <lwoodman@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org> [2.6.38+]
Cc: Mark Salter <msalter@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This branch takes the PowerPC irq_host infrastructure (reverse mapping
from Linux IRQ numbers to hardware irq numbering), generalizes it,
renames it to irq_domain, and makes it available to all architectures.
Originally the plan has been to create an all-new irq_domain
implementation which addresses some of the powerpc shortcomings such
as not handling 1:1 mappings well, but doing that proved to be far
more difficult and invasive than generalizing the working code and
refactoring it in-place. So, this branch rips out the 'new'
irq_domain and replaces it with the modified powerpc version (in a
fully bisectable way of course). It converts all users over to the
new API and makes irq_domain selectable on any architecture.
No architecture is forced to enable irq_domain, but the infrastructure
is required for doing OpenFirmware style irq translations. It will
even work on SPARC even though SPARC has it's own mechanism for
translating irqs at boot time. MIPS, microblaze, embedded x86 and c6x
are converted too.
The resulting irq_domain code is probably still too verbose and can be
optimized more, but that can be done incrementally and is a task for
follow-on patches.
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Merge tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6
Pull irq_domain support for all architectures from Grant Likely:
"Generialize powerpc's irq_host as irq_domain
This branch takes the PowerPC irq_host infrastructure (reverse mapping
from Linux IRQ numbers to hardware irq numbering), generalizes it,
renames it to irq_domain, and makes it available to all architectures.
Originally the plan has been to create an all-new irq_domain
implementation which addresses some of the powerpc shortcomings such
as not handling 1:1 mappings well, but doing that proved to be far
more difficult and invasive than generalizing the working code and
refactoring it in-place. So, this branch rips out the 'new'
irq_domain and replaces it with the modified powerpc version (in a
fully bisectable way of course). It converts all users over to the
new API and makes irq_domain selectable on any architecture.
No architecture is forced to enable irq_domain, but the infrastructure
is required for doing OpenFirmware style irq translations. It will
even work on SPARC even though SPARC has it's own mechanism for
translating irqs at boot time. MIPS, microblaze, embedded x86 and c6x
are converted too.
The resulting irq_domain code is probably still too verbose and can be
optimized more, but that can be done incrementally and is a task for
follow-on patches."
* tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6: (31 commits)
dt: fix twl4030 for non-dt compile on x86
mfd: twl-core: Add IRQ_DOMAIN dependency
devicetree: Add empty of_platform_populate() for !CONFIG_OF_ADDRESS (sparc)
irq_domain: Centralize definition of irq_dispose_mapping()
irq_domain/mips: Allow irq_domain on MIPS
irq_domain/x86: Convert x86 (embedded) to use common irq_domain
ppc-6xx: fix build failure in flipper-pic.c and hlwd-pic.c
irq_domain/microblaze: Convert microblaze to use irq_domains
irq_domain/powerpc: Replace custom xlate functions with library functions
irq_domain/powerpc: constify irq_domain_ops
irq_domain/c6x: Use library of xlate functions
irq_domain/c6x: constify irq_domain structures
irq_domain/c6x: Convert c6x to use generic irq_domain support.
irq_domain: constify irq_domain_ops
irq_domain: Create common xlate functions that device drivers can use
irq_domain: Remove irq_domain_add_simple()
irq_domain: Remove 'new' irq_domain in favour of the ppc one
mfd: twl-core.c: Fix the number of interrupts managed by twl4030
of/address: add empty static inlines for !CONFIG_OF
irq_domain: Add support for base irq and hwirq in legacy mappings
...
Assorted extensions and fixes including:
* Introduction of early/late suspend/hibernation device callbacks.
* Generic PM domains extensions and fixes.
* devfreq updates from Axel Lin and MyungJoo Ham.
* Device PM QoS updates.
* Fixes of concurrency problems with wakeup sources.
* System suspend and hibernation fixes.
