Update wasi-libc to a1c7c2c7a4b2813c6f67bd2ef6e0f430d31cebad

Some notable changes:
- `ENOENT` is returned instead of `ENOTCAPABLE` when a path has not
be pre-opened (https://github.com/WebAssembly/wasi-libc/pull/370)
- `fd_readdir()`: some implementations may not set the inode number,
so an additional call to `fstatat()` is now done in order to get it
when that happens.

lib/libc/include/wasm-wasi-musl/wasi/api.h

@@ -2099,7 +2099,7 @@ __wasi_errno_t __wasi_sock_shutdown(
  *
  * @see https://github.com/WebAssembly/wasi-threads/#readme
  */
-__wasi_errno_t __wasi_thread_spawn(
+int32_t __wasi_thread_spawn(
     /**
      * A pointer to an opaque struct to be passed to the module's entry
      * function.

lib/libc/wasi/libc-bottom-half/cloudlibc/src/libc/dirent/scandirat.c

@@ -11,6 +11,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "dirent_impl.h"
 
@@ -21,6 +22,8 @@ static int sel_true(const struct dirent *de) {
 int __wasilibc_nocwd_scandirat(int dirfd, const char *dir, struct dirent ***namelist,
                                int (*sel)(const struct dirent *),
                                int (*compar)(const struct dirent **, const struct dirent **)) {
+  struct stat statbuf;
+
   // Match all files if no select function is provided.
   if (sel == NULL)
     sel = sel_true;
@@ -89,10 +92,30 @@ int __wasilibc_nocwd_scandirat(int dirfd, const char *dir, struct dirent ***name
         malloc(offsetof(struct dirent, d_name) + entry.d_namlen + 1);
     if (dirent == NULL)
       goto bad;
-    dirent->d_ino = entry.d_ino;
     dirent->d_type = entry.d_type;
     memcpy(dirent->d_name, name, entry.d_namlen);
     dirent->d_name[entry.d_namlen] = '\0';
+
+    // `fd_readdir` implementations may set the inode field to zero if the
+    // the inode number is unknown. In that case, do an `fstatat` to get the
+    // inode number.
+    off_t d_ino = entry.d_ino;
+    unsigned char d_type = entry.d_type;
+    if (d_ino == 0) {
+      if (fstatat(fd, dirent->d_name, &statbuf, AT_SYMLINK_NOFOLLOW) != 0) {
+        return -1;
+      }
+
+      // Fill in the inode.
+      d_ino = statbuf.st_ino;
+
+      // In case someone raced with us and replaced the object with this name
+      // with another of a different type, update the type too.
+      d_type = __wasilibc_iftodt(statbuf.st_mode & S_IFMT);
+    }
+    dirent->d_ino = d_ino;
+    dirent->d_type = d_type;
+
     cookie = entry.d_next;
 
     if (sel(dirent)) {

lib/libc/wasi/libc-bottom-half/signal/signal.c

@@ -138,5 +138,5 @@ void (*signal(int sig, void (*func)(int)))(int) {
     return old;
 }
 
-extern __typeof(signal) bsd_signal __attribute__((__weak__, alias("signal")));
-extern __typeof(signal) __sysv_signal __attribute__((__weak__, alias("signal")));
+extern __typeof(signal) bsd_signal __attribute__((weak, alias("signal")));
+extern __typeof(signal) __sysv_signal __attribute__((weak, alias("signal")));

lib/libc/wasi/libc-bottom-half/sources/__wasilibc_real.c

@@ -665,8 +665,7 @@ int32_t __imported_wasi_thread_spawn(int32_t arg0) __attribute__((
     __import_name__("thread_spawn")
 ));
 
