reserve signal stack for handling stackoverflow

reserve 16K for 32bit system and 32K for 64bit system
as the stack is reserved by mmap, it may not take physical memory
until handle signal with SA_ONSTACK flag.
Signed-off-by: Nmaplestory <zengzhi5@huawei.com>

musl_src.gni

@@ -1854,6 +1854,7 @@ musl_src_porting_file = [
   "src/exit/atexit.c",
   "crt/arm/crti.s",
   "crt/aarch64/crti.s",
+  "src/thread/pthread_create.c",
 ]
 
 musl_inc_hook_files = [

musl_template.gni

@@ -163,6 +163,8 @@ template("musl_libs") {
       cflags_auto += [ "-DHOOK_ENABLE" ]
     }
 
+    cflags_auto += [ "-DRESERVE_SIGNAL_STACK" ]
+
     cflags_c99fse = [
       "-std=c99",
       "-nostdinc",

porting/linux/user/src/internal/pthread_impl.h

@@ -48,6 +48,9 @@ struct pthread {
 	volatile int killlock[1];
 	char *dlerror_buf;
 	void *stdio_locks;
+#ifdef RESERVE_SIGNAL_STACK
+	void *signal_stack;
+#endif
 
 	/* Part 3 -- the positions of these fields relative to
 	 * the end of the structure is external and internal ABI. */

