powerpc/rtas: make all exports GPL

The first symbol exports of RTAS functions and data came with the (now
removed) scanlog driver in 2003:

https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=f92e361842d5251e50562b09664082dcbd0548bb

At the time this was applied, EXPORT_SYMBOL_GPL() was very new, and
the exports of rtas_call() etc have remained non-GPL. As new APIs have
been added to the RTAS subsystem, their symbol exports have followed
the convention set by existing code.

However, the historical evidence is that RTAS function exports have been
added over time only to satisfy the needs of in-kernel users, and these
clients must have fairly intimate knowledge of how the APIs work to use
them safely. No out of tree users are known, and future ones seem
unlikely.

Arguably the default for RTAS symbols should have become
EXPORT_SYMBOL_GPL once it was available. Let's make it so now, and
exceptions can be evaluated as needed.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230124140448.45938-3-nathanl@linux.ibm.com

arch/powerpc/kernel/rtas.c

@@ -65,10 +65,10 @@ struct rtas_t rtas = {
 };
 
 DEFINE_SPINLOCK(rtas_data_buf_lock);
-EXPORT_SYMBOL(rtas_data_buf_lock);
+EXPORT_SYMBOL_GPL(rtas_data_buf_lock);
 
 char rtas_data_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
-EXPORT_SYMBOL(rtas_data_buf);
+EXPORT_SYMBOL_GPL(rtas_data_buf);
 
 unsigned long rtas_rmo_buf;
 
@@ -77,7 +77,7 @@ unsigned long rtas_rmo_buf;
  * This is done like this so rtas_flash can be a module.
  */
 void (*rtas_flash_term_hook)(int);
-EXPORT_SYMBOL(rtas_flash_term_hook);
+EXPORT_SYMBOL_GPL(rtas_flash_term_hook);
 
 /* RTAS use home made raw locking instead of spin_lock_irqsave
  * because those can be called from within really nasty contexts
@@ -325,7 +325,7 @@ void rtas_progress(char *s, unsigned short hex)
  
 	spin_unlock(&progress_lock);
 }
-EXPORT_SYMBOL(rtas_progress);		/* needed by rtas_flash module */
+EXPORT_SYMBOL_GPL(rtas_progress);		/* needed by rtas_flash module */
 
 int rtas_token(const char *service)
 {
@@ -335,7 +335,7 @@ int rtas_token(const char *service)
 	tokp = of_get_property(rtas.dev, service, NULL);
 	return tokp ? be32_to_cpu(*tokp) : RTAS_UNKNOWN_SERVICE;
 }
-EXPORT_SYMBOL(rtas_token);
+EXPORT_SYMBOL_GPL(rtas_token);
 
 int rtas_service_present(const char *service)
 {
@@ -582,7 +582,7 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 	}
 	return ret;
 }
-EXPORT_SYMBOL(rtas_call);
+EXPORT_SYMBOL_GPL(rtas_call);
 
 /**
  * rtas_busy_delay_time() - From an RTAS status value, calculate the
@@ -693,7 +693,7 @@ bool rtas_busy_delay(int status)
 
 	return ret;
 }
-EXPORT_SYMBOL(rtas_busy_delay);
+EXPORT_SYMBOL_GPL(rtas_busy_delay);
 
 static int rtas_error_rc(int rtas_rc)
 {
@@ -738,7 +738,7 @@ int rtas_get_power_level(int powerdomain, int *level)
 		return rtas_error_rc(rc);
 	return rc;
 }
-EXPORT_SYMBOL(rtas_get_power_level);
+EXPORT_SYMBOL_GPL(rtas_get_power_level);
 
 int rtas_set_power_level(int powerdomain, int level, int *setlevel)
 {
@@ -756,7 +756,7 @@ int rtas_set_power_level(int powerdomain, int level, int *setlevel)
 		return rtas_error_rc(rc);
 	return rc;
 }
-EXPORT_SYMBOL(rtas_set_power_level);
+EXPORT_SYMBOL_GPL(rtas_set_power_level);
 
 int rtas_get_sensor(int sensor, int index, int *state)
 {
@@ -774,7 +774,7 @@ int rtas_get_sensor(int sensor, int index, int *state)
 		return rtas_error_rc(rc);
 	return rc;
 }
-EXPORT_SYMBOL(rtas_get_sensor);
+EXPORT_SYMBOL_GPL(rtas_get_sensor);
 
 int rtas_get_sensor_fast(int sensor, int index, int *state)
 {
@@ -834,7 +834,7 @@ int rtas_set_indicator(int indicator, int index, int new_value)
 		return rtas_error_rc(rc);
 	return rc;
 }
-EXPORT_SYMBOL(rtas_set_indicator);
+EXPORT_SYMBOL_GPL(rtas_set_indicator);
 
 /*
  * Ignoring RTAS extended delay