07 Aug, 2010
1 commit
-
…git/tip/linux-2.6-tip
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (162 commits)
tracing/kprobes: unregister_trace_probe needs to be called under mutex
perf: expose event__process function
perf events: Fix mmap offset determination
perf, powerpc: fsl_emb: Restore setting perf_sample_data.period
perf, powerpc: Convert the FSL driver to use local64_t
perf tools: Don't keep unreferenced maps when unmaps are detected
perf session: Invalidate last_match when removing threads from rb_tree
perf session: Free the ref_reloc_sym memory at the right place
x86,mmiotrace: Add support for tracing STOS instruction
perf, sched migration: Librarize task states and event headers helpers
perf, sched migration: Librarize the GUI class
perf, sched migration: Make the GUI class client agnostic
perf, sched migration: Make it vertically scrollable
perf, sched migration: Parameterize cpu height and spacing
perf, sched migration: Fix key bindings
perf, sched migration: Ignore unhandled task states
perf, sched migration: Handle ignored migrate out events
perf: New migration tool overview
tracing: Drop cpparg() macro
perf: Use tracepoint_synchronize_unregister() to flush any pending tracepoint call
...Fix up trivial conflicts in Makefile and drivers/cpufreq/cpufreq.c
25 Jun, 2010
1 commit
-
Freeing a perf event can happen in several ways. A task
calls perf_event_exit_task() right before exiting. This helper
will detach all the events from the task context and queue their
removal through free_event() if they are child tasks. The task
also loses its context reference there.Releasing the breakpoint slot from the constraint table is made
from free_event() that calls release_bp_slot(). We count the number
of breakpoints this task is running by looking at the task's
perf_event_ctxp and iterating through its attached events.
But at this time, the reference to this context has been cleaned up
already.So looking at the event->ctx instead of task->perf_event_ctxp
to count the remaining breakpoints should solve the problem.
At least it would for child breakpoints, but not for parent ones.
If the parent exits before the child, it will remove all its
events from the context but free_event() will be called later,
on fd release time. And checking the number of breakpoints the
task has attached to its context at this time is unreliable as all
events have been removed from the context.To solve this, we keep track of the list of per task breakpoints.
On top of it, we maintain our array of numbers of breakpoints used
by the tasks. We use the context address as a task id.So, instead of looking at the number of events attached to a context,
we walk through our list of per task breakpoints and count the number
of breakpoints that use the same ctx than the one to be reserved or
released from the constraint table, and update the count on top of this
result.In the meantime it solves a bad refcounting, it also solves a warning,
reported by Paul.Badness at /home/paulus/kernel/perf/kernel/hw_breakpoint.c:114
NIP: c0000000000cb470 LR: c0000000000cb46c CTR: c00000000032d9b8
REGS: c000000118e7b570 TRAP: 0700 Not tainted (2.6.35-rc3-perf-00008-g76b0f13
)
MSR: 9000000000029032 CR: 44004424 XER: 000fffff
TASK = c0000001187dcad0[3143] 'perf' THREAD: c000000118e78000 CPU: 1
GPR00: c0000000000cb46c c000000118e7b7f0 c0000000009866a0 0000000000000020
GPR04: 0000000000000000 000000000000001d 0000000000000000 0000000000000001
GPR08: c0000000009bed68 c00000000086dff8 c000000000a5bf10 0000000000000001
GPR12: 0000000024004422 c00000000ffff200 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000018 00000000101150f4
GPR20: 0000000010206b40 0000000000000000 0000000000000000 00000000101150f4
GPR24: c0000001199090c0 0000000000000001 0000000000000000 0000000000000001
GPR28: 0000000000000000 0000000000000000 c0000000008ec290 0000000000000000
NIP [c0000000000cb470] .task_bp_pinned+0x5c/0x12c
LR [c0000000000cb46c] .task_bp_pinned+0x58/0x12c
Call Trace:
[c000000118e7b7f0] [c0000000000cb46c] .task_bp_pinned+0x58/0x12c (unreliable)
[c000000118e7b8a0] [c0000000000cb584] .toggle_bp_task_slot+0x44/0xe4
[c000000118e7b940] [c0000000000cb6c8] .toggle_bp_slot+0xa4/0x164
[c000000118e7b9f0] [c0000000000cbafc] .release_bp_slot+0x44/0x6c
[c000000118e7ba80] [c0000000000c4178] .bp_perf_event_destroy+0x10/0x24
[c000000118e7bb00] [c0000000000c4aec] .free_event+0x180/0x1bc
[c000000118e7bbc0] [c0000000000c54c4] .perf_event_release_kernel+0x14c/0x170Reported-by: Paul Mackerras
Signed-off-by: Frederic Weisbecker
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Prasad
Cc: Mahesh Salgaonkar
