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 /** Many integers are needed to store a pointer
22 * Support up to two ints. */
23 constexpr int CTX_ADDR_LEN = 2;
25 static_assert(sizeof(simgrid::kernel::context::UContext*) <= CTX_ADDR_LEN * sizeof(int),
26 "Ucontexts are not supported on this arch yet");
33 Context* UContextFactory::create_context(std::function<void()> code, void_pfn_smxprocess_t cleanup, smx_actor_t process)
35 return new_context<UContext>(std::move(code), cleanup, process, this);
41 UContext::UContext(std::function<void()> code, void_pfn_smxprocess_t cleanup_func, smx_actor_t process,
42 SwappedContextFactory* factory)
43 : SwappedContext(std::move(code), cleanup_func, process, factory)
45 /* if the user provided a function for the process then use it, otherwise it is the context for maestro */
47 getcontext(&this->uc_);
48 this->uc_.uc_link = nullptr;
49 this->uc_.uc_stack.ss_sp = sg_makecontext_stack_addr(get_stack());
50 this->uc_.uc_stack.ss_size = sg_makecontext_stack_size(smx_context_usable_stack_size);
51 #if PTH_STACKGROWTH == -1
52 ASAN_ONLY(this->asan_stack_ = static_cast<char*>(get_stack()) + smx_context_usable_stack_size);
54 ASAN_ONLY(this->asan_stack_ = get_stack());
56 UContext::make_ctx(&this->uc_, UContext::smx_ctx_sysv_wrapper, this);
60 if (MC_is_active() && has_code()) {
61 MC_register_stack_area(get_stack(), process, &(this->uc_), smx_context_usable_stack_size);
66 // The name of this function is currently hardcoded in the code (as string).
67 // Do not change it without fixing those references as well.
68 void UContext::smx_ctx_sysv_wrapper(int i1, int i2)
70 // Rebuild the Context* pointer from the integers:
71 int ctx_addr[CTX_ADDR_LEN] = {i1, i2};
72 simgrid::kernel::context::UContext* context;
73 memcpy(&context, ctx_addr, sizeof context);
75 ASAN_FINISH_SWITCH(nullptr, &context->asan_ctx_->asan_stack_, &context->asan_ctx_->asan_stack_size_);
78 } catch (simgrid::kernel::context::Context::StopRequest const&) {
79 XBT_DEBUG("Caught a StopRequest");
80 } catch (simgrid::Exception const& e) {
81 XBT_INFO("Actor killed by an uncatched exception %s", simgrid::xbt::demangle(typeid(e).name()).get());
84 context->Context::stop();
85 ASAN_ONLY(context->asan_stop_ = true);
89 /** A better makecontext
91 * Makecontext expects integer arguments, we the context variable is decomposed into a serie of integers and each
92 * integer is passed as argument to makecontext.
94 void UContext::make_ctx(ucontext_t* ucp, void (*func)(int, int), UContext* arg)
96 int ctx_addr[CTX_ADDR_LEN]{};
97 memcpy(ctx_addr, &arg, sizeof arg);
98 makecontext(ucp, (void (*)())func, 2, ctx_addr[0], ctx_addr[1]);
101 void UContext::swap_into(SwappedContext* to_)
103 UContext* to = static_cast<UContext*>(to_);
104 ASAN_ONLY(void* fake_stack = nullptr);
105 ASAN_ONLY(to->asan_ctx_ = this);
106 ASAN_START_SWITCH(this->asan_stop_ ? nullptr : &fake_stack, to->asan_stack_, to->asan_stack_size_);
107 swapcontext(&this->uc_, &to->uc_);
108 ASAN_FINISH_SWITCH(fake_stack, &this->asan_ctx_->asan_stack_, &this->asan_ctx_->asan_stack_size_);
112 XBT_PRIVATE ContextFactory* sysv_factory()
114 XBT_VERB("Activating SYSV context factory");
115 return new UContextFactory();
117 }}} // namespace simgrid::kernel::context