[PATCH v2 3/6] lib: sbi: send a double trap SSE event to supervisor

[Samuel Holland]

On 2024-09-13 9:34 AM, Clément Léger wrote:
> In case the double trap handler is called and the double trap happened
> in supervisor mode, send a double trap SSE event.
> 
> NOTE: this commit depends on the ratification of the new SSE event
> id for double trap [1].
> 
> Link: https://lists.riscv.org/g/tech-prs/message/985 [1]
> Signed-off-by: Clément Léger <cleger at rivosinc.com>
> ---
>  include/sbi/sbi_ecall_interface.h | 1 +
>  lib/sbi/sbi_double_trap.c         | 2 +-
>  lib/sbi/sbi_sse.c                 | 1 +
>  3 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
> index e9a8167..5428fba 100644
> --- a/include/sbi/sbi_ecall_interface.h
> +++ b/include/sbi/sbi_ecall_interface.h
> @@ -379,6 +379,7 @@ enum sbi_sse_state {
>  
>  /* SBI SSE Event IDs. */
>  #define SBI_SSE_EVENT_LOCAL_RAS			0x00000000
> +#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP		0x00000001
>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_END		0x00007fff
>  #define SBI_SSE_EVENT_GLOBAL_RAS		0x00008000
> diff --git a/lib/sbi/sbi_double_trap.c b/lib/sbi/sbi_double_trap.c
> index b961645..60ea0b1 100644
> --- a/lib/sbi/sbi_double_trap.c
> +++ b/lib/sbi/sbi_double_trap.c
> @@ -23,5 +23,5 @@ int sbi_double_trap_handler(struct sbi_trap_context *tcntx)
>  	if (prev_virt)
>  		return sbi_trap_redirect(regs, trap);
>  
> -	return SBI_ENOTSUPP;
> +	return sbi_sse_inject_event(SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP);

Reviewed-by: Samuel Holland <samuel.holland at sifive.com>

(sbi_sse_inject_event() doesn't check anywhere that the trap came from a lower
privilege mode, like sbi_trap_redirect() does. But that's fine for double trap,
because a double trap from M-mode doesn't go through the normal trap handler.)

>  }
> diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
> index 52172fc..b5f076a 100644
> --- a/lib/sbi/sbi_sse.c
> +++ b/lib/sbi/sbi_sse.c
> @@ -41,6 +41,7 @@
>  
>  static const uint32_t supported_events[] = {
>  	SBI_SSE_EVENT_LOCAL_RAS,
> +	SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP,
>  	SBI_SSE_EVENT_GLOBAL_RAS,
>  	SBI_SSE_EVENT_LOCAL_PMU,
>  	SBI_SSE_EVENT_LOCAL_SOFTWARE,