Cc: Will Deacon
Cc: Jason Wessel
22 Jun, 2010
1 commit
-
Certain architectures (such as PowerPC) have a need to clean up data
structures before a breakpoint is unregistered. This introduces an
arch-specific hook in release_bp_slot() along with a weak definition
in the form of a stub function.Signed-off-by: K.Prasad
Acked-by: Frederic Weisbecker
Signed-off-by: Paul Mackerras
04 May, 2010
1 commit
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Fix this build error:
kernel/hw_breakpoint.c:58:1: error: pasting "__pcpu_scope_" and "*" does not give a valid preprocessing token
It happens if CONFIG_DEBUG_FORCE_WEAK_PER_CPU, because we concatenate
someting with the name and we have the "*" in the name.Cc: Frederic Weisbecker
Cc: Will Deacon
Cc: Paul Mundt
Cc: Mahesh Salgaonkar
Cc: K. Prasad
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Jason Wessel
LKML-Reference:
Signed-off-by: Ingo Molnar
01 May, 2010
5 commits
-
The breakpoint generic layer assumes that archs always know in advance
the static number of address registers available to host breakpoints
through the HBP_NUM macro.However this is not true for every archs. For example Arm needs to get
this information dynamically to handle the compatiblity between
different versions.To solve this, this patch proposes to drop the static HBP_NUM macro
and let the arch provide the number of available slots through a
new hw_breakpoint_slots() function. For archs that have
CONFIG_HAVE_MIXED_BREAKPOINTS_REGS selected, it will be called once
as the number of registers fits for instruction and data breakpoints
together.
For the others it will be called first to get the number of
instruction breakpoint registers and another time to get the
data breakpoint registers, the targeted type is given as a
parameter of hw_breakpoint_slots().Reported-by: Will Deacon
Signed-off-by: Frederic Weisbecker
Acked-by: Paul Mundt
Cc: Mahesh Salgaonkar
Cc: K. Prasad
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Jason Wessel
Cc: Ingo Molnar -
Depending on their nature and on what an arch supports, breakpoints
may consume more than one address register. For example a simple
absolute address match usually only requires one address register.
But an address range match may consume two registers.Currently our slot allocation constraints, that tend to reflect the
limited arch's resources, always consider that a breakpoint consumes
one slot.Then provide a way for archs to tell us the weight of a breakpoint
through a new hw_breakpoint_weight() helper. This weight will be
computed against the generic allocation constraints instead of
a constant value.Signed-off-by: Frederic Weisbecker
Acked-by: Paul Mundt
Cc: Will Deacon
Cc: Mahesh Salgaonkar
Cc: K. Prasad
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar -
There are two outstanding fashions for archs to implement hardware
breakpoints.The first is to separate breakpoint address pattern definition
space between data and instruction breakpoints. We then have
typically distinct instruction address breakpoint registers
and data address breakpoint registers, delivered with
separate control registers for data and instruction breakpoints
as well. This is the case of PowerPc and ARM for example.The second consists in having merged breakpoint address space
definition between data and instruction breakpoint. Address
registers can host either instruction or data address and
the access mode for the breakpoint is defined in a control
register. This is the case of x86 and Super H.This patch adds a new CONFIG_HAVE_MIXED_BREAKPOINTS_REGS config
that archs can select if they belong to the second case. Those
will have their slot allocation merged for instructions and
data breakpoints.The others will have a separate slot tracking between data and
instruction breakpoints.Signed-off-by: Frederic Weisbecker
Acked-by: Paul Mundt
Cc: Will Deacon
Cc: Mahesh Salgaonkar
Cc: K. Prasad
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Ingo Molnar -
The current policies of breakpoints in x86 and SH are the following:
- task bound breakpoints can only break on userspace addresses
- cpu wide breakpoints can only break on kernel addressesThe former rule prevents ptrace breakpoints to be set to trigger on
kernel addresses, which is good. But as a side effect, we can't
breakpoint on kernel addresses for task bound breakpoints.The latter rule simply makes no sense, there is no reason why we
can't set breakpoints on userspace while performing cpu bound
profiles.We want the following new policies:
- task bound breakpoint can set userspace address breakpoints, with
no particular privilege required.
