base: Context negative num mpus segfault

This patch fixes a bug that would result in a segfault if a negative number of
mpus are requested when creating a MARS context.

Also the internal function mars_mpu_max() now returns 0 as a successful result.
The caller is responsible for handling a return of 0 appropriately.
MARS_ERROR_INTERNAL is only returned if there was some error to retrieve the
count.

Signed-off-by: Yuji Mano <yuji.mano@am.sony.com>
Acked-by: Kazunori Asayama <asayama@sm.sony.co.jp>

4 files changed, 16 insertions, 9 deletions

diff --git a/base/include/host/mars/context.h b/base/include/host/mars/context.h
index 7888320..db39470 100644
--- a/base/include/host/mars/context.h
+++ b/base/include/host/mars/context.h
@@ -88,12 +88,13 @@ extern "C" {
  * each MARS context will suffer the large over head of MPU context switches.
  *
  * \param[out] mars		- address of pointer to MARS context
- * \param[in] num_mpus		- number of mpus utilized by MARS context
+ * \param[in] num_mpus		- number of mpus requested by MARS context
  * \param[in] shared		- specifies if context is shared or not
  * \return
  *	MARS_SUCCESS		- successfully created MARS context
  * \n	MARS_ERROR_NULL		- null pointer specified
- * \n	MARS_ERROR_PARAMS	- bad MARS params specified
+ * \n	MARS_ERROR_LIMIT	- no more available MPUs
+ * \n	MARS_ERROR_PARAMS	- more MPUs requested than there are available
  * \n	MARS_ERROR_MEMORY	- not enough memory
  * \n	MARS_ERROR_INTERNAL	- some internal error occurred
  */
diff --git a/base/src/host/lib/context.c b/base/src/host/lib/context.c
index d6c7ad5..22dbbc9 100644
--- a/base/src/host/lib/context.c
+++ b/base/src/host/lib/context.c
@@ -183,7 +183,7 @@ int mars_context_create(struct mars_context **mars_ret, uint32_t num_mpus,
 			uint8_t shared)
 {
 	int ret;
-	int num_mpus_max;
+	uint32_t num_mpus_max;
 	struct mars_context *mars = NULL;
 
 	/* check function params */
@@ -194,7 +194,9 @@ int mars_context_create(struct mars_context **mars_ret, uint32_t num_mpus,
 	ret = mars_mpu_max(&num_mpus_max);
 	if (ret != MARS_SUCCESS)
 		return ret;
-	if (num_mpus_max < (int)num_mpus)
+	if (!num_mpus_max)
+		return MARS_ERROR_LIMIT;
+	if (num_mpus > num_mpus_max)
 		return MARS_ERROR_PARAMS;
 	if (!num_mpus)
 		num_mpus = num_mpus_max;
diff --git a/base/src/host/lib/context_internal.h b/base/src/host/lib/context_internal.h
index a5ca963..ef8e0e3 100644
--- a/base/src/host/lib/context_internal.h
+++ b/base/src/host/lib/context_internal.h
@@ -72,7 +72,7 @@ struct mars_context {
 	mars_callback_t callback_handler;
 };
 
-int mars_mpu_max(int *num);
+int mars_mpu_max(uint32_t *num);
 int mars_mpu_run(mars_mpu_context_t *mpu, uint64_t params_ea);
 int mars_mpu_wait(mars_mpu_context_t *mpu);
 
diff --git a/base/src/host/lib/mpu_cell.c b/base/src/host/lib/mpu_cell.c
index cff9233..49744fd 100644
--- a/base/src/host/lib/mpu_cell.c
+++ b/base/src/host/lib/mpu_cell.c
@@ -89,16 +89,20 @@ static int numa_mpu_max(void)
 
 extern const unsigned char mars_kernel_entry[];
 
-int mars_mpu_max(int *num)
+int mars_mpu_max(uint32_t *num)
 {
+	int mpu_max;
+
 	if (mars_numa_enabled())
-		*num = numa_mpu_max();
+		mpu_max = numa_mpu_max();
 	else
-		*num = spe_cpu_info_get(SPE_COUNT_USABLE_SPES, -1);
+		mpu_max = spe_cpu_info_get(SPE_COUNT_USABLE_SPES, -1);
 
-	if (*num <= 0)
+	if (mpu_max < 0)
 		return MARS_ERROR_INTERNAL;
 
+	*num = mpu_max;
+
 	return MARS_SUCCESS;
 }