[trace][intel pt] Add a cgroup filter

It turns out that cgroup filtering is relatively trivial and works
really nicely. Thid diffs adds automatic cgroup filtering when in
per-cpu mode, unless a new

[trace][intel pt] Add a cgroup filter

It turns out that cgroup filtering is relatively trivial and works
really nicely. Thid diffs adds automatic cgroup filtering when in
per-cpu mode, unless a new --disable-cgroup-filtering flag is passed in
the start command. At least on Meta machines, all processes are spawned
inside a cgroup by default, which comes super handy, because per cpu
tracing is now much more precise.

A manual test gave me this result

- Without filtering:
Total number of trace items: 36083
Total number of continuous executions found: 229
Number of continuous executions for this thread: 2
Total number of PSB blocks found: 98
Number of PSB blocks for this thread 2
Total number of unattributed PSB blocks found: 38

- With filtering:
Total number of trace items: 87756
Total number of continuous executions found: 123
Number of continuous executions for this thread: 2
Total number of PSB blocks found: 10
Number of PSB blocks for this thread 3
Total number of unattributed PSB blocks found: 2

Filtering gives us great results. The number of instructions collected
more than double (probalby because we have less noise in the trace), and
we have much less unattributed PSBs blocks and unrelated PSBs in
general. The ones that are unrelated probably belong to other processes
in the same cgroup.

Differential Revision: https://reviews.llvm.org/D129257

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[trace][intelpt] Support system-wide tracing [20] - Rename some fields in the schema

As discusses offline with @jj10305, we are updating some naming used throughout the code, specially in the json s

[trace][intelpt] Support system-wide tracing [20] - Rename some fields in the schema

As discusses offline with @jj10305, we are updating some naming used throughout the code, specially in the json schema

- traceBuffer -> iptTrace
- core -> cpu

Differential Revision: https://reviews.llvm.org/D127817

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[trace][intelpt] Support system-wide tracing [18] - some more improvements

This applies the changes requested for diff 12.

- use DenseMap<ConstString, _> instead of std::unordered_map<ConstString,

[trace][intelpt] Support system-wide tracing [18] - some more improvements

This applies the changes requested for diff 12.

- use DenseMap<ConstString, _> instead of std::unordered_map<ConstString, _>, which is more idiomatic and possibly performant.
- deduplicate some code in Trace.cpp by using helper functions for fetching in maps
- stop using size and offset when fetching binary data, because we in fact read the entire buffers all the time. If we ever need streaming, we can implement it then. Now, the size is used only to check that we are getting the correct amount of data. This is useful because in some cases determining the size doesn't involve fetching the actual data.
- added back the x86_64 macro to the perf tests
- added more documentation
- simplified some file handling
- fixed some comments

Differential Revision: https://reviews.llvm.org/D127752

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[trace][intelpt] Support system-wide tracing [12] - Support multi-core trace load and save

:q!
This diff is massive, but it's because it connects the client with lldb-server
and also ensures that th

[trace][intelpt] Support system-wide tracing [12] - Support multi-core trace load and save

:q!
This diff is massive, but it's because it connects the client with lldb-server
and also ensures that the postmortem case works.

- Flatten the postmortem trace schema. The reason is that the schema has become quite complex due to the new multicore case, which defeats the original purpose of having a schema that could work for every trace plug-in. At this point, it's better that each trace plug-in defines it's own full schema. This means that the only common field is "type".
-- Because of this new approach, I merged the "common" trace load and saving functionalities into the IntelPT one. This simplified the code quite a bit. If we eventually implement another trace plug-in, we can see then what we could reuse.
-- The new schema, which is flattened, has now better comments and is parsed better. A change I did was to disallow hex addresses, because they are a bit error prone. I'm asking now to print the address in decimal.
-- Renamed "intel" to "GenuineIntel" in the schema because that's what you see in /proc/cpuinfo.
- Implemented reading the context switch trace data buffer. I had to do
some refactors to do that cleanly.
-- A major change that I did here was to simplify the perf_event circular buffer reading logic. It was too complex. Maybe the original Intel author had something different in mind.
- Implemented all the necessary bits to read trace.json files with per-core data.
- Implemented all the necessary bits to save to disk per-core trace session.
- Added a test that ensures that parsing and saving to disk works.

Differential Revision: https://reviews.llvm.org/D126015

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[trace][intelpt] Support system-wide tracing [9] - Collect and return context switch traces

- Add collection of context switches per cpu grouped with the per-cpu intel pt traces.
- Move the state ha

[trace][intelpt] Support system-wide tracing [9] - Collect and return context switch traces

- Add collection of context switches per cpu grouped with the per-cpu intel pt traces.
- Move the state handling from the interl pt trace class to the PerfEvent one.
- Add support for stopping and enabling perf event groups.
- Return context switch entries as part of the jLLDBTraceGetState response.
- Move the triggers of whenever the process stopped or resumed. Now the will-resume notification is in a better location, which will ensure that we'll capture the instructions that will be executed.
- Remove IntelPTSingleBufferTraceUP. The unique pointer was useless.
- Add unit tests

Differential Revision: https://reviews.llvm.org/D125897

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[trace][intelpt] Support system-wide tracing [8] - Improve the single buffer perf_event configuration

We were setting some events to be written in the data buffer of the
perf_event, but we don't nee

[trace][intelpt] Support system-wide tracing [8] - Improve the single buffer perf_event configuration

We were setting some events to be written in the data buffer of the
perf_event, but we don't need that.

