[libc-commits] [libc] abc040e - [libc] Add linux implementations of thrd_create and thrd_join functions.
Siva Chandra Reddy via libc-commits
libc-commits at lists.llvm.org
Thu Mar 5 13:56:29 PST 2020
Author: Siva Chandra Reddy
Date: 2020-03-05T13:53:17-08:00
New Revision: abc040e9533011a62a25c93b07b4fc31c8a641f7
URL: https://github.com/llvm/llvm-project/commit/abc040e9533011a62a25c93b07b4fc31c8a641f7
DIFF: https://github.com/llvm/llvm-project/commit/abc040e9533011a62a25c93b07b4fc31c8a641f7.diff
LOG: [libc] Add linux implementations of thrd_create and thrd_join functions.
Reviewers: abrachet, phosek
Differential Revision: https://reviews.llvm.org/D75380
Added:
libc/config/linux/threads.h.in
libc/src/threads/CMakeLists.txt
libc/src/threads/linux/CMakeLists.txt
libc/src/threads/linux/thrd_create.cpp
libc/src/threads/linux/thrd_join.cpp
libc/src/threads/linux/thread_utils.h
libc/src/threads/thrd_create.h
libc/src/threads/thrd_join.h
libc/test/src/threads/CMakeLists.txt
libc/test/src/threads/thrd_test.cpp
Modified:
libc/config/linux/api.td
libc/include/CMakeLists.txt
libc/include/threads.h.def
libc/lib/CMakeLists.txt
libc/src/CMakeLists.txt
libc/test/src/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/api.td b/libc/config/linux/api.td
index 1c9fa8a36c2e..2f9a840c6d86 100644
--- a/libc/config/linux/api.td
+++ b/libc/config/linux/api.td
@@ -150,7 +150,15 @@ def SignalAPI : PublicAPI<"signal.h"> {
];
}
+def ThreadStartT : TypeDecl<"thrd_start_t"> {
+ let Decl = "typedef int (*thrd_start_t)(void *);";
+}
+
def ThreadsAPI : PublicAPI<"threads.h"> {
+ let TypeDeclarations = [
+ ThreadStartT,
+ ];
+
let Enumerations = [
"mtx_plain",
"mtx_recursive",
@@ -161,4 +169,9 @@ def ThreadsAPI : PublicAPI<"threads.h"> {
"thrd_error",
"thrd_nomem",
];
+
+ let Functions = [
+ "thrd_create",
+ "thrd_join",
+ ];
}
diff --git a/libc/config/linux/threads.h.in b/libc/config/linux/threads.h.in
new file mode 100644
index 000000000000..58f58a3add8b
--- /dev/null
+++ b/libc/config/linux/threads.h.in
@@ -0,0 +1,17 @@
+//===--------- Linux specific definitions of types from threads.h ---------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+%%begin()
+
+typedef struct {
+ unsigned char __clear_tid[4];
+ int __tid;
+ void *__stack;
+ int __stack_size;
+ int __retval;
+} thrd_t;
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index db5f371f75f3..bbc41b0ec151 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -39,8 +39,12 @@ add_gen_header(
threads_h
DEF_FILE threads.h.def
GEN_HDR threads.h
+ PARAMS
+ platform_threads=../config/${LIBC_TARGET_OS}/threads.h.in
DEPENDS
llvm_libc_common_h
+ DATA_FILES
+ ../config/${LIBC_TARGET_OS}/threads.h.in
)
add_gen_header(
diff --git a/libc/include/threads.h.def b/libc/include/threads.h.def
index 276f78bb35a7..e99fcfcd89f1 100644
--- a/libc/include/threads.h.def
+++ b/libc/include/threads.h.def
@@ -11,6 +11,8 @@
#include <__llvm-libc-common.h>
+%%include_file(${platform_threads})
+
%%public_api()
#endif // LLVM_LIBC_THREADS_H
diff --git a/libc/lib/CMakeLists.txt b/libc/lib/CMakeLists.txt
index b67f8e4c686b..83b19fd2c9ef 100644
--- a/libc/lib/CMakeLists.txt
+++ b/libc/lib/CMakeLists.txt
@@ -22,6 +22,10 @@ add_entrypoint_library(
# stdlib.h entrypoints
_Exit
abort
+
+ # threads.h entrypoints
+ thrd_create
+ thrd_join
)
add_entrypoint_library(
diff --git a/libc/src/CMakeLists.txt b/libc/src/CMakeLists.txt
index 7f8ef92e6cc5..4e661c838e51 100644
--- a/libc/src/CMakeLists.txt
+++ b/libc/src/CMakeLists.txt
@@ -5,5 +5,6 @@ add_subdirectory(stdlib)
add_subdirectory(string)
