lib: sbi: dbtr: Fix shared memory layout

The existing sbi_dbtr_shmem_entry has a size of 5 * XLEN with the final
entry being idx. This is in contrast to the SBI v3.0-rc7 Chapter 19.
Debug Triggers Extension [0] where idx and trig_state share the same
offset (0) in shared memory, with a total size of 4 * XLEN for all the
SBI calls.

Replace struct with union to match memory layout described in SBI.

[0] https://github.com/riscv-non-isa/riscv-sbi-doc/tree/v3.0-rc7/src/ext-debug-triggers.adoc

Fixes: 97f234f ("lib: sbi: Introduce the SBI debug triggers extension support")
Signed-off-by: Jesse Taube <[email protected]>
Reviewed-by: Charlie Jenkins <[email protected]>
Tested-by: Charlie Jenkins <[email protected]>
Reviewed-by: Himanshu Chauhan <[email protected]>
Tested-by: Himanshu Chauhan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Anup Patel <[email protected]>

Author: Mr-Bossman

include/sbi/sbi_dbtr.h

@@ -90,7 +90,7 @@ struct sbi_dbtr_hart_triggers_state {
 	}while (0);
 
 /** SBI shared mem messages layout */
-struct sbi_dbtr_shmem_entry {
+union sbi_dbtr_shmem_entry {
 	struct sbi_dbtr_data_msg data;
 	struct sbi_dbtr_id_msg id;
 };

lib/sbi/sbi_dbtr.c

@@ -506,7 +506,7 @@ int sbi_dbtr_read_trig(unsigned long smode,
 {
 	struct sbi_dbtr_data_msg *xmit;
 	struct sbi_dbtr_trigger *trig;
-	struct sbi_dbtr_shmem_entry *entry;
+	union sbi_dbtr_shmem_entry *entry;
 	void *shmem_base = NULL;
 	struct sbi_dbtr_hart_triggers_state *hs = NULL;
 
@@ -541,7 +541,7 @@ int sbi_dbtr_install_trig(unsigned long smode,
 			  unsigned long trig_count, unsigned long *out)
 {
 	void *shmem_base = NULL;
-	struct sbi_dbtr_shmem_entry *entry;
+	union sbi_dbtr_shmem_entry *entry;
 	struct sbi_dbtr_data_msg *recv;
 	struct sbi_dbtr_id_msg *xmit;
 	unsigned long ctrl;
@@ -659,7 +659,7 @@ int sbi_dbtr_update_trig(unsigned long smode,
 	struct sbi_dbtr_data_msg *recv;
 	unsigned long uidx = 0;
 	struct sbi_dbtr_trigger *trig;
-	struct sbi_dbtr_shmem_entry *entry;
+	union sbi_dbtr_shmem_entry *entry;
 	void *shmem_base = NULL;
 	struct sbi_dbtr_hart_triggers_state *hs = NULL;