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Subject[PATCH V4 00/13] perf/x86: Add perf text poke events
Date
Hi

Here are patches to add a text poke event to record changes to kernel text
(i.e. self-modifying code) in order to support tracers like Intel PT
decoding through jump labels, kprobes and ftrace trampolines.

The first 8 patches make the kernel changes and the subsequent patches are
tools changes.

The next 4 patches add support for updating perf tools' data cache
with the changed bytes.

The last patch is an Intel PT specific tools change.

Patches also here:

git://git.infradead.org/users/ahunter/linux-perf.git text_poke


Changes in V4

kprobes: Add symbols for kprobe insn pages

Change "module name" from kprobe to __builtin__kprobes
Added comment about "module name" use

ftrace: Add symbols for ftrace trampolines

Change "module name" from ftrace to __builtin__ftrace
Move calls of ftrace_add_trampoline_to_kallsyms() and
ftrace_remove_trampoline_from_kallsyms() into
kernel/trace/ftrace.c
Added comment about "module name" use

ftrace: Add perf ksymbol events for ftrace trampolines

Move changes into kernel/trace/ftrace.c

ftrace: Add perf text poke events for ftrace trampolines

Move changes into kernel/trace/ftrace.c

Changes in V3:

perf: Add perf text poke event

To prevent warning, cast pointer to (unsigned long) not (u64)

kprobes: Add symbols for kprobe insn pages

Expand commit message
Remove un-needed declarations of kprobe_cache_get_kallsym() and arch_kprobe_get_kallsym() when !CONFIG_KPROBES

ftrace: Add symbols for ftrace trampolines

Expand commit message
Make ftrace_get_trampoline_kallsym() static

Changes in V2:

perf: Add perf text poke event

Separate out x86 changes
The text poke event now has old len and new len
Revised commit message

perf/x86: Add support for perf text poke event for text_poke_bp_batch() callers

New patch containing x86 changes from original first patch

kprobes: Add symbols for kprobe insn pages
kprobes: Add perf ksymbol events for kprobe insn pages
perf/x86: Add perf text poke events for kprobes
ftrace: Add symbols for ftrace trampolines
ftrace: Add perf ksymbol events for ftrace trampolines
ftrace: Add perf text poke events for ftrace trampolines
perf kcore_copy: Fix module map when there are no modules loaded
perf evlist: Disable 'immediate' events last

New patches

perf tools: Add support for PERF_RECORD_TEXT_POKE

The text poke event now has old len and new len
Also select ksymbol events with text poke events

perf tools: Add support for PERF_RECORD_KSYMBOL_TYPE_OOL

New patch

perf intel-pt: Add support for text poke events

The text poke event now has old len and new len
Allow for the address not having a map yet


Changes since RFC:

Dropped 'flags' from the new event. The consensus seemed to be that text
pokes should employ a scheme similar to x86's INT3 method instead.

dropped tools patches already applied.


Example:

For jump labels, the kernel needs
CONFIG_JUMP_LABEL=y
and also an easy to flip jump label is in sysctl_schedstats() which needs
CONFIG_SCHEDSTATS=y
CONFIG_PROC_SYSCTL=y
CONFIG_SCHED_DEBUG=y

Also note the 'sudo perf record' is put into the background which, as
written, needs sudo credential caching (otherwise the background task
will stop awaiting the sudo password), hence the 'sudo echo' to start.

Before:

$ sudo echo
$ sudo perf record -o perf.data.before --kcore -a -e intel_pt//k -m,64M &
[1] 1640
$ cat /proc/sys/kernel/sched_schedstats
0
$ sudo bash -c 'echo 1 > /proc/sys/kernel/sched_schedstats'
$ cat /proc/sys/kernel/sched_schedstats
1
$ sudo bash -c 'echo 0 > /proc/sys/kernel/sched_schedstats'
$ cat /proc/sys/kernel/sched_schedstats
0
$ sudo kill 1640
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 16.635 MB perf.data.before ]
$ perf script -i perf.data.before --itrace=e >/dev/null
Warning:
1946 instruction trace errors

After:

$ sudo echo
$ sudo perf record -o perf.data.after --kcore -a -e intel_pt//k -m,64M &
[1] 1882
$ cat /proc/sys/kernel/sched_schedstats
0
$ sudo bash -c 'echo 1 > /proc/sys/kernel/sched_schedstats'
$ cat /proc/sys/kernel/sched_schedstats
1
$ sudo bash -c 'echo 0 > /proc/sys/kernel/sched_schedstats'
$ cat /proc/sys/kernel/sched_schedstats
0
$ sudo kill 1882
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 10.893 MB perf.data.after ]
$ perf script -i perf.data.after --itrace=e
$


Adrian Hunter (13):
perf: Add perf text poke event
perf/x86: Add support for perf text poke event for text_poke_bp_batch() callers
kprobes: Add symbols for kprobe insn pages
kprobes: Add perf ksymbol events for kprobe insn pages
perf/x86: Add perf text poke events for kprobes
ftrace: Add symbols for ftrace trampolines
ftrace: Add perf ksymbol events for ftrace trampolines
ftrace: Add perf text poke events for ftrace trampolines
perf kcore_copy: Fix module map when there are no modules loaded
perf evlist: Disable 'immediate' events last
perf tools: Add support for PERF_RECORD_TEXT_POKE
perf tools: Add support for PERF_RECORD_KSYMBOL_TYPE_OOL
perf intel-pt: Add support for text poke events

arch/x86/include/asm/kprobes.h | 4 ++
arch/x86/include/asm/text-patching.h | 2 +
arch/x86/kernel/alternative.c | 70 +++++++++++++++++----
arch/x86/kernel/kprobes/core.c | 7 +++
arch/x86/kernel/kprobes/opt.c | 18 +++++-
include/linux/ftrace.h | 12 ++--
include/linux/kprobes.h | 15 +++++
include/linux/perf_event.h | 8 +++
include/uapi/linux/perf_event.h | 26 +++++++-
kernel/events/core.c | 90 +++++++++++++++++++++++++-
kernel/kallsyms.c | 42 +++++++++++--
kernel/kprobes.c | 57 +++++++++++++++++
kernel/trace/ftrace.c | 101 +++++++++++++++++++++++++++++-
tools/include/uapi/linux/perf_event.h | 26 +++++++-
tools/lib/perf/include/perf/event.h | 9 +++
tools/perf/arch/x86/util/intel-pt.c | 4 ++
tools/perf/builtin-record.c | 45 +++++++++++++
tools/perf/util/dso.c | 3 +
tools/perf/util/dso.h | 1 +
tools/perf/util/event.c | 40 ++++++++++++
tools/perf/util/event.h | 5 ++
tools/perf/util/evlist.c | 31 ++++++---
tools/perf/util/evlist.h | 1 +
tools/perf/util/evsel.c | 7 ++-
tools/perf/util/intel-pt.c | 75 ++++++++++++++++++++++
tools/perf/util/machine.c | 49 +++++++++++++++
tools/perf/util/machine.h | 3 +
tools/perf/util/map.c | 5 ++
tools/perf/util/map.h | 3 +-
tools/perf/util/perf_event_attr_fprintf.c | 1 +
tools/perf/util/record.c | 10 +++
tools/perf/util/record.h | 1 +
tools/perf/util/session.c | 23 +++++++
tools/perf/util/symbol-elf.c | 7 +++
tools/perf/util/symbol.c | 1 +
tools/perf/util/tool.h | 3 +-
36 files changed, 765 insertions(+), 40 deletions(-)


Regards
Adrian

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