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[WIP] Threading phase 2 (#301)

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* Exponential back-off
* Removed "native" specifier
* Abstract away Futex for cthread
* Complete setup for TLS (including main thread)
This commit is contained in:
Florian Lemaitre 2021-10-26 01:02:26 +02:00 committed by GitHub
parent 660ff56d40
commit 45a7435788
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 249 additions and 78 deletions
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13
ape/ape.lds
View file

@ -342,6 +342,19 @@ SECTIONS {
/*END: Read Only Data (only needed for initialization) */
/*END: Read Only Data */
} :Rom
.tdata . : {
_tdata_start = .;
*(SORT_BY_ALIGNMENT(.tdata))
*(SORT_BY_ALIGNMENT(.tdata.*))
_tdata_end = .;
}
.tbss . : {
_tbss_start = .;
*(SORT_BY_ALIGNMENT(.tbss))
*(SORT_BY_ALIGNMENT(.tbss.*))
_tbss_end = .;
}
.data . : {
/*BEGIN: Read/Write Data */

25
examples/thread.c
View file

@ -7,35 +7,44 @@
│ • http://creativecommons.org/publicdomain/zero/1.0/ │
╚─────────────────────────────────────────────────────────────────*/
#endif
#include "libc/calls/calls.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/thread/create.h"
#include "libc/thread/self.h"
#include "libc/thread/detach.h"
#include "libc/thread/join.h"
#include "libc/thread/nativesem.h"
#include "libc/thread/sem.h"
#include "libc/time/time.h"
cthread_native_sem_t semaphore;
cthread_sem_t semaphore;
__thread int test_tls = 0x12345678;
int worker(void* arg) {
cthread_native_sem_signal(&semaphore);
void* p;
arch_prctl(ARCH_GET_FS, &p);
cthread_sem_signal(&semaphore);
cthread_t self = cthread_self();
int tid = self->tid;
sleep(1);
//sleep(10000);
//printf("[%p] %d\n", self, tid);
printf("[%p] %d -> 0x%x\n", self, tid, test_tls);
(void)arg;
return 4;
}
int main() {
cthread_native_sem_init(&semaphore, 0);
cthread_t self = cthread_self();
int tid = self->tid;
printf("[%p] %d -> 0x%x\n", self, tid, test_tls);
cthread_sem_init(&semaphore, 0);
cthread_t thread;
int rc = cthread_create(&thread, NULL, &worker, NULL);
if (rc == 0) {
cthread_native_sem_wait(&semaphore, 0, 0, NULL);
cthread_sem_wait(&semaphore, 0, NULL);
//printf("thread created: %p\n", thread);
sleep(1);
#if 1
@ -44,8 +53,8 @@ int main() {
rc = cthread_detach(thread);
sleep(2);
#endif
cthread_native_sem_signal(&semaphore);
cthread_native_sem_wait(&semaphore, 0, 0, NULL);
cthread_sem_signal(&semaphore);
cthread_sem_wait(&semaphore, 0, NULL);
//printf("thread joined: %p -> %d\n", thread, rc);
} else {
printf("ERROR: thread could not be started: %d\n", rc);

1
libc/runtime/cosmo.S
View file

@ -45,6 +45,7 @@ cosmo: push %rbp
pop %rax
#endif
call _init
call _main_thread_init # FIXME: use .init.start macro
ezlea __init_array_start,ax # static ctors in forward order
.weak __init_array_start # could be called multiple times
ezlea __init_array_end,cx # idempotency recommended

