-/* Copyright (c) 2009-2018. The SimGrid Team. All rights reserved. */
+/* Copyright (c) 2009-2021. The SimGrid Team. All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
* under the terms of the license (GNU LGPL) which comes with this package. */
-#include "src/kernel/context/context_private.hpp"
-#include "src/simix/ActorImpl.hpp"
+#include "simgrid/Exception.hpp"
+#include "simgrid/modelchecker.h"
+#include "src/internal_config.h"
+#include "src/kernel/actor/ActorImpl.hpp"
#include "src/simix/smx_private.hpp"
+#include "xbt/parmap.hpp"
-#include "ContextSwapped.hpp"
+#include "src/kernel/context/ContextSwapped.hpp"
+
+#include <memory>
+
+#ifdef _WIN32
+#include <malloc.h>
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#endif
+
+#ifdef __MINGW32__
+#define _aligned_malloc __mingw_aligned_malloc
+#define _aligned_free __mingw_aligned_free
+#endif /*MINGW*/
+
+#if HAVE_VALGRIND_H
+#include <valgrind/valgrind.h>
+#endif
+#if HAVE_SANITIZER_ADDRESS_FIBER_SUPPORT
+#include <sanitizer/asan_interface.h>
+#endif
+#if HAVE_SANITIZER_THREAD_FIBER_SUPPORT
+#include <sanitizer/tsan_interface.h>
+#endif
XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(simix_context);
+// The name of this function is currently hardcoded in MC (as string).
+// Do not change it without fixing those references as well.
+void smx_ctx_wrapper(simgrid::kernel::context::SwappedContext* context)
+{
+#if HAVE_SANITIZER_ADDRESS_FIBER_SUPPORT
+ __sanitizer_finish_switch_fiber(nullptr, &context->asan_ctx_->asan_stack_, &context->asan_ctx_->asan_stack_size_);
+#endif
+ try {
+ (*context)();
+ context->Context::stop();
+ } catch (simgrid::ForcefulKillException const&) {
+ XBT_DEBUG("Caught a ForcefulKillException");
+ } catch (simgrid::Exception const& e) {
+ XBT_INFO("Actor killed by an uncaught exception %s", simgrid::xbt::demangle(typeid(e).name()).get());
+ throw;
+ }
+#if HAVE_SANITIZER_ADDRESS_FIBER_SUPPORT
+ context->asan_stop_ = true;
+#endif
+ context->suspend();
+ THROW_IMPOSSIBLE;
+}
+
namespace simgrid {
namespace kernel {
namespace context {
-unsigned long SwappedContext::process_index_;
-
-SwappedContext* SwappedContext::maestro_context_ = nullptr;
+/* thread-specific storage for the worker's context */
+thread_local SwappedContext* SwappedContext::worker_context_ = nullptr;
-void SwappedContext::suspend()
+SwappedContext::SwappedContext(std::function<void()>&& code, smx_actor_t actor, SwappedContextFactory* factory)
+ : Context(std::move(code), actor), factory_(*factory)
{
- /* determine the next context */
- SwappedContext* next_context;
- unsigned long int i = process_index_;
- process_index_++;
+ // Save maestro (=first created context) in preparation for run_all
+ if (not SIMIX_context_is_parallel() && factory_.maestro_context_ == nullptr)
+ factory_.maestro_context_ = this;
+
+ if (has_code()) {
+ xbt_assert((actor->get_stacksize() & 0xf) == 0, "Actor stack size should be multiple of 16");
+ if (smx_context_guard_size > 0 && not MC_is_active()) {
+#if PTH_STACKGROWTH != -1
+ xbt_die(
+ "Stack overflow protection is known to be broken on your system: you stacks grow upwards (or detection is "
+ "broken). "
+ "Please disable stack guards with --cfg=contexts:guard-size:0");
+ /* Current code for stack overflow protection assumes that stacks are growing downward (PTH_STACKGROWTH == -1).