-__wasi_errno_t __wasi_thread_spawn(void* start_arg) {
-	int32_t ret = __imported_wasi_thread_spawn((int32_t) start_arg);
-    return (uint16_t) ret;
+int32_t __wasi_thread_spawn(void* start_arg) {
+    return __imported_wasi_thread_spawn((int32_t) start_arg);
 }
 #endif

lib/libc/wasi/libc-bottom-half/sources/isatty.c

@@ -19,4 +19,4 @@ int __isatty(int fd) {
 
     return 1;
 }
-extern __typeof(__isatty) isatty __attribute__((__weak__, alias("__isatty")));
+extern __typeof(__isatty) isatty __attribute__((weak, alias("__isatty")));

lib/libc/wasi/libc-bottom-half/sources/posix.c

@@ -58,9 +58,9 @@ int __wasilibc_open_nomode(const char *path, int oflag) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -71,9 +71,9 @@ int access(const char *path, int amode) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -88,9 +88,9 @@ ssize_t readlink(
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -101,9 +101,9 @@ int stat(const char *restrict path, struct stat *restrict buf) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -114,9 +114,9 @@ int lstat(const char *restrict path, struct stat *restrict buf) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -127,9 +127,9 @@ int utime(const char *path, const struct utimbuf *times) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -147,9 +147,9 @@ int utimes(const char *path, const struct timeval times[2]) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -169,9 +169,9 @@ int unlink(const char *path) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -185,9 +185,9 @@ int rmdir(const char *path) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -198,21 +198,21 @@ int remove(const char *path) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
     // First try to remove it as a file.
     int r = __wasilibc_nocwd___wasilibc_unlinkat(dirfd, relative_path);
-    if (r != 0 && (errno == EISDIR || errno == ENOTCAPABLE)) {
+    if (r != 0 && (errno == EISDIR || errno == ENOENT)) {
         // That failed, but it might be a directory.
         r = __wasilibc_nocwd___wasilibc_rmdirat(dirfd, relative_path);
 
         // If it isn't a directory, we lack capabilities to remove it as a file.
         if (errno == ENOTDIR)
-            errno = ENOTCAPABLE;
+            errno = ENOENT;
     }
     return r;
 }
@@ -221,9 +221,9 @@ int mkdir(const char *path, mode_t mode) {
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -234,9 +234,9 @@ DIR *opendir(const char *dirname) {
     char *relative_path;
     int dirfd = find_relpath(dirname, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return NULL;
     }
 
@@ -252,9 +252,9 @@ int scandir(
     char *relative_path;
     int dirfd = find_relpath(dir, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -265,9 +265,9 @@ int symlink(const char *target, const char *linkpath) {
     char *relative_path;
     int dirfd = find_relpath(linkpath, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -287,8 +287,8 @@ int link(const char *old, const char *new) {
                                            new_dirfd, new_relative_path, 0);
     }
 
-    // We couldn't find a preopen for it; indicate that we lack capabilities.
-    errno = ENOTCAPABLE;
+    // We couldn't find a preopen for it; fail as if we can't find the path.
+    errno = ENOENT;
     return -1;
 }
 
@@ -305,8 +305,8 @@ int rename(const char *old, const char *new) {
                                              new_dirfd, new_relative_path);
     }
 
-    // We couldn't find a preopen for it; indicate that we lack capabilities.
-    errno = ENOTCAPABLE;
+    // We couldn't find a preopen for it; fail as if we can't find the path.
+    errno = ENOENT;
     return -1;
 }
 
