Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

 * Fix cleanup in case of kzalloc failure, from Daniel Baluta.

 * Limit unwind support to x86 archs, fix from Jiri Olsa.

 * Initial GTK+ annotate browser, from Namhyung Kim.

 * Fix build with bison 2.3 and older, from Vinson Lee.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Obviously this is a typo and could result in memory leaks if kzalloc
fails on a given cpu.
Signed-off-by: NDaniel Baluta <dbaluta@ixiacom.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360186160-7566-1-git-send-email-dbaluta@ixiacom.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The %name-prefix "prefix" syntax is not available on bison 2.3 and
older. Substitute with the -p "prefix" command-line option for
compatibility with older versions of bison.

This patch fixes this build error with older versions of bison.

    CC util/sysfs.o
    BISON util/pmu-bison.c
util/pmu.y:2.14-24: syntax error, unexpected string, expecting =
make: *** [util/pmu-bison.c] Error 1
Signed-off-by: NVinson Lee <vlee@twitter.com>
Tested-by: NLi Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org # 3.4+
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Link: http://lkml.kernel.org/r/1360792138-29186-1-git-send-email-vlee@twitter.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

There's DWARF unwind support only for x86 archs, so limit the unwind.o
object to them only.

Without this building for other archs (e.g. cross compiling for ARM) is
broken.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NDirk Behme <dirk.behme@de.bosch.com>
Link: http://lkml.kernel.org/n/tip-viqtvd6hppqgt68zz4wlqm20@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add --skip-missing option for skipping symbols that cannot be used for
annotation.  It's the case of kernel symbols that user doesn't have a
vmlinux image file.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-8-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Don't need to setup a browser window if annotate cannot work.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-7-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

In order to differentiate source lines from asm line, print them with
gray color.  To do this, it needs to be escaped since sometimes it
contains "<" and/or ">" characters so that it should not be considered
as a markup tags.  Use glib's g_markup_escape_text() for this.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-4-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Show multiple annotation result for each evsel.  Each result represents
the most frquently sampled symbol/function for the evsel and it will be
shown in a tab window.

For this add a reference to main container (notebook) to the pgctx.  At
the first call to annotate browser, hist_entry__find_annotations() will
setup a new browser, and next calls will add new tabs to the browser.
But it requires final perf_gtk__show_annotations() to start processing
GUI events.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-3-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Basic implementation of perf annotate on GTK2.  Currently only
shows first symbol.  Add a new --gtk option to use it.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-2-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When perf annotate runs with no vmlinux file it cannot annotate kernel
symbols because the kallsyms only provides symbol addresses.  So it
recommends to run perf buildid-cache to install proper vmlinux image.

But running perf buildid-cache -av vmlinux as the message gives me a
following error:

  $ perf buildid-cache -av /home/namhyung/build/kernel/vmlinux
  Couldn't add v: No such file or directory

Since the -a option receives a parameter, 'v' should not be after the
option.

In addition -a option is not work for this case since the build-id cache
already has a kallsyms with same build-id so it'll fail with EEXIST.
Use recently added -u (--update) option for it.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-6-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When adding vmlinux file to build-id cache, it'd be fail since kallsyms
dso with a same build-id was already added by perf record.

So one needs to remove the kallsyms first to add vmlinux into the cache.
Add --update option for doing it at once.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-5-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Merge branch 'uprobes/core' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc into perf/core

Improve uprobes performance by adding 'pre-filtering' support,
by Oleg Nesterov:

	# time perl -e 'syscall -1 for 1..100_000'
	real    0m0.040s
	user    0m0.027s
	sys     0m0.010s

	# perf probe -x /lib/libc.so.6 syscall
	# perf record -e probe_libc:syscall sleep 100 &

Before this series:

	# time perl -e 'syscall -1 for 1..100_000'
	real    0m1.714s
	user    0m0.103s
	sys     0m1.607s

After:

	# time perl -e 'syscall -1 for 1..100_000'
	real    0m0.037s
	user    0m0.013s
	sys     0m0.023s
Signed-off-by: NIngo Molnar <mingo@kernel.org>

uprobe_perf_open/close call the costly uprobe_apply() every time,
we can avoid it if:

	- "nr_systemwide != 0" is not changed.

	- There is another process/thread with the same ->mm.

	- copy_proccess() does inherit_event(). dup_mmap() preserves the
	  inserted breakpoints.

	- event->attr.enable_on_exec == T, we can rely on uprobe_mmap()
	  called by exec/mmap paths.

