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Abstract away Futex for cthread

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This commit is contained in:
Lemaitre 2021-10-24 16:19:06 +02:00
parent 699bbfde97
commit 9cd5c6a27d
3 changed files with 69 additions and 16 deletions
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19
libc/thread/sem.c
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@ -17,9 +17,8 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/atomic.h"
#include "libc/sysv/consts/futex.h"
#include "libc/sysv/consts/nr.h"
#include "libc/thread/sem.h"
#include "libc/thread/wait.h"
#include "libc/thread/yield.h"
#define CTHREAD_THREAD_VAL_BITS 32
@ -51,14 +50,9 @@ int cthread_sem_signal(cthread_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;
@ -84,16 +78,9 @@ int cthread_sem_wait_futex(cthread_sem_t* sem, const struct timespec* timeout) {
}
}
int flags = FUTEX_WAIT;
register struct timespec* timeout_ asm("r10") = timeout;
// 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);
}

50
libc/thread/wait.c Normal file
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@ -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
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@ -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_ */