@@ -317,9 +317,9 @@ __wasilibc_access(const char *path, int mode, int flags)
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -334,9 +334,9 @@ __wasilibc_utimens(const char *path, const struct timespec times[2], int flags)
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -351,9 +351,9 @@ __wasilibc_stat(const char *__restrict path, struct stat *__restrict st, int fla
     char *relative_path;
     int dirfd = find_relpath(path, &relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -369,9 +369,9 @@ __wasilibc_link(const char *oldpath, const char *newpath, int flags)
     int old_dirfd = find_relpath(oldpath, &old_relative_path);
     int new_dirfd = find_relpath(newpath, &new_relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (old_dirfd == -1 || new_dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -387,9 +387,9 @@ __wasilibc_link_oldat(int olddirfd, const char *oldpath, const char *newpath, in
     char *new_relative_path;
     int new_dirfd = find_relpath(newpath, &new_relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (new_dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -405,9 +405,9 @@ __wasilibc_link_newat(const char *oldpath, int newdirfd, const char *newpath, in
     char *old_relative_path;
     int old_dirfd = find_relpath(oldpath, &old_relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (old_dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -423,9 +423,9 @@ __wasilibc_rename_oldat(int fromdirfd, const char *from, const char *to)
     char *to_relative_path;
     int to_dirfd = find_relpath(to, &to_relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (to_dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 
@@ -439,9 +439,9 @@ __wasilibc_rename_newat(const char *from, int todirfd, const char *to)
     char *from_relative_path;
     int from_dirfd = find_relpath(from, &from_relative_path);
 
-    // If we can't find a preopen for it, indicate that we lack capabilities.
+    // If we can't find a preopen for it, fail as if we can't find the path.
     if (from_dirfd == -1) {
-        errno = ENOTCAPABLE;
+        errno = ENOENT;
         return -1;
     }
 

lib/libc/wasi/libc-top-half/musl/include/pthread.h

@@ -85,7 +85,9 @@ extern "C" {
 
 int pthread_create(pthread_t *__restrict, const pthread_attr_t *__restrict, void *(*)(void *), void *__restrict);
 int pthread_detach(pthread_t);
+#ifdef __wasilibc_unmodified_upstream
 _Noreturn void pthread_exit(void *);
+#endif
 int pthread_join(pthread_t, void **);
 
 #ifdef __GNUC__

lib/libc/wasi/libc-top-half/musl/include/unistd.h

@@ -336,7 +336,9 @@ pid_t gettid(void);
 #endif
 #define _POSIX_VDISABLE         0
 
+#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
 #define _POSIX_THREADS          _POSIX_VERSION
+#endif
 #define _POSIX_THREAD_PROCESS_SHARED _POSIX_VERSION
 #define _POSIX_THREAD_SAFE_FUNCTIONS _POSIX_VERSION
 #define _POSIX_THREAD_ATTR_STACKADDR _POSIX_VERSION

lib/libc/wasi/libc-top-half/musl/src/env/__init_tls.c

@@ -16,6 +16,43 @@
 volatile int __thread_list_lock;
 
 #ifndef __wasilibc_unmodified_upstream
+
+/* These symbols are generated by wasm-ld. __stack_high/__stack_low
+ * symbols are only available in LLVM v16 and higher, therefore they're
+ * defined as weak symbols and if not available, __heap_base/__data_end
+ * is used instead.
+ *
+ * TODO: remove usage of __heap_base/__data_end for stack size calculation
+ * once we drop support for LLVM v15 and older.
+ */
+extern unsigned char __heap_base;
+extern unsigned char __data_end;
+extern unsigned char __global_base;
+extern weak unsigned char __stack_high;
+extern weak unsigned char __stack_low;
+
+static inline void setup_default_stack_size()
+{
+	ptrdiff_t stack_size;
+
+	if (&__stack_high)
+		stack_size = &__stack_high - &__stack_low;
+	else {
+		unsigned char *sp;
+		__asm__(
+			".globaltype __stack_pointer, i32\n"
+			"global.get __stack_pointer\n"
+			"local.set %0\n"
+			: "=r"(sp));
+		stack_size = sp > &__global_base ? &__heap_base - &__data_end : (ptrdiff_t)&__global_base;
+	}
+
+	if (stack_size > __default_stacksize)
+		__default_stacksize =
+			stack_size < DEFAULT_STACK_MAX ?
+			stack_size : DEFAULT_STACK_MAX;
+}
+
 void __wasi_init_tp() {
 	__init_tp((void *)__get_tp());
 }
@@ -31,6 +68,20 @@ int __init_tp(void *p)
 	if (!r) libc.can_do_threads = 1;
 	td->detach_state = DT_JOINABLE;
 	td->tid = __syscall(SYS_set_tid_address, &__thread_list_lock);
+#else
+	setup_default_stack_size();
+	td->detach_state = DT_JOINABLE;
+	/*
+	 * Initialize the TID to a value which doesn't conflict with
+	 * host-allocated TIDs, so that TID-based locks can work.
+	 *
+	 * Note:
+	 * - Host-allocated TIDs range from 1 to 0x1fffffff. (inclusive)
+	 * - __tl_lock and __lockfile uses TID 0 as "unlocked".
+	 * - __lockfile relies on the fact the most significant two bits
+	 *   of TIDs are 0.
+	 */
+	td->tid = 0x3fffffff;
 #endif
 	td->locale = &libc.global_locale;
 	td->robust_list.head = &td->robust_list.head;