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Merge tag 'pm-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates for 3.4 from Rafael Wysocki:
"Assorted extensions and fixes including:
* Introduction of early/late suspend/hibernation device callbacks.
* Generic PM domains extensions and fixes.
* devfreq updates from Axel Lin and MyungJoo Ham.
* Device PM QoS updates.
* Fixes of concurrency problems with wakeup sources.
* System suspend and hibernation fixes."
* tag 'pm-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (43 commits)
PM / Domains: Check domain status during hibernation restore of devices
PM / devfreq: add relation of recommended frequency.
PM / shmobile: Make MTU2 driver use pm_genpd_dev_always_on()
PM / shmobile: Make CMT driver use pm_genpd_dev_always_on()
PM / shmobile: Make TMU driver use pm_genpd_dev_always_on()
PM / Domains: Introduce "always on" device flag
PM / Domains: Fix hibernation restore of devices, v2
PM / Domains: Fix handling of wakeup devices during system resume
sh_mmcif / PM: Use PM QoS latency constraint
tmio_mmc / PM: Use PM QoS latency constraint
PM / QoS: Make it possible to expose PM QoS latency constraints
PM / Sleep: JBD and JBD2 missing set_freezable()
PM / Domains: Fix include for PM_GENERIC_DOMAINS=n case
PM / Freezer: Remove references to TIF_FREEZE in comments
PM / Sleep: Add more wakeup source initialization routines
PM / Hibernate: Enable usermodehelpers in hibernate() error path
PM / Sleep: Make __pm_stay_awake() delete wakeup source timers
PM / Sleep: Fix race conditions related to wakeup source timer function
PM / Sleep: Fix possible infinite loop during wakeup source destruction
PM / Hibernate: print physical addresses consistently with other parts of kernel
...
Pull kmap_atomic cleanup from Cong Wang.
It's been in -next for a long time, and it gets rid of the (no longer
used) second argument to k[un]map_atomic().
Fix up a few trivial conflicts in various drivers, and do an "evil
merge" to catch some new uses that have come in since Cong's tree.
* 'kmap_atomic' of git://github.com/congwang/linux: (59 commits)
feature-removal-schedule.txt: schedule the deprecated form of kmap_atomic() for removal
highmem: kill all __kmap_atomic() [swarren@nvidia.com: highmem: Fix ARM build break due to __kmap_atomic rename]
drbd: remove the second argument of k[un]map_atomic()
zcache: remove the second argument of k[un]map_atomic()
gma500: remove the second argument of k[un]map_atomic()
dm: remove the second argument of k[un]map_atomic()
tomoyo: remove the second argument of k[un]map_atomic()
sunrpc: remove the second argument of k[un]map_atomic()
rds: remove the second argument of k[un]map_atomic()
net: remove the second argument of k[un]map_atomic()
mm: remove the second argument of k[un]map_atomic()
lib: remove the second argument of k[un]map_atomic()
power: remove the second argument of k[un]map_atomic()
kdb: remove the second argument of k[un]map_atomic()
udf: remove the second argument of k[un]map_atomic()
ubifs: remove the second argument of k[un]map_atomic()
squashfs: remove the second argument of k[un]map_atomic()
reiserfs: remove the second argument of k[un]map_atomic()
ocfs2: remove the second argument of k[un]map_atomic()
ntfs: remove the second argument of k[un]map_atomic()
...
Here's the big driver core merge for 3.4-rc1.
Lots of various things here, sysfs fixes/tweaks (with the nlink breakage
reverted), dynamic debugging updates, w1 drivers, hyperv driver updates,
and a variety of other bits and pieces, full information in the
shortlog.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core patches for 3.4-rc1 from Greg KH:
"Here's the big driver core merge for 3.4-rc1.
Lots of various things here, sysfs fixes/tweaks (with the nlink
breakage reverted), dynamic debugging updates, w1 drivers, hyperv
driver updates, and a variety of other bits and pieces, full
information in the shortlog."