68
libc/runtime/cthread_init.c Normal file
View file

@ -0,0 +1,68 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/nr.h"
#include "libc/sysv/consts/prot.h"
#include "libc/thread/descriptor.h"
// TLS boundaries
extern char _tbss_start, _tbss_end, _tdata_start, _tdata_end;
void _main_thread_init(void) {
size_t tbsssize = &_tbss_end - &_tbss_start;
size_t tdatasize = &_tdata_end - &_tdata_start;
size_t tlssize = tbsssize + tdatasize;
size_t totalsize = tlssize + sizeof(struct cthread_descriptor_t);
totalsize = (totalsize + PAGESIZE - 1) & -PAGESIZE;
uintptr_t mem = (uintptr_t)mmap(NULL, totalsize, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (mem == -1) {
abort();
}
void* bottom = (void*)mem;
void* top = (void*)(mem + totalsize);
cthread_t td = (cthread_t)top - 1;
td->self = td;
td->stack.top = NULL;
td->stack.bottom = NULL;
td->tls.top = top;
td->tls.bottom = bottom;
td->alloc.top = top;
td->alloc.bottom = bottom;
td->state = cthread_main;
// Initialize TLS with content of .tdata section
memmove((void*)((uintptr_t)td - tlssize), &_tdata_start, tdatasize);
// Get TID of main thread
int gettid = __NR_gettid;
if (gettid == 0xfff) gettid = __NR_getpid;
td->tid = syscall(gettid);
// Set FS
if (arch_prctl(ARCH_SET_FS, td) != 0) {
abort();
}
}

15
libc/stubs/ld.S
View file

@ -36,6 +36,13 @@
__relo_start = 0
__relo_end = 0
// Thread local boundaries defined by linker script
// @see ape/ape.lds
_tbss_start = 0
_tbss_end = 0
_tdata_start = 0
_tdata_end = 0
.globl _base
.globl ape_xlm
.globl __relo_start
@ -48,6 +55,10 @@
.globl _end
.globl _ereal
.globl _etext
.globl _tbss_start
.globl _tbss_end
.globl _tdata_start
.globl _tdata_end
.weak _base
.weak ape_xlm
@ -61,3 +72,7 @@
.weak _end
.weak _ereal
.weak _etext
.weak _tbss_start
.weak _tbss_end
.weak _tdata_start
.weak _tdata_end

14
libc/thread/create.c
View file

@ -19,17 +19,25 @@
#include "libc/errno.h"
#include "libc/linux/clone.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/clone.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/nr.h"
#include "libc/sysv/consts/prot.h"
#include "libc/thread/create.h"
// TLS boundaries
extern char _tbss_start, _tbss_end, _tdata_start, _tdata_end;
static cthread_t _thread_allocate(const cthread_attr_t* attr) {
//extern void _main_thread_init(void);
//void (*dummy)(void) = &_main_thread_init;
//asm(""::"r"(dummy));
size_t stacksize = attr->stacksize;
size_t guardsize = attr->guardsize;
// FIXME: properly count TLS size
size_t tlssize = 0;
size_t tbsssize = &_tbss_end - &_tbss_start;
size_t tdatasize = &_tdata_end - &_tdata_start;
size_t tlssize = tbsssize + tdatasize;
size_t totalsize =
3 * guardsize + stacksize + tlssize + sizeof(struct cthread_descriptor_t);
@ -64,6 +72,8 @@ static cthread_t _thread_allocate(const cthread_attr_t* attr) {
td->alloc.bottom = alloc_bottom;
td->state = (attr->mode & CTHREAD_CREATE_DETACHED) ? cthread_detached
: cthread_started;
// Initialize TLS with content of .tdata section
memmove((void*)((uintptr_t)td - tlssize), &_tdata_start, tdatasize);
return td;
}

1
libc/thread/descriptor.h
View file

@ -12,6 +12,7 @@ enum cthread_state {
cthread_joining = 1,
cthread_finished = 2,
cthread_detached = 4,
cthread_main = 127,
};
struct cthread_descriptor_t {

