Re: [PATCH v2] lib: sbi: dbtr: Fix shared memory layout

[Charlie Jenkins <charlie@rivosinc.com>]

On Wed, Jun 04, 2025 at 06:52:25AM -0700, Jesse Taube wrote:
> 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: 97f234f15c96 ("lib: sbi: Introduce the SBI debug triggers extension support")
> Signed-off-by: Jesse Taube <jesse@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>

> ---
> V1 -> V2:
>  - Remove anonymous union
>  - Replace struct with union
>  - Update commit description
> ---
>  include/sbi/sbi_dbtr.h | 2 +-
>  lib/sbi/sbi_dbtr.c     | 6 +++---
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/include/sbi/sbi_dbtr.h b/include/sbi/sbi_dbtr.h
> index a8b3a02..9b87968 100644
> --- a/include/sbi/sbi_dbtr.h
> +++ b/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;
>  };
> diff --git a/lib/sbi/sbi_dbtr.c b/lib/sbi/sbi_dbtr.c
> index f0e9128..cfb6b2a 100644
> --- a/lib/sbi/sbi_dbtr.c
> +++ b/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;
>  
> -- 
> 2.43.0
> 

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