Improve AARCH64 execution

This change fixes bugs in the APE loader. The execve() unit tests are
now enabled for MODE=aarch64. See the README for how you need to have
binfmt_misc configured with Qemu to run them. Apple Silicon bugs have
been fixed too, e.g. tkill() now works.

libc/calls/execve-nt.greg.c

@@ -59,6 +59,7 @@
 #include "libc/sysv/errfuns.h"
 #include "libc/thread/posixthread.internal.h"
 #include "libc/thread/thread.h"
+#ifdef __x86_64__
 
 #define keywords textwindows dontasan dontubsan dontinstrument
 
@@ -275,3 +276,5 @@ static keywords void sys_execve_nt_relay(intptr_t h, long b, long c, long d) {
   __imp_ExitProcess(dwExitCode);
   __builtin_unreachable();
 }
+
+#endif /* __x86_64__ */

libc/calls/execve-sysv.c

@@ -17,15 +17,21 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "ape/ape.h"
+#include "libc/atomic.h"
 #include "libc/calls/blockcancel.internal.h"
 #include "libc/calls/blocksigs.internal.h"
 #include "libc/calls/calls.h"
-#include "libc/calls/execve-sysv.internal.h"
+#include "libc/calls/cp.internal.h"
+#include "libc/calls/execve.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
+#include "libc/cosmo.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
+#include "libc/fmt/magnumstrs.internal.h"
 #include "libc/intrin/bits.h"
+#include "libc/intrin/describeflags.internal.h"
 #include "libc/intrin/safemacros.internal.h"
+#include "libc/intrin/strace.internal.h"
 #include "libc/limits.h"
 #include "libc/mem/alloca.h"
 #include "libc/paths.h"
@@ -36,77 +42,100 @@
 #include "libc/sysv/consts/ok.h"
 #include "libc/sysv/errfuns.h"
 
-static bool CanExecute(const char *path) {
-  return !sys_faccessat(AT_FDCWD, path, X_OK, 0);
-}
+#define ELIBBAD_LINUX 80
+#define EBADEXEC_XNU  85
+#define EBADARCH_XNU  86
 
-bool IsAPEMagic(char buf[8]) {
-  return READ64LE(buf) == READ64LE("MZqFpD='") ||
-         READ64LE(buf) == READ64LE("JTqFpD='");
-}
+static struct {
+  atomic_uint once;
+  const char *home;
+  const char *tmpdir;
+} g_execve;
 
-static bool IsApeBinary(const char *path) {
-  int fd;
-  char buf[8];
-  bool res = false;
-  // TODO(jart): Should we block signals too?
-  BLOCK_CANCELLATIONS;
-  if ((fd = sys_openat(AT_FDCWD, path, O_RDONLY, 0)) != -1) {
-    res = sys_read(fd, buf, 8) == 8 && IsAPEMagic(buf);
-    sys_close(fd);
+static bool IsApeFile(const char *path) {
+  if (!endswith(path, ".com")) {
+    return true;
+  } else {
+    bool res = false;
+    BLOCK_CANCELLATIONS;
+    BEGIN_CANCELLATION_POINT;
+    int fd;
+    char buf[8];
+    int flags = O_RDONLY | O_NOCTTY | O_NONBLOCK | O_CLOEXEC;
+    if ((fd = sys_openat(AT_FDCWD, path, flags, 0)) != -1) {
+      res = sys_pread(fd, buf, 8, 0, 0) == 8 && IsApeLoadable(buf);
+      sys_close(fd);
+    }
+    END_CANCELLATION_POINT;
+    ALLOW_CANCELLATIONS;
+    return res;
   }
-  ALLOW_CANCELLATIONS;
-  return res;
 }
 
 static const char *Join(const char *a, const char *b, char buf[PATH_MAX]) {
   size_t n, m;
-  n = strlen(a);
-  m = strlen(b);
-  if (n + 1 + m + 1 < PATH_MAX) {
-    stpcpy(stpcpy(stpcpy(buf, a), "/"), b);
-    return buf;
-  } else {
-    return "";
+  if (a && *a) {
+    n = strlen(a);
+    m = strlen(b);
+    if (n + m + 1 < PATH_MAX) {
+      stpcpy(stpcpy(buf, a), b);
+      return buf;
+    }
+  }
+  return 0;
+}
+
+static void RetryExecve(const char *prog, char **argv, char *const *envp) {
+  if ((argv[0] = (char *)prog)) {
+    STRACE("execve(%#s, %s) due to %s", prog, DescribeStringList(argv),
+           _strerrno(errno));
+    __sys_execve(prog, argv, envp);
   }
 }
 
