android: Export symbols needed by Android drivers

We want to enable use of the Android ashmem and binder drivers to
support Anbox, but they should not be built-in as that would waste
resources and increase security attack surface on systems that don't
need them.

Export the currently un-exported symbols they depend on.

fs/file.c

@@ -788,6 +788,7 @@ int close_fd_get_file(unsigned int fd, struct file **res)
 
 	return ret;
 }
+EXPORT_SYMBOL(close_fd_get_file);
 
 void do_close_on_exec(struct files_struct *files)
 {

kernel/fork.c

@@ -1133,6 +1133,7 @@ void mmput_async(struct mm_struct *mm)
 		schedule_work(&mm->async_put_work);
 	}
 }
+EXPORT_SYMBOL_GPL(mmput_async);
 #endif
 
 /**

kernel/sched/core.c

@@ -5765,6 +5765,7 @@ int can_nice(const struct task_struct *p, const int nice)
 	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
 		capable(CAP_SYS_NICE));
 }
+EXPORT_SYMBOL_GPL(can_nice);
 
 #ifdef __ARCH_WANT_SYS_NICE
 

kernel/task_work.c

@@ -57,6 +57,7 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
 
 	return 0;
 }
+EXPORT_SYMBOL(task_work_add);
 
 /**
  * task_work_cancel - cancel a pending work added by task_work_add()

mm/memory.c

@@ -1548,6 +1548,7 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start,
 	mmu_notifier_invalidate_range_end(&range);
 	tlb_finish_mmu(&tlb);
 }
+EXPORT_SYMBOL_GPL(zap_page_range);
 
 /**
  * zap_page_range_single - remove user pages in a given range

mm/shmem.c

@@ -4233,6 +4233,7 @@ int shmem_zero_setup(struct vm_area_struct *vma)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(shmem_zero_setup);
 
 /**
  * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.

security/security.c

@@ -727,24 +727,28 @@ int security_binder_set_context_mgr(struct task_struct *mgr)
 {
 	return call_int_hook(binder_set_context_mgr, 0, mgr);
 }
+EXPORT_SYMBOL_GPL(security_binder_set_context_mgr);
 
 int security_binder_transaction(struct task_struct *from,
 				struct task_struct *to)
 {
 	return call_int_hook(binder_transaction, 0, from, to);
 }
+EXPORT_SYMBOL_GPL(security_binder_transaction);
 
 int security_binder_transfer_binder(struct task_struct *from,
 				    struct task_struct *to)
 {
 	return call_int_hook(binder_transfer_binder, 0, from, to);
 }
+EXPORT_SYMBOL_GPL(security_binder_transfer_binder);
 
 int security_binder_transfer_file(struct task_struct *from,
 				  struct task_struct *to, struct file *file)
 {
 	return call_int_hook(binder_transfer_file, 0, from, to, file);
 }
+EXPORT_SYMBOL_GPL(security_binder_transfer_file);
 
 int security_ptrace_access_check(struct task_struct *child, unsigned int mode)
 {