* tag 'driver-core-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (78 commits)
Tools: hv: Support enumeration from all the pools
Tools: hv: Fully support the new KVP verbs in the user level daemon
Drivers: hv: Support the newly introduced KVP messages in the driver
Drivers: hv: Add new message types to enhance KVP
regulator: Support driver probe deferral
Revert "sysfs: Kill nlink counting."
uevent: send events in correct order according to seqnum (v3)
driver core: minor comment formatting cleanups
driver core: move the deferred probe pointer into the private area
drivercore: Add driver probe deferral mechanism
DS2781 Maxim Stand-Alone Fuel Gauge battery and w1 slave drivers
w1_bq27000: Only one thread can access the bq27000 at a time.
w1_bq27000 - remove w1_bq27000_write
w1_bq27000: remove unnecessary NULL test.
sysfs: Fix memory leak in sysfs_sd_setsecdata().
intel_idle: Revert change of auto_demotion_disable_flags for Nehalem
w1: Fix w1_bq27000
driver-core: documentation: fix up Greg's email address
powernow-k6: Really enable auto-loading
powernow-k7: Fix CPU family number
...
Pull timer changes for v3.4 from Ingo Molnar
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
ntp: Fix integer overflow when setting time
math: Introduce div64_long
cs5535-clockevt: Allow the MFGPT IRQ to be shared
cs5535-clockevt: Don't ignore MFGPT on SMP-capable kernels
x86/time: Eliminate unused irq0_irqs counter
clocksource: scx200_hrt: Fix the build
x86/tsc: Reduce the TSC sync check time for core-siblings
timer: Fix bad idle check on irq entry
nohz: Remove ts->Einidle checks before restarting the tick
nohz: Remove update_ts_time_stat from tick_nohz_start_idle
clockevents: Leave the broadcast device in shutdown mode when not needed
clocksource: Load the ACPI PM clocksource asynchronously
clocksource: scx200_hrt: Convert scx200 to use clocksource_register_hz
clocksource: Get rid of clocksource_calc_mult_shift()
clocksource: dbx500: convert to clocksource_register_hz()
clocksource: scx200_hrt: use pr_<level> instead of printk
time: Move common updates to a function
time: Reorder so the hot data is together
time: Remove most of xtime_lock usage in timekeeping.c
ntp: Add ntp_lock to replace xtime_locking
...
Pull scheduler changes for v3.4 from Ingo Molnar
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
printk: Make it compile with !CONFIG_PRINTK
sched/x86: Fix overflow in cyc2ns_offset
sched: Fix nohz load accounting -- again!
sched: Update yield() docs
printk/sched: Introduce special printk_sched() for those awkward moments
sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer
sched: Cleanup cpu_active madness
sched: Fix load-balance wreckage
sched: Clean up parameter passing of proc_sched_autogroup_set_nice()
sched: Ditch per cgroup task lists for load-balancing
sched: Rename load-balancing fields
sched: Move load-balancing arguments into helper struct
sched/rt: Do not submit new work when PI-blocked
sched/rt: Prevent idle task boosting
sched/wait: Add __wake_up_all_locked() API
sched/rt: Document scheduler related skip-resched-check sites
sched/rt: Use schedule_preempt_disabled()
sched/rt: Add schedule_preempt_disabled()
sched/rt: Do not throttle when PI boosting
sched/rt: Keep period timer ticking when rt throttling is active
...
Pull perf events changes for v3.4 from Ingo Molnar:
- New "hardware based branch profiling" feature both on the kernel and
the tooling side, on CPUs that support it. (modern x86 Intel CPUs
with the 'LBR' hardware feature currently.)
This new feature is basically a sophisticated 'magnifying glass' for
branch execution - something that is pretty difficult to extract from
regular, function histogram centric profiles.