-int sys_execve(const char *prog, char *const argv[], char *const envp[]) {
-  size_t i;
-  int e, rc;
-  char *buf;
-  char **shargs;
-  const char *ape;
-  e = errno;
-  __sys_execve(prog, argv, envp);
-  if (errno == ENOEXEC) {
-    for (i = 0; argv[i];) ++i;
-    buf = alloca(PATH_MAX);
-    shargs = alloca((i + 4) * sizeof(char *));
-    if (IsApeBinary(prog) &&
-        (CanExecute((ape = "/usr/bin/ape")) ||
-         CanExecute((ape = Join(firstnonnull(getenv("TMPDIR"),
-                                             firstnonnull(getenv("HOME"), ".")),
-                                ".ape-" APE_VERSION_STR, buf))) ||
-         CanExecute((ape = Join(firstnonnull(getenv("HOME"), "."),
-                                ".ape-" APE_VERSION_STR, buf))))) {
-      shargs[0] = (char *)ape;
-      shargs[1] = (char *)"-";
-      shargs[2] = (char *)prog;
-      memcpy(shargs + 3, argv, (i + 1) * sizeof(char *));
-      errno = e;
-      rc = __sys_execve(shargs[0], shargs, envp);
-    } else if (CanExecute(prog)) {
-      shargs[0] = _PATH_BSHELL;
-      shargs[1] = (char *)prog;
-      memcpy(shargs + 2, argv + 1, i * sizeof(char *));
-      errno = e;
-      rc = __sys_execve(shargs[0], shargs, envp);
-    } else {
-      rc = enoexec();
-    }
-  } else {
-    rc = -1;
-  }
-  return rc;
+static void SetupExecve(void) {
+  g_execve.home = getenv("HOME");
+  g_execve.tmpdir = getenv("TMPDIR");
+}
+
+__attribute__((__constructor__)) static void InitExecve(void) {
+  cosmo_once(&g_execve.once, SetupExecve);
+}
+
+int sys_execve(const char *prog, char *const argv[], char *const envp[]) {
+
+  // try kernel
+  // this also checks execute bit
+  __sys_execve(prog, argv, envp);
+  if (!(errno == ENOEXEC || (IsLinux() && errno == ELIBBAD_LINUX))) {
+    return -1;
+  }
+
+  // allocate memory
+  int argc;
+  for (argc = 0; argv[argc];) ++argc;
+  char **shargs = alloca((argc + 4) * sizeof(char *));
+
+  // try ape loader
+  if (IsApeFile(prog)) {
+    shargs[1] = (char *)"-";
+    shargs[2] = (char *)prog;
+    memcpy(shargs + 3, argv, (argc + 1) * sizeof(char *));
+    RetryExecve("/usr/bin/ape", shargs, envp);
+    char *buf = alloca(PATH_MAX);
+    const char *name = "/.ape-" APE_VERSION_STR;
+    InitExecve();
+    RetryExecve(Join(g_execve.tmpdir, name, buf), shargs, envp);
+    RetryExecve(Join(g_execve.home, name, buf), shargs, envp);
+    RetryExecve(Join(".", name, buf), shargs, envp);
+  }
+
+  // try bourne shell
+  shargs[0] = _PATH_BSHELL;
+  shargs[1] = (char *)prog;
+  memcpy(shargs + 2, argv + 1, argc * sizeof(char *));
+  RetryExecve(shargs[0], shargs, envp);
+
+  enoexec();
+  return -1;
 }

libc/calls/execve.c

@@ -64,7 +64,7 @@ int execve(const char *prog, char *const argv[], char *const envp[]) {
                     !__asan_is_valid_strlist(envp)))) {
     rc = efault();
   } else {
-    STRACE("execve(%#s, %s, %s) → ...", prog, DescribeStringList(argv),
+    STRACE("execve(%#s, %s, %s)", prog, DescribeStringList(argv),
            DescribeStringList(envp));
     rc = 0;
     if (IsLinux() && __execpromises && _weaken(sys_pledge_linux)) {

libc/calls/execve.internal.h

@@ -3,7 +3,9 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-bool IsAPEMagic(char[8]);
+void __execve_lock(void);
+void __execve_unlock(void);
+bool IsApeLoadable(char[8]);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/calls/fexecve.c

