Provide and use standard functions to clear or copy CPU registers

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com> Reviewed-by: Eugene Loh <eugene.loh@oracle.com>
oracle · Jul 6, 2021 · 2cea90a · 2cea90a
1 parent 351d461
commit 2cea90a
Show file tree

Hide file tree

Showing 9 changed files with 54 additions and 77 deletions.
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
@@ -196,6 +196,50 @@ dt_cg_tramp_prologue(dt_pcb_t *pcb)
 	dt_cg_tramp_prologue_act(pcb, DT_ACTIVITY_ACTIVE);
 }
 
+/*
+ * Clear the content of the 'regs' member of the machine state.
+ *
+ * The caller must ensure that %r7 contains the value set by the
+ * dt_cg_tramp_prologue*() functions.
+ */
+void
+dt_cg_tramp_clear_regs(dt_pcb_t *pcb)
+{
+	dt_irlist_t	*dlp = &pcb->pcb_ir;
+	int		i;
+
+	/*
+	 *	memset(&dctx->mst->regs, 0, sizeof(dt_pt_regs);
+	 *				// stdw [%7 + DMST_REGS + 0 * 8], 0
+	 *				// stdw [%7 + DMST_REGS + 1 * 8], 0
+	 *				//     (...)
+	 */
+	for (i = 0; i < sizeof(dt_pt_regs); i += 8)
+		emit(dlp, BPF_STORE_IMM(BPF_DW, BPF_REG_7, DMST_REGS + i, 0));
+}
+
+/*
+ * Copy the content of a dt_pt_regs structure referenced by the 'rp' argument
+ * into the 'regs' member of the machine state.
+ *
+ * The caller must ensure that %r7 contains the value set by the
+ * dt_cg_tramp_prologue*() functions.
+ */
+void
+dt_cg_tramp_copy_regs(dt_pcb_t *pcb, int rp)
+{
+	dt_irlist_t	*dlp = &pcb->pcb_ir;
+	int		i;
+
+	/*
+	 *	dctx->mst->regs = *(dt_pt_regs *)rp;
+	 */
+	for (i = 0; i < sizeof(dt_pt_regs); i += 8) {
+		emit(dlp, BPF_LOAD(BPF_DW, BPF_REG_0, BPF_REG_8, i));
+		emit(dlp, BPF_STORE(BPF_DW, BPF_REG_7, DMST_REGS + i, BPF_REG_0));
+	}
+}
+
 /*
  * Copy arguments from a dt_pt_regs structure referenced by the 'rp' argument.
  *

diff --git a/libdtrace/dt_cg.h b/libdtrace/dt_cg.h
@@ -22,6 +22,8 @@ extern void dt_cg_xsetx(dt_irlist_t *, dt_ident_t *, uint_t, int, uint64_t);
 extern dt_irnode_t *dt_cg_node_alloc(uint_t, struct bpf_insn);
 extern void dt_cg_tramp_prologue_act(dt_pcb_t *pcb, dt_activity_t act);
 extern void dt_cg_tramp_prologue(dt_pcb_t *pcb);
+extern void dt_cg_tramp_clear_regs(dt_pcb_t *pcb);
+extern void dt_cg_tramp_copy_regs(dt_pcb_t *pcb, int rp);
 extern void dt_cg_tramp_copy_args_from_regs(dt_pcb_t *pcb, int rp);
 extern void dt_cg_tramp_call_clauses(dt_pcb_t *pcb, const dt_probe_t *prp,
 				     dt_activity_t act);

diff --git a/libdtrace/dt_dctx.h b/libdtrace/dt_dctx.h
@@ -25,9 +25,7 @@ typedef struct dt_mstate {
 	int32_t		syscall_errno;	/* syscall errno */
 	uint64_t	fault;		/* DTrace fault flags */
 	uint64_t	tstamp;		/* cached timestamp value */
-#if 0
 	dt_pt_regs	regs;		/* CPU registers */
-#endif
 	uint64_t	argv[10];	/* Probe arguments */
 } dt_mstate_t;
 

diff --git a/libdtrace/dt_prov_dtrace.c b/libdtrace/dt_prov_dtrace.c
@@ -155,21 +155,7 @@ static void trampoline(dt_pcb_t *pcb)
 	emit(dlp, BPF_MOV_IMM(BPF_REG_4, BPF_ANY));
 	emit(dlp, BPF_CALL_HELPER(BPF_FUNC_map_update_elem));
 
-#if 0
-	/*
-	 *     dctx->mst->regs = *(dt_pt_regs *)dctx->ctx;
-	 *				// lddw %r0, [%r8 + 0]
-	 *				// stdw [%r7 + DMST_REGS + 0], %r0
-	 *				// lddw %r0, [%r8 + 8]
-	 *				// stdw [%r7 + DMST_REGS + 8], %r0
-	 *				//     (...)
-	 */
-	for (i = 0; i < sizeof(dt_pt_regs); i += 8) {
-		emit(dlp, BPF_LOAD(BPF_DW, BPF_REG_0, BPF_REG_8, i));
-		emit(dlp, BPF_STORE(BPF_DW, BPF_REG_7, DMST_REGS + i, BPF_REG_0));
-	}
-#endif
-
+	dt_cg_tramp_copy_regs(pcb, BPF_REG_8);
 	dt_cg_tramp_copy_args_from_regs(pcb, BPF_REG_8);
 
 	dt_cg_tramp_epilogue_advance(pcb, act);

diff --git a/libdtrace/dt_prov_fbt.c b/libdtrace/dt_prov_fbt.c
@@ -168,16 +168,7 @@ static void trampoline(dt_pcb_t *pcb)
 	 *				//     (%r8 = dctx->ctx)
 	 */
 