lib/libc/wasi/libc-top-half/musl/src/include/pthread.h

@@ -7,7 +7,9 @@ hidden int __pthread_once(pthread_once_t *, void (*)(void));
 hidden void __pthread_testcancel(void);
 hidden int __pthread_setcancelstate(int, int *);
 hidden int __pthread_create(pthread_t *restrict, const pthread_attr_t *restrict, void *(*)(void *), void *restrict);
+#ifdef __wasilibc_unmodified_upstream
 hidden _Noreturn void __pthread_exit(void *);
+#endif
 hidden int __pthread_join(pthread_t, void **);
 hidden int __pthread_mutex_lock(pthread_mutex_t *);
 hidden int __pthread_mutex_trylock(pthread_mutex_t *);

lib/libc/wasi/libc-top-half/musl/src/internal/pthread_impl.h

@@ -216,7 +216,12 @@ extern hidden unsigned __default_stacksize;
 extern hidden unsigned __default_guardsize;
 
 #define DEFAULT_STACK_SIZE 131072
+#ifdef __wasilibc_unmodified_upstream
 #define DEFAULT_GUARD_SIZE 8192
+#else
+/* guard doesn't make much sense without mprotect. */
+#define DEFAULT_GUARD_SIZE 0
+#endif
 
 #define DEFAULT_STACK_MAX (8<<20)
 #define DEFAULT_GUARD_MAX (1<<20)

lib/libc/wasi/libc-top-half/musl/src/thread/__wait.c

@@ -48,7 +48,7 @@ void __wait(volatile int *addr, volatile int *waiters, int val, int priv)
 		__syscall(SYS_futex, addr, FUTEX_WAIT|priv, val, 0) != -ENOSYS
 		|| __syscall(SYS_futex, addr, FUTEX_WAIT, val, 0);
 #else
-		__wasilibc_futex_wait(addr, FUTEX_WAIT, val, 0);
+		__wasilibc_futex_wait(addr, FUTEX_WAIT, val, -1);
 #endif
 	}
 	if (waiters) a_dec(waiters);

lib/libc/wasi/libc-top-half/musl/src/thread/pthread_attr_get.c

@@ -17,6 +17,7 @@ int pthread_attr_getinheritsched(const pthread_attr_t *restrict a, int *restrict
 	return 0;
 }
 
+#ifdef __wasilibc_unmodified_upstream /* WASI has no CPU scheduling support. */
 int pthread_attr_getschedparam(const pthread_attr_t *restrict a, struct sched_param *restrict param)
 {
 	param->sched_priority = a->_a_prio;
@@ -28,6 +29,7 @@ int pthread_attr_getschedpolicy(const pthread_attr_t *restrict a, int *restrict
 	*policy = a->_a_policy;
 	return 0;
 }
+#endif
 
 int pthread_attr_getscope(const pthread_attr_t *restrict a, int *restrict scope)
 {
@@ -56,11 +58,13 @@ int pthread_barrierattr_getpshared(const pthread_barrierattr_t *restrict a, int
 	return 0;
 }
 