# TODO: Add this target conditional to the target OS.
add_subdirectory(sys)
+add_subdirectory(threads)
add_subdirectory(__support)
diff --git a/libc/src/threads/CMakeLists.txt b/libc/src/threads/CMakeLists.txt
new file mode 100644
index 000000000000..b4bbe81c92ff
--- /dev/null
+++ b/libc/src/threads/CMakeLists.txt
@@ -0,0 +1,3 @@
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
+ add_subdirectory(${LIBC_TARGET_OS})
+endif()
diff --git a/libc/src/threads/linux/CMakeLists.txt b/libc/src/threads/linux/CMakeLists.txt
new file mode 100644
index 000000000000..809a365a834d
--- /dev/null
+++ b/libc/src/threads/linux/CMakeLists.txt
@@ -0,0 +1,37 @@
+add_header_library(
+ threads_utils
+ HDRS
+ thread_utils.h
+)
+
+add_entrypoint_object(
+ thrd_create
+ SRCS
+ thrd_create.cpp
+ HDRS
+ ../thrd_create.h
+ DEPENDS
+ errno_h
+ linux_syscall_h
+ mmap
+ support_common_h
+ sys_syscall_h
+ threads_h
+ threads_utils
+ __errno_location
+)
+
+add_entrypoint_object(
+ thrd_join
+ SRCS
+ thrd_join.cpp
+ HDRS
+ ../thrd_join.h
+ DEPENDS
+ linux_syscall_h
+ munmap
+ support_common_h
+ sys_syscall_h
+ threads_h
+ threads_utils
+)
diff --git a/libc/src/threads/linux/thrd_create.cpp b/libc/src/threads/linux/thrd_create.cpp
new file mode 100644
index 000000000000..650c38cab924
--- /dev/null
+++ b/libc/src/threads/linux/thrd_create.cpp
@@ -0,0 +1,74 @@
+//===---------- Linux implementation of the thrd_create function ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "config/linux/syscall.h" // For syscall function.
+#include "include/errno.h" // For E* error values.
+#include "include/sys/mman.h" // For PROT_* and MAP_* definitions.
+#include "include/sys/syscall.h" // For syscall numbers.
+#include "include/threads.h" // For thrd_* type definitions.
+#include "src/__support/common.h"
+#include "src/errno/llvmlibc_errno.h"
+#include "src/sys/mman/mmap.h"
+#include "src/sys/mman/munmap.h"
+#include "src/threads/linux/thread_utils.h"
+
+#include <linux/futex.h> // For futex operations.
+#include <linux/sched.h> // For CLONE_* flags.
+#include <stdint.h>
+
+namespace __llvm_libc {
+
+static void start_thread(thrd_t *thread, thrd_start_t func, void *arg) {
+ __llvm_libc::syscall(SYS_exit, thread->__retval = func(arg));
+}
+
+int LLVM_LIBC_ENTRYPOINT(thrd_create)(thrd_t *thread, thrd_start_t func,
+ void *arg) {
+ unsigned clone_flags =
+ CLONE_VM // Share the memory space with the parent.
+ | CLONE_FS // Share the file system with the parent.
+ | CLONE_FILES // Share the files with the parent.
+ | CLONE_SIGHAND // Share the signal handlers with the parent.
+ | CLONE_THREAD // Same thread group as the parent.
+ | CLONE_SYSVSEM // Share a single list of System V semaphore adjustment
+ // values
+ | CLONE_PARENT_SETTID // Set child thread ID in |ptid| of the parent.