+ * Protected pages need to be put after the stack when PTH_STACKGROWTH == 1. */
+#endif
+
+ size_t size = actor->get_stacksize() + smx_context_guard_size;
+#if SIMGRID_HAVE_MC
+ /* Cannot use posix_memalign when SIMGRID_HAVE_MC. Align stack by hand, and save the
+ * pointer returned by xbt_malloc0. */
+ auto* alloc = static_cast<unsigned char*>(xbt_malloc0(size + xbt_pagesize));
+ stack_ = alloc - (reinterpret_cast<uintptr_t>(alloc) & (xbt_pagesize - 1)) + xbt_pagesize;
+ reinterpret_cast<unsigned char**>(stack_)[-1] = alloc;
+#elif !defined(_WIN32)
+ void* alloc;
+ if (posix_memalign(&alloc, xbt_pagesize, size) != 0)
+ xbt_die("Failed to allocate stack.");
+ this->stack_ = static_cast<unsigned char*>(alloc);
+#else
+ this->stack_ = static_cast<unsigned char*>(_aligned_malloc(size, xbt_pagesize));
+#endif
- if (i < simix_global->process_to_run.size()) {
- /* execute the next process */
- XBT_DEBUG("Run next process");
- next_context = static_cast<SwappedContext*>(simix_global->process_to_run[i]->context_);
+#ifndef _WIN32
+ if (mprotect(this->stack_, smx_context_guard_size, PROT_NONE) == -1) {
+ xbt_die(
+ "Failed to protect stack: %s.\n"
+ "If you are running a lot of actors, you may be exceeding the amount of mappings allowed per process.\n"
+ "On Linux systems, change this value with sudo sysctl -w vm.max_map_count=newvalue (default value: 65536)\n"
+ "Please see "
+ "https://simgrid.org/doc/latest/Configuring_SimGrid.html#configuring-the-user-code-virtualization for more "
+ "information.",
+ strerror(errno));
+ /* This is fatal. We are going to fail at some point when we try reusing this. */
+ }
+#endif
+ this->stack_ = this->stack_ + smx_context_guard_size;
+ } else {
+ this->stack_ = static_cast<unsigned char*>(xbt_malloc0(actor->get_stacksize()));
+ }
+
+#if HAVE_VALGRIND_H
+ if (RUNNING_ON_VALGRIND)
+ this->valgrind_stack_id_ = VALGRIND_STACK_REGISTER(this->stack_, this->stack_ + actor->get_stacksize());
+#endif
+#if HAVE_SANITIZER_ADDRESS_FIBER_SUPPORT
+ this->asan_stack_ = get_stack_bottom();
+#endif
+#if HAVE_SANITIZER_THREAD_FIBER_SUPPORT
+ this->tsan_fiber_ = __tsan_create_fiber(0);
+#endif
} else {
- /* all processes were run, return to maestro */
- XBT_DEBUG("No more process to run");
- next_context = static_cast<SwappedContext*>(get_maestro());
+ // not has_code(): in maestro context
+#if HAVE_SANITIZER_THREAD_FIBER_SUPPORT
+ this->tsan_fiber_ = __tsan_get_current_fiber();
+#endif
}
- Context::set_current(next_context);
- this->swap_into(next_context);
}
+SwappedContext::~SwappedContext()
+{
+ if (stack_ == nullptr) // maestro has no extra stack
+ return;
+
+#if HAVE_SANITIZER_THREAD_FIBER_SUPPORT
+ __tsan_destroy_fiber(tsan_fiber_);
+#endif
+#if HAVE_VALGRIND_H
+ if (RUNNING_ON_VALGRIND)
+ VALGRIND_STACK_DEREGISTER(valgrind_stack_id_);
+#endif
+
+#ifndef _WIN32
+ if (smx_context_guard_size > 0 && not MC_is_active()) {
+ stack_ = stack_ - smx_context_guard_size;
+ if (mprotect(stack_, smx_context_guard_size, PROT_READ | PROT_WRITE) == -1) {
+ XBT_WARN("Failed to remove page protection: %s", strerror(errno));
+ /* try to pursue anyway */
+ }
+#if SIMGRID_HAVE_MC
+ /* Retrieve the saved pointer. See SIMIX_context_stack_new above. */
+ stack_ = reinterpret_cast<unsigned char**>(stack_)[-1];
+#endif
+ }
+#endif /* not windows */
+
+ xbt_free(stack_);
+}
+
+unsigned char* SwappedContext::get_stack_bottom() const
+{
+ // Depending on the stack direction, its bottom (that make_fcontext needs) may be the lower or higher end
+#if PTH_STACKGROWTH == 1
+ return stack_;
+#else
+ return stack_ + get_actor()->get_stacksize();
+#endif
+}
+
+void SwappedContext::stop()
+{
+ Context::stop();
+ /* We must cut the actor execution using an exception to properly free the C++ RAII variables */
+ throw ForcefulKillException();
+}
+
+void SwappedContext::swap_into(SwappedContext* to)
+{
+#if HAVE_SANITIZER_ADDRESS_FIBER_SUPPORT
+ void* fake_stack = nullptr;
+ to->asan_ctx_ = this;
+ __sanitizer_start_switch_fiber(this->asan_stop_ ? nullptr : &fake_stack, to->asan_stack_, to->asan_stack_size_);
+#endif
+#if HAVE_SANITIZER_THREAD_FIBER_SUPPORT
+ __tsan_switch_to_fiber(to->tsan_fiber_, 0);
+#endif
+
+ swap_into_for_real(to);
+
+#if HAVE_SANITIZER_ADDRESS_FIBER_SUPPORT
+ __sanitizer_finish_switch_fiber(fake_stack, &this->asan_ctx_->asan_stack_, &this->asan_ctx_->asan_stack_size_);
+#endif
+}
+
+/** Maestro wants to run all ready actors */
+void SwappedContextFactory::run_all()
+{
+ /* This function is called by maestro at the beginning of a scheduling round to get all working threads executing some
+ * stuff It is much easier to understand what happens if you see the working threads as bodies that swap their soul
+ * for the ones of the simulated processes that must run.
