Enable PC sampling with attach/detach: add code_object tracking and dedicated background thread for attach/detach to prevent deadlocks

[julijose-amd]

Summary

PC Sampling: Code Object Tracking in Attach/Detach Mode

• PC sampling relies on CodeobjTableTranslatorSynchronized to map sampled PC addresses to code object IDs. In non-attach mode, this is populated via hsa_executable_freeze / hsa_executable_destroy hooks. In attach/detach mode, these hooks are not available as the profiler attaches after HSA initialization, so hsa_executable_freeze has already been called for all loaded executables. Without the attach table path, the translation table remains empty and PC samples cannot be correlated to code objects.
• Added a new initialization path in pc_sampling/code_object that uses the attach dispatch table to enumerate already‑loaded code objects and register a chained notify callback for newly loaded ones.
• Ensures CodeobjTableTranslatorSynchronized is correctly populated, enabling PC address → code object correlation when attaching mid‑execution.
• Skip buffer flushing for pre‑existing code objects during attach initialization, since the PC sampling service may not yet be active.
• Introduced pc_sampling::code_object::initialize(rocattach_api) and integrated it into registration.cpp so the PC sampling code object module initializes when rocattach registers.

Background Thread to avoid deadlocks during Attach/Detach

• Previously, ptrace‑based code injection targeted the main application thread, which could deadlock if that thread held internal mutexes.
• Added a dedicated idle background thread in librocprofiler-sdk-attach that:
  • Names itself "rocp-bg-attach" via pthread_setname_np
  • Blocks all signals
  • Waits on a condition variable indefinitely
  • Avoids taking any application‑owned locks
• The attacher now locates this safe injection thread by scanning /proc/<pid>/task/*/comm for "rocp-bg-attach" and uses its TID for all ptrace operations.

Changes

• pc_sampling/code_object.cpp

  • Added executable_freeze_internal() shared logic for HSA hook path and the attach path
  • Added chained_notify_new_code_object() for callback chaining
  • Added load_attach_code_objects() for attach‑time initialization
  • Added initialize(RocAttachDispatchTable*) overload

• pc_sampling/code_object.hpp

  • Included "lib/rocprofiler-sdk-attach/table.h"
  • Declared initialize(RocAttachDispatchTable*) overload

• registration.cpp

  • Initialize PC sampling code_object module when rocattach registers
    (guarded by ROCPROFILER_SDK_HSA_PC_SAMPLING)

• rocprofiler-sdk-attach/attach.cpp

  • Added BackgroundThread with thread naming, signal blocking, and idle wait

• rocprofiler-sdk-rocattach/rocattach.cpp

  • Added resolve_attach_tid() to scan /proc/<pid>/task/*/comm
  • Updated setup() to use the background thread’s TID

Testing

• Verified PC sampling with attach/detach on the transpose application — no deadlocks across multiple runs.
• Confirmed background thread TID discovery via /proc/<pid>/task/*/comm.
• The generated PC sampling CSV output contains:
  • Instruction addresses
  • Dispatch IDs
  • Correlation IDs

[meserve-amd]

Looks good so far, some minor comments on the draft
Please add tests or add-on to existing tests in the full PR

[meserve-amd]

Suggested change

	#include <condition_variable>
	#include <mutex>
	#include <signal.h>
	#include <thread>
	#include <unistd.h>
	#include <signal.h>
	#include <unistd.h>
	#include <condition_variable>
	#include <mutex>
	#include <thread>

Give system headers their own category separate from C++ library headers

[meserve-amd]

Prefer to use the rocprofiler common::static_object and hide this in a separate "get" function
See here for an example.
Available in lib/common/static_object.hpp