112
libc/thread/nativesem.c → libc/thread/sem.c
View file

@ -17,23 +17,32 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/atomic.h"
#include "libc/sysv/consts/futex.h"
#include "libc/sysv/consts/nr.h"
#include "libc/thread/nativesem.h"
#include "libc/thread/sem.h"
#include "libc/thread/wait.h"
#include "libc/thread/yield.h"
#define CTHREAD_THREAD_VAL_BITS 32
int cthread_native_sem_init(cthread_native_sem_t* sem, int count) {
static void pause(int attempt) {
if (attempt < 16) {
for (int i = 0; i < (1 << attempt); ++i) {
asm("pause");
}
} else {
cthread_yield();
}
}
int cthread_sem_init(cthread_sem_t* sem, int count) {
sem->linux.count = count;
return 0;
}
int cthread_native_sem_destroy(cthread_native_sem_t* sem) {
int cthread_sem_destroy(cthread_sem_t* sem) {
(void)sem;
return 0;
}
int cthread_native_sem_signal(cthread_native_sem_t* sem) {
int cthread_sem_signal(cthread_sem_t* sem) {
uint64_t count;
asm volatile("lock xadd\t%1, %0"
: "+m"(sem->linux.count), "=r"(count)
@ -41,21 +50,15 @@ int cthread_native_sem_signal(cthread_native_sem_t* sem) {
: "cc");
if ((count >> CTHREAD_THREAD_VAL_BITS)) {
int flags = FUTEX_WAKE;
// WARNING: an offset of 4 bytes would be required on little-endian archs
void* wait_address = &sem->linux.count;
asm volatile("syscall"
: /* no outputs */
: "a"(__NR_futex), "D"(wait_address), "S"(flags), "d"(1)
: "rcx", "r11", "cc", "memory");
cthread_memory_wake32(wait_address, 1);
}
return 0;
}
int cthread_native_sem_wait_slow(cthread_native_sem_t* sem,
const struct timespec* timeout) {
int cthread_sem_wait_futex(cthread_sem_t* sem, const struct timespec* timeout) {
uint64_t count;
// record current thread as waiter
@ -66,67 +69,52 @@ int cthread_native_sem_wait_slow(cthread_native_sem_t* sem,
for (;;) {
// try to acquire the semaphore, as well as remove itself from waiters
if ((uint32_t)count > 0 &&
atomic_compare_exchange_weak(
&sem->linux.count, count,
count - 1 - ((uint64_t)1 << CTHREAD_THREAD_VAL_BITS)))
break;
int flags = FUTEX_WAIT;
register struct timespec* timeout_ asm("r10") = timeout;
while ((uint32_t)count > 0) {
// without spin, we could miss a futex wake
if (atomic_compare_exchange_weak(
&sem->linux.count, count,
count - 1 - ((uint64_t)1 << CTHREAD_THREAD_VAL_BITS))) {
return 0;
}
}
// WARNING: an offset of 4 bytes would be required on little-endian archs
void* wait_address = &sem->linux.count;
asm volatile("syscall"
: /* no outputs */
: "a"(__NR_futex), "D"(wait_address), "S"(flags), "d"(count),
"r"(timeout_)
: "rcx", "r11", "cc", "memory");
cthread_memory_wait32(wait_address, count, timeout);
count = atomic_load(&sem->linux.count);
}
return 0;
}
int cthread_native_sem_wait_spin_yield(cthread_native_sem_t* sem,
uint64_t count, int yield,
const struct timespec* timeout) {
// spin on yield
while (yield-- > 0) {
if ((count >> CTHREAD_THREAD_VAL_BITS) != 0)
break; // a thread is already waiting in queue
if ((uint32_t)count > 0 &&
atomic_compare_exchange_weak(&sem->linux.count, count, count - 1))
return 0;
cthread_yield();
}
return cthread_native_sem_wait_slow(sem, timeout);
}
int cthread_native_sem_wait_spin(cthread_native_sem_t* sem, uint64_t count,
int spin, int yield,
const struct timespec* timeout) {
int cthread_sem_wait_spin(cthread_sem_t* sem, uint64_t count, int spin,
const struct timespec* timeout) {
// spin on pause
while (spin-- > 0) {
if ((count >> CTHREAD_THREAD_VAL_BITS) != 0) break;
if ((uint32_t)count > 0 &&
atomic_compare_exchange_weak(&sem->linux.count, count, count - 1))
return 0;
asm volatile("pause");
for (int attempt = 0; attempt < spin; ++attempt) {
//if ((count >> CTHREAD_THREAD_VAL_BITS) != 0) break;
while ((uint32_t)count > 0) {
// spin is useful if multiple waiters can acquire the semaphore at the same time
if (atomic_compare_exchange_weak(&sem->linux.count, count, count - 1)) {
return 0;
}
}
pause(attempt);
}
return cthread_native_sem_wait_spin_yield(sem, count, yield, timeout);
return cthread_sem_wait_futex(sem, timeout);
}
int cthread_native_sem_wait(cthread_native_sem_t* sem, int spin, int yield,
const struct timespec* timeout) {
int cthread_sem_wait(cthread_sem_t* sem, int spin,
const struct timespec* timeout) {
uint64_t count = atomic_load(&sem->linux.count);
// uncontended
if ((count >> 32) == 0 && (uint32_t)count > 0 &&
atomic_compare_exchange_weak(&sem->linux.count, count, count - 1))
return 0;
return cthread_native_sem_wait_spin(sem, count, spin, yield, timeout);
while ((uint32_t)count > 0) {
// spin is useful if multiple waiters can acquire the semaphore at the same time
if (atomic_compare_exchange_weak(&sem->linux.count, count, count - 1)) {
return 0;
}
}
return cthread_sem_wait_spin(sem, count, spin, timeout);
}

