[DTrace-devel] [PATCH 4/7] Add support for indexed built-in variables lookup

[Kris Van Hees]

On Thu, May 26, 2022 at 01:31:29PM -0700, Eugene Loh via DTrace-devel wrote:
> This patch breaks disassembly of built-in variables.  How about:
> 
> 1)  moving this (pretty small) patch into #5/7, or
> 
> 2)  moving the bvar disassembly fix from #5/7 back into this patch

AH yes, that chunk was actually supposed to be part of this pathc.  I must have
accidentally failed to add it here and so it ended up in the next patch.
Operator error.  Will fix.

> That is, the break and the fix should be in the same patch.
> 
> On 5/26/22 11:24, Kris Van Hees via DTrace-devel wrote:
> > Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> > ---
> >   bpf/get_bvar.c    | 7 ++++++-
> >   libdtrace/dt_cg.c | 1 +
> >   2 files changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/bpf/get_bvar.c b/bpf/get_bvar.c
> > index 0da4b35a..4ff9b695 100644
> > --- a/bpf/get_bvar.c
> > +++ b/bpf/get_bvar.c
> > @@ -33,7 +33,7 @@ extern uint64_t BOOTTM;
> >   		-1; \
> >   	})
> > -noinline uint64_t dt_get_bvar(const dt_dctx_t *dctx, uint32_t id)
> > +noinline uint64_t dt_get_bvar(const dt_dctx_t *dctx, uint32_t id, uint32_t idx)
> >   {
> >   	dt_mstate_t	*mst = dctx->mst;
> > @@ -54,6 +54,11 @@ noinline uint64_t dt_get_bvar(const dt_dctx_t *dctx, uint32_t id)
> >   	case DIF_VAR_ARG6: case DIF_VAR_ARG7: case DIF_VAR_ARG8:
> >   	case DIF_VAR_ARG9:
> >   		return mst->argv[id - DIF_VAR_ARG0];
> > +	case DIF_VAR_ARGS:
> > +		if (idx >= sizeof(mst->argv) / sizeof(mst->argv[0]))
> > +			return error(dctx, DTRACEFLT_ILLOP, 0);
> > +
> > +		return mst->argv[idx];
> >   	case DIF_VAR_STACKDEPTH:
> >   	case DIF_VAR_USTACKDEPTH: {
> >   		uint32_t bufsiz = (uint32_t) (uint64_t) (&STKSIZ);
> > diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
> > index a08fac89..bbddc986 100644
> > --- a/libdtrace/dt_cg.c
> > +++ b/libdtrace/dt_cg.c
> > @@ -2236,6 +2236,7 @@ dt_cg_load_var(dt_node_t *dst, dt_irlist_t *dlp, dt_regset_t *drp)
> >   	emit(dlp, BPF_LOAD(BPF_DW, BPF_REG_1, BPF_REG_FP, DT_STK_DCTX));
> >   	emit(dlp, BPF_MOV_IMM(BPF_REG_2, idp->di_id));
> > +	emit(dlp, BPF_MOV_IMM(BPF_REG_3, 0));
> >   	idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_get_bvar");
> >   	assert(idp != NULL);
> >   	dt_regset_xalloc(drp, BPF_REG_0);
> 
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