porting/linux/user/src/thread/pthread_create.c

+#define _GNU_SOURCE
+#include "pthread_impl.h"
+#include "stdio_impl.h"
+#include "libc.h"
+#include "lock.h"
+#include <sys/mman.h>
+#include <string.h>
+#include <stddef.h>
+#include <stdarg.h>
+
+void log_print(const char* info,...)
+{
+    va_list ap;
+    va_start(ap, info);
+    vfprintf(stdout,info, ap);
+    va_end(ap);
+}
+
+#ifdef RESERVE_SIGNAL_STACK
+#include <sys/prctl.h>
+#if defined (__LF64__)
+#define RESERVE_SIGNAL_STACK_SIZE (32 * 1024)
+#else
+#define RESERVE_SIGNAL_STACK_SIZE (20 * 1024)
+#endif
+static void __pthread_reserve_signal_stack()
+{
+	void* stack = mmap(NULL, RESERVE_SIGNAL_STACK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1 , 0);
+	if (stack != MAP_FAILED) {
+		if (mprotect(stack, __default_guardsize, PROT_NONE) == -1) {
+			munmap(stack, RESERVE_SIGNAL_STACK_SIZE);
+			return;
+		}
+	}
+
+	stack_t signal_stack;
+	signal_stack.ss_sp = (uint8_t*)stack + __default_guardsize;
+	signal_stack.ss_size = RESERVE_SIGNAL_STACK_SIZE - __default_guardsize;
+	signal_stack.ss_flags = 0;
+	sigaltstack(&signal_stack, NULL);
+
+	pthread_t self = __pthread_self();
+	self->signal_stack = stack;
+	prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, signal_stack.ss_sp, signal_stack.ss_size, "signal_stack:musl");
+	return;
+}
+
+static void __pthread_release_signal_stack()
+{
+	pthread_t self = __pthread_self();
+	if (self->signal_stack == NULL) {
+		return;
+	}
+
+	stack_t signal_stack;
+	memset(&signal_stack, 0, sizeof(signal_stack));
+	signal_stack.ss_flags = SS_DISABLE;
+	sigaltstack(&signal_stack, NULL);
+	munmap(self->signal_stack, RESERVE_SIGNAL_STACK_SIZE);
+	self->signal_stack = NULL;
+}
+#endif
+
+static void dummy_0()
+{
+}
+weak_alias(dummy_0, __acquire_ptc);
+weak_alias(dummy_0, __release_ptc);
+weak_alias(dummy_0, __pthread_tsd_run_dtors);
+weak_alias(dummy_0, __do_orphaned_stdio_locks);
+weak_alias(dummy_0, __dl_thread_cleanup);
+weak_alias(dummy_0, __membarrier_init);
+
+static int tl_lock_count;
+static int tl_lock_waiters;
+
+void __tl_lock(void)
+{
+	int tid = __pthread_self()->tid;
+	int val = __thread_list_lock;
+	if (val == tid) {
+		tl_lock_count++;
+		return;
+	}
+	while ((val = a_cas(&__thread_list_lock, 0, tid)))
+		__wait(&__thread_list_lock, &tl_lock_waiters, val, 0);
+}
+
+void __tl_unlock(void)
+{
+	if (tl_lock_count) {
+		tl_lock_count--;
+		return;
+	}
+	a_store(&__thread_list_lock, 0);
+	if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
+}
+
+void __tl_sync(pthread_t td)
+{
+	a_barrier();
+	int val = __thread_list_lock;
+	if (!val) return;
+	__wait(&__thread_list_lock, &tl_lock_waiters, val, 0);
+	if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
+}
+
+_Noreturn void __pthread_exit(void *result)
+{
+	pthread_t self = __pthread_self();
+	sigset_t set;
+
+	self->canceldisable = 1;
+	self->cancelasync = 0;
+	self->result = result;
+
+	while (self->cancelbuf) {
+		void (*f)(void *) = self->cancelbuf->__f;
+		void *x = self->cancelbuf->__x;
+		self->cancelbuf = self->cancelbuf->__next;
+		f(x);
+	}
+
+	__pthread_tsd_run_dtors();
+
+	/* Access to target the exiting thread with syscalls that use
+	 * its kernel tid is controlled by killlock. For detached threads,
+	 * any use past this point would have undefined behavior, but for
+	 * joinable threads it's a valid usage that must be handled. */
+	LOCK(self->killlock);
+
+	/* The thread list lock must be AS-safe, and thus requires
+	 * application signals to be blocked before it can be taken. */
+	__block_app_sigs(&set);
+	__tl_lock();
+
+#ifdef RESERVE_SIGNAL_STACK
+	__pthread_release_signal_stack();
+#endif
+	/* If this is the only thread in the list, don't proceed with
+	 * termination of the thread, but restore the previous lock and
+	 * signal state to prepare for exit to call atexit handlers. */
+	if (self->next == self) {
+		__tl_unlock();
+		__restore_sigs(&set);
+		UNLOCK(self->killlock);
+		exit(0);
+	}
+
+	/* At this point we are committed to thread termination. Unlink
+	 * the thread from the list. This change will not be visible
+	 * until the lock is released, which only happens after SYS_exit
+	 * has been called, via the exit futex address pointing at the lock. */
+	libc.threads_minus_1--;
+	self->next->prev = self->prev;
+	self->prev->next = self->next;
+	self->prev = self->next = self;
+
+	/* Process robust list in userspace to handle non-pshared mutexes
+	 * and the detached thread case where the robust list head will
+	 * be invalid when the kernel would process it. */
+	__vm_lock();
+	volatile void *volatile *rp;