The simplest mode is activated via 'perf record -b', and the result
looks like this in perf report:
$ perf record -b any_call,u -e cycles:u branchy
$ perf report -b --sort=symbol
52.34% [.] main [.] f1
24.04% [.] f1 [.] f3
23.60% [.] f1 [.] f2
0.01% [k] _IO_new_file_xsputn [k] _IO_file_overflow
0.01% [k] _IO_vfprintf_internal [k] _IO_new_file_xsputn
0.01% [k] _IO_vfprintf_internal [k] strchrnul
0.01% [k] __printf [k] _IO_vfprintf_internal
0.01% [k] main [k] __printf
This output shows from/to branch columns and shows the highest
percentage (from,to) jump combinations - i.e. the most likely taken
branches in the system. "branches" can also include function calls
and any other synchronous and asynchronous transitions of the
instruction pointer that are not 'next instruction' - such as system
calls, traps, interrupts, etc.
This feature comes with (hopefully intuitive) flat ascii and TUI
support in perf report.
- Various 'perf annotate' visual improvements for us assembly junkies.
It will now recognize function calls in the TUI and by hitting enter
you can follow the call (recursively) and back, amongst other
improvements.
- Multiple threads/processes recording support in perf record, perf
stat, perf top - which is activated via a comma-list of PIDs:
perf top -p 21483,21485
perf stat -p 21483,21485 -ddd
perf record -p 21483,21485
- Support for per UID views, via the --uid paramter to perf top, perf
report, etc. For example 'perf top --uid mingo' will only show the
tasks that I am running, excluding other users, root, etc.
- Jump label restructurings and improvements - this includes the
factoring out of the (hopefully much clearer) include/linux/static_key.h
generic facility:
struct static_key key = STATIC_KEY_INIT_FALSE;
...
if (static_key_false(&key))
do unlikely code
else
do likely code
...
static_key_slow_inc();
...
static_key_slow_inc();
...
The static_key_false() branch will be generated into the code with as
little impact to the likely code path as possible. the
static_key_slow_*() APIs flip the branch via live kernel code patching.
This facility can now be used more widely within the kernel to
micro-optimize hot branches whose likelihood matches the static-key
usage and fast/slow cost patterns.
- SW function tracer improvements: perf support and filtering support.
- Various hardenings of the perf.data ABI, to make older perf.data's
smoother on newer tool versions, to make new features integrate more
smoothly, to support cross-endian recording/analyzing workflows
better, etc.
- Restructuring of the kprobes code, the splitting out of 'optprobes',
and a corner case bugfix.
- Allow the tracing of kernel console output (printk).
- Improvements/fixes to user-space RDPMC support, allowing user-space
self-profiling code to extract PMU counts without performing any
system calls, while playing nice with the kernel side.
- 'perf bench' improvements
- ... and lots of internal restructurings, cleanups and fixes that made
these features possible. And, as usual this list is incomplete as
there were also lots of other improvements
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (120 commits)
perf report: Fix annotate double quit issue in branch view mode
perf report: Remove duplicate annotate choice in branch view mode
perf/x86: Prettify pmu config literals
perf report: Enable TUI in branch view mode
perf report: Auto-detect branch stack sampling mode
perf record: Add HEADER_BRANCH_STACK tag
perf record: Provide default branch stack sampling mode option
perf tools: Make perf able to read files from older ABIs
perf tools: Fix ABI compatibility bug in print_event_desc()
perf tools: Enable reading of perf.data files from different ABI rev
perf: Add ABI reference sizes
perf report: Add support for taken branch sampling
perf record: Add support for sampling taken branch
perf tools: Add code to support PERF_SAMPLE_BRANCH_STACK
x86/kprobes: Split out optprobe related code to kprobes-opt.c
x86/kprobes: Fix a bug which can modify kernel code permanently
x86/kprobes: Fix instruction recovery on optimized path
perf: Add callback to flush branch_stack on context switch
perf: Disable PERF_SAMPLE_BRANCH_* when not supported
perf/x86: Add LBR software filter support for Intel CPUs
...