@@ -21,7 +21,7 @@
 #include "libc/calls/blocksigs.internal.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/cp.internal.h"
-#include "libc/calls/execve-sysv.internal.h"
+#include "libc/calls/execve.internal.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/struct/stat.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
@@ -30,6 +30,7 @@
 #include "libc/fmt/itoa.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/describeflags.internal.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/intrin/safemacros.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
@@ -46,7 +47,7 @@
 
 static bool IsAPEFd(const int fd) {
   char buf[8];
-  return (sys_pread(fd, buf, 8, 0, 0) == 8) && IsAPEMagic(buf);
+  return (sys_pread(fd, buf, 8, 0, 0) == 8) && IsApeLoadable(buf);
 }
 
 static int fexecve_impl(const int fd, char *const argv[], char *const envp[]) {
@@ -141,7 +142,7 @@ static int fd_to_mem_fd(const int infd, char *path) {
     ssize_t readRc;
     readRc = pread(infd, space, st.st_size, 0);
     bool success = readRc != -1;
-    if (success && (st.st_size > 8) && IsAPEMagic(space)) {
+    if (success && (st.st_size > 8) && IsApeLoadable(space)) {
       int flags = fcntl(fd, F_GETFD);
       if ((success = (flags != -1) &&
                      (fcntl(fd, F_SETFD, flags & (~FD_CLOEXEC)) != -1) &&

libc/calls/getprogramexecutablename.greg.c

@@ -93,9 +93,9 @@ static inline void GetProgramExecutableNameImpl(char *p, char *e) {
 
   // if argv[0] exists then turn it into an absolute path. we also try
   // adding a .com suffix since the ape auto-appends it when resolving
-  if (((q = __argv[0]) && !sys_faccessat(AT_FDCWD, q, F_OK, 0)) ||
-      ((q = StrCat(u.path, __argv[0], ".com")) &&
-       !sys_faccessat(AT_FDCWD, q, F_OK, 0))) {
+  if ((q = __argv[0]) && ((!sys_faccessat(AT_FDCWD, q, F_OK, 0)) ||
+                          ((q = StrCat(u.path, __argv[0], ".com")) &&
+                           !sys_faccessat(AT_FDCWD, q, F_OK, 0)))) {
     if (*q != '/') {
       if (q[0] == '.' && q[1] == '/') {
         q += 2;

libc/calls/isapemagic.c

@@ -0,0 +1,29 @@
+/*-*- 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 2023 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/intrin/bits.h"
+
+/**
+ * Returns true if executable image is supported by APE Loader.
+ */
+bool IsApeLoadable(char buf[8]) {
+  return READ32LE(buf) == READ32LE("\177ELF") ||
+         READ64LE(buf) == READ64LE("MZqFpD='") ||
+         READ64LE(buf) == READ64LE("JTqFpD='");
+}

libc/calls/ntspawn.c

@@ -34,6 +34,7 @@
 #include "libc/nt/struct/securityattributes.h"
 #include "libc/nt/struct/startupinfo.h"
 #include "libc/sysv/errfuns.h"
+#ifdef __x86_64__
 
 struct SpawnBlock {
   union {
@@ -108,3 +109,5 @@ textwindows int ntspawn(
   if (handle) CloseHandle(handle);
   return __fix_enotdir(rc, prog16);
 }
+
+#endif /* __x86_64__ */

libc/calls/tkill.c

@@ -32,6 +32,7 @@
 #include "libc/nt/runtime.h"
 #include "libc/nt/struct/context.h"
 #include "libc/nt/thread.h"
+#include "libc/runtime/syslib.internal.h"
 #include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/consts/sig.h"
 #include "libc/sysv/errfuns.h"
@@ -97,10 +98,17 @@ static dontinline textwindows int __tkill_nt(int tid, int sig,
   }
 }
 
+static int __tkill_m1(int tid, int sig, struct CosmoTib *tib) {
+  struct PosixThread *pt = (struct PosixThread *)__get_tls()->tib_pthread;
+  return __syslib->pthread_kill(pt->next, sig);
+}
+
 // OpenBSD has an optional `tib` parameter for extra safety.
 int __tkill(int tid, int sig, void *tib) {
   int rc;
-  if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd() || IsNetbsd()) {
+  if (IsXnuSilicon()) {
+    return __tkill_m1(tid, sig, tib);
+  } else if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd() || IsNetbsd()) {
     rc = sys_tkill(tid, sig, tib);
   } else if (IsWindows()) {
     rc = __tkill_nt(tid, sig, tib);

