Date: Sun, 3 Nov 2013 18:59:36 -0500 From: Mark Johnston <markj@freebsd.org> To: John Luk <john.37@gmail.com> Cc: freebsd-dtrace@freebsd.org Subject: Re: dtrace showed matched probes but nothing in output on FreeBSD 9.1-RELEASE Message-ID: <20131103235936.GB15661@raichu> In-Reply-To: <CAHkCX6j1H4cxeb255gdH_cLop5Lv0xJABbuma%2B835gNNq-Nshg@mail.gmail.com> References: <CAHkCX6j1H4cxeb255gdH_cLop5Lv0xJABbuma%2B835gNNq-Nshg@mail.gmail.com>
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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@home:/home/spin6lock/test # dtrace -V > dtrace: Sun D 1.7 > root@home:/home/spin6lock/test # uname -a > FreeBSD 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Mon Oct 28 20:52:03 CST > 2013 root@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;
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