12
libc/thread/nativesem.h → libc/thread/sem.h
View file

@ -7,19 +7,19 @@ COSMOPOLITAN_C_START_
* @fileoverview native semaphore for implementation details
*/
typedef union cthread_native_sem_t {
typedef union cthread_sem_t {
struct {
uint64_t count;
} linux;
} cthread_native_sem_t;
} cthread_sem_t;
struct timespec;
int cthread_native_sem_init(cthread_native_sem_t*, int);
int cthread_native_sem_destroy(cthread_native_sem_t*);
int cthread_sem_init(cthread_sem_t*, int);
int cthread_sem_destroy(cthread_sem_t*);
int cthread_native_sem_wait(cthread_native_sem_t*, int, int, const struct timespec*);
int cthread_native_sem_signal(cthread_native_sem_t*);
int cthread_sem_wait(cthread_sem_t*, int, const struct timespec*);
int cthread_sem_signal(cthread_sem_t*);
COSMOPOLITAN_C_END_

50
libc/thread/wait.c Normal file
View file

@ -0,0 +1,50 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/sysv/consts/futex.h"
#include "libc/sysv/consts/nr.h"
#include "libc/thread/wait.h"
int cthread_memory_wait32(uint32_t* addr, uint32_t val,
const struct timespec* timeout) {
if (__NR_futex != 0xfff) {
int flags = FUTEX_WAIT;
int rc;
register struct timespec* timeout_ asm("r10") = timeout;
asm volatile("syscall"
: "=a"(rc)
: "0"(__NR_futex), "D"(addr), "S"(flags), "d"(val),
"r"(timeout_)
: "rcx", "r11", "cc", "memory");
return rc;
}
return -1;
}
int cthread_memory_wake32(uint32_t* addr, int n) {
if (__NR_futex != 0xfff) {
int flags = FUTEX_WAKE;
int rc;
asm volatile("syscall"
: "=a"(rc)
: "0"(__NR_futex), "D"(addr), "S"(flags), "d"(n)
: "rcx", "r11", "cc", "memory");
return rc;
}
return -1;
}

16
libc/thread/wait.h Normal file
View file

@ -0,0 +1,16 @@
#ifndef COSMOPOLITAN_LIBC_THREAD_WAIT_H_
#define COSMOPOLITAN_LIBC_THREAD_WAIT_H_
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_
/**
* @fileoverview wait on memory
*/
struct timespec;
int cthread_memory_wait32(uint32_t*, uint32_t, const struct timespec*);
int cthread_memory_wake32(uint32_t*, int);
COSMOPOLITAN_C_END_
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
#endif /* COSMOPOLITAN_LIBC_THREAD_WAIT_H_ */