[DTrace-devel] [PATCH v2 02/08] The exit() action must set the activity state to DRAINING

[Kris Van Hees]

Now that activity state is supported, the exit() action needs to move
the activity state to DRAINING to prevent further probe firings from
being processed.

The recording of the exit code is now done using the dt_cg_store_val()
function since that is the preferred manner of storing values into the
output buffer.

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_cg.c | 54 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 44 insertions(+), 10 deletions(-)

diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index e94a605f..14e11f06 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -676,7 +676,9 @@ dt_cg_act_discard(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind)
 }
 
 /*
- * Signal that tracing should be terminated with the given return code.
+ * Signal that tracing should be terminated with the given return code.  This
+ * action also forces the activity state to be set to DRAINING to signal that
+ * tracing is ending.
  *
  * Stores:
  *	integer (4 bytes)		-- return code
@@ -684,19 +686,51 @@ dt_cg_act_discard(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind)
 static void
 dt_cg_act_exit(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind)
 {
-	struct bpf_insn	instr;
 	dt_irlist_t	*dlp = &pcb->pcb_ir;
-	uint_t		off;
-
-	dt_cg_node(dnp->dn_args, &pcb->pcb_ir, pcb->pcb_regs);
+	dt_ident_t	*state = dt_dlib_get_map(pcb->pcb_hdl, "state");
+	struct bpf_insn	instr;
 
-	off = dt_rec_add(pcb->pcb_hdl, dt_cg_fill_gap, DTRACEACT_EXIT,
-			 sizeof(uint32_t), sizeof(uint32_t), NULL,
-			 DT_ACT_EXIT);
+	/* Record the exit code. */
+	dt_cg_store_val(pcb, dnp->dn_args, DTRACEACT_EXIT, NULL, DT_ACT_EXIT);
 
-	instr = BPF_STORE(BPF_W, BPF_REG_9, off, dnp->dn_args->dn_reg);
+	/*
+	 * Force the activity state to DRAINING.
+	 *
+	 *	key = DT_STATE_ACTIVITY;// stw [%fp + DT_STK_SPILL(0)],
+	 *				//		DT_STATE_ACTIVITY
+	 *	val = DT_ACTIVITY_DRAINING;
+	 *				// stw [%fp + DT_STK_SPILL(1)],
+	 *				//		DT_ACTIVITY_DRAINING
+	 *	rc = bpf_map_update_elem(&state, &key, &val, BPF_ANY);
+	 *				// lddw %r1, &state
+	 *				// mov %r2, %fp
+	 *				// add %r2, DT_STK_SPILL(0)
+	 *				// mov %r3, %fp
+	 *				// add %r3, DT_STK_SPILL(1)
+	 *				// mov %r4, BPF_ANY
+	 *				// call bpf_map_update_elem
+	 *				//     (%r1 ... %r5 clobbered)
+	 *				//     (%r0 = map value)
+	 */
+	instr = BPF_STORE_IMM(BPF_W, BPF_REG_FP, DT_STK_SPILL(0),
+			      DT_STATE_ACTIVITY);
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	instr = BPF_STORE_IMM(BPF_W, BPF_REG_FP, DT_STK_SPILL(1),
+			      DT_ACTIVITY_DRAINING);
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	dt_cg_xsetx(dlp, state, DT_LBL_NONE, BPF_REG_1, state->di_id);
+	instr = BPF_MOV_REG(BPF_REG_2, BPF_REG_FP);
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	instr = BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, DT_STK_SPILL(0));
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	instr = BPF_MOV_REG(BPF_REG_3, BPF_REG_FP);
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	instr = BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, DT_STK_SPILL(1));
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	instr = BPF_MOV_IMM(BPF_REG_4, BPF_ANY);
+	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
+	instr = BPF_CALL_HELPER(BPF_FUNC_map_update_elem);
 	dt_irlist_append(dlp, dt_cg_node_alloc(DT_LBL_NONE, instr));
-	dt_regset_free(pcb->pcb_regs, dnp->dn_args->dn_reg);
 }
 
 static void
-- 
2.28.0