- task bound breakpoints can set kernelspace address breakpoints but
must be privileged to do that.
- cpu bound breakpoints can do what they want as they are privileged
already.To implement these new policies, this patch checks if we are dealing
with a kernel address breakpoint, if so and if the exclude_kernel
parameter is set, we tell the user that the breakpoint is invalid,
which makes a good generic ptrace protection.
If we don't have exclude_kernel, ensure the user has the right
privileges as kernel breakpoints are quite sensitive (risk of
trap recursion attacks and global performance impacts).[ Paul Mundt: keep addr space check for sh signal delivery and fix
double function declaration]Signed-off-by: Frederic Weisbecker
Cc: Will Deacon
Cc: Mahesh Salgaonkar
Cc: K. Prasad
Cc: Paul Mundt
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Jason Wessel
Cc: Ingo Molnar
Signed-off-by: Paul Mundt -
We stopped checking disabled breakpoints because we weren't
allowing breakpoints on NULL addresses. And gdb tends to set
NULL addresses on inactive breakpoints.But refusing NULL addresses was actually a regression that has
been fixed now. There is no reason anymore to not validate
inactive breakpoint settings.Signed-off-by: Frederic Weisbecker
Acked-by: Paul Mundt
Cc: Will Deacon
Cc: Mahesh Salgaonkar
Cc: K. Prasad
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Jason Wessel
Cc: Ingo Molnar
04 Mar, 2010
1 commit
-
Merge reason: Switch from pre-merge topical split to the post-merge urgent track
Signed-off-by: Ingo Molnar
01 Mar, 2010
1 commit
-
We support event unthrottling in breakpoint events. It means
that if we have more than sysctl_perf_event_sample_rate/HZ,
perf will throttle, ignoring subsequent events until the next
tick.So if ptrace exceeds this max rate, it will omit events, which
breaks the ptrace determinism that is supposed to report every
triggered breakpoints. This is likely to happen if we set
sysctl_perf_event_sample_rate to 1.This patch removes support for unthrottling in breakpoint
events to break throttling and restore ptrace determinism.Signed-off-by: Frederic Weisbecker
Cc: 2.6.33.x
Cc: Peter Zijlstra
Cc: K.Prasad
Cc: Paul Mackerras
27 Feb, 2010
1 commit
-
Add __percpu sparse annotations to hw_breakpoint.