Besides that, we don't need the data buffer to be larger than 1, so we
can reduce its size.

Differential Revision: https://reviews.llvm.org/D125850

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Fix conversion error to Expected

On Ubuntu 18.04 with GCC 7.5 Intel trace code fails to build due to
failure to convert from
lldb_private::process_linux::IntelPTPerThreadProcessTraceUP to
Expected<l

Fix conversion error to Expected

On Ubuntu 18.04 with GCC 7.5 Intel trace code fails to build due to
failure to convert from
lldb_private::process_linux::IntelPTPerThreadProcessTraceUP to
Expected<lldb_private::process_linux::IntelPTPerThreadProcessTraceUP>.
This commit explicitely marks those unique_ptr values as being moved
which fixes the conversion error.

Reviewed By: wallace

Differential Revision: https://reviews.llvm.org/D126402

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[trace][intelpt] Support system-wide tracing [5] - Disable/enable per-core tracing based on the process state

When tracing on per-core mode, we are tracing all processes, which means
that after hitt

[trace][intelpt] Support system-wide tracing [5] - Disable/enable per-core tracing based on the process state

When tracing on per-core mode, we are tracing all processes, which means
that after hitting a breakpoint, our process will stop running (thus
producing no more tracing data) but other processes will continue
writing to our trace buffers. This causes a big data loss for our trace.
As a way to remediate this, I'm adding some logic to pause and unpause
tracing based on the target's state. The earlier we do it the better,
however, I'm not adding the trigger at the earliest possible point for
simplicity of this diff. Later we can improve that part.

Differential Revision: https://reviews.llvm.org/D124962

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[trace][intelpt] Support system-wide tracing [4] - Support per core tracing on lldb-server

This diffs implements per-core tracing on lldb-server. It also includes tests that ensure that tracing can

[trace][intelpt] Support system-wide tracing [4] - Support per core tracing on lldb-server

This diffs implements per-core tracing on lldb-server. It also includes tests that ensure that tracing can be initiated from the client and that the jLLDBGetState ppacket returns the list of trace buffers per core.

This doesn't include any decoder changes.

Finally, this makes some little changes here and there improving the existing code.

A specific piece of code that can't reliably be tested is when tracing
per core fails due to permissions. In this case we add a
troubleshooting message and this is the manual test:

```
/proc/sys/kernel/perf_event_paranoid set to 1

(lldb) process trace start --per-core-tracing error: perf event syscall failed: Permission denied
You might need that /proc/sys/kernel/perf_event_paranoid has a value of 0 or -1.
``

Differential Revision: https://reviews.llvm.org/D124858

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[lldb] Fix 7b73de9ec2b19df040c919d3004dfbead9b6ac59

It turns out that the issue in
https://lab.llvm.org/buildbot/#/builders/17/builds/21754 is that a
size_t is attempted to be used inter

[lldb] Fix 7b73de9ec2b19df040c919d3004dfbead9b6ac59

It turns out that the issue in
https://lab.llvm.org/buildbot/#/builders/17/builds/21754 is that a
size_t is attempted to be used interchangeably with uint64_t.

show more ...

[lldb] Fix 7b73de9ec2b19df040c919d3004dfbead9b6ac59

It turns out that the issue in
https://lab.llvm.org/buildbot/#/builders/17/builds/21754 is that a
size_t is attempted to be used interchangeably w

[lldb] Fix 7b73de9ec2b19df040c919d3004dfbead9b6ac59

It turns out that the issue in
https://lab.llvm.org/buildbot/#/builders/17/builds/21754 is that a
size_t is attempted to be used interchangeably with uint64_t.

show more ...

[lldb] Fix 7b73de9ec2b19df040c919d3004dfbead9b6ac59

This commit causes
https://lab.llvm.org/buildbot/#/builders/17/builds/21743 to fail
seemingly because of bad handling of the PERF_ATTR_SIZE_VER5 s

[lldb] Fix 7b73de9ec2b19df040c919d3004dfbead9b6ac59

This commit causes
https://lab.llvm.org/buildbot/#/builders/17/builds/21743 to fail
seemingly because of bad handling of the PERF_ATTR_SIZE_VER5 symbol.

This patch tries to handle better the absence of this symbol.

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[trace][intelpt] Support system-wide tracing [3] - Refactor IntelPTThreadTrace

I'm refactoring IntelPTThreadTrace into IntelPTSingleBufferTrace so that it can
both single threads or single cores. In

[trace][intelpt] Support system-wide tracing [3] - Refactor IntelPTThreadTrace

I'm refactoring IntelPTThreadTrace into IntelPTSingleBufferTrace so that it can
both single threads or single cores. In this diff I'm basically renaming the
class, moving it to its own file, and removing all the pieces that are not used
along with some basic cleanup.

Differential Revision: https://reviews.llvm.org/D124648

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