| // Copyright 2019 The Marl Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| // Minimal assembly implementations of fiber context switching for Unix-based |
| // platforms. |
| // |
| // Note: Unlike makecontext, swapcontext or the Windows fiber APIs, these |
| // assembly implementations *do not* save or restore signal masks, |
| // floating-point control or status registers, FS and GS segment registers, |
| // thread-local storage state nor any SIMD registers. This should not be a |
| // problem as the marl scheduler requires fibers to be executed on the same |
| // thread throughout their lifetime. |
| |
| #if defined(__x86_64__) |
| #include "osfiber_asm_x64.h" |
| #elif defined(__i386__) |
| #include "osfiber_asm_x86.h" |
| #elif defined(__aarch64__) |
| #include "osfiber_asm_aarch64.h" |
| #elif defined(__arm__) |
| #include "osfiber_asm_arm.h" |
| #elif defined(__powerpc64__) |
| #include "osfiber_asm_ppc64.h" |
| #elif defined(__mips__) && _MIPS_SIM == _ABI64 |
| #include "osfiber_asm_mips64.h" |
| #elif defined(__riscv) && __riscv_xlen == 64 |
| #include "osfiber_asm_rv64.h" |
| #else |
| #error "Unsupported target" |
| #endif |
| |
| #include "marl/export.h" |
| #include "marl/memory.h" |
| |
| #include <functional> |
| #include <memory> |
| |
| extern "C" { |
| |
| MARL_EXPORT |
| extern void marl_fiber_set_target(marl_fiber_context*, |
| void* stack, |
| uint32_t stack_size, |
| void (*target)(void*), |
| void* arg); |
| MARL_EXPORT |
| extern void marl_fiber_swap(marl_fiber_context* from, |
| const marl_fiber_context* to); |
| |
| } // extern "C" |
| |
| namespace marl { |
| |
| class OSFiber { |
| public: |
| inline OSFiber(Allocator*); |
| inline ~OSFiber(); |
| |
| // createFiberFromCurrentThread() returns a fiber created from the current |
| // thread. |
| MARL_NO_EXPORT static inline Allocator::unique_ptr<OSFiber> |
| createFiberFromCurrentThread(Allocator* allocator); |
| |
| // createFiber() returns a new fiber with the given stack size that will |
| // call func when switched to. func() must end by switching back to another |
| // fiber, and must not return. |
| MARL_NO_EXPORT static inline Allocator::unique_ptr<OSFiber> createFiber( |
| Allocator* allocator, |
| size_t stackSize, |
| const std::function<void()>& func); |
| |
| // switchTo() immediately switches execution to the given fiber. |
| // switchTo() must be called on the currently executing fiber. |
| MARL_NO_EXPORT inline void switchTo(OSFiber*); |
| |
| private: |
| MARL_NO_EXPORT |
| static inline void run(OSFiber* self); |
| |
| Allocator* allocator; |
| marl_fiber_context context; |
| std::function<void()> target; |
| Allocation stack; |
| }; |
| |
| OSFiber::OSFiber(Allocator* allocator) : allocator(allocator) {} |
| |
| OSFiber::~OSFiber() { |
| if (stack.ptr != nullptr) { |
| allocator->free(stack); |
| } |
| } |
| |
| Allocator::unique_ptr<OSFiber> OSFiber::createFiberFromCurrentThread( |
| Allocator* allocator) { |
| auto out = allocator->make_unique<OSFiber>(allocator); |
| out->context = {}; |
| return out; |
| } |
| |
| Allocator::unique_ptr<OSFiber> OSFiber::createFiber( |
| Allocator* allocator, |
| size_t stackSize, |
| const std::function<void()>& func) { |
| Allocation::Request request; |
| request.size = stackSize; |
| request.alignment = 16; |
| request.usage = Allocation::Usage::Stack; |
| #if MARL_USE_FIBER_STACK_GUARDS |
| request.useGuards = true; |
| #endif |
| |
| auto out = allocator->make_unique<OSFiber>(allocator); |
| out->context = {}; |
| out->target = func; |
| out->stack = allocator->allocate(request); |
| marl_fiber_set_target( |
| &out->context, out->stack.ptr, static_cast<uint32_t>(stackSize), |
| reinterpret_cast<void (*)(void*)>(&OSFiber::run), out.get()); |
| return out; |
| } |
| |
| void OSFiber::run(OSFiber* self) { |
| self->target(); |
| } |
| |
| void OSFiber::switchTo(OSFiber* fiber) { |
| marl_fiber_swap(&context, &fiber->context); |
| } |
| |
| } // namespace marl |