These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors. This patch doesn't affect normal builds.In kernel/hw_breakpoint.c, per_cpu(nr_task_bp_pinned, cpu)'s will
trigger spurious noderef related warnings from sparse. Changing it to
&per_cpu(nr_task_bp_pinned[0], cpu) will work around the problem but
deemed to ugly by the maintainer. Leave it alone until better
solution can be found.Signed-off-by: Tejun Heo
Cc: Stephen Rothwell
Cc: K.Prasad
LKML-Reference:
Signed-off-by: Frederic Weisbecker
04 Feb, 2010
1 commit
-
Change 'bp_len' type to __u64 to make it work across archs as
the s390 architecture watch point length can be upto 2^64.reference:
http://lkml.org/lkml/2010/1/25/212This is an ABI change that is not backward compatible with
the previous hardware breakpoint info layout integrated in this
development cycle, a rebuilt of perf tools is necessary for
versions based on 2.6.33-rc1 - 2.6.33-rc6 to work with a
kernel based on this patch.Signed-off-by: Mahesh Salgaonkar
Acked-by: Peter Zijlstra
Cc: Ananth N Mavinakayanahalli
Cc: "K. Prasad"
Cc: Maneesh Soni
Cc: Heiko Carstens
Cc: Martin
LKML-Reference:
Signed-off-by: Frederic Weisbecker
30 Jan, 2010
1 commit
-
This patch fixes the regression in functionality where the
kernel debugger and the perf API do not nicely share hw
breakpoint reservations.The kernel debugger cannot use any mutex_lock() calls because it
can start the kernel running from an invalid context.A mutex free version of the reservation API needed to get
created for the kernel debugger to safely update hw breakpoint
reservations.The possibility for a breakpoint reservation to be concurrently
processed at the time that kgdb interrupts the system is
improbable. Should this corner case occur the end user is
warned, and the kernel debugger will prohibit updating the
hardware breakpoint reservations.Any time the kernel debugger reserves a hardware breakpoint it
will be a system wide reservation.Signed-off-by: Jason Wessel
Acked-by: Frederic Weisbecker
Cc: kgdb-bugreport@lists.sourceforge.net
Cc: K.Prasad
Cc: Peter Zijlstra
Cc: Alan Stern
Cc: torvalds@linux-foundation.org
LKML-Reference:
Signed-off-by: Ingo Molnar
28 Jan, 2010
1 commit
-
On a given architecture, when hardware breakpoint registration fails
due to un-supported access type (read/write/execute), we lose the bp
slot since register_perf_hw_breakpoint() does not release the bp slot
on failure.
Hence, any subsequent hardware breakpoint registration starts failing
with 'no space left on device' error.This patch introduces error handling in register_perf_hw_breakpoint()
function and releases bp slot on error.Signed-off-by: Mahesh Salgaonkar
Cc: Ananth N Mavinakayanahalli
Cc: K. Prasad
Cc: Maneesh Soni
LKML-Reference:
Signed-off-by: Frederic Weisbecker
01 Jan, 2010
1 commit
-
…nel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: Fix sign fields in ftrace_define_fields_##call()
tracing/syscalls: Fix typo in SYSCALL_DEFINE0
tracing/kprobe: Show sign of fields in trace_kprobe format files
ksym_tracer: Remove trace_stat
ksym_tracer: Fix race when incrementing count
ksym_tracer: Fix to allow writing newline to ksym_trace_filter
ksym_tracer: Fix to make the tracer work
tracing: Kconfig spelling fixes and cleanups
tracing: Fix setting tracer specific options
Documentation: Update ftrace-design.txt
Documentation: Update tracepoint-analysis.txt
Documentation: Update mmiotrace.txt
30 Dec, 2009
1 commit
-
ksym tracer doesn't work:
# echo tasklist_lock:rw- > ksym_trace_filter
-bash: echo: write error: No such deviceIt's because we pass to perf_event_create_kernel_counter()
a cpu number which is not present.Signed-off-by: Li Zefan
Cc: Steven Rostedt
Cc: K.Prasad
Cc: Frederic Weisbecker
LKML-Reference:
Signed-off-by: Ingo Molnar
15 Dec, 2009
1 commit
-
Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.Signed-off-by: Thomas Gleixner
Acked-by: Peter Zijlstra
Acked-by: Ingo Molnar
09 Dec, 2009
1 commit
-
Currently, when ptrace needs to modify a breakpoint, like disabling
it, changing its address, type or len, it calls
modify_user_hw_breakpoint(). This latter will perform the heavy and
racy task of unregistering the old breakpoint and registering a new
one.This is racy as someone else might steal the reserved breakpoint
slot under us, which is undesired as the breakpoint is only
supposed to be modified, sometimes in the middle of a debugging
workflow. We don't want our slot to be stolen in the middle.So instead of unregistering/registering the breakpoint, just
disable it while we modify its breakpoint fields and re-enable it
after if necessary.Signed-off-by: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Prasad
LKML-Reference:
Signed-off-by: Ingo Molnar
08 Dec, 2009
1 commit
-
Today's linux-next build failed with:
kernel/hw_breakpoint.c:86: error: 'task_bp_pinned' redeclared as different kind of symbol
...Caused by commit dd17c8f72993f9461e9c19250e3f155d6d99df22 ("percpu:
remove per_cpu__ prefix") from the percpu tree interacting with
commit 56053170ea2a2c0dc17420e9b94aa3ca51d80408 ("hw-breakpoints:
Fix task-bound breakpoint slot allocation") from the tip tree.Signed-off-by: Stephen Rothwell
Acked-by: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Tejun Heo
Cc: Rusty Russell
Cc: Christoph Lameter
Cc: Andrew Morton
Cc: Linus Torvalds
LKML-Reference:
Signed-off-by: Ingo Molnar
07 Dec, 2009
1 commit
-
Whatever the context nature of a breakpoint, we always perform the
following constraint checks before allocating it a slot:- Check the number of pinned breakpoint bound the concerned cpus
- Check the max number of task-bound breakpoints that are belonging
to a task.