Pull irq/core changes for v3.4 from Ingo Molnar
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Remove paranoid warnons and bogus fixups
genirq: Flush the irq thread on synchronization
genirq: Get rid of unnecessary IRQTF_DIED flag
genirq: No need to check IRQTF_DIED before stopping a thread handler
genirq: Get rid of unnecessary irqaction field in task_struct
genirq: Fix incorrect check for forced IRQ thread handler
softirq: Reduce invoke_softirq() code duplication
genirq: Fix long-term regression in genirq irq_set_irq_type() handling
x86-32/irq: Don't switch to irq stack for a user-mode irq
Upon resume from hibernation, CPU 0's hvclock area contains the old
values for system_time and tsc_timestamp. It is necessary for the
hypervisor to update these values with uptodate ones before the CPU uses
them.
Abstract TSC's save/restore sched_clock_state functions and use
restore_state to write to KVM_SYSTEM_TIME MSR, forcing an update.
Also move restore_sched_clock_state before __restore_processor_state,
since the later calls CONFIG_LOCK_STAT's lockstat_clock (also for TSC).
Thanks to Igor Mammedov for tracking it down.
Fixes suspend-to-disk with kvmclock.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Fix the following section warnings :
WARNING: vmlinux.o(.text+0x49dbc): Section mismatch in reference
from the function acpi_map_cpu2node() to the variable
.cpuinit.data:__apicid_to_node The function acpi_map_cpu2node()
references the variable __cpuinitdata __apicid_to_node. This is
often because acpi_map_cpu2node lacks a __cpuinitdata
annotation or the annotation of __apicid_to_node is wrong.
WARNING: vmlinux.o(.text+0x49dc1): Section mismatch in reference
from the function acpi_map_cpu2node() to the function
.cpuinit.text:numa_set_node() The function acpi_map_cpu2node()
references the function __cpuinit numa_set_node(). This is often
because acpi_map_cpu2node lacks a __cpuinit annotation or the
annotation of numa_set_node is wrong.
WARNING: vmlinux.o(.text+0x526e77): Section mismatch in
reference from the function prealloc_protection_domains() to the
function .init.text:alloc_passthrough_domain() The function
prealloc_protection_domains() references the function __init
alloc_passthrough_domain(). This is often because
prealloc_protection_domains lacks a __init annotation or the annotation of alloc_passthrough_domain is wrong.
Signed-off-by: Steffen Persvold <sp@numascale.com>
Link: http://lkml.kernel.org/r/1331810188-24785-1-git-send-email-sp@numascale.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Adding sysfs group 'format' attribute for pmu device that
contains a syntax description on how to construct raw events.
The event configuration is described in following
struct pefr_event_attr attributes:
config
config1
config2
Each sysfs attribute within the format attribute group,
describes mapping of name and bitfield definition within
one of above attributes.
eg:
"/sys/...<dev>/format/event" contains "config:0-7"
"/sys/...<dev>/format/umask" contains "config:8-15"
"/sys/...<dev>/format/usr" contains "config:16"
the attribute value syntax is:
line: config ':' bits
config: 'config' | 'config1' | 'config2"
bits: bits ',' bit_term | bit_term
bit_term: VALUE '-' VALUE | VALUE
Adding format attribute definitions for x86 cpu pmus.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-vhdk5y2hyype9j63prymty36@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
While running the latest Linux as guest under VMware in highly
over-committed situations, we have seen cases when the refined TSC
algorithm fails to get a valid tsc_start value in
tsc_refine_calibration_work from multiple attempts. As a result the
kernel keeps on scheduling the tsc_irqwork task for later. Subsequently
after several attempts when it gets a valid start value it goes through
the refined calibration and either bails out or uses the new results.
