[DTrace-devel] [PATCH] Record clause id in mstate
Eugene Loh
eugene.loh at oracle.com
Tue Jan 19 17:18:02 PST 2021
From: dtrace-devel-bounces at oss.oracle.com <dtrace-devel-bounces at oss.oracle.com> on behalf of Kris Van Hees <kris.van.hees at oracle.com>
Sent: Saturday, January 16, 2021 12:21 AM
To: dtrace-devel at oss.oracle.com <dtrace-devel at oss.oracle.com>
Subject: [DTrace-devel] [PATCH] Record clause id in mstate
Support for the ERROR probe requires a per-probe unique id to identify
the clause the ERROR probe was triggered from. Add a clid member to
the machine state, and initialize it in the prologue.
diff --git a/libdtrace/dt_bpf.h b/libdtrace/dt_bpf.h
@@ -20,7 +20,8 @@ extern "C" {
#define DT_CONST_EPID 1
#define DT_CONST_ARGC 2
-#define DT_CONST_PRID 3
+#define DT_CONST_CLID 3
+#define DT_CONST_PRID 4
I'm curious what dictates the ordering here? Why insert rather than append? Why not a more consistent ordering of these things -- e.g., here, dt_dlibs.c, in MST, etc. Even the DT_IDENT_SCALAR case in dt_link_construct(). Not a big deal, but uniformity would seem nice.
diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
@@ -2324,7 +2324,8 @@ dt_link_layout(dtrace_hdl_t *dtp, const dtrace_difo_t *dp, uint_t *pcp,
static int
dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
const dtrace_difo_t *sdp, dt_strtab_t *stab,
- uint_t *pcp, uint_t *rcp, uint_t *vcp, dtrace_epid_t epid)
+ uint_t *pcp, uint_t *rcp, uint_t *vcp, dtrace_epid_t epid,
+ uint_t clid)
{
uint_t pc = *pcp;
uint_t rc = *rcp;
@@ -2412,6 +2413,9 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
case DT_CONST_PRID:
nrp->dofr_data = prp->desc->id;
break;
+ case DT_CONST_CLID:
+ nrp->dofr_data = clid;
+ break;
case DT_CONST_ARGC:
nrp->dofr_data = 0; /* FIXME */
break;
@@ -2427,13 +2431,14 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
rdp = dt_dlib_get_func_difo(dtp, idp);
if (rdp == NULL)
return -1;
- if (rdp->dtdo_ddesc != NULL)
+ if (rdp->dtdo_ddesc != NULL) {
nepid = dt_epid_add(dtp, rdp->dtdo_ddesc,
prp->desc->id);
- else
+ clid++;
+ } else
nepid = 0;
ipc = dt_link_construct(dtp, prp, dp, rdp, stab,
- pcp, rcp, vcp, nepid);
+ pcp, rcp, vcp, nepid, clid);
if (ipc == -1)
return -1;
@@ -2543,7 +2548,8 @@ dt_link(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp)
if (stab == NULL)
goto nomem;
- rc = dt_link_construct(dtp, prp, fdp, dp, stab, &insc, &relc, &varc, 0);
+ rc = dt_link_construct(dtp, prp, fdp, dp, stab, &insc, &relc, &varc,
+ 0, 0);
dt_dlib_reset(dtp, B_FALSE);
if (rc == -1)
goto fail;
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
@@ -263,6 +263,7 @@ dt_cg_prologue(dt_pcb_t *pcb, dt_node_t *pred)
dt_irlist_t *dlp = &pcb->pcb_ir;
dt_ident_t *epid = dt_dlib_get_var(pcb->pcb_hdl, "EPID");
dt_ident_t *prid = dt_dlib_get_var(pcb->pcb_hdl, "PRID");
+ dt_ident_t *clid = dt_dlib_get_var(pcb->pcb_hdl, "CLID");
assert(epid != NULL);
assert(prid != NULL);
I cannot tell: should there now be a "+ assert(clid)"?
@@ -292,6 +293,7 @@ dt_cg_prologue(dt_pcb_t *pcb, dt_node_t *pred)
* dctx->mst->tstamp = 0; // stdw [%r0 + DMST_TSTAMP], 0
* dctx->mst->epid = EPID; // stw [%r0 + DMST_EPID], EPID
* dctx->mst->prid = PRID; // stw [%r0 + DMST_PRID], PRID
+ * dctx->mst->prid = CLID; // stw [%r0 + DMST_CLID], CLID
dctx->mst->clid? Or, just skip these comments altogether since they are no more readable than the actual code (and clearly the comments and code get out of sync).
* *((uint32_t *)&buf[0]) = EPID;
* // stw [%r9 + 0], EPID
*/
@@ -300,6 +302,7 @@ dt_cg_prologue(dt_pcb_t *pcb, dt_node_t *pred)
emit(dlp, BPF_STORE_IMM(BPF_DW, BPF_REG_0, DMST_TSTAMP, 0));
emite(dlp, BPF_STORE_IMM(BPF_W, BPF_REG_0, DMST_EPID, -1), epid);
emite(dlp, BPF_STORE_IMM(BPF_W, BPF_REG_0, DMST_PRID, -1), prid);
+ emite(dlp, BPF_STORE_IMM(BPF_W, BPF_REG_0, DMST_CLID, -1), clid);
emite(dlp, BPF_STORE_IMM(BPF_W, BPF_REG_9, 0, -1), epid);
/*
diff --git a/libdtrace/dt_dctx.h b/libdtrace/dt_dctx.h
@@ -20,6 +20,7 @@
typedef struct dt_mstate {
uint32_t epid; /* Enabled probe ID */
uint32_t prid; /* Probe ID */
+ uint32_t clid; /* Clause ID (unique per probe) */
uint32_t tag; /* Tag (for future use) */
uint64_t fault; /* DTrace fault flags */
uint64_t tstamp; /* cached timestamp value */
@@ -55,6 +56,7 @@ typedef struct dt_dctx {
#define DMST_EPID offsetof(dt_mstate_t, epid)
#define DMST_PRID offsetof(dt_mstate_t, prid)
+#define DMST_CLID offsetof(dt_mstate_t, clid)
#define DMST_TAG offsetof(dt_mstate_t, tag)
#define DMST_FAULT offsetof(dt_mstate_t, fault)
#define DMST_TSTAMP offsetof(dt_mstate_t, tstamp)
diff --git a/libdtrace/dt_dlibs.c b/libdtrace/dt_dlibs.c
@@ -74,6 +74,7 @@ static const dt_ident_t dt_bpf_symbols[] = {
/* BPF internal identifiers */
DT_BPF_SYMBOL_ID(EPID, DT_IDENT_SCALAR, DT_CONST_EPID),
DT_BPF_SYMBOL_ID(PRID, DT_IDENT_SCALAR, DT_CONST_PRID),
+ DT_BPF_SYMBOL_ID(CLID, DT_IDENT_SCALAR, DT_CONST_CLID),
DT_BPF_SYMBOL_ID(ARGC, DT_IDENT_SCALAR, DT_CONST_ARGC),
/* End-of-list marker */
{ NULL, }
I don't really follow the code but:
Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
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