-#if 0
-	/*
-	 *	dctx->mst->regs = *(dt_pt_regs *)dctx->ctx;
-	 */
-	for (i = 0; i < sizeof(dt_pt_regs); i += 8) {
-		emit(dlp, BPF_LOAD(BPF_DW, BPF_REG_0, BPF_REG_8, i));
-		emit(dlp, BPF_STORE(BPF_DW, BPF_REG_7, DMST_REGS + i, BPF_REG_0));
-	}
-#endif
-
+	dt_cg_tramp_copy_regs(pcb, BPF_REG_8);
 	dt_cg_tramp_copy_args_from_regs(pcb, BPF_REG_8);
 	dt_cg_tramp_epilogue(pcb);
 }

diff --git a/libdtrace/dt_prov_pid.c b/libdtrace/dt_prov_pid.c
@@ -210,21 +210,7 @@ static void trampoline(dt_pcb_t *pcb)
 	 *				//     (%r8 = dctx->ctx)
 	 */
 
-#if 0
-	/*
-	 *     dctx->mst->regs = *(dt_pt_regs *)dctx->ctx;
-	 *				// lddw %r0, [%r8 + 0]
-	 *				// stdw [%r7 + DMST_REGS + 0], %r0
-	 *				// lddw %r0, [%r8 + 8]
-	 *				// stdw [%r7 + DMST_REGS + 8], %r0
-	 *				//     (...)
-	 */
-	for (i = 0; i < sizeof(dt_pt_regs); i += 8) {
-		emit(dlp, BPF_LOAD(BPF_DW, BPF_REG_0, BPF_REG_8, i));
-		emit(dlp, BPF_STORE(BPF_DW, BPF_REG_7, DMST_REGS + i, BPF_REG_0));
-	}
-#endif
-
+	dt_cg_tramp_copy_regs(pcb, BPF_REG_8);
 	dt_cg_tramp_copy_args_from_regs(pcb, BPF_REG_8);
 
 	/*

diff --git a/libdtrace/dt_prov_profile.c b/libdtrace/dt_prov_profile.c
@@ -226,18 +226,7 @@ static void trampoline(dt_pcb_t *pcb)
 	 *				//     (%r8 = dctx->ctx)
 	 */
 
-#if 0
-	/*
-	 *     dctx->mst->regs = *(dt_pt_regs *)&dctx->ctx->regs;
-	 *                              // (we use the fact that regs is the
-	 *                              //  member at offset 0, and there can
-	 *                              //  copy *(dt_pt_regs *)dctx->ctx)
-	 */
-	for (i = 0; i < sizeof(dt_pt_regs); i += 8) {
-		emit(dlp, BPF_LOAD(BPF_DW, BPF_REG_0, BPF_REG_8, i));
-		emit(dlp, BPF_STORE(BPF_DW, BPF_REG_7, DMST_REGS + i, BPF_REG_0));
-	}
-#endif
+	dt_cg_tramp_copy_regs(pcb, BPF_REG_8);
 
 	/*
 	 * TODO:

diff --git a/libdtrace/dt_prov_sdt.c b/libdtrace/dt_prov_sdt.c
@@ -121,7 +121,7 @@ static int populate(dtrace_hdl_t *dtp)
  * The trampoline function is called when a SDT probe triggers, and it must
  * satisfy the following prototype:
  *
- *	int dt_sdt(struct syscall_data *scd)
+ *	int dt_sdt(void *data)
  *
  * The trampoline will populate a dt_dctx_t struct and then call the function
  * that implements the compiled D clause.  It returns the value that it gets
@@ -142,17 +142,7 @@ static void trampoline(dt_pcb_t *pcb)
 	 *				//     (%r8 = dctx->ctx)
 	 */
 
-#if 0
-	/*
-	 *	memset(&dctx->mst->regs, 0, sizeof(dt_pt_regs);
-	 *				// stdw [%7 + DMST_REGS + 0], 0
-	 *				// stdw [%7 + DMST_REGS + 8], 0
-	 *				//     (...)
-	 */
-	for (i = 0; i < sizeof(dt_pt_regs); i += 8) {
-		emit(dlp, BPF_STORE_IMM(BPF_DW, BPF_REG_7, DMST_REGS + i, 0));
-	}
-#endif
+	dt_cg_tramp_clear_regs(pcb);
 
 	/*
 	 *	for (i = 0; i < ARRAY_SIZE(((dt_mstate_t *)0)->argv); i++)
@@ -175,7 +165,7 @@ static int probe_info(dtrace_hdl_t *dtp, const dt_probe_t *prp,
 
 	/*
 	 * If the tracepoint has already been created and we have its info,
-	 * there is no need to retrive the info again.
+	 * there is no need to retrieve the info again.
 	 */
 	if (dt_tp_is_created(tpp))
 		return -1;

diff --git a/libdtrace/dt_prov_syscall.c b/libdtrace/dt_prov_syscall.c
@@ -156,16 +156,7 @@ static void trampoline(dt_pcb_t *pcb)
 	 *				//     (%r8 = dctx->ctx)
 	 */
 
-#if 0
-	/*
-	 *	memset(&dctx->mst->regs, 0, sizeof(dt_pt_regs);
-	 *				// stdw [%7 + DMST_REGS + 0], 0
-	 *				// stdw [%7 + DMST_REGS + 8], 0
-	 *				//     (...)
-	 */
-	for (i = 0; i < sizeof(dt_pt_regs); i += 8)
-		emit(dlp, BPF_STORE_IMM(BPF_DW, BPF_REG_7, DMST_REGS + i, 0));
-#endif
+	dt_cg_tramp_clear_regs(pcb);
 
 	/*
 	 *	for (i = 0; i < argc; i++)