linux-toradex.git/kernel/events/hw_breakpoint.c, branch v3.11

hw_breakpoint: Introduce "struct bp_cpuinfo"

2013-06-20T15:58:57+00:00

This patch simply moves all per-cpu variables into the new
single per-cpu "struct bp_cpuinfo".

To me this looks more logical and clean, but this can also
simplify the further potential changes. In particular, I do not
think this memory should be per-cpu, it is never used "locally".
After this change it is trivial to turn it into, say,
bootmem[nr_cpu_ids].

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/20130620155020.GA6350@redhat.com
Signed-off-by: Ingo Molnar

hw_breakpoint: Simplify *register_wide_hw_breakpoint()

2013-06-20T15:58:57+00:00

1. register_wide_hw_breakpoint() can use unregister_ if failure,
   no need to duplicate the code.

2. "struct perf_event **pevent" adds the unnecesary lever of
   indirection and complication, use per_cpu(*cpu_events, cpu).

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/20130620155018.GA6347@redhat.com
Signed-off-by: Ingo Molnar

hw_breakpoint: Introduce cpumask_of_bp()

2013-06-20T15:58:56+00:00

Add the trivial helper which simply returns cpumask_of() or
cpu_possible_mask depending on bp->cpu.

Change fetch_bp_busy_slots() and toggle_bp_slot() to always do
for_each_cpu(cpumask_of_bp) to simplify the code and avoid the
code duplication.

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/20130620155015.GA6340@redhat.com
Signed-off-by: Ingo Molnar

hw_breakpoint: Simplify the "weight" usage in toggle_bp_slot() paths

2013-06-20T15:58:55+00:00

Change toggle_bp_slot() to make "weight" negative if !enable.
This way we can always use "+ weight" without additional "if
(enable)" check and toggle_bp_task_slot() no longer needs this
arg.

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/20130620155013.GA6337@redhat.com
Signed-off-by: Ingo Molnar

hw_breakpoint: Simplify list/idx mess in toggle_bp_slot() paths

2013-06-20T15:58:55+00:00

The enable/disable logic in toggle_bp_slot() is not symmetrical
and imho very confusing. "old_count" in toggle_bp_task_slot() is
actually new_count because this bp was already removed from the
list.

Change toggle_bp_slot() to always call list_add/list_del after
toggle_bp_task_slot(). This way old_idx is task_bp_pinned() and
this entry should be decremented, new_idx is +/-weight and we
need to increment this element. The code/logic looks obvious.

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/20130620155011.GA6330@redhat.com
Signed-off-by: Ingo Molnar

Merge branch 'perf/urgent' into perf/core

2013-06-20T15:57:40+00:00

Merge in two hw_breakpoint fixes, before applying another 5.

Signed-off-by: Ingo Molnar

hw_breakpoint: Use cpu_possible_mask in {reserve,release}_bp_slot()

2013-06-20T15:57:01+00:00

fetch_bp_busy_slots() and toggle_bp_slot() use
for_each_online_cpu(), this is obviously wrong wrt cpu_up() or
cpu_down(), we can over/under account the per-cpu numbers.

For example:

	# echo 0 >> /sys/devices/system/cpu/cpu1/online
	# perf record -e mem:0x10 -p 1 &
	# echo 1 >> /sys/devices/system/cpu/cpu1/online
	# perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10 -C1 -a &
	# taskset -p 0x2 1

triggers the same WARN_ONCE("Can't find any breakpoint slot") in
arch_install_hw_breakpoint().

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Cc: 
Link: http://lkml.kernel.org/r/20130620155009.GA6327@redhat.com
Signed-off-by: Ingo Molnar

hw_breakpoint: Fix cpu check in task_bp_pinned(cpu)

2013-06-20T15:57:00+00:00

trinity fuzzer triggered WARN_ONCE("Can't find any breakpoint
slot") in arch_install_hw_breakpoint() but the problem is not
arch-specific.

The problem is, task_bp_pinned(cpu) checks "cpu == iter->cpu"
but this doesn't account the "all cpus" events with iter->cpu <
0.

This means that, say, register_user_hw_breakpoint(tsk) can
happily create the arbitrary number > HBP_NUM of breakpoints
which can not be activated. toggle_bp_task_slot() is equally
wrong by the same reason and nr_task_bp_pinned[] can have
negative entries.

Simple test:

	# perl -e 'sleep 1 while 1' &
	# perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10,mem:0x10 -p `pidof perl`

Before this patch this triggers the same problem/WARN_ON(),
after the patch it correctly fails with -ENOSPC.

Reported-by: Vince Weaver 
Signed-off-by: Oleg Nesterov 
Acked-by: Frederic Weisbecker 
Cc: 
Link: http://lkml.kernel.org/r/20130620155006.GA6324@redhat.com
Signed-off-by: Ingo Molnar

perf: Fix hw breakpoints overflow period sampling

2013-05-28T06:59:54+00:00

The hw breakpoint pmu 'add' function is missing the
period_left update needed for SW events.

The perf HW breakpoint events use the SW events framework
to process the overflow, so it needs to be properly initialized
in the PMU 'add' method.

Signed-off-by: Jiri Olsa 
Reviewed-by: Peter Zijlstra 
Cc: H. Peter Anvin 
Cc: Oleg Nesterov 
Cc: Arnaldo Carvalho de Melo 
Cc: Ingo Molnar 
Cc: Paul Mackerras 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Vince Weaver 
Cc: Stephane Eranian 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1367421944-19082-5-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar

perf/hwbp: Fix cleanup in case of kzalloc failure

2013-02-14T20:06:39+00:00

Obviously this is a typo and could result in memory leaks if kzalloc
fails on a given cpu.

Signed-off-by: Daniel Baluta 
Acked-by: Frederic Weisbecker 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1360186160-7566-1-git-send-email-dbaluta@ixiacom.com
Signed-off-by: Arnaldo Carvalho de Melo