+#ifdef __wasilibc_unmodified_upstream /* Forward declaration of WASI's `__clockid` type. */
 int pthread_condattr_getclock(const pthread_condattr_t *restrict a, clockid_t *restrict clk)
 {
 	*clk = a->__attr & 0x7fffffff;
 	return 0;
 }
+#endif
 
 int pthread_condattr_getpshared(const pthread_condattr_t *restrict a, int *restrict pshared)
 {

lib/libc/wasi/libc-top-half/musl/src/thread/pthread_barrier_destroy.c

@@ -9,7 +9,9 @@ int pthread_barrier_destroy(pthread_barrier_t *b)
 			while ((v = b->_b_lock) & INT_MAX)
 				__wait(&b->_b_lock, 0, v, 0);
 		}
+#ifdef __wasilibc_unmodified_upstream /* WASI does not understand processes or locking between them. */
 		__vm_wait();
+#endif
 	}
 	return 0;
 }

lib/libc/wasi/libc-top-half/musl/src/thread/pthread_barrier_wait.c

@@ -23,7 +23,9 @@ static int pshared_barrier_wait(pthread_barrier_t *b)
 			__wait(&b->_b_count, &b->_b_waiters2, v, 0);
 	}
 
+#ifdef __wasilibc_unmodified_upstream /* WASI does not understand processes or locking between them. */
 	__vm_lock();
+#endif
 
 	/* Ensure all threads have a vm lock before proceeding */
 	if (a_fetch_add(&b->_b_count, -1)==1-limit) {
@@ -44,7 +46,9 @@ static int pshared_barrier_wait(pthread_barrier_t *b)
 	if (v==INT_MIN+1 || (v==1 && w))
 		__wake(&b->_b_lock, 1, 0);
 
+#ifdef __wasilibc_unmodified_upstream /* WASI does not understand processes or locking between them. */
 	__vm_unlock();
+#endif
 
 	return ret;
 }
@@ -84,8 +88,12 @@ int pthread_barrier_wait(pthread_barrier_t *b)
 			a_spin();
 		a_inc(&inst->finished);
 		while (inst->finished == 1)
+#ifdef __wasilibc_unmodified_upstream
 			__syscall(SYS_futex,&inst->finished,FUTEX_WAIT|FUTEX_PRIVATE,1,0) != -ENOSYS
 			|| __syscall(SYS_futex,&inst->finished,FUTEX_WAIT,1,0);
+#else
+			__futexwait(&inst->finished, 1, 0);
+#endif
 		return PTHREAD_BARRIER_SERIAL_THREAD;
 	}
 

lib/libc/wasi/libc-top-half/musl/src/thread/pthread_create.c

@@ -60,7 +60,11 @@ void __tl_sync(pthread_t td)
 	if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
 }
 
+#ifdef __wasilibc_unmodified_upstream
 _Noreturn void __pthread_exit(void *result)
+#else
+static void __pthread_exit(void *result)
+#endif
 {
 	pthread_t self = __pthread_self();
 	sigset_t set;
@@ -191,7 +195,7 @@ _Noreturn void __pthread_exit(void *result)
 		__tl_unlock();
 		free(self->map_base);
 		// Can't use `exit()` here, because it is too high level
-		for (;;) __wasi_proc_exit(0);
+		return;
 	}
 #endif
 
@@ -212,7 +216,6 @@ _Noreturn void __pthread_exit(void *result)
 	// do it manually here
 	__tl_unlock();
 	// Can't use `exit()` here, because it is too high level
-	for (;;) __wasi_proc_exit(0);
 #endif
 }
 
