3 files changed, 44 insertions, 1 deletions
diff --git a/tools/include/linux/rwsem.h b/tools/include/linux/rwsem.h
new file mode 100644
index 000000000000..83971b3cbfce
--- /dev/null
+++ b/tools/include/linux/rwsem.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef _TOOLS__RWSEM_H
+#define _TOOLS__RWSEM_H
+
+#include <pthread.h>
+
+struct rw_semaphore {
+	pthread_rwlock_t lock;
+};
+
+static inline int init_rwsem(struct rw_semaphore *sem)
+{
+	return pthread_rwlock_init(&sem->lock, NULL);
+}
+
+static inline int exit_rwsem(struct rw_semaphore *sem)
+{
+	return pthread_rwlock_destroy(&sem->lock);
+}
+
+static inline int down_read(struct rw_semaphore *sem)
+{
+	return pthread_rwlock_rdlock(&sem->lock);
+}
+
+static inline int up_read(struct rw_semaphore *sem)
+{
+	return pthread_rwlock_unlock(&sem->lock);
+}
+
+static inline int down_write(struct rw_semaphore *sem)
+{
+	return pthread_rwlock_wrlock(&sem->lock);
+}
+
+static inline int up_write(struct rw_semaphore *sem)
+{
+	return pthread_rwlock_unlock(&sem->lock);
+}
+#endif /* _TOOLS_RWSEM_H */
diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h
index 64415b9fac77..28c26a00a762 100644
--- a/tools/include/nolibc/arch-i386.h
+++ b/tools/include/nolibc/arch-i386.h
@@ -167,7 +167,9 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 	__asm__ volatile (
 		"xor  %ebp, %ebp\n"       /* zero the stack frame                                */
 		"mov  %esp, %eax\n"       /* save stack pointer to %eax, as arg1 of _start_c     */
-		"and  $-16, %esp\n"       /* last pushed argument must be 16-byte aligned        */
+		"add  $12, %esp\n"        /* avoid over-estimating after the 'and' & 'sub' below */
+		"and  $-16, %esp\n"       /* the %esp must be 16-byte aligned on 'call'          */
+		"sub  $12, %esp\n"        /* sub 12 to keep it aligned after the push %eax       */
 		"push %eax\n"             /* push arg1 on stack to support plain stack modes too */
 		"call _start_c\n"         /* transfer to c runtime                               */
 		"hlt\n"                   /* ensure it does not return                           */
diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h
index a5f33fef1672..a05655b4ce1d 100644
--- a/tools/include/nolibc/crt.h
+++ b/tools/include/nolibc/crt.h
@@ -13,6 +13,7 @@ const unsigned long *_auxv __attribute__((weak));
 static void __stack_chk_init(void);
 static void exit(int);
 
+__attribute__((weak))
 void _start_c(long *sp)
 {
 	long argc;