- Add both and see if we have a reamining slot for the new breakpointThis is the right thing to do when we are about to register a cpu-only
bound breakpoint. But not if we are dealing with a task bound
breakpoint. What we want in this case is:- Check the number of pinned breakpoint bound the concerned cpus
- Check the number of breakpoints that already belong to the task
in which the breakpoint to register is bound to.
- Add bothThis fixes a regression that makes the "firefox -g" command fail to
register breakpoints once we deal with a secondary thread.Reported-by: Walt
Signed-off-by: Frederic Weisbecker
Cc: Prasad
06 Dec, 2009
2 commits
-
struct perf_event::event callback was called when a breakpoint
triggers. But this is a rather opaque callback, pretty
tied-only to the breakpoint API and not really integrated into perf
as it triggers even when we don't overflow.We prefer to use overflow_handler() as it fits into the perf events
rules, being called only when we overflow.Reported-by: Peter Zijlstra
Signed-off-by: Frederic Weisbecker
Cc: Paul Mackerras
Cc: Arnaldo Carvalho de Melo
Cc: "K. Prasad" -
Drop the callback and task parameters from modify_user_hw_breakpoint().
For now we have no user that need to modify a breakpoint to the point
of changing its handler or its task context.Signed-off-by: Frederic Weisbecker
Cc: "K. Prasad"
27 Nov, 2009
2 commits
-
Kernel breakpoints are created using functions in which we pass
breakpoint parameters as individual variables: address, length
and type.Although it fits well for x86, this just does not scale across
architectures that may support this api later as these may have
more or different needs. Pass in a perf_event_attr structure
instead because it is meant to evolve as much as possible into
a generic hardware breakpoint parameter structure.Reported-by: K.Prasad
Signed-off-by: Frederic Weisbecker
LKML-Reference:
Signed-off-by: Ingo Molnar -
In-kernel user breakpoints are created using functions in which
we pass breakpoint parameters as individual variables: address,
length and type.Although it fits well for x86, this just does not scale across
archictectures that may support this api later as these may have
more or different needs. Pass in a perf_event_attr structure
instead because it is meant to evolve as much as possible into
a generic hardware breakpoint parameter structure.Reported-by: K.Prasad
Signed-off-by: Frederic Weisbecker
LKML-Reference:
Signed-off-by: Ingo Molnar
26 Nov, 2009
2 commits
-
If the new percpu tree is combined with the perf events tree
the following new warning triggers:kernel/hw_breakpoint.c: In function 'toggle_bp_task_slot':
kernel/hw_breakpoint.c:151: warning: 'task_bp_pinned' is used uninitialized in this functionBecause it's not valid anymore to define a local variable
and a percpu variable (even if it's file scope local) with
the same name.Rename the local variable to resolve this.
Signed-off-by: Andrew Morton
Cc: Frederic Weisbecker
Cc: K.Prasad
Cc: Tejun Heo
Cc: Linus Torvalds
LKML-Reference:
[ v2: added changelog ]
Signed-off-by: Ingo Molnar -
This simplifies the error handling when we create a breakpoint.
We don't need to check the NULL return value corner case anymore
since we have improved perf_event_create_kernel_counter() to
always return an error code in the failure case.Signed-off-by: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Paul Mackerras
Cc: Steven Rostedt
Cc: Prasad
LKML-Reference:
Signed-off-by: Ingo Molnar
24 Nov, 2009
2 commits
-
Perf tools create perf events as disabled in the beginning.