Given that the kernel originally read the TSC frequency from the
platform, which is the best it can get, I don't think there is much
value in refining it.
So for systems which get the TSC frequency from the platform we
should skip the refined tsc algorithm.
We can use the TSC_RELIABLE cpu cap flag to detect this, right now it is
set only on VMware and for Moorestown Penwell both of which have there
own TSC calibration methods.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Dirk Brandewie <dirk.brandewie@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable@kernel.org
[jstultz: Reworked to simply not schedule the refining work,
rather then scheduling the work and bombing out later]
Signed-off-by: John Stultz <john.stultz@linaro.org>
The update of the vdso data happens under xtime_lock, so adding a
nested lock is pointless. Just use a seqcount to sync the readers.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Changing the sequence count in update_vsyscall_tz() is completely
pointless.
The vdso code copies the data unprotected. There is no point to change
this as sys_tz is nowhere protected at all. See sys_gettimeofday().
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Move APIC ID validity check into platform APIC code, so it can
be overridden when needed. For NumaChip systems, always trust
MADT, as it's constructed with high APIC IDs.
Behaviour verifies on standard x86 systems and on NumaChip
systems with this, and compile-tested with allyesconfig.
Signed-off-by: Daniel J Blueman <daniel@numascale-asia.com>
Reviewed-by: Steffen Persvold <sp@numascale.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1331709454-27966-1-git-send-email-daniel@numascale-asia.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Merge tag 'v3.3-rc7' into x86/mce
Merge reason: Update from an ancient -rc1 base to an almost-final stable kernel.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Uprobes uses exception notifiers to get to know if a thread hit
a breakpoint or a singlestep exception.
When a thread hits a uprobe or is singlestepping post a uprobe
hit, the uprobe exception notifier sets its TIF_UPROBE bit,
which will then be checked on its return to userspace path
(do_notify_resume() ->uprobe_notify_resume()), where the
consumers handlers are run (in task context) based on the
defined filters.
Uprobe hits are thread specific and hence we need to maintain
information about if a task hit a uprobe, what uprobe was hit,
the slot where the original instruction was copied for xol so
that it can be singlestepped with appropriate fixups.
In some cases, special care is needed for instructions that are
executed out of line (xol). These are architecture specific
artefacts, such as handling RIP relative instructions on x86_64.
Since the instruction at which the uprobe was inserted is
executed out of line, architecture specific fixups are added so
that the thread continues normal execution in the presence of a
uprobe.
Postpone the signals until we execute the probed insn.
post_xol() path does a recalc_sigpending() before return to
user-mode, this ensures the signal can't be lost.
Uprobes relies on DIE_DEBUG notification to notify if a
singlestep is complete.
Adds x86 specific uprobe exception notifiers and appropriate
hooks needed to determine a uprobe hit and subsequent post
processing.
Add requisite x86 fixups for xol for uprobes. Specific cases
needing fixups include relative jumps (x86_64), calls, etc.
Where possible, we check and skip singlestepping the
breakpointed instructions. For now we skip single byte as well
as few multibyte nop instructions. However this can be extended
to other instructions too.
Credits to Oleg Nesterov for suggestions/patches related to
signal, breakpoint, singlestep handling code.
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/20120313180011.29771.89027.sendpatchset@srdronam.in.ibm.com
[ Performed various cleanliness edits ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
.. as appropiately. As tboot_sleep now returns values.
remove tboot_sleep_wrapper.
Suggested-and-Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Joseph Cihula <joseph.cihula@intel.com>
[v1: Return -1/0/+1 instead of ACPI_xx values]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The ACPI suspend path makes a call to tboot_sleep right before
it writes the PM1A, PM1B values. We replace the direct call to
tboot via an registration callback similar to __acpi_register_gsi.