+ | CLONE_CHILD_CLEARTID; // Let the kernel clear the tid address and futex
+ // wake the joining thread.
+ // TODO: Add the CLONE_SETTLS flag and setup the TLS area correctly when
+ // making the clone syscall.
+
+ void *stack = __llvm_libc::mmap(nullptr, ThreadParams::DefaultStackSize,
+ PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ if (stack == MAP_FAILED)
+ return llvmlibc_errno == ENOMEM ? thrd_nomem : thrd_error;
+
+ thread->__stack = stack;
+ thread->__stack_size = ThreadParams::DefaultStackSize;
+ thread->__retval = -1;
+ FutexData *clear_tid_address =
+ reinterpret_cast<FutexData *>(thread->__clear_tid);
+ *clear_tid_address = ThreadParams::ClearTIDValue;
+
+ long clone_result = __llvm_libc::syscall(
+ SYS_clone, clone_flags,
+ reinterpret_cast<uintptr_t>(stack) + ThreadParams::DefaultStackSize - 1,
+ &thread->__tid, clear_tid_address, 0);
+
+ if (clone_result == 0) {
+ start_thread(thread, func, arg);
+ } else if (clone_result < 0) {
+ int error_val = -clone_result;
+ return error_val == ENOMEM ? thrd_nomem : thrd_error;
+ }
+
+ return thrd_success;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/linux/thrd_join.cpp b/libc/src/threads/linux/thrd_join.cpp
new file mode 100644
index 000000000000..7237354f89e9
--- /dev/null
+++ b/libc/src/threads/linux/thrd_join.cpp
@@ -0,0 +1,44 @@
+//===----------- Linux implementation of the thrd_join function -----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "config/linux/syscall.h" // For syscall function.
+#include "include/sys/syscall.h" // For syscall numbers.
+#include "include/threads.h" // For thrd_* type definitions.
+#include "src/__support/common.h"
+#include "src/sys/mman/munmap.h"
+#include "src/threads/linux/thread_utils.h"
+
+#include <linux/futex.h> // For futex operations.
+#include <stdatomic.h> // For atomic_load.
+
+namespace __llvm_libc {
+
+int LLVM_LIBC_ENTRYPOINT(thrd_join)(thrd_t *thread, int *retval) {
+ FutexData *clear_tid_address =
+ reinterpret_cast<FutexData *>(thread->__clear_tid);
+
+ while (atomic_load(clear_tid_address) != 0) {
+ // We cannot do a FUTEX_WAIT_PRIVATE here as the kernel does a
+ // FUTEX_WAKE and not a FUTEX_WAKE_PRIVATE.
+ __llvm_libc::syscall(SYS_futex, clear_tid_address, FUTEX_WAIT,
+ ThreadParams::ClearTIDValue, nullptr);
+
+ // The kernel should set the value at the clear tid address to zero.
+ // If not, it is a spurious wake and we should continue to wait on
+ // the futex.
