dtrace showed matched probes but nothing in output on FreeBSD 9.1-RELEASE

[John Luk]

Thanks, Mark. But I still got nothing :(
The line number of your patch wasn't match with mine, I patched it
on hand. Was it because I was on an older version of src? The head
of proc_sym.c shows:

 $FreeBSD: release/9.1.0/lib/libproc/proc_sym.c 211184 2010-08-11
17:33:26Z rpaulo

And the patch of mine is include below, is it correct?

Cheers,
spin6lock

diff --git a/proc_sym.c b/proc_sym.c
index baa7f98..1969d7e 100644
--- a/proc_sym.c
+++ b/proc_sym.c
@@ -439,7 +439,9 @@ proc_name2sym(struct proc_handle *p, const char
*object, const char *symbol,
                s = elf_strptr(e, dynsymstridx, sym.st_name);
                if (s && strcmp(s, symbol) == 0) {
                        memcpy(symcopy, &sym, sizeof(sym));
-                       symcopy->st_value = map->pr_vaddr + sym.st_value;
+                       if (ehdr.e_type != ET_EXEC)
+                       symcopy->st_value = map->pr_vaddr +
+                               sym.st_value;
                        error = 0;
                        goto out;
                }
@@ -484,6 +486,7 @@ proc_iter_symbyaddr(struct proc_handle *p, const
char *object, int which,
        prmap_t *map;
        Elf_Scn *scn, *foundscn = NULL;
        Elf_Data *data;
+       GElf_Ehdr ehdr;
        GElf_Shdr shdr;
        GElf_Sym sym;
        unsigned long stridx = -1;
@@ -500,6 +503,10 @@ proc_iter_symbyaddr(struct proc_handle *p, const
char *object, int which,
                warn("ERROR: elf_begin() failed");
                goto err1;
        }
+       if (gelf_getehdr(e, &ehdr) == NULL) {
+               warn("ERROR: gelf_getehdr() failed");
+               goto err2;
+       }
        /*
         * Find the section we are looking for.
         */
@@ -551,6 +558,9 @@ proc_iter_symbyaddr(struct proc_handle *p, const
char *object, int which,
                        continue;
                s = elf_strptr(e, stridx, sym.st_name);
                sym.st_value += map->pr_vaddr;
+               if (ehdr.e_type != ET_EXEC)
+                       sym.st_value += map->pr_vaddr;
+               sym.st_value += map->pr_vaddr;
                (*func)(cd, &sym, s);
        }
        error = 0;

2013/11/4 Mark Johnston <markj at freebsd.org>:
> On Sat, Nov 02, 2013 at 11:56:49AM +0800, John Luk wrote:
>> Hi all,
>> I'm a newbie in dtrace, and I following this tutorial from Oracle:
>> http://docs.oracle.com/cd/E19205-01/820-4221/ to learn dtrace. In the
>> example of test.c and ufunc.d, I expected output like this:
>>
>>  % dtrace -s ufunc.d -c ./a.out a.out
>>
>>     dtrace: script 'ufunc.d' matched 5 probes
>>     dtrace: pid 27210 has exited
>>
>>     inet_makeaddr            1
>>     foo1                     1
>>     foo                      1
>>     main                     1
>>     __fsr                    1
>>
>>
>> But I got this instead:
>>
>> # dtrace -s ufunc.d  -c ./a.out a.out
>> dtrace: script 'ufunc.d' matched 5 probes
>> dtrace: pid 86498 has exited
>>
>> #
>>
>> My system info:
>> root at home:/home/spin6lock/test # dtrace -V
>> dtrace: Sun D 1.7
>> root at home:/home/spin6lock/test # uname -a
>> FreeBSD 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Mon Oct 28 20:52:03 CST
>> 2013     root at xiangling:/usr/obj/usr/src/sys/DTRACE  amd64
>>
>> Any clues? Thanks in advanced.
>
> This seems to be the result of a bug in libproc. I've included a patch
> below; could you apply it and verify that it fixes the problem? Once
> you've applied the patch, libproc can be rebuilt with
>
> # cd $SRCBASE/lib/libproc
> # make && make install
>
> Thanks,
> -Mark
>
> diff --git a/lib/libproc/proc_sym.c b/lib/libproc/proc_sym.c
> index 87ac471..73e9742 100644
> --- a/lib/libproc/proc_sym.c
> +++ b/lib/libproc/proc_sym.c
> @@ -465,7 +465,9 @@ proc_name2sym(struct proc_handle *p, const char *object, const char *symbol,
>                         s = elf_strptr(e, dynsymstridx, sym.st_name);
>                         if (s && strcmp(s, symbol) == 0) {
>                                 memcpy(symcopy, &sym, sizeof(sym));
> -                               symcopy->st_value = map->pr_vaddr + sym.st_value;
> +                               if (ehdr.e_type != ET_EXEC)
> +                                       symcopy->st_value = map->pr_vaddr +
> +                                           sym.st_value;
>                                 error = 0;
>                                 goto out;
>                         }
> @@ -509,6 +511,7 @@ proc_iter_symbyaddr(struct proc_handle *p, const char *object, int which,
>         prmap_t *map;
>         Elf_Scn *scn, *foundscn = NULL;
>         Elf_Data *data;
> +       GElf_Ehdr ehdr;
>         GElf_Shdr shdr;
>         GElf_Sym sym;
>         unsigned long stridx = -1;
> @@ -525,6 +528,10 @@ proc_iter_symbyaddr(struct proc_handle *p, const char *object, int which,
>                 DPRINTFX("ERROR: elf_begin() failed: %s", elf_errmsg(-1));
>                 goto err1;
>         }
> +       if (gelf_getehdr(e, &ehdr) == NULL) {
> +               DPRINTFX("ERROR: gelf_getehdr() failed: %s", elf_errmsg(-1));
> +               goto err2;
> +       }
>         /*
>          * Find the section we are looking for.
>          */
> @@ -575,7 +582,8 @@ proc_iter_symbyaddr(struct proc_handle *p, const char *object, int which,
>                     (mask & TYPE_FILE) == 0)
>                         continue;
>                 s = elf_strptr(e, stridx, sym.st_name);
> -               sym.st_value += map->pr_vaddr;
> +               if (ehdr.e_type != ET_EXEC)
> +                       sym.st_value += map->pr_vaddr;
>                 (*func)(cd, &sym, s);
>         }
>         error = 0;