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  1. 10 Nov, 2009 3 commits
  3. 08 Nov, 2009 3 commits
    • Li Zefan's avatar
      ksym_tracer: Remove KSYM_SELFTEST_ENTRY · 30ff21e3
      Li Zefan authored 
      The macro used to be used in both trace_selftest.c and
trace_ksym.c, but no longer, so remove it from header file.
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      30ff21e3
    • Frederic Weisbecker's avatar
      hw-breakpoints: Arbitrate access to pmu following registers constraints · ba1c813a
      Frederic Weisbecker authored 
      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_NUM

Changes 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: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
      ba1c813a
    • Frederic Weisbecker's avatar
      hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events · 24f1e32c
      Frederic Weisbecker authored 
      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 tools

Changes 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 arch

Changes 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.c

Changes in v6:

- Fix wrong header inclusion in trace.h (triggered a build
  error with CONFIG_FTRACE_SELFTEST
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
      24f1e32c
  5. 05 Nov, 2009 1 commit
  7. 03 Nov, 2009 3 commits
    • Frederic Weisbecker's avatar
      perf/core: Add a callback to perf events · 97eaf530
      Frederic Weisbecker authored 
      A simple callback in a perf event can be used for multiple purposes.
For example it is useful for triggered based events like hardware
breakpoints that need a callback to dispatch a triggered breakpoint
event.

v2: Simplify a bit the callback attribution as suggested by Paul
    Mackerras
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mundt <lethal@linux-sh.org>
      97eaf530
    • Paul Mundt's avatar
      x86/hw-breakpoints: Actually flush thread breakpoints in flush_thread(). · 41a48d14
      Paul Mundt authored 
      flush_thread() tries to do a TIF_DEBUG check before calling in to
flush_thread_hw_breakpoint() (which subsequently clears the thread flag),
but for some reason, the x86 code is manually clearing TIF_DEBUG
immediately before the test, so this path will never be taken.

This kills off the erroneous clear_tsk_thread_flag() and lets
flush_thread_hw_breakpoint() actually get invoked.

Presumably folks were getting lucky with testing and the
free_thread_info() -> free_thread_xstate() path was taking care of the
flush there.
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
Acked-by: default avatar"K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alan Stern <stern@rowland.harvard.edu>
LKML-Reference: <20091005102306.GA7889@linux-sh.org>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      41a48d14
    • Arjan van de Ven's avatar
      perf/core: Provide a kernel-internal interface to get to performance counters · fb0459d7
      Arjan van de Ven authored 
      There are reasons for kernel code to ask for, and use, performance
counters.
For example, in CPU freq governors this tends to be a good idea, but
there are other examples possible as well of course.

This patch adds the needed bits to do enable this functionality; they
have been tested in an experimental cpufreq driver that I'm working on,
and the changes are all that I needed to access counters properly.

[fweisbec@gmail.com: added pid to perf_event_create_kernel_counter so
that we can profile a particular task too

TODO: Have a better error reporting, don't just return NULL in fail
case.]

v2: Remove the wrong comment about the fact
    perf_event_create_kernel_counter must be called from a kernel
    thread.
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Avi Kivity <avi@redhat.com>
LKML-Reference: <20090925122556.2f8bd939@infradead.org>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      fb0459d7
  9. 17 Oct, 2009 2 commits
  11. 15 Oct, 2009 21 commits
  13. 14 Oct, 2009 7 commits
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