+ }
+
+ *retval = thread->__retval;
+
+ if (__llvm_libc::munmap(thread->__stack, thread->__stack_size) == -1)
+ return thrd_error;
+
+ return thrd_success;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/linux/thread_utils.h b/libc/src/threads/linux/thread_utils.h
new file mode 100644
index 000000000000..b6f41b47d81e
--- /dev/null
+++ b/libc/src/threads/linux/thread_utils.h
@@ -0,0 +1,21 @@
+//===--- Linux specific definitions to support mutex operations --*- C++ -*===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H
+#define LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H
+
+#include <stdint.h>
+
+using FutexData = _Atomic uint32_t;
+
+struct ThreadParams {
+ static constexpr uintptr_t DefaultStackSize = 1 << 15; // 32 KB
+ static constexpr uint32_t ClearTIDValue = 0xABCD1234;
+};
+
+#endif // LLVM_LIBC_SRC_THREADS_LINUX_THREAD_UTILS_H
diff --git a/libc/src/threads/thrd_create.h b/libc/src/threads/thrd_create.h
new file mode 100644
index 000000000000..311929020905
--- /dev/null
+++ b/libc/src/threads/thrd_create.h
@@ -0,0 +1,20 @@
+//===------- Implementation header for thrd_create function ------ *-C++-* ===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_LINUX_THRD_CREATE_H
+#define LLVM_LIBC_SRC_THREADS_LINUX_THRD_CREATE_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+int thrd_create(thrd_t *thread, thrd_start_t func, void *arg);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_LINUX_THRD_CREATE_H
diff --git a/libc/src/threads/thrd_join.h b/libc/src/threads/thrd_join.h
new file mode 100644
index 000000000000..495b049d5f06
--- /dev/null
+++ b/libc/src/threads/thrd_join.h
@@ -0,0 +1,20 @@
+//===-------- Implementation header for thrd_join function ------- *-C++-* ===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_LINUX_THRD_JOIN_H
+#define LLVM_LIBC_SRC_THREADS_LINUX_THRD_JOIN_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+int thrd_join(thrd_t *thread, int *retval);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_LINUX_THRD_JOIN_H
diff --git a/libc/test/src/CMakeLists.txt b/libc/test/src/CMakeLists.txt
index bf56591e1d47..2ff4ca4d1252 100644
--- a/libc/test/src/CMakeLists.txt
+++ b/libc/test/src/CMakeLists.txt
@@ -3,3 +3,4 @@ add_subdirectory(signal)
add_subdirectory(stdlib)
add_subdirectory(string)
add_subdirectory(sys)
+add_subdirectory(threads)
diff --git a/libc/test/src/threads/CMakeLists.txt b/libc/test/src/threads/CMakeLists.txt
new file mode 100644
index 000000000000..9607a258cd66
--- /dev/null
+++ b/libc/test/src/threads/CMakeLists.txt
@@ -0,0 +1,16 @@
+add_libc_testsuite(libc_threads_unittests)
+
+add_libc_unittest(
+ thrd_test
+ SUITE
+ libc_threads_unittests
+ SRCS
+ thrd_test.cpp
+ DEPENDS
+ __errno_location
+ mmap
+ munmap
+ threads_h
+ thrd_create
+ thrd_join
+)
diff --git a/libc/test/src/threads/thrd_test.cpp b/libc/test/src/threads/thrd_test.cpp
new file mode 100644
index 000000000000..be9e410a46aa
--- /dev/null
+++ b/libc/test/src/threads/thrd_test.cpp
@@ -0,0 +1,52 @@
+//===---------------------- Unittests for thrd_t --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "include/threads.h"
+#include "src/threads/thrd_create.h"
+#include "src/threads/thrd_join.h"
+#include "utils/UnitTest/Test.h"
+
+static constexpr int thread_count = 1000;
+static int counter = 0;
+static int thread_func(void *) {
+ ++counter;
+ return 0;
+}
+
+TEST(ThreadTest, CreateAndJoin) {
+ for (counter = 0; counter <= thread_count;) {
+ thrd_t thread;
+ int old_counter_val = counter;
+ ASSERT_EQ(__llvm_libc::thrd_create(&thread, thread_func, nullptr),
+ (int)thrd_success);
+ int retval = thread_count + 1; // Start with a retval we dont expect.
+ ASSERT_EQ(__llvm_libc::thrd_join(&thread, &retval), (int)thrd_success);
+ ASSERT_EQ(retval, 0);
+ ASSERT_EQ(counter, old_counter_val + 1);
+ }
+}
+
+static int return_arg(void *arg) { return *reinterpret_cast<int *>(arg); }
+
+TEST(ThreadTest, SpawnAndJoin) {
+ thrd_t thread_list[thread_count];
+ int args[thread_count];
+
+ for (int i = 0; i < thread_count; ++i) {
+ args[i] = i;
+ ASSERT_EQ(__llvm_libc::thrd_create(thread_list + i, return_arg, args + i),
+ (int)thrd_success);
+ }
+
+ for (int i = 0; i < thread_count; ++i) {
+ int retval = thread_count + 1; // Start with a retval we dont expect.
+ ASSERT_EQ(__llvm_libc::thrd_join(&thread_list[i], &retval),
+ (int)thrd_success);
+ ASSERT_EQ(retval, i);
+ }
+}
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