CC: Len Brown <len.brown@intel.com>
Acked-by: Joseph Cihula <joseph.cihula@intel.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
[v1: Added __attribute__ ((unused))]
[v2: Introduced a wrapper instead of changing tboot_sleep return values]
[v3: Added return value AE_CTRL_SKIP for acpi_os_sleep_prepare]
Signed-off-by: Tang Liang <liang.tang@oracle.com>
[v1: Fix compile issues on IA64 and PPC64]
[v2: Fix where __acpi_os_prepare_sleep==NULL and did not go in sleep properly]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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>
If a function takes struct uprobe or struct arch_uprobe, then it
is passed as the first parameter.
This is pure cleanup, no functional change intended.
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/20120312092530.5379.18394.sendpatchset@srdronam.in.ibm.com
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>
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>
This patch implements 64 bit counter support for IBS. The
sampling period is no longer limited to the hw counter width.
The functions perf_event_set_period() and
perf_event_try_update() can be used as generic functions. They
can replace similar code that is duplicate across architectures.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-5-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add code to control the IBS pmu. We need to maintain per-cpu
states. Since some states are used and changed by the nmi
handler, access to these states must be atomic.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-4-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch implements code to handle ibs interrupts. If ibs data
is available a raw perf_event data sample is created and sent
back to the userland. This patch only implements the storage of
ibs data in the raw sample, but this could be extended in a
later patch by generating generic event data such as the rip
from the ibs sampling data.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-3-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch implements perf configuration for AMD IBS. The IBS
pmu is selected using the type attribute in sysfs. There are two
types of ibs pmus, for instruction fetch (IBS_FETCH) and for
instruction execution (IBS_OP):
/sys/bus/event_source/devices/ibs_fetch/type
/sys/bus/event_source/devices/ibs_op/type
Except for the sample period IBS can only be set up with raw
config values and raw data samples. The event attributes for the
syscall should be programmed like this (IBS_FETCH):
type = get_pmu_type("/sys/bus/event_source/devices/ibs_fetch/type");
memset(&attr, 0, sizeof(attr));
attr.type = type;
attr.sample_type = PERF_SAMPLE_CPU | PERF_SAMPLE_RAW;
attr.config = IBS_FETCH_CONFIG_DEFAULT;
This implementation does not yet support 64 bit counters. It is
limited to the hardware counter bit width which is 20 bits. 64
bit support can be added later.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-2-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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>
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>
X32 ptrace is a hybrid of 64bit ptrace and compat ptrace with 32bit
address and longs. It use 64bit ptrace to access the full 64bit
registers. PTRACE_PEEKUSR and PTRACE_POKEUSR are only allowed to access
segment and debug registers. PTRACE_PEEKUSR returns the lower 32bits
and PTRACE_POKEUSR zero-extends 32bit value to 64bit. It works since
the upper 32bits of segment and debug registers of x32 process are always
zero. GDB only uses PTRACE_PEEKUSR and PTRACE_POKEUSR to access
segment and debug registers.
[ hpa: changed TIF_X32 test to use !is_ia32_task() instead, and moved
the system call number to the now-unused 521 slot. ]
Signed-off-by: "H.J. Lu" <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/1329696488-16970-1-git-send-email-hpa@zytor.com
With branch stack sampling, it is possible to filter by priv levels.
In system-wide mode, that means it is possible to capture only user
level branches. The builtin SW LBR filter needs to disassemble code
based on LBR captured addresses. For that, it needs to know the task
the addresses are associated with. Because of context switches, the
content of the branch stack buffer may contain addresses from
different tasks.
We need a callback on context switch to either flush the branch stack
or save it. This patch adds a new callback in struct pmu which is called
during context switches. The callback is called only when necessary.
That is when a system-wide context has, at least, one event which
uses PERF_SAMPLE_BRANCH_STACK. The callback is never called for
per-thread context.
In this version, the Intel x86 code simply flushes (resets) the LBR
on context switches (fills it with zeroes). Those zeroed branches are
then filtered out by the SW filter.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-11-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
