/*-*- 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 2021 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/calls/strace.internal.h" #include "libc/calls/struct/ucontext-netbsd.internal.h" #include "libc/calls/syscall-sysv.internal.h" #include "libc/dce.h" #include "libc/errno.h" #include "libc/intrin/asan.internal.h" #include "libc/intrin/spinlock.h" #include "libc/limits.h" #include "libc/macros.internal.h" #include "libc/nexgen32e/gettls.h" #include "libc/nexgen32e/threaded.h" #include "libc/nt/runtime.h" #include "libc/nt/thread.h" #include "libc/nt/thunk/msabi.h" #include "libc/runtime/internal.h" #include "libc/runtime/runtime.h" #include "libc/str/str.h" #include "libc/sysv/consts/clone.h" #include "libc/sysv/consts/futex.h" #include "libc/sysv/consts/nr.h" #include "libc/sysv/consts/nrlinux.h" #include "libc/sysv/errfuns.h" #include "libc/thread/freebsd.internal.h" #include "libc/thread/openbsd.internal.h" #include "libc/thread/xnu.internal.h" STATIC_YOINK("gettid"); // for kprintf() #define __NR_thr_new 455 #define __NR_clone_linux 56 #define __NR__lwp_create 309 #define __NR_getcontext_netbsd 307 #define __NR_bsdthread_create 0x02000168 #define __NR_thread_fast_set_cthread_self 0x03000003 #define PTHREAD_START_CUSTOM_XNU 0x01000000 #define LWP_DETACHED 0x00000040 #define LWP_SUSPENDED 0x00000080 __msabi extern typeof(TlsSetValue) *const __imp_TlsSetValue; __msabi extern typeof(ExitThread) *const __imp_ExitThread; struct CloneArgs { union { int tid; uint32_t utid; int64_t tid64; }; char lock; int *ptid; int *ctid; int *ztid; char *tls; int (*func)(void *, int); void *arg; }; //////////////////////////////////////////////////////////////////////////////// // THE NEW TECHNOLOGY int WinThreadLaunch(void *arg, // rdi int tid, // rsi int (*func)(void *, int), // rdx intptr_t rsp); // rcx // we can't log this function because: // 1. windows owns the backtrace pointer right now // 2. ftrace unwinds rbp to determine depth // we can't use address sanitizer because: // 1. __asan_handle_no_return wipes stack // 2. windows owns the stack memory right now // we need win32 raw imports because: // 1. generated thunks are function logged noasan noinstrument static textwindows wontreturn void // WinThreadEntry(int rdi, // rcx int rsi, // rdx int rdx, // r8 struct CloneArgs *wt) { // r9 int rc; if (wt->tls) { asm("mov\t%1,%%gs:%0" : "=m"(*((long *)0x1480 + __tls_index)) : "r"(wt->tls)); } *wt->ptid = wt->tid; *wt->ctid = wt->tid; rc = WinThreadLaunch(wt->arg, wt->tid, wt->func, (intptr_t)wt & -16); // we can now clear ctid directly since we're no longer using our own // stack memory, which can now be safely free'd by the parent thread. *wt->ztid = 0; // since we didn't indirect this function through NT2SYSV() it's not // safe to simply return, and as such, we just call ExitThread(). __imp_ExitThread(rc); unreachable; } static textwindows int CloneWindows(int (*func)(void *, int), char *stk, size_t stksz, int flags, void *arg, void *tls, size_t tlssz, int *ptid, int *ctid) { int64_t h; struct CloneArgs *wt; wt = (struct CloneArgs *)(((intptr_t)(stk + stksz) - sizeof(struct CloneArgs)) & -alignof(struct CloneArgs)); wt->ptid = flags & CLONE_PARENT_SETTID ? ptid : &wt->tid; wt->ctid = flags & CLONE_CHILD_SETTID ? ctid : &wt->tid; wt->ztid = flags & CLONE_CHILD_CLEARTID ? ctid : &wt->tid; wt->func = func; wt->arg = arg; wt->tls = flags & CLONE_SETTLS ? tls : 0; if ((h = CreateThread(0, 4096, (void *)WinThreadEntry, wt, 0, &wt->utid))) { CloseHandle(h); return wt->tid; } else { return -1; } } //////////////////////////////////////////////////////////////////////////////// // XNU'S NOT UNIX void XnuThreadThunk(void *pthread, // rdi int machport, // rsi void *(*func)(void *), // rdx void *arg, // rcx intptr_t *stack, // r8 unsigned xnuflags); // r9 asm("XnuThreadThunk:\n\t" "xor\t%ebp,%ebp\n\t" "mov\t%r8,%rsp\n\t" "and\t$-16,%rsp\n\t" "push\t%rax\n\t" "jmp\tXnuThreadMain\n\t" ".size\tXnuThreadThunk,.-XnuThreadThunk"); __attribute__((__used__, __no_reorder__)) static wontreturn void XnuThreadMain(void *pthread, // rdi int tid, // rsi int (*func)(void *arg, int tid), // rdx void *arg, // rcx struct CloneArgs *wt, // r8 unsigned xnuflags) { // r9 int ax; wt->tid = tid; *wt->ptid = tid; *wt->ctid = tid; _spunlock(&wt->lock); if (wt->tls) { // XNU uses the same 0x30 offset as the WIN32 TIB x64. They told the // Go team at Google that they Apply stands by our ability to use it // https://github.com/golang/go/issues/23617#issuecomment-376662373 asm volatile("syscall" : "=a"(ax) : "0"(__NR_thread_fast_set_cthread_self), "D"(wt->tls - 0x30) : "rcx", "r11", "memory", "cc"); } func(arg, tid); // we no longer use the stack after this point // %rax = int bsdthread_terminate(%rdi = void *stackaddr, // %rsi = size_t freesize, // %rdx = uint32_t port, // %r10 = uint32_t sem); asm volatile("movl\t$0,%0\n\t" // *wt->ztid = 0 "xor\t%%r10d,%%r10d\n\t" // sem = 0 "syscall\n\t" // __bsdthread_terminate() "ud2" : "=m"(*wt->ztid) : "a"(0x2000000 | 361), "D"(0), "S"(0), "d"(0) : "rcx", "r10", "r11", "memory"); unreachable; } static int CloneXnu(int (*fn)(void *), char *stk, size_t stksz, int flags, void *arg, void *tls, size_t tlssz, int *ptid, int *ctid) { int rc; bool failed; static bool once; static int broken; struct CloneArgs *wt; if (!once) { if (bsdthread_register(XnuThreadThunk, 0, 0, 0, 0, 0, 0) == -1) { broken = errno; } once = true; } if (broken) { errno = broken; return -1; } wt = (struct CloneArgs *)(((intptr_t)(stk + stksz) - sizeof(struct CloneArgs)) & -alignof(struct CloneArgs)); wt->ptid = flags & CLONE_PARENT_SETTID ? ptid : &wt->tid; wt->ctid = flags & CLONE_CHILD_SETTID ? ctid : &wt->tid; wt->ztid = flags & CLONE_CHILD_CLEARTID ? ctid : &wt->tid; wt->tls = flags & CLONE_SETTLS ? tls : 0; wt->lock = 1; if ((rc = bsdthread_create(fn, arg, wt, 0, PTHREAD_START_CUSTOM_XNU)) != -1) { _spinlock(&wt->lock); rc = wt->tid; _spunlock(&wt->lock); } return rc; } //////////////////////////////////////////////////////////////////////////////// // FREE BESIYATA DISHMAYA static wontreturn void FreebsdThreadMain(void *p) { struct CloneArgs *wt = p; *wt->ptid = wt->tid; *wt->ctid = wt->tid; wt->func(wt->arg, wt->tid); // we no longer use the stack after this point // void thr_exit(%rdi = long *state); asm volatile("movl\t$0,%0\n\t" // *wt->ztid = 0 "syscall" // thr_exit() : "=m"(*wt->ztid) : "a"(431), "D"(0) : "rcx", "r11", "memory"); unreachable; } static int CloneFreebsd(int (*func)(void *, int), char *stk, size_t stksz, int flags, void *arg, void *tls, size_t tlssz, int *ptid, int *ctid) { int ax; bool failed; int64_t tid; struct CloneArgs *wt; wt = (struct CloneArgs *)(((intptr_t)(stk + stksz) - sizeof(struct CloneArgs)) & -alignof(struct CloneArgs)); wt->ptid = flags & CLONE_PARENT_SETTID ? ptid : &wt->tid; wt->ctid = flags & CLONE_CHILD_SETTID ? ctid : &wt->tid; wt->ztid = flags & CLONE_CHILD_CLEARTID ? ctid : &wt->tid; wt->tls = tls; wt->func = func; wt->arg = arg; struct thr_param params = { .start_func = FreebsdThreadMain, .arg = wt, .stack_base = stk, .stack_size = (((intptr_t)wt - (intptr_t)stk) & -16) - 8, .tls_base = flags & CLONE_SETTLS ? tls : 0, .tls_size = flags & CLONE_SETTLS ? tlssz : 0, .child_tid = &wt->tid64, .parent_tid = &tid, }; asm volatile(CFLAG_ASM("syscall") : CFLAG_CONSTRAINT(failed), "=a"(ax) : "1"(__NR_thr_new), "D"(¶ms), "S"(sizeof(params)) : "rcx", "rdx", "r8", "r9", "r10", "r11", "memory"); if (failed) { errno = ax; tid = -1; } return tid; } //////////////////////////////////////////////////////////////////////////////// // OPEN BESIYATA DISHMAYA static void *oldrsp; __attribute__((__constructor__)) static void OpenbsdGetSafeRsp(void) { // main thread stack should never be freed during process lifetime. we // won't actually change this stack below. we just need need a place // where threads can park RSP for a few instructions while dying. oldrsp = __builtin_frame_address(0); } static wontreturn void OpenbsdThreadMain(void *p) { struct CloneArgs *wt = p; *wt->ptid = wt->tid; *wt->ctid = wt->tid; wt->func(wt->arg, wt->tid); // we no longer use the stack after this point. however openbsd // validates the rsp register too so a race condition can still // happen if the parent tries to free the stack. we'll solve it // by simply changing rsp back to the old value before exiting! // although ideally there should be a better solution. // // void __threxit(%rdi = int32_t *notdead); asm volatile("mov\t%2,%%rsp\n\t" // set stack "movl\t$0,(%%rdi)\n\t" // *wt->ztid = 0 "syscall" // __threxit() : "=m"(*wt->ztid) : "a"(302), "m"(oldrsp), "D"(wt->ztid) : "rcx", "r11", "memory"); unreachable; } static int CloneOpenbsd(int (*func)(void *, int), char *stk, size_t stksz, int flags, void *arg, void *tls, size_t tlssz, int *ptid, int *ctid) { int tid; intptr_t sp; struct __tfork *tf; struct CloneArgs *wt; sp = (intptr_t)stk + stksz; sp -= sizeof(struct __tfork); sp &= -alignof(struct __tfork); tf = (struct __tfork *)sp; sp -= sizeof(struct CloneArgs); sp &= -MAX(16, alignof(struct CloneArgs)); wt = (struct CloneArgs *)sp; wt->ptid = flags & CLONE_PARENT_SETTID ? ptid : &wt->tid; wt->ctid = flags & CLONE_CHILD_SETTID ? ctid : &wt->tid; wt->ztid = flags & CLONE_CHILD_CLEARTID ? ctid : &wt->tid; wt->arg = arg; wt->func = func; tf->tf_stack = (char *)wt - 8; tf->tf_tcb = flags & CLONE_SETTLS ? tls : 0; tf->tf_tid = &wt->tid; if ((tid = __tfork_thread(tf, sizeof(*tf), OpenbsdThreadMain, wt)) < 0) { errno = -tid; tid = -1; } return tid; } //////////////////////////////////////////////////////////////////////////////// // NET BESIYATA DISHMAYA static wontreturn void NetbsdThreadMain(void *arg, // rdi int (*func)(void *, int), // rsi int *tid, // rdx int *ctid, // rcx int *ztid, // r8 int *ptid) { // r9 int ax, dx; ax = *tid; *ptid = ax; *ctid = ax; func(arg, ax); // we no longer use the stack after this point // %eax = int __lwp_exit(void); asm volatile("movl\t$0,%2\n\t" // *wt->ztid = 0 "syscall\n\t" // __lwp_exit() "ud2" : "=a"(ax), "=d"(dx), "=m"(*ztid) : "0"(310) : "rcx", "r11", "memory"); unreachable; } static int CloneNetbsd(int (*func)(void *, int), char *stk, size_t stksz, int flags, void *arg, void *tls, size_t tlssz, int *ptid, int *ctid) { // NetBSD has its own clone() and it works, but it's technically a // second-class API, intended to help Linux folks migrate to this. bool failed; int ax, *tid; intptr_t dx, sp; static bool once; static int broken; struct ucontext_netbsd *ctx; static struct ucontext_netbsd netbsd_clone_template; // memoize arbitrary valid processor state structure if (!once) { asm volatile(CFLAG_ASM("syscall") : CFLAG_CONSTRAINT(failed), "=a"(ax) : "1"(__NR_getcontext_netbsd), "D"(&netbsd_clone_template) : "rcx", "rdx", "r11", "memory"); if (failed) { broken = ax; } once = true; } if (broken) { errno = broken; return -1; } sp = (intptr_t)(stk + stksz); // allocate memory for tid sp -= sizeof(int); sp = sp & -alignof(int); tid = (int *)sp; // align the stack sp = sp & -16; // simulate call to misalign stack and ensure backtrace looks good sp -= 8; *(intptr_t *)sp = (intptr_t)CloneNetbsd + 1; // place the giant 784 byte ucontext structure in the red zone! // it only has to live long enough for the thread to come alive ctx = (struct ucontext_netbsd *)((sp - sizeof(struct ucontext_netbsd)) & -alignof(struct ucontext_netbsd)); // pass parameters in process state memcpy(ctx, &netbsd_clone_template, sizeof(*ctx)); ctx->uc_link = 0; ctx->uc_mcontext.rbp = 0; ctx->uc_mcontext.rsp = sp; ctx->uc_mcontext.rip = (intptr_t)NetbsdThreadMain; ctx->uc_mcontext.rdi = (intptr_t)arg; ctx->uc_mcontext.rsi = (intptr_t)func; ctx->uc_mcontext.rdx = (intptr_t)tid; ctx->uc_mcontext.rcx = (intptr_t)(flags & CLONE_CHILD_SETTID ? ctid : tid); ctx->uc_mcontext.r8 = (intptr_t)(flags & CLONE_CHILD_CLEARTID ? ctid : tid); ctx->uc_mcontext.r9 = (intptr_t)(flags & CLONE_PARENT_SETTID ? ptid : tid); ctx->uc_flags |= _UC_STACK; ctx->uc_stack.ss_sp = stk; ctx->uc_stack.ss_size = stksz; ctx->uc_stack.ss_flags = 0; if (flags & CLONE_SETTLS) { ctx->uc_flags |= _UC_TLSBASE; ctx->uc_mcontext._mc_tlsbase = (intptr_t)tls; } // perform the system call asm volatile(CFLAG_ASM("syscall") : CFLAG_CONSTRAINT(failed), "=a"(ax), "=d"(dx) : "1"(__NR__lwp_create), "D"(ctx), "S"(LWP_DETACHED), "2"(tid) : "rcx", "r11", "memory"); if (!failed) { return *tid; } else { errno = ax; return -1; } } //////////////////////////////////////////////////////////////////////////////// // GNU/SYSTEMD int sys_clone_linux(int flags, // rdi long sp, // rsi int *ptid, // rdx int *ctid, // rcx void *tls, // r8 void *func, // r9 void *arg); // 8(rsp) static int CloneLinux(int (*func)(void *arg, int tid), char *stk, size_t stksz, int flags, void *arg, void *tls, size_t tlssz, int *ptid, int *ctid) { long sp; sp = (intptr_t)(stk + stksz); if (~flags & CLONE_CHILD_SETTID) { flags |= CLONE_CHILD_SETTID; sp -= sizeof(int); sp = sp & -alignof(int); ctid = (int *)sp; } sp = sp & -16; // align the stack return sys_clone_linux(flags, sp, ptid, ctid, tls, func, arg); } //////////////////////////////////////////////////////////////////////////////// // COSMOPOLITAN /** * Creates thread. * * Threads are created in a detached manner. They currently can't be * synchronized using wait() or posix signals. Threads created by this * function should be synchronized using shared memory operations. * * Any memory that's required by this system call wrapper is allocated * to the top of your stack. This shouldn't be more than 128 bytes. * * Your function is called from within the stack you specify. A return * address is pushed onto your