target/cortex: malloc/free tdesc on attach/detach instead of once on probe

src/target/cortexa.c

@@ -505,13 +505,6 @@ bool cortexa_probe(ADIv5_AP_t *apb, uint32_t debug_base)
 	t->attach = cortexa_attach;
 	t->detach = cortexa_detach;
 
-	// Find the buffer size needed for the target description string we need to send to GDB,
-	// and then compute the string itself.
-	size_t size_needed = create_tdesc_cortex_a(NULL, 0) + 1;
-	char *buffer = malloc(size_needed);
-	create_tdesc_cortex_a(buffer, size_needed);
-
-	t->tdesc = buffer;
 	t->regs_read = cortexa_regs_read;
 	t->regs_write = cortexa_regs_write;
 	t->reg_read = cortexa_reg_read;
@@ -534,6 +527,16 @@ bool cortexa_attach(target *t)
 	struct cortexa_priv *priv = t->priv;
 	int tries;
 
+	if (!t->tdesc) {
+		// Find the buffer size needed for the target description string we need to send to GDB,
+		// and then compute the string itself.
+		size_t size_needed = create_tdesc_cortex_a(NULL, 0) + 1;
+		t->tdesc = malloc(size_needed);
+		create_tdesc_cortex_a(t->tdesc, size_needed);
+	} else {
+		DEBUG_WARN("Cortex-A: target description already allocated before attach");
+	}
+
 	/* Clear any pending fault condition */
 	target_check_error(t);
 
@@ -567,6 +570,14 @@ void cortexa_detach(target *t)
 {
 	struct cortexa_priv *priv = t->priv;
 
+	if (t->tdesc) {
+		// Free the target description string that was allocated in cortexa_attach().
+		free(t->tdesc);
+		t->tdesc = NULL;
+	} else {
+		DEBUG_WARN("Cortex-A: target description already NULL before detach");
+	}
+
 	/* Clear any stale breakpoints */
 	for(unsigned i = 0; i < priv->hw_breakpoint_max; i++) {
 		apb_write(t, DBGBCR(i), 0);

src/target/cortexm.c

@@ -594,21 +594,6 @@ bool cortexm_probe(ADIv5_AP_t *ap)
 
 	/* Should probe here to make sure it's Cortex-M3 */
 
-	// Find the buffer size needed for the target description string we need to send to GDB,
-	// and then compute the string itself.
-	size_t size_needed;
-	char *buffer;
-	if (!is_cortexmf) {
-		size_needed = create_tdesc_cortex_m(NULL, 0) + 1;
-		buffer = malloc(size_needed);
-		create_tdesc_cortex_m(buffer, size_needed);
-	} else {
-		size_needed = create_tdesc_cortex_mf(NULL, 0) + 1;
-		buffer = malloc(size_needed);
-		create_tdesc_cortex_mf(buffer, size_needed);
-	}
-
-	t->tdesc = buffer;
 	t->regs_read = cortexm_regs_read;
 	t->regs_write = cortexm_regs_write;
 	t->reg_read = cortexm_reg_read;
@@ -755,6 +740,26 @@ bool cortexm_probe(ADIv5_AP_t *ap)
 
 bool cortexm_attach(target *t)
 {
+	bool is_cortexmf = (t->target_options & TOPT_FLAVOUR_V7MF) == TOPT_FLAVOUR_V7MF;
+
+	if (!t->tdesc) {
+		// Find the buffer size needed for the target description string we need to send to GDB,
+		// and then compute the string itself.
+		size_t size_needed;
+		if (!is_cortexmf) {
+			size_needed = create_tdesc_cortex_m(NULL, 0) + 1;
+			t->tdesc = malloc(size_needed);
+			create_tdesc_cortex_m(t->tdesc, size_needed);
+		} else {
+			size_needed = create_tdesc_cortex_mf(NULL, 0) + 1;
+			t->tdesc = malloc(size_needed);
+			create_tdesc_cortex_mf(t->tdesc, size_needed);
+		}
+	} else {
+		DEBUG_WARN("Cortex-M: target description already allocated before attach");
+	}
+
+
 	ADIv5_AP_t *ap = cortexm_ap(t);
 	ap->dp->fault = 1; /* Force switch to this multi-drop device*/
 	struct cortexm_priv *priv = t->priv;
@@ -820,6 +825,14 @@ void cortexm_detach(target *t)
 	struct cortexm_priv *priv = t->priv;
 	unsigned i;
 
+	if (t->tdesc) {
+		// Free the target description string that was allocated in cortexm_attach().
+		free(t->tdesc);
+		t->tdesc = NULL;
+	} else {
+		DEBUG_WARN("Cortex-M: target description already NULL before detach");
+	}
+
 	/* Clear any stale breakpoints */
 	for (i = 0; i < priv->hw_breakpoint_max; i++)
 		target_mem_write32(t, CORTEXM_FPB_COMP(i), 0);

src/target/target_internal.h

@@ -98,7 +98,7 @@ struct target_s {
 
 	/* Register access functions */
 	size_t regs_size;
-	const char *tdesc;
+	char *tdesc;
 	void (*regs_read)(target *t, void *data);
 	void (*regs_write)(target *t, const void *data);
 	ssize_t (*reg_read)(target *t, int reg, void *data, size_t max);