sysdeps/linux: implement threading support

sysdeps/linux/generic/sysdeps.cpp

@@ -5,6 +5,7 @@
 #include <bits/ensure.h>
 #include <mlibc/debug.hpp>
 #include <mlibc/all-sysdeps.hpp>
+#include <mlibc/thread-entry.hpp>
 #include "cxx-syscall.hpp"
 
 #define STUB_ONLY { __ensure(!"STUB_ONLY function was called"); __builtin_unreachable(); }
@@ -17,15 +18,18 @@
 #define NR_fstat 5
 #define NR_lseek 8
 #define NR_mmap 9
+#define NR_mprotect 10
 #define NR_sigaction 13
 #define NR_rt_sigprocmask 14
 #define NR_ioctl 16
 #define NR_pipe 22
 #define NR_select 23
+#define NR_nanosleep 35
 #define NR_socket 41
 #define NR_connect 42
 #define NR_sendmsg 46
 #define NR_recvmsg 47
+#define NR_clone 56
 #define NR_fork 57
 #define NR_execve 59
 #define NR_exit 60
@@ -35,6 +39,7 @@
 #define NR_arch_prctl 158
 #define NR_sys_futex 202
 #define NR_clock_gettime 228
+#define NR_exit_group 231
 #define NR_pselect6 270
 #define NR_pipe2 293
 
@@ -196,9 +201,26 @@ int sys_unlink(const char *path) {
 	return 0;
 }
 
+int sys_sleep(time_t *secs, long *nanos) {
+	struct timespec req = {
+		.tv_sec = *secs,
+		.tv_nsec = *nanos
+	};
+	struct timespec rem = {0};
+
+	auto ret = do_syscall(NR_nanosleep, &req, &rem);
+        if (int e = sc_error(ret); e)
+                return e;
+
+	*secs = rem.tv_sec;
+	*nanos = rem.tv_nsec;
+	return 0;
+}
+
 #if __MLIBC_POSIX_OPTION
 
 #include <sys/ioctl.h>
+#include <sched.h>
 
 int sys_isatty(int fd) {
         struct winsize ws;
@@ -278,13 +300,39 @@ int sys_sigprocmask(int how, const sigset_t *set, sigset_t *old) {
         auto ret = do_syscall(NR_rt_sigprocmask, how, set, old, NSIG / 8);
         if (int e = sc_error(ret); e)
                 return e;
+	return 0;
+}
+
+int sys_clone(void *entry, void *user_arg, void *tcb, pid_t *pid_out) {
+        void *stack = prepare_stack(entry, user_arg);
+
+	unsigned long flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
+		| CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS | CLONE_SETTLS
+		| CLONE_PARENT_SETTID;
+
+	auto ret = __mlibc_spawn_thread(flags, stack, pid_out, NULL, tcb);
+	if (ret < 0)
+		return ret;
+
         return 0;
 }
 
 #endif // __MLIBC_POSIX_OPTION
 
+int sys_vm_protect(void *pointer, size_t size, int prot) {
+	auto ret = do_syscall(NR_mprotect, pointer, size, prot);
+	if (int e = sc_error(ret); e)
+		return e;
+	return 0;
+}
+
+void sys_thread_exit() {
+	do_syscall(NR_exit, 0);
+	__builtin_trap();
+}
+
 void sys_exit(int status) {
-	do_syscall(NR_exit, status);
+	do_syscall(NR_exit_group, status);
 	__builtin_trap();
 }
 

sysdeps/linux/include/mlibc/thread-entry.hpp

@@ -0,0 +1,12 @@
+#ifndef MLIBC_THREAD_ENTRY
+
+#include <mlibc/tcb.hpp>
+
+extern "C" int __mlibc_spawn_thread(int flags, void *stack, void *pid_out, void *child_tid, void *tcb);
+extern "C" void __mlibc_enter_thread(void *entry, void *user_arg);
+
+namespace mlibc {
+	void *prepare_stack(void *entry, void *user_arg);
+}
+
+#endif // MLIBC_THREAD_ENTRY

sysdeps/linux/meson.build

@@ -9,6 +9,13 @@ libc_sources += files(
 	'generic/sysdeps.cpp',
 )
 
