[kvm-unit-tests] powerpc: Rework the rtas_token() function

Submitted by Thomas Huth on May 31, 2017, 11:15 a.m.

Details

Message ID 1496229338-7113-1-git-send-email-thuth@redhat.com
State New
Headers show

Commit Message

Thomas Huth May 31, 2017, 11:15 a.m.
RTAS tokens can have any value, also 0xffffffff is theoretically
allowed (which is currently used for the RTAS_UNKNOWN_SERVICE error
code). Thus we should not mix error codes and tokens in the return
value here and return the token value via a pointer parameter
instead.

This patch also adds a check to rtas_token() to test whether the device
tree is available at all. This fixes a possible endless loop that
happens without device tree, spamming the console with "rtas_node:
/rtas: FDT_ERR_BADMAGIC" messages: Somewhere the code calls abort()
due to the missing device tree, and abort() calls exit() which in
turn tries to shut down the VM with rtas_power_off(). rtas_power_off()
needs the device tree again to look up the right RTAS token, where we
then end up in the next iteration.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 lib/powerpc/asm/rtas.h |  2 +-
 lib/powerpc/rtas.c     | 30 ++++++++++++++++++++++--------
 lib/powerpc/smp.c      | 11 ++++++-----
 powerpc/rtas.c         | 24 +++++++++++++-----------
 4 files changed, 42 insertions(+), 25 deletions(-)