Breakpoints are then considered like ptrace temporary
breakpoints, only meant to reserve a breakpoint slot until we
get all the necessary informations from the user.In this case, we don't check the address that is breakpointed as
it is NULL in the ptrace case.But perf tools don't have the same purpose, events are created
disabled to wait for all events to be created before enabling
all of them. We want to check the breakpoint parameters in this
case.Signed-off-by: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Paul Mackerras
Cc: Prasad
LKML-Reference:
Signed-off-by: Ingo Molnar -
Attribute authorship to developers of hw-breakpoint related
files.Signed-off-by: K.Prasad
Cc: Alan Stern
Cc: Frederic Weisbecker
LKML-Reference:
[ v2: moved it to latest -tip ]
Signed-off-by: Ingo Molnar
22 Nov, 2009
1 commit
-
Remove asm/processor.h and asm/debugreg.h as these headers are
not used anymore in the hw-breakpoints core file.Signed-off-by: Frederic Weisbecker
Cc: Prasad
LKML-Reference:
Signed-off-by: Ingo Molnar
10 Nov, 2009
1 commit
-
The hw-breakpoint sample module has been broken during the
hw-breakpoint internals refactoring. Propagate the changes
to it.Reported-by: "K. Prasad"
Signed-off-by: Frederic Weisbecker
08 Nov, 2009
2 commits
-
Allow or refuse to build a counter using the breakpoints pmu following
given constraints.We keep track of the pmu users by using three per cpu variables:
- nr_cpu_bp_pinned stores the number of pinned cpu breakpoints counters
in the given cpu- nr_bp_flexible stores the number of non-pinned breakpoints counters
in the given cpu.- task_bp_pinned stores the number of pinned task breakpoints in a cpu
The latter is not a simple counter but gathers the number of tasks that
have n pinned breakpoints.
Considering HBP_NUM the number of available breakpoint address
registers:
task_bp_pinned[0] is the number of tasks having 1 breakpoint
task_bp_pinned[1] is the number of tasks having 2 breakpoints
[...]
task_bp_pinned[HBP_NUM - 1] is the number of tasks having the
maximum number of registers (HBP_NUM).When a breakpoint counter is created and wants an access to the pmu,
we evaluate the following constraints:== Non-pinned counter ==
- If attached to a single cpu, check:
(per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu)
+ max(per_cpu(task_bp_pinned, cpu)))) < HBP_NUM-> If there are already non-pinned counters in this cpu, it
means there is already a free slot for them.
Otherwise, we check that the maximum number of per task
breakpoints (for this cpu) plus the number of per cpu
breakpoint (for this cpu) doesn't cover every registers.- If attached to every cpus, check:
(per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *))
+ max(per_cpu(task_bp_pinned, *)))) < HBP_NUM-> This is roughly the same, except we check the number of per
cpu bp for every cpu and we keep the max one. Same for the
per tasks breakpoints.== Pinned counter ==
- If attached to a single cpu, check:
((per_cpu(nr_bp_flexible, cpu) > 1)
+ per_cpu(nr_cpu_bp_pinned, cpu)
+ max(per_cpu(task_bp_pinned, cpu))) < HBP_NUM-> Same checks as before. But now the nr_bp_flexible, if any,
must keep one register at least (or flexible breakpoints will
never be be fed).- If attached to every cpus, check:
((per_cpu(nr_bp_flexible, *) > 1)
+ max(per_cpu(nr_cpu_bp_pinned, *))
+ max(per_cpu(task_bp_pinned, *))) < HBP_NUMChanges in v2:
- Counter -> event rename
Changes in v5:
- Fix unreleased non-pinned task-bound-only counters. We only released
it in the first cpu. (Thanks to Paul Mackerras for reporting that)Changes in v6:
- Currently, events scheduling are done in this order: cpu context
pinned + cpu context non-pinned + task context pinned + task context
non-pinned events. Then our current constraints are right theoretically
but not in practice, because non-pinned counters may be scheduled
before we can apply every possible pinned counters. So consider
non-pinned counters as pinned for now.Signed-off-by: Frederic Weisbecker