+ */
+ if (SIMIX_context_is_parallel()) {
+ // We lazily create the parmap so that all options are actually processed when doing so.
+ if (parmap_ == nullptr)
+ parmap_ = std::make_unique<simgrid::xbt::Parmap<smx_actor_t>>(SIMIX_context_get_nthreads(),
+ SIMIX_context_get_parallel_mode());
+
+ // Usually, Parmap::apply() executes the provided function on all elements of the array.
+ // Here, the executed function does not return the control to the parmap before all the array is processed:
+ // - suspend() should switch back to the worker_context (either maestro or one of its minions) to return
+ // the control to the parmap. Instead, it uses parmap_->next() to steal another work, and does it directly.
+ // It only yields back to worker_context when the work array is exhausted.
+ // - So, resume() is only launched from the parmap for the first job of each minion.
+ parmap_->apply(
+ [](const actor::ActorImpl* process) {
+ auto* context = static_cast<SwappedContext*>(process->context_.get());
+ context->resume();
+ },
+ simix_global->actors_to_run);
+ } else { // sequential execution
+ if (simix_global->actors_to_run.empty())
+ return;
+
+ /* maestro is already saved in the first slot of workers_context_ */
+ const actor::ActorImpl* first_actor = simix_global->actors_to_run.front();
+ process_index_ = 1;
+ /* execute the first actor; it will chain to the others when using suspend() */
+ static_cast<SwappedContext*>(first_actor->context_.get())->resume();
+ }
+}
+
+/** Maestro wants to yield back to a given actor, so awake it on the current thread
+ *
+ * In parallel, it is only applied to the N first elements of the parmap array,
+ * where N is the amount of worker threads in the parmap.
+ * See SwappedContextFactory::run_all for details.
+ */
void SwappedContext::resume()
{
- SwappedContext* old = static_cast<SwappedContext*>(self());
+ auto* old = static_cast<SwappedContext*>(self());
+ if (SIMIX_context_is_parallel()) {
+ // Save my current soul (either maestro, or one of the minions) in a thread-specific area
+ worker_context_ = old;
+ }
+ // Switch my soul and the actor's one
Context::set_current(this);
old->swap_into(this);
+ // No body runs that soul anymore at this point, but it is stored in a safe place.
+ // When the executed actor will do a blocking action, ActorImpl::yield() will call suspend(), below.
}
-void SwappedContext::run_all()
+/** The actor wants to yield back to maestro, because it is blocked in a simcall (i.e., in ActorImpl::yield())
+ *
+ * Actually, it does not really yield back to maestro, but directly into the next executable actor.
+ *
+ * This makes the parmap::apply awkward (see SwappedContextFactory::run_all()) because it only apply regularly
+ * on the few first elements of the array, but it saves a lot of context switches back to maestro,
+ * and directly forth to the next executable actor.
+ */
+void SwappedContext::suspend()
{
- if (simix_global->process_to_run.empty())
- return;
- smx_actor_t first_process = simix_global->process_to_run.front();
- process_index_ = 1;
- /* execute the first process */
- static_cast<SwappedContext*>(first_process->context_)->resume();
+ SwappedContext* next_context;
+ if (SIMIX_context_is_parallel()) {
+ // Get some more work to directly swap into the next executable actor instead of yielding back to the parmap
+ boost::optional<smx_actor_t> next_work = factory_.parmap_->next();
+ if (next_work) {
+ // There is a next soul to embody (ie, another executable actor)
+ XBT_DEBUG("Run next process");
+ next_context = static_cast<SwappedContext*>(next_work.get()->context_.get());
+ } else {
+ // All actors were run, go back to the parmap context
+ XBT_DEBUG("No more actors to run");
+ // worker_context_ is my own soul, stored in thread_local when starting the scheduling round
+ next_context = worker_context_;
+ // When given that soul, the body will wait for the next scheduling round
+ }
+ } else { // sequential execution
+ /* determine the next context */
+ unsigned long int i = factory_.process_index_;
+ factory_.process_index_++;
+
+ if (i < simix_global->actors_to_run.size()) {
+ /* Actually swap into the next actor directly without transiting to maestro */
+ XBT_DEBUG("Run next actor");
+ next_context = static_cast<SwappedContext*>(simix_global->actors_to_run[i]->context_.get());
+ } else {
+ /* all processes were run, actually return to maestro */
+ XBT_DEBUG("No more actors to run");
+ next_context = factory_.maestro_context_;
+ }
+ }
+ Context::set_current(next_context);
+ this->swap_into(next_context);
}
+
} // namespace context
} // namespace kernel
} // namespace simgrid