stack, that causes returning to jump to * _Exit1() which terminates the thread. Even though the callback says * it supports a return code, that'll only work on Linux and Windows. * * The `tls` parameter is for thread-local storage. If you specify this * then clone() will implicitly rewire libc (e.g. errno) to use TLS: * * static char tib[64]; * __initialize_tls(tib); * __install_tls(tib); * * If you want a main process TLS size that's larger call it manually. * Once you've done the above and/or started creating your own threads * you'll be able to access your `tls` thread information block, using * * char *p = __get_tls(); * printf("errno is %d\n", *(int *)(p + 0x3c)); * * This function follows the same ABI convention as the Linux userspace * libraries, with a few small changes. The varargs has been removed to * help prevent broken code, and the stack size and tls size parameters * are introduced for compatibility with FreeBSD. * * To keep this system call lightweight, only the thread creation use * case is polyfilled across platforms. For example, if you want fork * that works on OpenBSD for example, don't do it with clone(SIGCHLD) * and please just call fork(). Even if you do that on Linux, it will * effectively work around libc features like atfork(), so that means * other calls like getpid() may return incorrect values. * * @param func is your callback function, which this wrapper requires * not be null, otherwise EINVAL is raised. It is passed two args * within the child thread: (1) the caller-supplied `arg` and (2) * the new tid is always passed in the second arg for convenience * * @param stk points to the bottom of a caller allocated stack, which * must be allocated via mmap() using the MAP_STACK flag, or else * you won't get optimal performance and it won't work on OpenBSD * * @param stksz is the size of that stack in bytes, we recommend that * that this be set to GetStackSize() or else memory safety tools * like kprintf() can't do as good and quick of a job; this value * must be 16-aligned plus it must be at least 4192 bytes in size * and it's advised to have the bottom-most page, be a guard page * * @param flags which SHOULD always have all of these flags: * * - `CLONE_THREAD` * - `CLONE_VM` * - `CLONE_FS` * - `CLONE_FILES` * - `CLONE_SIGHAND` * * This system call wrapper is intended for threads, and as such, we * won't polyfill Linux's ability to simulate unrelated calls (e.g. * fork, vfork) via clone() on other platforms. Please just call * fork() and vfork() when that's what you want. * * Your `flags` may also optionally also additionally bitwise-OR any * combination of the following additional flags: * * - `CLONE_PARENT_SETTID` must be specified if you intend to set * the `ptid` argument, which is guaranteed to be updated with the * child tid BEFORE BOTH clone() returns and `func` is invoked * * - `CLONE_CHILD_SETTID` must be specified if you intend to set the * `ctid` argument, which is guaranteed to be updated with the * child tid before `func` is called, however we CAN NOT guarantee * this will happen BEFORE clone() returns * * - `CLONE_CHILD_CLEARTID` causes `*ctid = 0` upon child thread * termination. This is used to implement join so that the parent * may know when it's safe to free the child's stack memory, and * as such, is guaranteed to happen AFTER the child thread has * either terminated or has finished using its