Comments

Andrew Jones May 31, 2017, 11:58 a.m.
On Wed, May 31, 2017 at 01:15:38PM +0200, Thomas Huth wrote:
> RTAS tokens can have any value, also 0xffffffff is theoretically
> allowed (which is currently used for the RTAS_UNKNOWN_SERVICE error
> code). Thus we should not mix error codes and tokens in the return
> value here and return the token value via a pointer parameter
> instead.
> 
> This patch also adds a check to rtas_token() to test whether the device
> tree is available at all. This fixes a possible endless loop that
> happens without device tree, spamming the console with "rtas_node:
> /rtas: FDT_ERR_BADMAGIC" messages: Somewhere the code calls abort()
> due to the missing device tree, and abort() calls exit() which in
> turn tries to shut down the VM with rtas_power_off(). rtas_power_off()
> needs the device tree again to look up the right RTAS token, where we
> then end up in the next iteration.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  lib/powerpc/asm/rtas.h |  2 +-
>  lib/powerpc/rtas.c     | 30 ++++++++++++++++++++++--------
>  lib/powerpc/smp.c      | 11 ++++++-----
>  powerpc/rtas.c         | 24 +++++++++++++-----------
>  4 files changed, 42 insertions(+), 25 deletions(-)
> 
> diff --git a/lib/powerpc/asm/rtas.h b/lib/powerpc/asm/rtas.h
> index 9012a1e..6fb407a 100644
> --- a/lib/powerpc/asm/rtas.h
> +++ b/lib/powerpc/asm/rtas.h
> @@ -21,7 +21,7 @@ struct rtas_args {
>  };
>  
>  extern void rtas_init(void);
> -extern int rtas_token(const char *service);
> +extern int rtas_token(const char *service, uint32_t *token);
>  extern int rtas_call(int token, int nargs, int nret, int *outputs, ...);
>  
>  extern void rtas_power_off(void);
> diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> index 3407e25..2e7e0da 100644
> --- a/lib/powerpc/rtas.c
> +++ b/lib/powerpc/rtas.c
> @@ -69,17 +69,22 @@ void rtas_init(void)
>  	}
>  }
>  
> -int rtas_token(const char *service)
> +int rtas_token(const char *service, uint32_t *token)
>  {
>  	const struct fdt_property *prop;
> -	u32 *token;
> +	u32 *data;
> +
> +	if (!dt_available())
> +		return RTAS_UNKNOWN_SERVICE;
>  
>  	prop = fdt_get_property(dt_fdt(), rtas_node(), service, NULL);
> -	if (prop) {
> -		token = (u32 *)prop->data;
> -		return fdt32_to_cpu(*token);
> -	}
> -	return RTAS_UNKNOWN_SERVICE;
> +	if (!prop)
> +		return RTAS_UNKNOWN_SERVICE;
> +
> +	data = (u32 *)prop->data;
> +	*token = fdt32_to_cpu(*data);
> +
> +	return 0;
>  }
>  
>  int rtas_call(int token, int nargs, int nret, int *outputs, ...)
> @@ -116,6 +121,15 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
>  
>  void rtas_power_off(void)
>  {
> -	int ret = rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1);
> +	uint32_t token;
> +	int ret;
> +
> +	ret = rtas_token("power-off", &token);
> +	if (ret) {
> +		puts("RTAS power-off not available\n");
> +		return;
> +	}
> +
> +	ret = rtas_call(token, 2, 1, NULL, -1, -1);
>  	printf("RTAS power-off returned %d\n", ret);
>  }
> diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
> index e18894b..afe4361 100644
> --- a/lib/powerpc/smp.c
> +++ b/lib/powerpc/smp.c
> @@ -27,12 +27,13 @@ struct secondary_entry_data {
>   */
>  int start_thread(int cpu_id, secondary_entry_fn entry, uint32_t r3)
>  {
> -	int query_token, start_token, outputs[1], ret;
> +	uint32_t query_token, start_token;
> +	int outputs[1], ret;
>  
> -	query_token = rtas_token("query-cpu-stopped-state");
> -	start_token = rtas_token("start-cpu");
> -	assert(query_token != RTAS_UNKNOWN_SERVICE &&
> -		start_token != RTAS_UNKNOWN_SERVICE);
> +	ret = rtas_token("query-cpu-stopped-state", &query_token);
> +	assert(ret == 0);
> +	ret = rtas_token("start-cpu", &start_token);
> +	assert(ret == 0);
>  
>  	ret = rtas_call(query_token, 1, 2, outputs, cpu_id);
>  	if (ret) {
> diff --git a/powerpc/rtas.c b/powerpc/rtas.c
> index 1b1e9c7..5d43f33 100644
> --- a/powerpc/rtas.c
> +++ b/powerpc/rtas.c
> @@ -39,14 +39,14 @@ static unsigned long mktime(int year, int month, int day,
>  
>  static void check_get_time_of_day(unsigned long start)
>  {
> -	int token;
> +	uint32_t token;
>  	int ret;
>  	int now[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("get-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("get-time-of-day", &token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	ret = rtas_call(token, 0, 8, now);
> @@ -74,23 +74,25 @@ static void check_get_time_of_day(unsigned long start)
>  
>  static void check_set_time_of_day(void)
>  {
> -	int token;
> +	uint32_t stod_token, gtod_token;
>  	int ret;
>  	int date[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("set-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("set-time-of-day", &stod_token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	/* 23:59:59 28/2/2000 */
>  
> -	ret = rtas_call(token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
> +	ret = rtas_call(stod_token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
>  	report("execution", ret == 0);
>  
>  	/* check it has worked */
> -	ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +	ret = rtas_token("get-time-of-day", &gtod_token);
> +	assert(ret == 0);
> +	ret = rtas_call(gtod_token, 0, 8, date);
>  	report("re-read", ret == 0);
>  	t1 = mktime(2000, 2, 28, 23, 59, 59);
>  	t2 = mktime(date[0], date[1], date[2],
> @@ -100,7 +102,7 @@ static void check_set_time_of_day(void)
>  	/* check it is running */
>  	count = 0;
>  	do {
> -		ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +		ret = rtas_call(gtod_token, 0, 8, date);
>  		t2 = mktime(date[0], date[1], date[2],
>  			    date[3], date[4], date[5]);
>  		count++;
> -- 
> 1.8.3.1
>

