[DTrace-devel] [PATCH 3/6] bpf: implement additional relocation types

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
and an explanation in the commit msg what motivates this patch?

On 1/28/25 01:31, Kris Van Hees wrote:
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>   include/port.h     | 6 ++++++
>   libdtrace/dt_as.c  | 2 +-
>   libdtrace/dt_cc.c  | 3 ++-
>   libdtrace/dt_dis.c | 9 ++++++++-
>   4 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/include/port.h b/include/port.h
> index 6ce8611e..0aadacb8 100644
> --- a/include/port.h
> +++ b/include/port.h
> @@ -88,6 +88,12 @@ pid_t gettid(void);
>   #ifndef R_BPF_64_64
>   #define R_BPF_64_64		1
>   #endif
> +#ifndef R_BPF_64_ABS64
> +#define R_BPF_64_ABS64		2
> +#endif
> +#ifndef R_BPF_64_ABS32
> +#define R_BPF_64_ABS32		3
> +#endif
>   #ifndef R_BPF_64_32
>   #define R_BPF_64_32		10
>   #endif
> diff --git a/libdtrace/dt_as.c b/libdtrace/dt_as.c
> index a634b855..d3126f9a 100644
> --- a/libdtrace/dt_as.c
> +++ b/libdtrace/dt_as.c
> @@ -492,7 +492,7 @@ fail:
>   			case BPF_ST | BPF_MEM | BPF_DW:		/* stdw */
>   			case BPF_ALU64 | BPF_MOV | BPF_K:	/* mov */
>   			case BPF_ALU64 | BPF_ADD | BPF_K:	/* add */
> -				rp->dofr_type = R_BPF_64_32;
> +				rp->dofr_type = R_BPF_64_ABS32;
>   				break;
>   			case BPF_LD | BPF_IMM | BPF_DW:		/* lddw */
>   				rp->dofr_type = R_BPF_64_64;
> diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
> index eebd923c..29cfbd84 100644
> --- a/libdtrace/dt_cc.c
> +++ b/libdtrace/dt_cc.c
> @@ -1266,7 +1266,8 @@ dt_link_resolve(dtrace_hdl_t *dtp, dtrace_difo_t *dp)
>   		if (rp->dofr_type == R_BPF_64_64) {
>   			buf[ioff].imm = val & 0xffffffff;
>   			buf[ioff + 1].imm = val >> 32;
> -		} else if (rp->dofr_type == R_BPF_64_32)
> +		} else if (rp->dofr_type == R_BPF_64_32 ||
> +			   rp->dofr_type == R_BPF_64_ABS32)
>   			buf[ioff].imm = (uint32_t)val;
>   	}
>   }
> diff --git a/libdtrace/dt_dis.c b/libdtrace/dt_dis.c
> index d983c099..b2e66754 100644
> --- a/libdtrace/dt_dis.c
> +++ b/libdtrace/dt_dis.c
> @@ -639,6 +639,12 @@ dt_dis_rtab(const char *rtag, const dtrace_difo_t *dp, FILE *fp,
>   		case R_BPF_64_32:
>   			tstr = "R_BPF_INSN_DISP32";
>   			break;
> +		case R_BPF_64_ABS64:
> +			tstr = "R_BPF_DATA_64";
> +			break;
> +		case R_BPF_64_ABS32:
> +			tstr = "R_BPF_DATA_32";
> +			break;
>   		default:
>   			tstr = "R_???";
>   		}
> @@ -853,7 +859,8 @@ dt_dis_difo(const dtrace_difo_t *dp, FILE *fp, const dt_ident_t *idp,
>   		for (; cnt; cnt--, rp++) {
>   			if (rp->dofr_offset < i * sizeof(uint64_t))
>   				continue;
> -			if (rp->dofr_offset == i * sizeof(uint64_t))
> +			if (rp->dofr_offset >= i * sizeof(uint64_t) &&
> +			    rp->dofr_offset < (i + 1) * sizeof(uint64_t))
>   				rname = dt_difo_getstr(dp, rp->dofr_name);
>   
>   			break;