[DTrace-devel] [PATCH] Provide the maximum string length as BPF symbol STRSZ

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
though the value isn't so much provided by STRSZ as by &STRSZ.  So, the 
subject line could perhaps be a little more precise, though I suppose it 
doesn't matter.  Good enough as is.

On 8/20/21 2:46 AM, Kris Van Hees wrote:
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>   libdtrace/dt_bpf.h   | 7 ++++---
>   libdtrace/dt_cc.c    | 4 ++++
>   libdtrace/dt_dlibs.c | 1 +
>   3 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/libdtrace/dt_bpf.h b/libdtrace/dt_bpf.h
> index dcc82b80..68e4aa07 100644
> --- a/libdtrace/dt_bpf.h
> +++ b/libdtrace/dt_bpf.h
> @@ -23,9 +23,10 @@ extern "C" {
>   #define DT_CONST_CLID	3
>   #define DT_CONST_ARGC	4
>   #define DT_CONST_STBSZ	5
> -#define DT_CONST_STKOFF	6
> -#define DT_CONST_STKSIZ	7
> -#define DT_CONST_BOOTTM	8
> +#define DT_CONST_STRSZ	6
> +#define DT_CONST_STKOFF	7
> +#define DT_CONST_STKSIZ	8
> +#define DT_CONST_BOOTTM	9
>   
>   extern int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu,
>   			   int group_fd, unsigned long flags);
> diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
> index 2a6904a0..f69c750d 100644
> --- a/libdtrace/dt_cc.c
> +++ b/libdtrace/dt_cc.c
> @@ -2348,6 +2348,10 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
>   			case DT_CONST_STBSZ:
>   				nrp->dofr_data = dtp->dt_strlen;
>   				continue;
> +			case DT_CONST_STRSZ:
> +				nrp->dofr_data =
> +					dtp->dt_options[DTRACEOPT_STRSIZE];
> +				continue;
>   			case DT_CONST_STKOFF:
>   				nrp->dofr_data = roundup(dtp->dt_maxreclen, 8);
>   				continue;
> diff --git a/libdtrace/dt_dlibs.c b/libdtrace/dt_dlibs.c
> index 35a18596..53abe2f7 100644
> --- a/libdtrace/dt_dlibs.c
> +++ b/libdtrace/dt_dlibs.c
> @@ -78,6 +78,7 @@ static const dt_ident_t		dt_bpf_symbols[] = {
>   	DT_BPF_SYMBOL_ID(CLID, DT_IDENT_SCALAR, DT_CONST_CLID),
>   	DT_BPF_SYMBOL_ID(ARGC, DT_IDENT_SCALAR, DT_CONST_ARGC),
>   	DT_BPF_SYMBOL_ID(STBSZ, DT_IDENT_SCALAR, DT_CONST_STBSZ),
> +	DT_BPF_SYMBOL_ID(STRSZ, DT_IDENT_SCALAR, DT_CONST_STRSZ),
>   	DT_BPF_SYMBOL_ID(STKOFF, DT_IDENT_SCALAR, DT_CONST_STKOFF),
>   	DT_BPF_SYMBOL_ID(STKSIZ, DT_IDENT_SCALAR, DT_CONST_STKSIZ),
>   	DT_BPF_SYMBOL_ID(BOOTTM, DT_IDENT_SCALAR, DT_CONST_BOOTTM),