libc/intrin/asan.c

@@ -406,11 +406,9 @@ static bool __asan_is_mapped(int x) {
   // xxx: we can't lock because no reentrant locks yet
   int i;
   bool res;
-  struct MemoryIntervals *m;
   __mmi_lock();
-  m = _weaken(_mmi);
-  i = __find_memory(m, x);
-  res = i < m->i && x >= m->p[i].x;
+  i = __find_memory(&_mmi, x);
+  res = i < _mmi.i && x >= _mmi.p[i].x;
   __mmi_unlock();
   return res;
 }
@@ -902,7 +900,7 @@ static __wur __asan_die_f *__asan_report(const void *addr, int size,
   p = __asan_format_section(p, _etext, _edata, ".data", addr);
   p = __asan_format_section(p, _end, _edata, ".bss", addr);
   __mmi_lock();
-  for (m = _weaken(_mmi), i = 0; i < m->i; ++i) {
+  for (m = &_mmi, i = 0; i < m->i; ++i) {
     x = m->p[i].x;
     y = m->p[i].y;
     p = __asan_format_interval(p, x << 16, (y << 16) + (FRAMESIZE - 1));
@@ -1396,7 +1394,7 @@ void __asan_map_shadow(uintptr_t p, size_t n) {
     kprintf("error: %p size %'zu overlaps shadow space\n", p, n);
     _Exit(1);
   }
-  m = _weaken(_mmi);
+  m = &_mmi;
   a = (0x7fff8000 + (p >> 3)) >> 16;
   b = (0x7fff8000 + (p >> 3) + (n >> 3) + 0xffff) >> 16;
   for (; a <= b; a += i) {
@@ -1413,12 +1411,11 @@ void __asan_map_shadow(uintptr_t p, size_t n) {
     addr = (void *)ADDR_32_TO_48(a);
     prot = PROT_READ | PROT_WRITE;
     flag = MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS;
-    sm = _weaken(sys_mmap)(addr, size, prot, flag, -1, 0);
+    sm = sys_mmap(addr, size, prot, flag, -1, 0);
     if (sm.addr == MAP_FAILED ||
-        _weaken(__track_memory)(m, a, a + i - 1, sm.maphandle,
-                                PROT_READ | PROT_WRITE,
-                                MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, false,
-                                false, 0, size) == -1) {
+        __track_memory(m, a, a + i - 1, sm.maphandle, PROT_READ | PROT_WRITE,
+                       MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, false, false, 0,
+                       size) == -1) {
       kprintf("error: could not map asan shadow memory\n");
       __asan_die()();
       __asan_unreachable();
@@ -1539,9 +1536,6 @@ void __asan_init(int argc, char **argv, char **envp, unsigned long *auxv) {
     __write_str("error: asan binaries require windows10\r\n");
     _Exit(0); /* So `make MODE=dbg test` passes w/ Windows7 */
   }
-  REQUIRE(_mmi);
-  REQUIRE(sys_mmap);
-  REQUIRE(__track_memory);
   if (_weaken(hook_malloc) || _weaken(hook_calloc) || _weaken(hook_realloc) ||
       _weaken(hook_realloc_in_place) || _weaken(hook_free) ||
       _weaken(hook_malloc_usable_size)) {

libc/intrin/describeflags.c

@@ -18,7 +18,6 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/intrin/describeflags.internal.h"
 
-// TODO(jart): Fork this function into ASAN and non-ASAN versions.
 const char *DescribeFlags(char *p, size_t n, const struct DescribeFlags *d,
                           size_t m, const char *prefix, unsigned x) {
   bool t;

libc/intrin/findmemoryinterval.c

@@ -16,7 +16,6 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/assert.h"
 #include "libc/runtime/memtrack.internal.h"
 
 dontasan unsigned __find_memory(const struct MemoryIntervals *mm, int x) {
@@ -31,6 +30,5 @@ dontasan unsigned __find_memory(const struct MemoryIntervals *mm, int x) {
       r = m;
     }
   }
-  unassert(l == mm->i || x <= mm->p[l].y);
   return l;
 }

libc/runtime/clone.c

@@ -487,6 +487,10 @@ static errno_t CloneSilicon(int (*fn)(void *, int), char *stk, size_t stksz,
   if (!(res = __syslib->pthread_create(&th, 0, SiliconThreadMain, wt)) &&
       (flags & CLONE_PARENT_SETTID)) {
     *ptid = tid;
+    if (flags & CLONE_SETTLS) {
+      struct CosmoTib *tib = tls;
+      tib[-1].tib_pthread = th;
+    }
   }
   return res;
 }

