Fix(sim): pass context helpers to AICore SO instead of dlsym(RTLD_DEFAULT)

[hw-native-sys-bot]

Summary

The AICore kernel SO used dlsym(RTLD_DEFAULT, "pto_cpu_sim_*") to resolve sim context functions defined in cpu_sim_context.cpp. This works with RTLD_GLOBAL but fails with RTLD_LOCAL — the symbols are not in the global table, so dlsym(RTLD_DEFAULT) returns NULL.

This is a prerequisite for loading libhost_runtime.so with RTLD_LOCAL (needed when multiple runtimes coexist in the same process without symbol pollution).

Fix: Replace dlsym(RTLD_DEFAULT) with explicit function pointer injection:

• kernel.cpp (a2a3 + a5): add set_sim_context_helpers() extern-C entry point, stores 3 function pointers
• inner_kernel.h (a2a3 + a5): use stored pointers instead of static auto fn = dlsym(RTLD_DEFAULT, ...)
• device_runner.cpp (a2a3 + a5): call set_sim_context_helpers() after loading AICore SO
• cpu_sim_context.h (a2a3 + a5): declare the extern-C context functions for device_runner

No behavioral change with current RTLD_GLOBAL loading — the function pointers are resolved at the same time (AICore SO load) and point to the same functions.

Testing

• python ci.py -p a2a3sim -c 6622890 -t 600 — 20/20 PASS

[gemini-code-assist]

Code Review

This pull request refactors the simulation context bridging between the AICore kernel and host runtime for the a2a3 and a5 platforms. By replacing dlsym(RTLD_DEFAULT) with an explicit function pointer registration mechanism (set_sim_context_helpers), the implementation avoids resolution failures when the host library is loaded with RTLD_LOCAL. The review feedback recommends enhancing the robustness of symbol resolution in DeviceRunner by using dlerror() to check for errors after calling dlsym and ensuring proper error reporting.

[gemini-code-assist]

To robustly check for errors with dlsym, call dlerror() to clear any prior errors before the call, and then check the result of dlerror() afterwards. Additionally, ensure that resource cleanup (like dlclose) is handled if initialization fails to prevent leaks.

Suggested change

	auto set_helpers =
	reinterpret_cast<void (*)(void *, void *, void *)>(dlsym(aicore_so_handle_, "set_sim_context_helpers"));
	if (set_helpers != nullptr) {
	set_helpers(
	reinterpret_cast<void *>(pto_cpu_sim_set_execution_context),
	reinterpret_cast<void *>(pto_cpu_sim_set_task_cookie),
	reinterpret_cast<void *>(platform_get_cpu_sim_task_cookie)
	);
	}
	(void)dlerror();
	auto set_helpers = reinterpret_cast<void (*)(void *, void *, void *)>(dlsym(aicore_so_handle_, "set_sim_context_helpers"));
	const char *dlsym_err = dlerror();
	if (dlsym_err != nullptr) {
	LOG_ERROR("dlsym failed for set_sim_context_helpers: %s", dlsym_err);
	return -1;
	}
	set_helpers(reinterpret_cast<void *>(pto_cpu_sim_set_execution_context), reinterpret_cast<void *>(pto_cpu_sim_set_task_cookie),
	reinterpret_cast<void *>(platform_get_cpu_sim_task_cookie));

References

1. To robustly check for errors with dlsym, call dlerror() to clear any prior errors, then call dlsym, and then check the result of dlerror() to see if an error occurred.
2. To prevent resource leaks with handles acquired via dlopen, use a try-catch block to ensure dlclose is called if any subsequent initialization steps fail.

[gemini-code-assist]

To robustly check for errors with dlsym, call dlerror() to clear any prior errors before the call, and then check the result of dlerror() afterwards. Additionally, ensure that resource cleanup (like dlclose) is handled if initialization fails to prevent leaks.

Suggested change

	auto set_helpers =
	reinterpret_cast<void (*)(void *, void *, void *)>(dlsym(aicore_so_handle_, "set_sim_context_helpers"));
	if (set_helpers != nullptr) {
	set_helpers(
	reinterpret_cast<void *>(pto_cpu_sim_set_execution_context),
	reinterpret_cast<void *>(pto_cpu_sim_set_task_cookie),
	reinterpret_cast<void *>(platform_get_cpu_sim_task_cookie)
	);
	}
	(void)dlerror();
	auto set_helpers = reinterpret_cast<void (*)(void *, void *, void *)>(dlsym(aicore_so_handle_, "set_sim_context_helpers"));
	const char *dlsym_err = dlerror();
	if (dlsym_err != nullptr) {
	LOG_ERROR("dlsym failed for set_sim_context_helpers: %s", dlsym_err);
	return -1;
	}
	set_helpers(reinterpret_cast<void *>(pto_cpu_sim_set_execution_context), reinterpret_cast<void *>(pto_cpu_sim_set_task_cookie),
	reinterpret_cast<void *>(platform_get_cpu_sim_task_cookie));

References

1. To robustly check for errors with dlsym, call dlerror() to clear any prior errors, then call dlsym, and then check the result of dlerror() to see if an error occurred.
2. To prevent resource leaks with handles acquired via dlopen, use a try-catch block to ensure dlclose is called if any subsequent initialization steps fail.