Cc: Prasad
Cc: Alan Stern
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Steven Rostedt
Cc: Ingo Molnar
Cc: Jan Kiszka
Cc: Jiri Slaby
Cc: Li Zefan
Cc: Avi Kivity
Cc: Paul Mackerras
Cc: Mike Galbraith
Cc: Masami Hiramatsu
Cc: Paul Mundt -
This patch rebase the implementation of the breakpoints API on top of
perf events instances.Each breakpoints are now perf events that handle the
register scheduling, thread/cpu attachment, etc..The new layering is now made as follows:
ptrace kgdb ftrace perf syscall
\ | / /
\ | / /
/
Core breakpoint API /
/
| /
| /Breakpoints perf events
|
|Breakpoints PMU ---- Debug Register constraints handling
(Part of core breakpoint API)
|
|Hardware debug registers
Reasons of this rewrite:
- Use the centralized/optimized pmu registers scheduling,
implying an easier arch integration
- More powerful register handling: perf attributes (pinned/flexible
events, exclusive/non-exclusive, tunable period, etc...)Impact:
- New perf ABI: the hardware breakpoints counters
- Ptrace breakpoints setting remains tricky and still needs some per
thread breakpoints references.Todo (in the order):
- Support breakpoints perf counter events for perf tools (ie: implement
perf_bpcounter_event())
- Support from perf toolsChanges in v2:
- Follow the perf "event " rename
- The ptrace regression have been fixed (ptrace breakpoint perf events
weren't released when a task ended)
- Drop the struct hw_breakpoint and store generic fields in
perf_event_attr.
- Separate core and arch specific headers, drop
asm-generic/hw_breakpoint.h and create linux/hw_breakpoint.h
- Use new generic len/type for breakpoint
- Handle off case: when breakpoints api is not supported by an archChanges in v3:
- Fix broken CONFIG_KVM, we need to propagate the breakpoint api
changes to kvm when we exit the guest and restore the bp registers
to the host.Changes in v4:
- Drop the hw_breakpoint_restore() stub as it is only used by KVM
- EXPORT_SYMBOL_GPL hw_breakpoint_restore() as KVM can be built as a
module
- Restore the breakpoints unconditionally on kvm guest exit:
TIF_DEBUG_THREAD doesn't anymore cover every cases of running
breakpoints and vcpu->arch.switch_db_regs might not always be
set when the guest used debug registers.
(Waiting for a reliable optimization)Changes in v5:
- Split-up the asm-generic/hw-breakpoint.h moving to
linux/hw_breakpoint.h into a separate patch
- Optimize the breakpoints restoring while switching from kvm guest
to host. We only want to restore the state if we have active
breakpoints to the host, otherwise we don't care about messed-up
address registers.
- Add asm/hw_breakpoint.h to Kbuild
- Fix bad breakpoint type in trace_selftest.cChanges in v6:
- Fix wrong header inclusion in trace.h (triggered a build
error with CONFIG_FTRACE_SELFTESTSigned-off-by: Frederic Weisbecker
Cc: Prasad
Cc: Alan Stern
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Steven Rostedt
Cc: Ingo Molnar
Cc: Jan Kiszka
Cc: Jiri Slaby
Cc: Li Zefan
Cc: Avi Kivity
Cc: Paul Mackerras
Cc: Mike Galbraith
Cc: Masami Hiramatsu
Cc: Paul Mundt
03 Jun, 2009
1 commit
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This patch introduces the generic Hardware Breakpoint interfaces for both user
and kernel space requests.
This core Api handles the hardware breakpoints through new helpers. It
handles the user-space breakpoints and kernel breakpoints in front of
arch implementation.One can choose kernel wide breakpoints using the following helpers
and passing them a generic struct hw_breakpoint:- register_kernel_hw_breakpoint()
- unregister_kernel_hw_breakpoint()
- modify_kernel_hw_breakpoint()On the other side, you can choose per task breakpoints.
- register_user_hw_breakpoint()
- unregister_user_hw_breakpoint()
- modify_user_hw_breakpoint()[ fweisbec@gmail.com: fix conflict against perfcounter ]
Original-patch-by: Alan Stern
Signed-off-by: K.Prasad
Reviewed-by: Alan Stern
Signed-off-by: Frederic Weisbecker