Reviewed-by: Andrew Jones <drjones@redhat.com>
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Laurent Vivier May 31, 2017, 12:07 p.m.
On 31/05/2017 13:15, Thomas Huth wrote:
> RTAS tokens can have any value, also 0xffffffff is theoretically
> allowed (which is currently used for the RTAS_UNKNOWN_SERVICE error
> code). Thus we should not mix error codes and tokens in the return
> value here and return the token value via a pointer parameter
> instead.
> 
> This patch also adds a check to rtas_token() to test whether the device
> tree is available at all. This fixes a possible endless loop that
> happens without device tree, spamming the console with "rtas_node:
> /rtas: FDT_ERR_BADMAGIC" messages: Somewhere the code calls abort()
> due to the missing device tree, and abort() calls exit() which in
> turn tries to shut down the VM with rtas_power_off(). rtas_power_off()
> needs the device tree again to look up the right RTAS token, where we
> then end up in the next iteration.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  lib/powerpc/asm/rtas.h |  2 +-
>  lib/powerpc/rtas.c     | 30 ++++++++++++++++++++++--------
>  lib/powerpc/smp.c      | 11 ++++++-----
>  powerpc/rtas.c         | 24 +++++++++++++-----------
>  4 files changed, 42 insertions(+), 25 deletions(-)
> 
> diff --git a/lib/powerpc/asm/rtas.h b/lib/powerpc/asm/rtas.h
> index 9012a1e..6fb407a 100644
> --- a/lib/powerpc/asm/rtas.h
> +++ b/lib/powerpc/asm/rtas.h
> @@ -21,7 +21,7 @@ struct rtas_args {
>  };
>  
>  extern void rtas_init(void);
> -extern int rtas_token(const char *service);
> +extern int rtas_token(const char *service, uint32_t *token);
>  extern int rtas_call(int token, int nargs, int nret, int *outputs, ...);
>  
>  extern void rtas_power_off(void);
> diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> index 3407e25..2e7e0da 100644
> --- a/lib/powerpc/rtas.c
> +++ b/lib/powerpc/rtas.c
> @@ -69,17 +69,22 @@ void rtas_init(void)
>  	}
>  }
>  
> -int rtas_token(const char *service)
> +int rtas_token(const char *service, uint32_t *token)
>  {
>  	const struct fdt_property *prop;
> -	u32 *token;
> +	u32 *data;
> +
> +	if (!dt_available())
> +		return RTAS_UNKNOWN_SERVICE;
>  
>  	prop = fdt_get_property(dt_fdt(), rtas_node(), service, NULL);
> -	if (prop) {
> -		token = (u32 *)prop->data;
> -		return fdt32_to_cpu(*token);
> -	}
> -	return RTAS_UNKNOWN_SERVICE;
> +	if (!prop)
> +		return RTAS_UNKNOWN_SERVICE;
> +
> +	data = (u32 *)prop->data;
> +	*token = fdt32_to_cpu(*data);
> +
> +	return 0;
>  }
>  
>  int rtas_call(int token, int nargs, int nret, int *outputs, ...)
> @@ -116,6 +121,15 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
>  
>  void rtas_power_off(void)
>  {
> -	int ret = rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1);
> +	uint32_t token;
> +	int ret;
> +
> +	ret = rtas_token("power-off", &token);
> +	if (ret) {
