threads: implement init of TLS and stack pointer (WebAssembly#342)

* threads: implement init of TLS and stack pointer

* fix: rename wasi_snapshot_preview2_thread_spawn to wasi_thread_spawn

Signed-off-by: Harald Hoyer <[email protected]>

* fix: change signature of wasi_thread_start

Signed-off-by: Harald Hoyer <[email protected]>

* fix: pthread_exit for WASI

Can't use `exit()` because it is too high level.
Have to unlock the thread list.

Signed-off-by: Harald Hoyer <[email protected]>

* fix: initialize struct pthread for the main thread

Signed-off-by: Harald Hoyer <[email protected]>

* fix: store the aligned stack minus `struct start_args`

Signed-off-by: Harald Hoyer <[email protected]>

Signed-off-by: Harald Hoyer <[email protected]>
Co-authored-by: Harald Hoyer <[email protected]>

Author: 2 people

Makefile

@@ -220,9 +220,16 @@ LIBC_TOP_HALF_MUSL_SOURCES = \
 ifeq ($(THREAD_MODEL), posix)
 LIBC_TOP_HALF_MUSL_SOURCES += \
     $(addprefix $(LIBC_TOP_HALF_MUSL_SRC_DIR)/, \
+        env/__init_tls.c \
+        stdio/__lockfile.c \
         thread/__lock.c \
         thread/__wait.c \
         thread/__timedwait.c \
+        thread/default_attr.c \
+        thread/pthread_attr_destroy.c \
+        thread/pthread_attr_init.c \
+        thread/pthread_attr_setstack.c \
+        thread/pthread_attr_setstacksize.c \
         thread/pthread_cleanup_push.c \
         thread/pthread_cond_broadcast.c \
         thread/pthread_cond_destroy.c \
@@ -263,6 +270,7 @@ LIBC_TOP_HALF_MUSL_SOURCES += \
         thread/pthread_rwlockattr_init.c \
         thread/pthread_rwlockattr_setpshared.c \
         thread/pthread_setcancelstate.c \
+        thread/pthread_self.c \
         thread/pthread_testcancel.c \
         thread/sem_destroy.c \
         thread/sem_getvalue.c \

expected/wasm32-wasi/posix/defined-symbols.txt

@@ -411,6 +411,7 @@ __wasi_futex_wake_all
 __wasi_getcwd
 __wasi_http_request
 __wasi_http_status
+__wasi_init_tp
 __wasi_path_create_directory
 __wasi_path_filestat_get
 __wasi_path_filestat_set_times
@@ -531,6 +532,7 @@ __wasilibc_nocwd_utimensat
 __wasilibc_open_nomode
 __wasilibc_pgrp
 __wasilibc_populate_preopens_init
+__wasilibc_pthread_self
 __wasilibc_register_preopened_fd
 __wasilibc_rename_newat
 __wasilibc_rename_oldat

expected/wasm32-wasi/posix/undefined-symbols.txt

@@ -150,7 +150,5 @@ __tls_size
 __trunctfdf2
 __trunctfsf2
 __unordtf2
-__wasilibc_pthread_self
 __wasm_call_ctors
 __wasm_init_tls
-main

libc-bottom-half/crt/crt1-command.c

@@ -1,5 +1,6 @@
 #ifdef _REENTRANT
 #include <stdatomic.h>
+extern void __wasi_init_tp(void);
 #endif
 #include <wasi/api.h>
 extern void __wasm_call_ctors(void);
@@ -29,6 +30,10 @@ void _start(void) {
     started = 1;
 #endif
 
+#ifdef _REENTRANT
+	__wasi_init_tp();
+#endif
+
     // The linker synthesizes this to call constructors.
     __wasm_call_ctors();
 

libc-top-half/musl/arch/wasm32/pthread_arch.h

@@ -1,11 +1,5 @@
-static inline uintptr_t __get_tp(void) {
-#if _REENTRANT
-  int val;
-  __asm__("global.get __wasilibc_pthread_self\n"
-          "local.set %0"
-          : "=r"(val));
-  return val;
-#else
-  return 0;
-#endif
+extern _Thread_local struct __pthread __wasilibc_pthread_self;
+
+static inline uintptr_t __get_tp() {
+  return (uintptr_t)&__wasilibc_pthread_self;
 }

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

@@ -1,7 +1,11 @@
+#ifdef __wasilibc_unmodified_upstream
 #define SYSCALL_NO_TLS 1
 #include <elf.h>
+#endif
 #include <limits.h>
+#ifdef __wasilibc_unmodified_upstream
 #include <sys/mman.h>
+#endif
 #include <string.h>
 #include <stddef.h>
 #include "pthread_impl.h"
@@ -15,20 +19,22 @@
 
 volatile int __thread_list_lock;
 