+	while ((rp=self->robust_list.head) && rp != &self->robust_list.head) {
+		pthread_mutex_t *m = (void *)((char *)rp
+			- offsetof(pthread_mutex_t, _m_next));
+		int waiters = m->_m_waiters;
+		int priv = (m->_m_type & 128) ^ 128;
+		self->robust_list.pending = rp;
+		self->robust_list.head = *rp;
+		int cont = a_swap(&m->_m_lock, 0x40000000);
+		self->robust_list.pending = 0;
+		if (cont < 0 || waiters)
+			__wake(&m->_m_lock, 1, priv);
+	}
+	__vm_unlock();
+
+	__do_orphaned_stdio_locks();
+	__dl_thread_cleanup();
+
+	/* This atomic potentially competes with a concurrent pthread_detach
+	 * call; the loser is responsible for freeing thread resources. */
+	int state = a_cas(&self->detach_state, DT_JOINABLE, DT_EXITING);
+
+	if (state==DT_DETACHED && self->map_base) {
+		/* Detached threads must block even implementation-internal
+		 * signals, since they will not have a stack in their last
+		 * moments of existence. */
+		__block_all_sigs(&set);
+
+		/* Robust list will no longer be valid, and was already
+		 * processed above, so unregister it with the kernel. */
+		if (self->robust_list.off)
+			__syscall(SYS_set_robust_list, 0, 3*sizeof(long));
+
+		/* Since __unmapself bypasses the normal munmap code path,
+		 * explicitly wait for vmlock holders first. */
+		__vm_wait();
+
+		/* The following call unmaps the thread's stack mapping
+		 * and then exits without touching the stack. */
+		__unmapself(self->map_base, self->map_size);
+	}
+
+	/* Wake any joiner. */
+	__wake(&self->detach_state, 1, 1);
+
+	/* After the kernel thread exits, its tid may be reused. Clear it
+	 * to prevent inadvertent use and inform functions that would use
+	 * it that it's no longer available. */
+	self->tid = 0;
+	UNLOCK(self->killlock);
+
+	for (;;) __syscall(SYS_exit, 0);
+}
+
+void __do_cleanup_push(struct __ptcb *cb)
+{
+	struct pthread *self = __pthread_self();
+	cb->__next = self->cancelbuf;
+	self->cancelbuf = cb;
+}
+
+void __do_cleanup_pop(struct __ptcb *cb)
+{
+	__pthread_self()->cancelbuf = cb->__next;
+}
+
+struct start_args {
+	void *(*start_func)(void *);
+	void *start_arg;
+	volatile int control;
+	unsigned long sig_mask[_NSIG/8/sizeof(long)];
+};
+
+static int start(void *p)
+{
+	struct start_args *args = p;
+	int state = args->control;
+	if (state) {
+		if (a_cas(&args->control, 1, 2)==1)
+			__wait(&args->control, 0, 2, 1);
+		if (args->control) {
+			__syscall(SYS_set_tid_address, &args->control);
+			for (;;) __syscall(SYS_exit, 0);
+		}
+	}
+	__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &args->sig_mask, 0, _NSIG/8);
+#ifdef RESERVE_SIGNAL_STACK
+	__pthread_reserve_signal_stack();
+#endif
+	__pthread_exit(args->start_func(args->start_arg));
+	return 0;
+}
+
+static int start_c11(void *p)
+{
+#ifdef RESERVE_SIGNAL_STACK
+	__pthread_reserve_signal_stack();
+#endif
+	struct start_args *args = p;
+	int (*start)(void*) = (int(*)(void*)) args->start_func;
+	__pthread_exit((void *)(uintptr_t)start(args->start_arg));
+	return 0;
+}
+
+#define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
+
+/* pthread_key_create.c overrides this */
+static volatile size_t dummy = 0;
+weak_alias(dummy, __pthread_tsd_size);
+static void *dummy_tsd[1] = { 0 };
+weak_alias(dummy_tsd, __pthread_tsd_main);
+
+static FILE *volatile dummy_file = 0;
+weak_alias(dummy_file, __stdin_used);
+weak_alias(dummy_file, __stdout_used);
+weak_alias(dummy_file, __stderr_used);
+
+static void init_file_lock(FILE *f)
+{
+	if (f && f->lock<0) f->lock = 0;
+}
+
+int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
+{
+	int ret, c11 = (attrp == __ATTRP_C11_THREAD);
+	size_t size, guard;
+	struct pthread *self, *new;
+	unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
+	unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
+		| CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
+		| CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
+	pthread_attr_t attr = { 0 };
+	sigset_t set;
+
+	if (!libc.can_do_threads) return ENOSYS;
+	self = __pthread_self();
+	if (!libc.threaded) {
+		for (FILE *f=*__ofl_lock(); f; f=f->next)
+			init_file_lock(f);
+		__ofl_unlock();
+		init_file_lock(__stdin_used);
+		init_file_lock(__stdout_used);
+		init_file_lock(__stderr_used);
+		__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
+		self->tsd = (void **)__pthread_tsd_main;
+		__membarrier_init();
+		libc.threaded = 1;
+	}
+	if (attrp && !c11) attr = *attrp;
+
+	__acquire_ptc();
+	if (!attrp || c11) {
+		attr._a_stacksize = __default_stacksize;
+		attr._a_guardsize = __default_guardsize;
+	}
+
+	if (attr._a_stackaddr) {