> +		puts("RTAS power-off not available\n");
> +		return;
> +	}
> +
> +	ret = rtas_call(token, 2, 1, NULL, -1, -1);
>  	printf("RTAS power-off returned %d\n", ret);
>  }
> diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
> index e18894b..afe4361 100644
> --- a/lib/powerpc/smp.c
> +++ b/lib/powerpc/smp.c
> @@ -27,12 +27,13 @@ struct secondary_entry_data {
>   */
>  int start_thread(int cpu_id, secondary_entry_fn entry, uint32_t r3)
>  {
> -	int query_token, start_token, outputs[1], ret;
> +	uint32_t query_token, start_token;
> +	int outputs[1], ret;
>  
> -	query_token = rtas_token("query-cpu-stopped-state");
> -	start_token = rtas_token("start-cpu");
> -	assert(query_token != RTAS_UNKNOWN_SERVICE &&
> -		start_token != RTAS_UNKNOWN_SERVICE);
> +	ret = rtas_token("query-cpu-stopped-state", &query_token);
> +	assert(ret == 0);
> +	ret = rtas_token("start-cpu", &start_token);
> +	assert(ret == 0);
>  
>  	ret = rtas_call(query_token, 1, 2, outputs, cpu_id);
>  	if (ret) {
> diff --git a/powerpc/rtas.c b/powerpc/rtas.c
> index 1b1e9c7..5d43f33 100644
> --- a/powerpc/rtas.c
> +++ b/powerpc/rtas.c
> @@ -39,14 +39,14 @@ static unsigned long mktime(int year, int month, int day,
>  
>  static void check_get_time_of_day(unsigned long start)
>  {
> -	int token;
> +	uint32_t token;
>  	int ret;
>  	int now[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("get-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("get-time-of-day", &token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	ret = rtas_call(token, 0, 8, now);
> @@ -74,23 +74,25 @@ static void check_get_time_of_day(unsigned long start)
>  
>  static void check_set_time_of_day(void)
>  {
> -	int token;
> +	uint32_t stod_token, gtod_token;
>  	int ret;
>  	int date[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("set-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("set-time-of-day", &stod_token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	/* 23:59:59 28/2/2000 */
>  
> -	ret = rtas_call(token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
> +	ret = rtas_call(stod_token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
>  	report("execution", ret == 0);
>  
>  	/* check it has worked */
> -	ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +	ret = rtas_token("get-time-of-day", &gtod_token);
> +	assert(ret == 0);
> +	ret = rtas_call(gtod_token, 0, 8, date);
>  	report("re-read", ret == 0);
>  	t1 = mktime(2000, 2, 28, 23, 59, 59);
>  	t2 = mktime(date[0], date[1], date[2],
> @@ -100,7 +102,7 @@ static void check_set_time_of_day(void)
>  	/* check it is running */
>  	count = 0;
>  	do {
> -		ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +		ret = rtas_call(gtod_token, 0, 8, date);
>  		t2 = mktime(date[0], date[1], date[2],
>  			    date[3], date[4], date[5]);
>  		count++;
> 
Reviewed-by: Laurent Vivier <lvivier@redhat.com>

