From: Masami Hiramatsu <mhiramat@redhat.com>
To: wenji.huang@oracle.com
Cc: SystemTAP <systemtap@sources.redhat.com>
Subject: Re: [PATCH 3/3] PR4886: Check build-id in module_init function if able.
Date: Wed, 01 Oct 2008 21:41:00 -0000 [thread overview]
Message-ID: <48E3EDDC.8000000@redhat.com> (raw)
In-Reply-To: <48DEEA31.9010004@oracle.com>
Hi Wenji,
I'm not sure when the build-id is updated, but interested in your
enhancement. :-)
If I'm using an out-of-tree driver, is build-id updated when I updated
the driver's source code but didn't change running kernel?
In other words, would each driver have its build-id which is different
from other drivers and kernel?
Thank you,
Wenji Huang wrote:
> There are several cases to be considered, whether build-id exists in
> debuginfo file or not, whether module is loaded or not and whether
> build-id exists in loaded module/kernel or not.
> ---
> runtime/sym.c | 66
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> translate.cxx | 1 +
> 2 files changed, 67 insertions(+), 0 deletions(-)
>
> diff --git a/runtime/sym.c b/runtime/sym.c
> index 1a9e26b..38323c9 100644
> --- a/runtime/sym.c
> +++ b/runtime/sym.c
> @@ -160,6 +160,72 @@ static const char *_stp_kallsyms_lookup(unsigned
> long addr, unsigned long *symbo
> return NULL;
> }
>
> +/* Validate module/kernel based on build-id if there
> +* The completed case is the following combination:
> +* Debuginfo Module Kernel
> +* X X
> +* has build-id/not unloaded has
> build-id/not
> +* loaded && (has build-id/not)
> +*
> +* NB: build-id exists only if ld>=2.18 and kernel>= 2.6.23
> +*/
> +static int _stp_module_check(void)
> +{
> + struct _stp_module *m = NULL;
> + unsigned long notes_addr, base_addr;
> + unsigned i;
> +
> + for (i = 0; i < _stp_num_modules; i++)
> + {
> + m = _stp_modules[i];
> +
> + /* unloaded module */
> + if (m->notes_sect == 0) {
> + _stp_warn("skip checking %s\n", m->name);
> + continue;
> + }
> + if (m->build_id_len > 0) { /* build-id in debuginfo file */
> + dbug_sym(1, "validate %s based on build-id\n", m->name);
> +
> + /* loaded module/kernel, but without build-id */
> + if (m->notes_sect == 1) {
> + _stp_error("missing build-id in %s\n", m->name);
> + return 1;
> + }
> + /* notes end address */
> + if (!strcmp(m->name, "kernel")) {
> + notes_addr = m->build_id_offset;
> + base_addr = _stp_module_relocate("kernel",
> + "_stext", 0);
> + } else {
> + notes_addr = m->notes_sect + m->build_id_offset;
> + base_addr = m->notes_sect;
> + }
> + /* notes start address */
> + notes_addr -= m->build_id_len;
> + if (notes_addr > base_addr) {
> + if (memcmp(m->build_id_bits,
> + (unsigned char *) notes_addr,
> + m->build_id_len))
> + {
> + _stp_error("inconsistent build-id in %s with
> debuginfo\n", m->name);
> + return 1;
> + }
> + } else { /* bug, shouldn't come here */
> + _stp_error("unknown failure in checking %s\n",
> + m->name);
> + return 1;
> + } /* end comparing */
> + } else {
> + /* build-id in module/kernel, absent in
> debuginfo */
> + if (m->notes_sect > 1) {
> + _stp_error("unexpected build-id in %s\n",
> m->name);
> + return 1;
> + }
> + } /* end checking */
> + } /* end loop */
> + return 0;
> +}
>
> /** Print an address symbolically.
> * @param address The address to lookup.
> diff --git a/translate.cxx b/translate.cxx
> index a9695f1..0ee5179 100644
> --- a/translate.cxx
> +++ b/translate.cxx
> @@ -1113,6 +1113,7 @@ c_unparser::emit_module_init ()
> o->newline(-1) << "}";
>
> // XXX: perform buildid-based checking if able
> + o->newline() << "if (_stp_module_check()) rc = -EINVAL;";
>
> o->newline(-1) << "}";
> o->newline() << "if (rc) goto out;";
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2008-10-01 21:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-28 2:26 Wenji Huang
2008-09-28 13:38 ` Frank Ch. Eigler
2008-09-30 16:29 ` Elena Zannoni
2008-10-01 21:41 ` Masami Hiramatsu [this message]
2008-10-01 21:44 ` Roland McGrath
2008-10-01 21:45 ` Frank Ch. Eigler
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