1 /* Copyright (c) 2009-2019. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 /* \file UContext.cpp Context switching with ucontexts from System V */
8 #include "context_private.hpp"
11 #include "simgrid/Exception.hpp"
12 #include "src/mc/mc_ignore.hpp"
13 #include "src/simix/ActorImpl.hpp"
14 #include "src/simix/smx_private.hpp"
16 #include "ContextUnix.hpp"
18 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(simix_context);
20 /** Up to two integers may be needed to store a pointer on the system we target */
21 constexpr int CTX_ADDR_LEN = 2;
23 static_assert(sizeof(simgrid::kernel::context::UContext*) <= CTX_ADDR_LEN * sizeof(int),
24 "Ucontexts are not supported on this arch yet. Please increase CTX_ADDR_LEN.");
30 // The name of this function is currently hardcoded in MC (as string).
31 // Do not change it without fixing those references as well.
32 static void smx_ctx_wrapper(int i1, int i2)
34 // Rebuild the Context* pointer from the integers:
35 int ctx_addr[CTX_ADDR_LEN] = {i1, i2};
36 simgrid::kernel::context::UContext* context;
37 memcpy(&context, ctx_addr, sizeof context);
39 ASAN_FINISH_SWITCH(nullptr, &context->asan_ctx_->asan_stack_, &context->asan_ctx_->asan_stack_size_);
42 } catch (simgrid::kernel::context::Context::StopRequest const&) {
43 XBT_DEBUG("Caught a StopRequest");
44 } catch (simgrid::Exception const& e) {
45 XBT_INFO("Actor killed by an uncatched exception %s", simgrid::xbt::demangle(typeid(e).name()).get());
48 context->Context::stop();
49 ASAN_ONLY(context->asan_stop_ = true);
54 Context* UContextFactory::create_context(std::function<void()> code, void_pfn_smxprocess_t cleanup, smx_actor_t actor)
56 return new_context<UContext>(std::move(code), cleanup, actor, this);
62 UContext::UContext(std::function<void()> code, void_pfn_smxprocess_t cleanup_func, smx_actor_t actor,
63 SwappedContextFactory* factory)
64 : SwappedContext(std::move(code), cleanup_func, actor, factory)
66 /* if the user provided a function for the actor then use it. If not, nothing to do for maestro. */
68 getcontext(&this->uc_);
69 this->uc_.uc_link = nullptr;
70 this->uc_.uc_stack.ss_sp = sg_makecontext_stack_addr(get_stack());
71 this->uc_.uc_stack.ss_size = sg_makecontext_stack_size(smx_context_usable_stack_size);
72 #if PTH_STACKGROWTH == -1
73 ASAN_ONLY(this->asan_stack_ = static_cast<char*>(get_stack()) + smx_context_usable_stack_size);
75 ASAN_ONLY(this->asan_stack_ = get_stack());
77 // Makecontext expects integer arguments; we want to pass a pointer.
78 // This context address is decomposed into a serie of integers, which are passed as arguments to makecontext.
80 int ctx_addr[CTX_ADDR_LEN]{};
82 memcpy(ctx_addr, &arg, sizeof this);
83 makecontext(&this->uc_, (void (*)())smx_ctx_wrapper, 2, ctx_addr[0], ctx_addr[1]);
87 if (MC_is_active() && has_code()) {
88 MC_register_stack_area(get_stack(), actor, &(this->uc_), smx_context_usable_stack_size);
93 void UContext::swap_into(SwappedContext* to_)
95 UContext* to = static_cast<UContext*>(to_);
96 ASAN_ONLY(void* fake_stack = nullptr);
97 ASAN_ONLY(to->asan_ctx_ = this);
98 ASAN_START_SWITCH(this->asan_stop_ ? nullptr : &fake_stack, to->asan_stack_, to->asan_stack_size_);
99 swapcontext(&this->uc_, &to->uc_);
100 ASAN_FINISH_SWITCH(fake_stack, &this->asan_ctx_->asan_stack_, &this->asan_ctx_->asan_stack_size_);
104 XBT_PRIVATE ContextFactory* sysv_factory()
106 XBT_VERB("Activating SYSV context factory");
107 return new UContextFactory();
109 }}} // namespace simgrid::kernel::context