+if not disable_posix_option
+	libc_sources += files(
+		'x86_64/thread.cpp',
+		'x86_64/thread_entry.S'
+	)
+endif
+
 if not no_headers
 	install_headers(
 		'include/abi-bits/abi.h',
@@ -42,7 +49,7 @@ if not headers_only
 	crt = custom_target('crt1',
 		build_by_default: true,
 		command: c_compiler.cmd_array() + ['-c', '-o', '@OUTPUT@', '@INPUT@'],
-		input: 'x86_64-crt/crt1.S',
+		input: 'x86_64/crt-src/crt1.S',
 		output: 'crt1.o',
 		install: true,
 		install_dir: get_option('libdir')
@@ -51,7 +58,7 @@ if not headers_only
 	custom_target('Scrt1',
 		build_by_default: true,
 		command: c_compiler.cmd_array() + ['-c', '-o', '@OUTPUT@', '@INPUT@'],
-		input: 'x86_64-crt/Scrt1.S',
+		input: 'x86_64/crt-src/Scrt1.S',
 		output: 'Scrt1.o',
 		install: true,
 		install_dir: get_option('libdir')
@@ -60,7 +67,7 @@ if not headers_only
 	custom_target('crti',
 		build_by_default: true,
 		command: c_compiler.cmd_array() + ['-c', '-o', '@OUTPUT@', '@INPUT@'],
-		input: 'x86_64-crt/crti.S',
+		input: 'x86_64/crt-src/crti.S',
 		output: 'crti.o',
 		install: true,
 		install_dir: get_option('libdir')
@@ -69,7 +76,7 @@ if not headers_only
 	custom_target('crtn',
 		build_by_default: true,
 		command: c_compiler.cmd_array() + ['-c', '-o', '@OUTPUT@', '@INPUT@'],
-		input: 'x86_64-crt/crtn.S',
+		input: 'x86_64/crt-src/crtn.S',
 		output: 'crtn.o',
 		install: true,
 		install_dir: get_option('libdir')

sysdeps/linux/x86_64/thread.cpp

@@ -0,0 +1,50 @@
+#include <mlibc/thread-entry.hpp>
+#include <mlibc/all-sysdeps.hpp>
+#include <mlibc/thread.hpp>
+#include <bits/ensure.h>
+#include <sys/mman.h>
+#include <stdint.h>
+#include <stddef.h>
+
+namespace {
+	constexpr unsigned int STACK_SIZE = 0x200000;
+	constexpr unsigned int GUARD_SIZE = 0x2000;
+}
+
+extern "C" void __mlibc_enter_thread(void *entry, void *user_arg) {
+	// The linux kernel already sets the TCB in sys_clone().
+	auto tcb = mlibc::get_current_tcb();
+
+	// Wait until our parent sets up the TID.
+	while(!__atomic_load_n(&tcb->tid, __ATOMIC_RELAXED))
+		mlibc::sys_futex_wait(&tcb->tid, 0);
+
+	void *(*func)(void *) = reinterpret_cast<void *(*)(void *)>(entry);
+	auto result = func(user_arg);
+
+	tcb->returnValue = result;
+	__atomic_store_n(&tcb->didExit, 1, __ATOMIC_RELEASE);
+	mlibc::sys_futex_wake(&tcb->didExit);
+
+	mlibc::sys_thread_exit();
+}
+
+namespace mlibc {
+
+void *prepare_stack(void *entry, void *user_arg) {
+	uintptr_t map = reinterpret_cast<uintptr_t>(
+			mmap(nullptr, STACK_SIZE + GUARD_SIZE,
+				PROT_NONE,
+				MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)
+			);
+	__ensure(reinterpret_cast<void*>(map) != MAP_FAILED);
+	int ret = mprotect(reinterpret_cast<void*>(map + GUARD_SIZE), STACK_SIZE,
+			PROT_READ | PROT_WRITE);
+	__ensure(!ret);
+
+	auto sp = reinterpret_cast<uintptr_t*>(map + STACK_SIZE + GUARD_SIZE);
+	*--sp = reinterpret_cast<uintptr_t>(user_arg);
+	*--sp = reinterpret_cast<uintptr_t>(entry);
+	return sp;
+}
+} // namespace mlibc

sysdeps/linux/x86_64/thread_entry.S

@@ -0,0 +1,21 @@
+
+.section .text
+.global __mlibc_spawn_thread
+.type __mlibc_spawn_thread, "function"
+__mlibc_spawn_thread:
+	xor %eax, %eax
+	/* The rest of the args are already in the right registers,
+	* only need to fixup rcx to r10
+	*/
+	mov %rcx, %r10
+	mov $56, %al
+	syscall
+	test %eax, %eax
+	jnz 1f
+	xor %ebp, %ebp
+	pop %rdi
+	pop %rsi
+	call __mlibc_enter_thread
+	hlt
+1:
+	ret

tests/meson.build

@@ -15,6 +15,7 @@ posix_test_cases = [
 	'inet_ntop',
 	'inet_pton',
 	'pthread_rwlock',
+	'pthread_create',
 	'getaddrinfo',
 	'dprintf',
 	'posix_spawn',

tests/posix/pthread_create.c

@@ -0,0 +1,22 @@
+#include <assert.h>
+#include <time.h>
+#include <pthread.h>
+
+int variable = 0;
+
+static void *worker(void *arg) {
+	(void) arg;
+	variable = 1;
+	return NULL;
+}
+
+int main() {
+	pthread_t thread;
+	int ret = pthread_create(&thread, NULL, &worker, NULL);
+	assert(!ret);
+
+	ret = pthread_join(thread, NULL);
+	assert(!ret);
+	assert(variable == 1);
+	return 0;
+}