libc/runtime/syslib.internal.h

@@ -16,7 +16,7 @@ COSMOPOLITAN_C_START_
  */
 
 #define SYSLIB_MAGIC   ('s' | 'l' << 8 | 'i' << 16 | 'b' << 24)
-#define SYSLIB_VERSION 1
+#define SYSLIB_VERSION 2
 
 typedef uint64_t dispatch_time_t;
 typedef uint64_t dispatch_semaphore_t;
@@ -42,6 +42,8 @@ struct Syslib {
   long (*dispatch_semaphore_signal)(dispatch_semaphore_t);
   long (*dispatch_semaphore_wait)(dispatch_semaphore_t, dispatch_time_t);
   dispatch_time_t (*dispatch_walltime)(const struct timespec *, int64_t);
+  /* v2 (2023-09-10) */
+  long (*pthread_self)(void);
 };
 
 extern struct Syslib *__syslib;

libc/sysv/dos2errno.sh

@@ -89,6 +89,8 @@ dos	kNtErrorUnexpNetErr             ECONNABORTED
 dos	kNtErrorWorkingSetQuota         ENOMEM
 dos	kNtErrorWriteProtect            EACCES
 dos	kNtErrorWrongDisk               EACCES
+dos	kNtErrorExeMarkedInvalid	ENOEXEC
+dos	kNtErrorExeMachineTypeMismatch	ENOEXEC
 dos	WSAEACCES                       EACCES
 dos	WSAEDISCON                      EPIPE
 dos	WSAEFAULT                       EFAULT

libc/sysv/dos2errno/ENOEXEC.S

@@ -0,0 +1,15 @@
+//	generated by libc/sysv/dos2errno.sh
+#include "libc/nt/errors.h"
+#ifndef __x86_64__
+        .end
+#endif
+	.macro	.e doscode systemv
+	.short	\doscode
+	.long	\systemv
+	.endm
+	.section .sort.rodata.dos2errno.2,"a",@progbits
+	.globl	kDos2Errno.ENOEXEC
+	.type	kDos2Errno.ENOEXEC,@object
+kDos2Errno.ENOEXEC:
+	.e	kNtErrorExeMarkedInvalid,ENOEXEC
+	.e	kNtErrorExeMachineTypeMismatch,ENOEXEC

libc/testlib/extract.c

@@ -17,6 +17,8 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
+#include "libc/runtime/runtime.h"
+#include "libc/stdio/stdio.h"
 #include "libc/sysv/consts/o.h"
 #include "libc/testlib/testlib.h"
 
@@ -31,9 +33,24 @@ __static_yoink("zipos");
  */
 void testlib_extract(const char *zip, const char *to, int mode) {
   int fdin, fdout;
-  ASSERT_NE(-1, (fdin = open(zip, O_RDONLY)));
-  ASSERT_NE(-1, (fdout = creat(to, mode)));
-  ASSERT_NE(-1, copyfd(fdin, fdout, -1));
-  ASSERT_NE(-1, close(fdout));
-  ASSERT_NE(-1, close(fdin));
+  if ((fdin = open(zip, O_RDONLY)) == -1) {
+    perror(zip);
+    exit(1);
+  }
+  if ((fdout = creat(to, mode)) == -1) {
+    perror(to);
+    exit(1);
+  }
+  if (copyfd(fdin, fdout, -1) == -1) {
+    perror(zip);
+    exit(1);
+  }
+  if (close(fdout)) {
+    perror(to);
+    exit(1);
+  }
+  if (close(fdin)) {
+    perror(zip);
+    exit(1);
+  }
 }

libc/thread/posixthread.internal.h

@@ -79,6 +79,7 @@ struct PosixThread {
   char *tls;               // bottom of tls allocation
   struct CosmoTib *tib;    // middle of tls allocation
   struct Dll list;         // list of threads
+  pthread_t next;          // for xnu silicon
   jmp_buf exiter;          // for pthread_exit
   pthread_attr_t attr;
   struct _pthread_cleanup_buffer *cleanup;

libc/thread/pthread_create.c

@@ -78,6 +78,7 @@ static int PosixThread(void *arg, int tid) {
   }
   // set long jump handler so pthread_exit can bring control back here
   if (!setjmp(pt->exiter)) {
+    pt->next = __get_tls()->tib_pthread;
     __get_tls()->tib_pthread = (pthread_t)pt;
     unassert(!sigprocmask(SIG_SETMASK, (sigset_t *)pt->attr.__sigmask, 0));
     rc = pt->start(pt->arg);