	- tp_target is exiting. Only _close() checks PF_EXITING, I don't
	  think TRACE_REG_PERF_OPEN can hit the dying task too often.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

Change uprobe_trace_func() and uprobe_perf_func() to return "int". Change
uprobe_dispatcher() to return "trace_ret | perf_ret" although this is not
needed, currently TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive.

The only functional change is that uprobe_perf_func() checks the filtering
too and returns UPROBE_HANDLER_REMOVE if nobody wants to trace current.

Testing:

	# perf probe -x /lib/libc.so.6 syscall

	# perf record -e probe_libc:syscall -i perl -e 'fork; syscall -1 for 1..10; wait'

	# perf report --show-total-period
		100.00%            10     perl  libc-2.8.so    [.] syscall

Before this patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				20

A child process doesn't have a counter, but still it hits this breakoint
"copied" by dup_mmap().

After the patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				11

The child process hits this int3 only once and does unapply_uprobe().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

Finally implement uprobe_perf_filter() which checks ->nr_systemwide or
->perf_events to figure out whether we need to insert the breakpoint.

uprobe_perf_open/close are changed to do uprobe_apply(true/false) when
the new perf event comes or goes away.

Note that currently this is very suboptimal:

	- uprobe_register() called by TRACE_REG_PERF_REGISTER becomes a
	  heavy nop, consumer->filter() always returns F at this stage.

	  As it was already discussed we need uprobe_register_only() to
	  avoid the costly register_for_each_vma() when possible.

	- uprobe_apply() is oftenly overkill. Unless "nr_systemwide != 0"
	  changes we need uprobe_apply_mm(), unapply_uprobe() is almost
	  what we need.

	- uprobe_apply() can be simply avoided sometimes, see the next
	  changes.

Testing:

	# perf probe -x /lib/libc.so.6 syscall

	# perl -e 'syscall -1 while 1' &
	[1] 530

	# perf record -e probe_libc:syscall perl -e 'syscall -1 for 1..10; sleep 1'

	# perf report --show-total-period
		100.00%            10     perl  libc-2.8.so    [.] syscall

Before this patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				79291

A huge ->nrhit == 79291 reflects the fact that the background process
530 constantly hits this breakpoint too, even if doesn't contribute to
the output.

After the patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				10

This shows that only the target process was punished by int3.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

Introduce "struct trace_uprobe_filter" which records the "active"
perf_event's attached to ftrace_event_call. For the start we simply
use list_head, we can optimize this later if needed. For example, we
do not really need to record an event with ->parent != NULL, we can
rely on parent->child_list. And we can certainly do some optimizations
for the case when 2 events have the same ->tp_target or tp_target->mm.

Change trace_uprobe_register() to process TRACE_REG_PERF_OPEN/CLOSE
and add/del this perf_event to the list.

We can probably avoid any locking, but lets start with the "obvioulsy
correct" trace_uprobe_filter->rwlock which protects everything.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

Currently it is not possible to change the filtering constraints after
uprobe_register(), so a consumer can not, say, start to trace a task/mm
which was previously filtered out, or remove the no longer needed bp's.

Introduce uprobe_apply() which simply does register_for_each_vma() again
to consult uprobe_consumer->filter() and install/remove the breakpoints.
The only complication is that register_for_each_vma() can no longer
assume that uprobe->consumers should be consulter if is_register == T,
so we change it to accept "struct uprobe_consumer *new" instead.

Unlike uprobe_register(), uprobe_apply(true) doesn't do "unregister" if
register_for_each_vma() fails, it is up to caller to handle the error.

Note: we probably need to cleanup the current interface, it is strange
that uprobe_apply/unregister need inode/offset. We should either change
uprobe_register() to return "struct uprobe *", or add a private ->uprobe
member in uprobe_consumer. And in the long term uprobe_apply() should
take a single argument, uprobe or consumer, even "bool add" should go
away.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

sys_perf_event_open()->perf_init_event(event) is called before
find_get_context(event), this means that event->ctx == NULL when
class->reg(TRACE_REG_PERF_REGISTER/OPEN) is called and thus it
can't know if this event is per-task or system-wide.

This patch adds hw_perf_event->tp_target for PERF_TYPE_TRACEPOINT,
this is analogous to PERF_TYPE_BREAKPOINT/bp_target we already have.
The patch also moves ->bp_target up so that it can overlap with the
new member, this can help the compiler to generate the better code.

trace_uprobe_register() will use it for prefiltering to avoid the
unnecessary breakpoints in mm's we do not want to trace.

