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https://github.com/jart/cosmopolitan.git
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Make _Thread_local work across platforms
We now rewrite the binary image at runtime on Windows and XNU to change mov %fs:0,%reg instructions to use %gs instead. There's also simpler threading API introduced by this change and it's called _spawn() and _join(), which has replaced most clone() usage.
This commit is contained in:
Justine Tunney
parent
e4d6e263d4
commit
5f4f6b0e69
51 changed files with 808 additions and 1043 deletions
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@ -18,6 +18,7 @@
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/strace.internal.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/errno.h"
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#include "libc/fmt/itoa.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/futex.internal.h"
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@ -108,7 +108,6 @@ o/$(MODE)/libc/intrin/describeprotflags.o: \
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OVERRIDE_CFLAGS += \
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-fno-sanitize=address
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o/$(MODE)/libc/intrin/tls.greg.o \
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o/$(MODE)/libc/intrin/exit.greg.o \
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o/$(MODE)/libc/intrin/exit1.greg.o \
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o/$(MODE)/libc/intrin/getenv.greg.o \
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@ -1,125 +0,0 @@
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/nexgen32e/threaded.h"
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#include "libc/nt/thread.h"
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#include "libc/nt/thunk/msabi.h"
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#include "libc/sysv/consts/nrlinux.h"
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#define __NR_sysarch 0x000000a5 // freebsd+netbsd
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#define AMD64_SET_GSBASE 131 // freebsd
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#define AMD64_SET_FSBASE 129 // freebsd
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#define X86_SET_GSBASE 16 // netbsd
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#define X86_SET_FSBASE 17 // netbsd
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#define __NR___set_tcb 0x00000149
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#define __NR__lwp_setprivate 0x0000013d
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#define __NR_thread_fast_set_cthread_self 0x03000003
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/**
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* Initializes thread information block.
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*
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* Here's the layout your c library assumes:
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*
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* offset size description
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* 0x0000 0x08 linear address pointer
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* 0x0030 0x08 linear address pointer
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* 0x0038 0x04 tid
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* 0x003c 0x04 errno
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*
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*/
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privileged void *__initialize_tls(char tib[64]) {
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if (tib) {
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*(intptr_t *)(tib + 0x00) = (intptr_t)tib;
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*(intptr_t *)(tib + 0x30) = (intptr_t)tib;
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*(int *)(tib + 0x38) = -1; // tid
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*(int *)(tib + 0x3c) = 0;
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}
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return tib;
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}
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/**
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* Installs thread information block on main process.
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*
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* For example, to set up TLS correctly for the main thread, without
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* creating any threads, then it's sufficient to say:
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*
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* __attribute__((__constructor__)) static void InitTls(void) {
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* static char tls[64];
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* __initialize_tls(tls);
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* *(int *)(tls + 0x38) = gettid();
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* *(int *)(tls + 0x3c) = __errno;
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* __install_tls(tls);
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* }
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*
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* We use a constructor here to make sure it only happens once. Please
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* note that calling `clone` will do this automatically.
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*
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* Installing TLS causes the `__tls_enabled` variable to be set. This
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* causes C library features such as `errno` and `gettid()` to use TLS.
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* This can help things like recursive mutexes go significantly faster.
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*
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* To access your TLS storage, you can call `__get_tls()` or
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* __get_tls_inline()` which return the address of the `tib`.
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*
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* @param tib is your thread information block, which must have at least
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* 64 bytes on the righthand side of the tib pointer since those are
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* the values your C library reserves for itself. memory on the left
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* side of the pointer is reserved by the linker for _Thread_local.
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*/
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privileged void __install_tls(char tib[64]) {
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int ax, dx;
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assert(tib);
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assert(!__tls_enabled);
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assert(*(int *)(tib + 0x38) != -1);
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if (IsWindows()) {
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__tls_index = TlsAlloc();
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asm("mov\t%1,%%gs:%0" : "=m"(*((long *)0x1480 + __tls_index)) : "r"(tib));
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} else if (IsFreebsd()) {
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asm volatile("syscall"
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: "=a"(ax)
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: "0"(__NR_sysarch), "D"(AMD64_SET_FSBASE), "S"(tib)
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: "rcx", "r11", "memory", "cc");
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} else if (IsNetbsd()) {
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asm volatile("syscall"
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: "=a"(ax), "=d"(dx)
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: "0"(__NR_sysarch), "D"(X86_SET_FSBASE), "S"(tib)
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: "rcx", "r11", "memory", "cc");
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} else if (IsXnu()) {
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asm volatile("syscall"
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: "=a"(ax)
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: "0"(__NR_thread_fast_set_cthread_self),
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"D"((intptr_t)tib - 0x30)
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: "rcx", "r11", "memory", "cc");
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} else if (IsOpenbsd()) {
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asm volatile("syscall"
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: "=a"(ax)
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: "0"(__NR___set_tcb), "D"(tib)
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: "rcx", "r11", "memory", "cc");
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} else {
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asm volatile("syscall"
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: "=a"(ax)
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: "0"(__NR_linux_arch_prctl), "D"(ARCH_SET_FS), "S"(tib)
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: "rcx", "r11", "memory");
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}
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__tls_enabled = true;
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}
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@ -16,10 +16,10 @@
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/bits/atomic.h"
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#include "libc/calls/calls.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/futex.internal.h"
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#include "libc/intrin/wait0.internal.h"
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#include "libc/linux/futex.h"
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@ -31,13 +31,13 @@
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* by the clone() system call when a thread terminates. The purpose of
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* this operation is to know when it's safe to munmap() a thread stack.
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*/
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void _wait0(const int *ptid) {
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void _wait0(const int *ctid) {
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int x;
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for (;;) {
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if (!(x = atomic_load_explicit(ptid, memory_order_acquire))) {
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if (!(x = atomic_load_explicit(ctid, memory_order_acquire))) {
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break;
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} else if (IsLinux() /* || IsOpenbsd() */) {
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_futex_wait(ptid, x, &(struct timespec){2});
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_futex_wait(ctid, x, &(struct timespec){2});
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} else {
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sched_yield();
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}
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