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Paolo Bonzini May 31, 2017, 12:31 p.m.
On 31/05/2017 13:15, Thomas Huth wrote:
> RTAS tokens can have any value, also 0xffffffff is theoretically
> allowed (which is currently used for the RTAS_UNKNOWN_SERVICE error
> code). Thus we should not mix error codes and tokens in the return
> value here and return the token value via a pointer parameter
> instead.
> 
> This patch also adds a check to rtas_token() to test whether the device
> tree is available at all. This fixes a possible endless loop that
> happens without device tree, spamming the console with "rtas_node:
> /rtas: FDT_ERR_BADMAGIC" messages: Somewhere the code calls abort()
> due to the missing device tree, and abort() calls exit() which in
> turn tries to shut down the VM with rtas_power_off(). rtas_power_off()
> needs the device tree again to look up the right RTAS token, where we
> then end up in the next iteration.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  lib/powerpc/asm/rtas.h |  2 +-
>  lib/powerpc/rtas.c     | 30 ++++++++++++++++++++++--------
>  lib/powerpc/smp.c      | 11 ++++++-----
>  powerpc/rtas.c         | 24 +++++++++++++-----------
>  4 files changed, 42 insertions(+), 25 deletions(-)
> 
> diff --git a/lib/powerpc/asm/rtas.h b/lib/powerpc/asm/rtas.h
> index 9012a1e..6fb407a 100644
> --- a/lib/powerpc/asm/rtas.h
> +++ b/lib/powerpc/asm/rtas.h
> @@ -21,7 +21,7 @@ struct rtas_args {
>  };
>  
>  extern void rtas_init(void);
> -extern int rtas_token(const char *service);
> +extern int rtas_token(const char *service, uint32_t *token);
>  extern int rtas_call(int token, int nargs, int nret, int *outputs, ...);
>  
>  extern void rtas_power_off(void);
> diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> index 3407e25..2e7e0da 100644
> --- a/lib/powerpc/rtas.c
> +++ b/lib/powerpc/rtas.c
> @@ -69,17 +69,22 @@ void rtas_init(void)
>  	}
>  }
>  
> -int rtas_token(const char *service)
> +int rtas_token(const char *service, uint32_t *token)
>  {
>  	const struct fdt_property *prop;
> -	u32 *token;
> +	u32 *data;
> +
> +	if (!dt_available())
> +		return RTAS_UNKNOWN_SERVICE;
>  
>  	prop = fdt_get_property(dt_fdt(), rtas_node(), service, NULL);
> -	if (prop) {
> -		token = (u32 *)prop->data;
> -		return fdt32_to_cpu(*token);
> -	}
> -	return RTAS_UNKNOWN_SERVICE;
> +	if (!prop)
> +		return RTAS_UNKNOWN_SERVICE;
> +
> +	data = (u32 *)prop->data;
> +	*token = fdt32_to_cpu(*data);
> +
> +	return 0;
>  }
>  
>  int rtas_call(int token, int nargs, int nret, int *outputs, ...)
> @@ -116,6 +121,15 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
>  
>  void rtas_power_off(void)
>  {
> -	int ret = rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1);
> +	uint32_t token;
> +	int ret;
> +
> +	ret = rtas_token("power-off", &token);
> +	if (ret) {
> +		puts("RTAS power-off not available\n");
> +		return;
> +	}
> +
> +	ret = rtas_call(token, 2, 1, NULL, -1, -1);
>  	printf("RTAS power-off returned %d\n", ret);
>  }
> diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
> index e18894b..afe4361 100644
> --- a/lib/powerpc/smp.c
> +++ b/lib/powerpc/smp.c
> @@ -27,12 +27,13 @@ struct secondary_entry_data {
>   */
>  int start_thread(int cpu_id, secondary_entry_fn entry, uint32_t r3)
>  {
> -	int query_token, start_token, outputs[1], ret;
> +	uint32_t query_token, start_token;
> +	int outputs[1], ret;
>  
> -	query_token = rtas_token("query-cpu-stopped-state");
> -	start_token = rtas_token("start-cpu");
> -	assert(query_token != RTAS_UNKNOWN_SERVICE &&
> -		start_token != RTAS_UNKNOWN_SERVICE);
> +	ret = rtas_token("query-cpu-stopped-state", &query_token);
> +	assert(ret == 0);
> +	ret = rtas_token("start-cpu", &start_token);
> +	assert(ret == 0);
>  
>  	ret = rtas_call(query_token, 1, 2, outputs, cpu_id);
>  	if (ret) {
> diff --git a/powerpc/rtas.c b/powerpc/rtas.c
> index 1b1e9c7..5d43f33 100644
> --- a/powerpc/rtas.c
> +++ b/powerpc/rtas.c
> @@ -39,14 +39,14 @@ static unsigned long mktime(int year, int month, int day,
>  
>  static void check_get_time_of_day(unsigned long start)
>  {
> -	int token;
> +	uint32_t token;
>  	int ret;
>  	int now[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("get-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("get-time-of-day", &token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	ret = rtas_call(token, 0, 8, now);
> @@ -74,23 +74,25 @@ static void check_get_time_of_day(unsigned long start)
>  
>  static void check_set_time_of_day(void)
>  {
> -	int token;
> +	uint32_t stod_token, gtod_token;
>  	int ret;
>  	int date[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("set-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("set-time-of-day", &stod_token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	/* 23:59:59 28/2/2000 */
>  
> -	ret = rtas_call(token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
> +	ret = rtas_call(stod_token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
>  	report("execution", ret == 0);
>  
>  	/* check it has worked */
> -	ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +	ret = rtas_token("get-time-of-day", &gtod_token);
> +	assert(ret == 0);
> +	ret = rtas_call(gtod_token, 0, 8, date);
>  	report("re-read", ret == 0);
>  	t1 = mktime(2000, 2, 28, 23, 59, 59);
>  	t2 = mktime(date[0], date[1], date[2],
> @@ -100,7 +102,7 @@ static void check_set_time_of_day(void)
>  	/* check it is running */
>  	count = 0;
>  	do {
> -		ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +		ret = rtas_call(gtod_token, 0, 8, date);
>  		t2 = mktime(date[0], date[1], date[2],
>  			    date[3], date[4], date[5]);
>  		count++;
> 