+		size_t need = libc.tls_size + __pthread_tsd_size;
+		size = attr._a_stacksize;
+		stack = (void *)(attr._a_stackaddr & -16);
+		stack_limit = (void *)(attr._a_stackaddr - size);
+		/* Use application-provided stack for TLS only when
+		 * it does not take more than ~12% or 2k of the
+		 * application's stack space. */
+		if (need < size/8 && need < 2048) {
+			tsd = stack - __pthread_tsd_size;
+			stack = tsd - libc.tls_size;
+			memset(stack, 0, need);
+		} else {
+			size = ROUND(need);
+		}
+		guard = 0;
+	} else {
+		guard = ROUND(attr._a_guardsize);
+		size = guard + ROUND(attr._a_stacksize
+			+ libc.tls_size +  __pthread_tsd_size);
+	}
+
+	if (!tsd) {
+		if (guard) {
+			map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
+			if (map == MAP_FAILED) goto fail;
+			if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)
+			    && errno != ENOSYS) {
+				__munmap(map, size);
+				goto fail;
+			}
+		} else {
+			map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+			if (map == MAP_FAILED) goto fail;
+		}
+		tsd = map + size - __pthread_tsd_size;
+		if (!stack) {
+			stack = tsd - libc.tls_size;
+			stack_limit = map + guard;
+		}
+	}
+
+	new = __copy_tls(tsd - libc.tls_size);
+	new->map_base = map;
+	new->map_size = size;
+	new->stack = stack;
+	new->stack_size = stack - stack_limit;
+	new->guard_size = guard;
+	new->self = new;
+	new->tsd = (void *)tsd;
+	new->locale = &libc.global_locale;
+	if (attr._a_detach) {
+		new->detach_state = DT_DETACHED;
+	} else {
+		new->detach_state = DT_JOINABLE;
+	}
+	new->robust_list.head = &new->robust_list.head;
+	new->CANARY = self->CANARY;
+	new->sysinfo = self->sysinfo;
+
+	/* Setup argument structure for the new thread on its stack.
+	 * It's safe to access from the caller only until the thread
+	 * list is unlocked. */
+	stack -= (uintptr_t)stack % sizeof(uintptr_t);
+	stack -= sizeof(struct start_args);
+	struct start_args *args = (void *)stack;
+	args->start_func = entry;
+	args->start_arg = arg;
+	args->control = attr._a_sched ? 1 : 0;
+
+	/* Application signals (but not the synccall signal) must be
+	 * blocked before the thread list lock can be taken, to ensure
+	 * that the lock is AS-safe. */
+	__block_app_sigs(&set);
+
+	/* Ensure SIGCANCEL is unblocked in new thread. This requires
+	 * working with a copy of the set so we can restore the
+	 * original mask in the calling thread. */
+	memcpy(&args->sig_mask, &set, sizeof args->sig_mask);
+	args->sig_mask[(SIGCANCEL-1)/8/sizeof(long)] &=
+		~(1UL<<((SIGCANCEL-1)%(8*sizeof(long))));
+
+	__tl_lock();
+	libc.threads_minus_1++;
+	ret = __clone((c11 ? start_c11 : start), stack, flags, args, &new->tid, TP_ADJ(new), &__thread_list_lock);
+
+	/* All clone failures translate to EAGAIN. If explicit scheduling
+	 * was requested, attempt it before unlocking the thread list so
+	 * that the failed thread is never exposed and so that we can
+	 * clean up all transient resource usage before returning. */
+	if (ret < 0) {
+		ret = -EAGAIN;
+	} else if (attr._a_sched) {
+		ret = __syscall(SYS_sched_setscheduler,
+			new->tid, attr._a_policy, &attr._a_prio);
+		if (a_swap(&args->control, ret ? 3 : 0)==2)
+			__wake(&args->control, 1, 1);
+		if (ret)
+			__wait(&args->control, 0, 3, 0);
+	}
+
+	if (ret >= 0) {
+		new->next = self->next;
+		new->prev = self;
+		new->next->prev = new;
+		new->prev->next = new;
+	} else {
+		libc.threads_minus_1--;
+	}
+	__tl_unlock();
+	__restore_sigs(&set);
+	__release_ptc();
+
+	if (ret < 0) {
+		if (map) __munmap(map, size);
+		return -ret;
+	}
+
+	*res = new;
+	return 0;
+fail:
+	__release_ptc();
+	return EAGAIN;
+}
+
+weak_alias(__pthread_exit, pthread_exit);
+weak_alias(__pthread_create, pthread_create);
+
+struct pthread* __pthread_list_find(pthread_t thread_id, const char* info)
+{
+    struct pthread *thread = (struct pthread *)thread_id; 
+    if (NULL == thread) {
+        log_print("invalid pthread_t (0) passed to %s\n", info);
+        return NULL;
+    }
+
+    struct pthread *self = __pthread_self();
+    if (thread == self) {
+        return thread;
+    }
+    struct pthread *t = self;
+    t = t->next ;
+    while (t != self) {
+        if (t == thread) return thread;
+        t = t->next ;
+    }
+    log_print("invalid pthread_t %p passed to %s\n", thread, info); 
+    return NULL;
+}
+
+pid_t __pthread_gettid_np(pthread_t t)
+{
+    __tl_lock();
+    struct pthread* thread = __pthread_list_find(t, "pthread_gettid_np");
+    __tl_unlock();
+    return thread ? thread->tid : -1;
+}
+weak_alias(__pthread_gettid_np, pthread_gettid_np);
\ No newline at end of file