+#ifndef __wasilibc_unmodified_upstream
+void __wasi_init_tp() {
+	__init_tp((void *)__get_tp());
+}
+#endif
+
 int __init_tp(void *p)
 {
 	pthread_t td = p;
 	td->self = td;
+#ifdef __wasilibc_unmodified_upstream
 	int r = __set_thread_area(TP_ADJ(p));
 	if (r < 0) return -1;
 	if (!r) libc.can_do_threads = 1;
 	td->detach_state = DT_JOINABLE;
-#ifdef __wasilibc_unmodified_upstream
 	td->tid = __syscall(SYS_set_tid_address, &__thread_list_lock);
-#else
-	td->tid = 0;
-	r = __wasi_thread_id(&td->tid);
-	if (r != 0) return r;
 #endif
 	td->locale = &libc.global_locale;
 	td->robust_list.head = &td->robust_list.head;
@@ -37,6 +43,8 @@ int __init_tp(void *p)
 	return 0;
 }
 
+#ifdef __wasilibc_unmodified_upstream
+
 static struct builtin_tls {
 	char c;
 	struct pthread pt;
@@ -45,9 +53,15 @@ static struct builtin_tls {
 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
 
 static struct tls_module main_tls;
+#endif
+
+#ifndef __wasilibc_unmodified_upstream
+extern void __wasm_init_tls(void*);
+#endif
 
 void *__copy_tls(unsigned char *mem)
 {
+#ifdef __wasilibc_unmodified_upstream
 	pthread_t td;
 	struct tls_module *p;
 	size_t i;
@@ -79,9 +93,24 @@ void *__copy_tls(unsigned char *mem)
 	dtv[0] = libc.tls_cnt;
 	td->dtv = dtv;
 	return td;
+#else
+	size_t tls_align = __builtin_wasm_tls_align();
+	volatile void* tls_base = __builtin_wasm_tls_base();
+	mem += tls_align;
+	mem -= (uintptr_t)mem & (tls_align-1);
+	__wasm_init_tls(mem);
+  	__asm__("local.get %0\n"
+			"global.set __tls_base\n"
+			:: "r"(tls_base));
+	return mem;
+#endif
 }
 
+<<<<<<< HEAD
 
+=======
+#ifdef __wasilibc_unmodified_upstream
+>>>>>>> a00bf32 (threads: implement init of TLS and stack pointer (#342))
 #if ULONG_MAX == 0xffffffff
 typedef Elf32_Phdr Phdr;
 #else
@@ -164,3 +193,9 @@ void __init_tls(size_t *aux)
 	if (__init_tp(__copy_tls(mem)) < 0)
 		a_crash();
 }
+<<<<<<< HEAD
+=======
+
+weak_alias(static_init_tls, __init_tls);
+#endif
+>>>>>>> a00bf32 (threads: implement init of TLS and stack pointer (#342))

libc-top-half/musl/src/internal/libc.h

@@ -18,8 +18,10 @@ struct tls_module {
 };
 
 struct __libc {
-#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
+#ifdef __wasilibc_unmodified_upstream
 	char can_do_threads;
+#endif
+#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
 	char threaded;
 #endif
 #ifdef __wasilibc_unmodified_upstream // WASI doesn't currently use any code that needs "secure" mode
@@ -32,7 +34,7 @@ struct __libc {
 #ifdef __wasilibc_unmodified_upstream // WASI has no auxv
 	size_t *auxv;
 #endif
-#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
+#ifdef __wasilibc_unmodified_upstream // WASI use different TLS implement
 	struct tls_module *tls_head;
 	size_t tls_size, tls_align, tls_cnt;
 #endif

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

@@ -26,8 +26,10 @@ struct pthread {
 	/* Part 1 -- these fields may be external or
 	 * internal (accessed via asm) ABI. Do not change. */
 	struct pthread *self;
+#ifdef __wasilibc_unmodified_upstream
 #ifndef TLS_ABOVE_TP
 	uintptr_t *dtv;
+#endif
 #endif
 	struct pthread *prev, *next; /* non-ABI */
 	uintptr_t sysinfo;

libc-top-half/musl/src/thread/__tls_get_addr.c

@@ -2,6 +2,11 @@
 
 void *__tls_get_addr(tls_mod_off_t *v)
 {
+#ifdef __wasilibc_unmodified_upstream
 	pthread_t self = __pthread_self();
 	return (void *)(self->dtv[v[0]] + v[1]);
+#else
+	uintptr_t *dtv = __builtin_wasm_tls_base();
+	return (void *)(dtv[v[0]] + v[1]);
+#endif
 }