@@ -235,9 +238,14 @@ struct start_args {
 	volatile int control;
 	unsigned long sig_mask[_NSIG/8/sizeof(long)];
 #else
+	/*
+	 * Note: the offset of the "stack" and "tls_base" members
+	 * in this structure is hardcoded in wasi_thread_start.
+	 */
+	void *stack;
+	void *tls_base;
 	void *(*start_func)(void *);
 	void *start_arg;
-	void *tls_base;
 #endif
 };
 
@@ -271,32 +279,41 @@ static int start_c11(void *p)
 	return 0;
 }
 #else
-__attribute__((export_name("wasi_thread_start")))
-_Noreturn void wasi_thread_start(int tid, void *p)
+
+/*
+ * We want to ensure wasi_thread_start is linked whenever
+ * pthread_create is used. The following reference is to ensure that.
+ * Otherwise, the linker doesn't notice the dependency because
+ * wasi_thread_start is used indirectly via a wasm export.
+ */
+void wasi_thread_start(int tid, void *p);
+hidden void *__dummy_reference = wasi_thread_start;
+
+hidden void __wasi_thread_start_C(int tid, void *p)
 {
 	struct start_args *args = p;
-  	__asm__(".globaltype __tls_base, i32\n"
-			"local.get %0\n"
-			"global.set __tls_base\n"
-			:: "r"(args->tls_base));
 	pthread_t self = __pthread_self();
 	// Set the thread ID (TID) on the pthread structure. The TID is stored
 	// atomically since it is also stored by the parent thread; this way,
 	// whichever thread (parent or child) reaches this point first can proceed
 	// without waiting.
 	atomic_store((atomic_int *) &(self->tid), tid);
-	// Set the stack pointer.
-  	__asm__(".globaltype __stack_pointer, i32\n"
-			"local.get %0\n"
-			"global.set __stack_pointer\n"
-			:: "r"(self->stack));
 	// Execute the user's start function.
-	int (*start)(void*) = (int(*)(void*)) args->start_func;
-	__pthread_exit((void *)(uintptr_t)start(args->start_arg));
+	__pthread_exit(args->start_func(args->start_arg));
 }
 #endif
 
+#ifdef __wasilibc_unmodified_upstream
 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
+#else
+/*
+ * As we allocate stack with malloc() instead of mmap/mprotect,
+ * there is no point to round it up to PAGE_SIZE.
+ * Instead, round up to a sane alignment.
+ * Note: PAGE_SIZE is rather big on WASM. (65536)
+ */
+#define ROUND(x) (((x)+16-1)&-16)
+#endif
 
 /* pthread_key_create.c overrides this */
 static volatile size_t dummy = 0;
@@ -484,6 +501,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
 	/* Correct the stack size */
 	new->stack_size = stack - stack_limit;
 
+	args->stack = new->stack; /* just for convenience of asm trampoline */
 	args->start_func = entry;
 	args->start_arg = arg;
 	args->tls_base = (void*)new_tls_base;
@@ -561,5 +579,7 @@ fail:
 	return EAGAIN;
 }
 
+#ifdef __wasilibc_unmodified_upstream
 weak_alias(__pthread_exit, pthread_exit);
+#endif
 weak_alias(__pthread_create, pthread_create);

lib/libc/wasi/libc-top-half/musl/src/thread/pthread_key_create.c

@@ -50,7 +50,9 @@ int __pthread_key_delete(pthread_key_t k)
 	sigset_t set;
 	pthread_t self = __pthread_self(), td=self;
 
+#ifdef __wasilibc_unmodified_upstream
 	__block_app_sigs(&set);
+#endif
 	__pthread_rwlock_wrlock(&key_lock);
 
 	__tl_lock();
@@ -61,7 +63,9 @@ int __pthread_key_delete(pthread_key_t k)
 	keys[k] = 0;
 
 	__pthread_rwlock_unlock(&key_lock);
+#ifdef __wasilibc_unmodified_upstream
 	__restore_sigs(&set);
+#endif
 
 	return 0;
 }