Re: binary in dtrace output

[RVP <rvp%SDF.ORG@localhost>]

On Fri, 8 Dec 2023, Patrick Welche wrote:

> When profiling my simulation with
>
> dtrace -x ustackframes=100 -n 'profile-9 / execname == "mds" / { @[ustack()] = count(); } tick-180s { exit(0); }' -o /tmp/out.stacks
>
> every function name is preceded by c0 df ff ff 7f 7f e.g.,
>
> 00000060  20 20 20 20 20 20 20 20  20 c0 df ff ff 7f 7f 60  |         ......`|
> 00000070  66 5f 70 61 69 72 5f 44  4c 56 4f 28 61 74 6f 6d  |f_pair_DLVO(atom|
>
> which is making perl, i.e., FlameGraph unhappy.
>
> 6 bytes seems a strange number.
>
> Is this normal / any hints on what I can do about it?

This looks like junk on the stack:

src/external/cddl/osnet/dist/lib/libdtrace/common/dt_consume.c:dt_print_ustack()
doesn't initialize `objname' and doesn't check the return of proc_objname()
(line 1385) either.

Can you try this patch (fudged from FreeBSD)?

```
diff -urN a/src/external/bsd/libproc/dist/proc_sym.c b/src/external/bsd/libproc/dist/proc_sym.c
--- a/src/external/bsd/libproc/dist/proc_sym.c	2017-06-16 00:44:58.000000000 +0100
+++ b/src/external/bsd/libproc/dist/proc_sym.c	2023-12-27 00:05:55.133763583 +0000
@@ -141,6 +141,10 @@
 	size_t i;
 	rd_loadobj_t *rdl;

+	if (p->nobjs == 0)
+		if (proc_rdagent(p) == NULL)
+			return (NULL);
+
 	for (i = 0; i < p->nobjs; i++) {
 		rdl = &p->rdobjs[i];
 		if (addr >= rdl->rdl_saddr && addr < rdl->rdl_eaddr) {
```

-RVP