Dropped "powerpc: Fix endless loop that occurs without a device tree",
and queued.

Paolo
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Patch hide | download patch | download mbox

diff --git a/lib/powerpc/asm/rtas.h b/lib/powerpc/asm/rtas.h
index 9012a1e..6fb407a 100644
--- a/lib/powerpc/asm/rtas.h
+++ b/lib/powerpc/asm/rtas.h
@@ -21,7 +21,7 @@  struct rtas_args {
 };
 
 extern void rtas_init(void);
-extern int rtas_token(const char *service);
+extern int rtas_token(const char *service, uint32_t *token);
 extern int rtas_call(int token, int nargs, int nret, int *outputs, ...);
 
 extern void rtas_power_off(void);
diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
index 3407e25..2e7e0da 100644
--- a/lib/powerpc/rtas.c
+++ b/lib/powerpc/rtas.c
@@ -69,17 +69,22 @@  void rtas_init(void)
 	}
 }
 
-int rtas_token(const char *service)
+int rtas_token(const char *service, uint32_t *token)
 {
 	const struct fdt_property *prop;
-	u32 *token;
+	u32 *data;
+
+	if (!dt_available())
+		return RTAS_UNKNOWN_SERVICE;
 
 	prop = fdt_get_property(dt_fdt(), rtas_node(), service, NULL);
-	if (prop) {
-		token = (u32 *)prop->data;
-		return fdt32_to_cpu(*token);
-	}
-	return RTAS_UNKNOWN_SERVICE;
+	if (!prop)
+		return RTAS_UNKNOWN_SERVICE;
+
+	data = (u32 *)prop->data;
+	*token = fdt32_to_cpu(*data);
+
+	return 0;
 }
 
 int rtas_call(int token, int nargs, int nret, int *outputs, ...)
@@ -116,6 +121,15 @@  int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 
 void rtas_power_off(void)
 {
-	int ret = rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1);
+	uint32_t token;
+	int ret;
+
+	ret = rtas_token("power-off", &token);
+	if (ret) {
+		puts("RTAS power-off not available\n");
+		return;
+	}
+
+	ret = rtas_call(token, 2, 1, NULL, -1, -1);
 	printf("RTAS power-off returned %d\n", ret);
 }
diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
index e18894b..afe4361 100644
--- a/lib/powerpc/smp.c
+++ b/lib/powerpc/smp.c
@@ -27,12 +27,13 @@  struct secondary_entry_data {
  */
 int start_thread(int cpu_id, secondary_entry_fn entry, uint32_t r3)
 {
-	int query_token, start_token, outputs[1], ret;
+	uint32_t query_token, start_token;
+	int outputs[1], ret;
 
-	query_token = rtas_token("query-cpu-stopped-state");
-	start_token = rtas_token("start-cpu");
-	assert(query_token != RTAS_UNKNOWN_SERVICE &&
-		start_token != RTAS_UNKNOWN_SERVICE);
+	ret = rtas_token("query-cpu-stopped-state", &query_token);
+	assert(ret == 0);
+	ret = rtas_token("start-cpu", &start_token);
+	assert(ret == 0);
 
 	ret = rtas_call(query_token, 1, 2, outputs, cpu_id);
 	if (ret) {
diff --git a/powerpc/rtas.c b/powerpc/rtas.c
index 1b1e9c7..5d43f33 100644
--- a/powerpc/rtas.c
+++ b/powerpc/rtas.c
@@ -39,14 +39,14 @@  static unsigned long mktime(int year, int month, int day,
 
 static void check_get_time_of_day(unsigned long start)
 {
-	int token;
+	uint32_t token;
 	int ret;
 	int now[8];
 	unsigned long t1, t2, count;
 
-	token = rtas_token("get-time-of-day");
-	report("token available", token != RTAS_UNKNOWN_SERVICE);
-	if (token == RTAS_UNKNOWN_SERVICE)
+	ret = rtas_token("get-time-of-day", &token);
+	report("token available", ret == 0);
+	if (ret)
 		return;
 
 	ret = rtas_call(token, 0, 8, now);
@@ -74,23 +74,25 @@  static void check_get_time_of_day(unsigned long start)
 
 static void check_set_time_of_day(void)
 {
-	int token;
+	uint32_t stod_token, gtod_token;
 	int ret;
 	int date[8];
 	unsigned long t1, t2, count;
 
-	token = rtas_token("set-time-of-day");
-	report("token available", token != RTAS_UNKNOWN_SERVICE);
-	if (token == RTAS_UNKNOWN_SERVICE)
+	ret = rtas_token("set-time-of-day", &stod_token);
+	report("token available", ret == 0);
+	if (ret)
 		return;
 
 	/* 23:59:59 28/2/2000 */
 
-	ret = rtas_call(token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
+	ret = rtas_call(stod_token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
 	report("execution", ret == 0);
 
 	/* check it has worked */
-	ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
+	ret = rtas_token("get-time-of-day", &gtod_token);
+	assert(ret == 0);
+	ret = rtas_call(gtod_token, 0, 8, date);
 	report("re-read", ret == 0);
 	t1 = mktime(2000, 2, 28, 23, 59, 59);
 	t2 = mktime(date[0], date[1], date[2],
@@ -100,7 +102,7 @@  static void check_set_time_of_day(void)
 	/* check it is running */
 	count = 0;
 	do {
-		ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
+		ret = rtas_call(gtod_token, 0, 8, date);
 		t2 = mktime(date[0], date[1], date[2],
 			    date[3], date[4], date[5]);
 		count++;