->tp_target doesn't have its own reference, but we can rely on the
fact that either sys_perf_event_open() holds a reference, or it is
equal to event->ctx->task. So this pointer is always valid until
free_event().

Also add the "struct list_head tp_list" into this union. It is not
strictly necessary, but it can simplify the next changes and we can
add it for free.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

Move tu->nhit++ from uprobe_trace_func() to uprobe_dispatcher().

->nhit counts how many time we hit the breakpoint inserted by this
uprobe, we do not want to loose this info if uprobe was enabled by
sys_perf_event_open().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

trace_uprobe->consumer and "struct uprobe_trace_consumer" add the
unnecessary indirection and complicate the code for no reason.

This patch simply embeds uprobe_consumer into "struct trace_uprobe",
all other changes only fix the compilation errors.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

probe_event_enable/disable() check tu->consumer != NULL to avoid the
wrong uprobe_register/unregister().

We are going to kill this pointer and "struct uprobe_trace_consumer",
so we add the new helper, is_trace_uprobe_enabled(), which can rely
on TP_FLAG_TRACE/TP_FLAG_PROFILE instead.

Note: the current logic doesn't look optimal, it is not clear why
TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive, we will probably
change this later.

Also kill the unused TP_FLAG_UPROBE.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

probe_event_enable/disable() check tu->inode != NULL at the start.
This is ugly, if igrab() can fail create_trace_uprobe() should not
succeed and "postpone" the failure.

And S_ISREG(inode->i_mode) check added by d24d7dbf is not safe.

Note: alloc_uprobe() should probably check igrab() != NULL as well.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

probe_event_enable() does uprobe_register() and only after that sets
utc->tu and tu->consumer/flags. This can race with uprobe_dispatcher()
which can miss these assignments or see them out of order. Nothing
really bad can happen, but this doesn't look clean/safe.

And this does not allow to use uprobe_consumer->filter() we are going
to add, it is called by uprobe_register() and it needs utc->tu.

Change this code to initialize everything before uprobe_register(), and
reset tu->consumer/flags if it fails. We can't race with event_disable(),
the caller holds event_mutex, and if we could the code would be wrong
anyway.

In fact I think uprobe_trace_consumer should die, it buys nothing but
complicates the code. We can simply add uprobe_consumer into trace_uprobe.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

create_trace_uprobe() does kern_path() to find ->d_inode, but forgets
to do path_put(). We can do this right after igrab().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

The original pull message for uprobes (commit 654443e2) noted:

  This tree includes uprobes support in 'perf probe' - but SystemTap
  (and other tools) can take advantage of user probe points as well.

In order to actually be usable in module-based tools like SystemTap, the
interface needs to be exported.  This patch first adds the obvious
exports for uprobe_register and uprobe_unregister.  Then it also adds
one for task_user_regset_view, which is necessary to get the correct
state of userspace registers.
Signed-off-by: NJosh Stone <jistone@redhat.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>

utask->xol_vaddr is either zero or valid, remove the bogus
IS_ERR_VALUE() check in xol_free_insn_slot().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

handle_swbp() does get_utask() before can_skip_sstep() for no reason,
we do not need ->utask if can_skip_sstep() succeeds.

Move get_utask() to pre_ssout() who actually starts to use it. Move
the initialization of utask->active_uprobe/state as well. This way
the whole initialization is consolidated in pre_ssout().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>

pre_ssout() should do xol_free_insn_slot() if arch_uprobe_pre_xol()
fails, otherwise nobody will free the allocated slot.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

pre_ssout()->xol_get_insn_slot() path is confusing and buggy. This patch
cleanups the code, the next one fixes the bug.

Change xol_get_insn_slot() to only allocate the slot and do nothing more,
move the initialization of utask->xol_vaddr/vaddr into pre_ssout().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Rename add_utask() into get_utask() and change it to allocate on
demand to simplify the caller. Like get_xol_area() it will have
more users.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Currently only xol_get_insn_slot() does get_xol_area() + xol_alloc_area(),
but this will have more users and we do not want to copy-and-paste this
code. This patch simply moves xol_alloc_area() into get_xol_area() to
simplify the current and future code.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Move alloc_page() from xol_add_vma() to xol_alloc_area() to cleanup
the code. This separates the memory allocations and consolidates the
-EALREADY cleanups and the error handling.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Change handle_swbp() to set regs->ip = bp_vaddr in advance, this is
what consumer->handler() needs but uprobe_get_swbp_addr() is not
exported.