stack memory * * - `CLONE_SETTLS` is needed if you intend to specify the `tls` * argument, which provides a fast-path solution for changing the * appropriate TLS segment register within the child thread. The * child thread may then obtain a reference to the TIB address you * supplied, by calling __get_tls(). Your C library holds certain * expectations about the layout of your Thread Information Block * (TIB), which are all documented by __initialize_tls(). That * function can be used to initialize the first positive 64 bytes * of your TLS allocation, which is the memory Cosmopolitan Libc * wants for itself (and negative addresses are reserved by the * GNU Linker). Using this flag will transition the C runtime to a * `__tls_enabled` state automatically. If you use TLS for just * one thread, then you must be specify TLS for ALL THREADS. It's * a good idea to do that since TLS can offer considerable (i.e. * multiple orders of a magnitude) performance improvement for * TID-dependent C library services, e.g. recursive mutexes. * * @param arg is passed as an argument to `func` in the child thread * @param tls may be used to set the thread local storage segment; * this parameter is ignored if `CLONE_SETTLS` is not set * @param tlssz is the size of tls in bytes which must be at least 64 * @param ctid lets the child receive its thread id without having to * call gettid() and is ignored if `CLONE_CHILD_SETTID` isn't set * @return tid of child on success, or -1 w/ errno * @threadsafe */ int clone(void *func, void *stk, size_t stksz, int flags, void *arg, int *ptid, void *tls, size_t tlssz, int *ctid) { int rc; struct CloneArgs *wt; if (flags & CLONE_SETTLS) __enable_tls(); if (flags & CLONE_THREAD) __enable_threads(); if (!func) { rc = einval(); } else if (!IsTiny() && (((flags & CLONE_VM) && (stksz < PAGESIZE || (stksz & 15))) || ((flags & CLONE_SETTLS) && (tlssz < 64 || (tlssz & 7))))) { rc = einval(); } else if (IsAsan() && ((stksz > PAGESIZE && !__asan_is_valid((char *)stk + PAGESIZE, stksz - PAGESIZE)) || ((flags & CLONE_SETTLS) && !__asan_is_valid(tls, tlssz)) || ((flags & CLONE_SETTLS) && !__asan_is_valid(tls, sizeof(long))) || ((flags & CLONE_PARENT_SETTID) && !__asan_is_valid(ptid, sizeof(*ptid))) || ((flags & CLONE_CHILD_SETTID) && !__asan_is_valid(ctid, sizeof(*ctid))))) { rc = efault(); } else if (IsLinux()) { rc = CloneLinux(func, stk, stksz, flags, arg, tls, tlssz, ptid, ctid); } else if (!IsTiny() && (flags & ~(CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID)) != (CLONE_THREAD | CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND)) { STRACE("clone flag unsupported on this platform"); rc = einval(); } else if (IsXnu()) { rc = CloneXnu(func, stk, stksz, flags, arg, tls, tlssz, ptid, ctid); } else if (IsFreebsd()) { rc = CloneFreebsd(func, stk, stksz, flags, arg, tls, tlssz, ptid, ctid); } else if (IsNetbsd()) { rc = CloneNetbsd(func, stk, stksz, flags, arg, tls, tlssz, ptid, ctid); } else if (IsOpenbsd()) { rc = CloneOpenbsd(func, stk, stksz, flags, arg, tls, tlssz, ptid, ctid); } else if (IsWindows()) { rc = CloneWindows(func, stk, stksz, flags, arg, tls, tlssz, ptid, ctid); } else { rc = enosys(); } // TODO(jart): do we need it? if (rc != -1 && (flags & CLONE_PARENT_SETTID)) { *ptid = rc; } STRACE("clone(%p, %p, %'zu, %#x, %p, %p, %p, %'zu, %p) → %d% m", func, stk, stksz, flags, arg, ptid, tls, tlssz, ctid, rc); return rc; }