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/* Copyright (c) 2020 Johannes Stoelp */
#include "thread.h"
#include "arch.h"
#include "executor.h"
#include <cassert>
#include <exception>
#include <iostream>
#include <sys/mman.h> // mmap
#include <unistd.h> // sysconf
namespace {
static long get_pagesize() {
return ::sysconf(_SC_PAGESIZE);
}
} // namespace
namespace nMatcha {
Thread::Thread() : mStackPtr(nullptr), mFinished(false), mExecutor(nullptr) {
const long PAGE_SIZE = get_pagesize();
const long STACK_SIZE = 8 * PAGE_SIZE;
// Allocate new stack.
void* stack = ::mmap(nullptr, STACK_SIZE, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1 /* fd */, 0 /* offset */);
assert(stack != MAP_FAILED);
// Simple stack overflow detection by removing permissions from last
// stack page (lowest addr).
// In theory stack pointer could be decremented by more than one page
// and the page below last stack page could be used. However we don't
// take care of that now and risk the memory corruption.
int ret = ::mprotect(stack, PAGE_SIZE, PROT_NONE);
assert(ret == 0);
// Adjust stack pointer, as stack grows downwards.
mStackPtr = static_cast<uint8_t*>(stack) + STACK_SIZE;
// Arch specific stack initialization.
mStackPtr = init_stack(mStackPtr, Thread::entry, static_cast<void*>(this));
}
void Thread::entry(void* obj) {
Thread* t = static_cast<Thread*>(obj);
try {
t->threadFn();
} catch (const std::exception& e) {
std::cerr << "Thread: caught unhandled std::exception!\n" << e.what() << std::endl;
} catch (...) {
std::cerr << "Thread: caught unhandled unknown exception!" << std::endl;
}
t->mFinished = true;
t->yield();
}
void Thread::yield() {
assert(mExecutor);
::yield(mExecutor->getStackPtr(), &mStackPtr);
}
std::unique_ptr<Thread> FnThread::make(UserFn f) {
return std::make_unique<FnThread>(CreatorToken{}, f);
}
void FnThread::threadFn() {
mUserFn(*this);
}
void FnThread::yield() {
Thread::yield();
}
} // namespace nMatcha
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