This also simplifies the code and makes it more consistent across
the supported architectures. handle_swbp() becomes the only caller
of uprobe_get_swbp_addr().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnanth N Mavinakayanahalli <ananth@in.ibm.com>

__skip_sstep() doesn't update regs->ip. Currently this is correct
but only "by accident" and it doesn't skip the whole insn. Change
it to advance ->ip by the length of the detected 0x66*0x90 sequence.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Currrently the are 2 problems with pre-filtering:

1. It is not possible to add/remove a task (mm) after uprobe_register()

2. A forked child inherits all breakpoints and uprobe_consumer can not
   control this.

This patch does the first step to improve the filtering. handler_chain()
removes the breakpoints installed by this uprobe from current->mm if all
handlers return UPROBE_HANDLER_REMOVE.

Note that handler_chain() relies on ->register_rwsem to avoid the race
with uprobe_register/unregister which can add/del a consumer, or even
remove and then insert the new uprobe at the same address.

Perhaps we will add uprobe_apply_mm(uprobe, mm, is_register) and teach
copy_mm() to do filter(UPROBE_FILTER_FORK), but I think this change makes
sense anyway.

Note: instead of checking the retcode from uc->handler, we could add
uc->filter(UPROBE_FILTER_BPHIT). But I think this is not optimal to
call 2 hooks in a row. This buys nothing, and if handler/filter do
something nontrivial they will probably do the same work twice.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Finally add uprobe_consumer->filter() and change consumer_filter()
to actually call this method.

Note that ->filter() accepts mm_struct, not task_struct. Because:

	1. We do not have for_each_mm_user(mm, task).

	2. Even if we implement for_each_mm_user(), ->filter() can
	   use it itself.

	3. It is not clear who will actually need this interface to
	   do the "nontrivial" filtering.

Another argument is "enum uprobe_filter_ctx", consumer->filter() can
use it to figure out why/where it was called. For example, perhaps
we can add UPROBE_FILTER_PRE_REGISTER used by build_map_info() to
quickly "nack" the unwanted mm's. In this case consumer should know
that it is called under ->i_mmap_mutex.

See the previous discussion at http://marc.info/?t=135214229700002
Perhaps we should pass more arguments, vma/vaddr?

Note: this patch obviously can't help to filter out the child created
by fork(), this will be addressed later.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

filter_chain() was added into install_breakpoint/remove_breakpoint to
simplify the initial changes but this is sub-optimal.

This patch shifts the callsite to the callers, register_for_each_vma()
and uprobe_mmap(). This way:

- It will be easier to add the new arguments. This is the main reason,
  we can do more optimizations later.

- register_for_each_vma(is_register => true) can be optimized, we only
  need to consult the new consumer. The previous consumers were already
  asked when they called uprobe_register().

This patch also moves the MMF_HAS_UPROBES check from remove_breakpoint(),
this allows to avoid the potentionally costly filter_chain(). Note that
register_for_each_vma(is_register => false) doesn't really need to take
->consumer_rwsem, but I don't think it makes sense to optimize this and
introduce filter_chain_lockless().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

uprobe_register() and uprobe_unregister() are the only users of
mutex_lock(uprobes_hash(inode)), and the only reason why we can't
simply remove it is that we need to ensure that delete_uprobe() is
not possible after alloc_uprobe() and before consumer_add().

IOW, we need to ensure that when we take uprobe->register_rwsem
this uprobe is still valid and we didn't race with _unregister()
which called delete_uprobe() in between.

With this patch uprobe_register() simply checks uprobe_is_active()
and retries if it hits this very unlikely race. uprobes_mutex[] is
no longer needed and can be removed.

There is another reason for this change, prepare_uprobe() should be
folded into alloc_uprobe() and we do not want to hold the extra locks
around read_mapping_page/etc.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

The lifetime of uprobe->rb_node and uprobe->inode is not refcounted,
delete_uprobe() is called when we detect that uprobe has no consumers,
and it would be deadly wrong to do this twice.

Change delete_uprobe() to WARN() if it was already called. We use
RB_CLEAR_NODE() to mark uprobe "inactive", then RB_EMPTY_NODE() can
be used to detect this case.

RB_EMPTY_NODE() is not used directly, we add the trivial helper for
the next change.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

uprobe_events counts the number of uprobes in uprobes_tree but
it is used as a boolean. We can use RB_EMPTY_ROOT() instead.

Probably no_uprobe_events() added by this patch can have more
callers, say, mmf_recalc_uprobes().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NAnton Arapov <anton@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>