blob: 9387bf9ff88da95bc887f8c206147c09c06e3081 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
#include <cassert>
#include <cstdint>
#include <cstdio>
#include <sys/mman.h>
#include <unistd.h> // sysconf
extern "C" void thread_create();
extern "C" void yield(void* new_stack, void** old_stack);
long get_pagesize() {
return sysconf(_SC_PAGESIZE);
}
struct Thread {
Thread(const Thread&) = delete;
Thread& operator=(const Thread&) = delete;
Thread(void (*fn)());
static void entry(void* obj);
// private:
void* mStackPtr;
void (*mUserFn)();
};
Thread::Thread(void (*fn)()) : mUserFn(fn) {
const long PAGE_SIZE = get_pagesize();
const long STACK_SIZE = 8 * PAGE_SIZE;
// create new stack
void* stack = mmap(nullptr, STACK_SIZE, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1 /* fd */, 0 /* offset */);
assert(stack != MAP_FAILED);
// protect last stack page (lowest addr)
int ret = mprotect(stack, PAGE_SIZE, PROT_NONE);
assert(ret == 0);
// stack grows downwards
mStackPtr = static_cast<uint8_t*>(stack) + STACK_SIZE;
{
uint64_t* stack = static_cast<uint64_t*>(mStackPtr);
*(--stack) = (uint64_t)this;
*(--stack) = (uint64_t)Thread::entry;
// initial values for yield epilog
*(--stack) = (uint64_t)thread_create;
*(--stack) = (uint64_t)0;
// initial values for callee saved regs
*(--stack) = (uint64_t)0; // rbx
*(--stack) = (uint64_t)(static_cast<uint64_t*>(mStackPtr) - 4); // rbp
*(--stack) = (uint64_t)0; // r12
*(--stack) = (uint64_t)0; // r13
*(--stack) = (uint64_t)0; // r14
*(--stack) = (uint64_t)0; // r15
mStackPtr = static_cast<void*>(stack);
}
}
void Thread::entry(void* obj) {
Thread* t = static_cast<Thread*>(obj);
puts("thread entry");
t->mUserFn();
puts("thread done");
}
void* gOriginalStack;
void yield_to(const Thread& t) {
yield(t.mStackPtr, &gOriginalStack);
}
void yield_from(Thread& t) {
yield(gOriginalStack, &t.mStackPtr);
}
|
