On Tue 2015-12-08 12:32:12, Josh Poimboeuf wrote:
> On Mon, Nov 30, 2015 at 11:21:15PM -0500, Jessica Yu wrote:
> > For livepatch modules, copy Elf section, symbol, and string information
> > from the load_info struct in the module loader.
> >
> > Livepatch uses special relocation sections in order to be able to patch
> > modules that are not yet loaded, as well as apply patches to the kernel
> > when the addresses of symbols cannot be determined at compile time (for
> > example, when kaslr is enabled). Livepatch modules must preserve Elf
> > information such as section indices in order to apply the remaining
> > relocation sections at the appropriate time (i.e. when the target module
> > loads).
> >
> > Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
> > ---
> > include/linux/module.h | 9 +++++
> > kernel/module.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++--
> > 2 files changed, 105 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/module.h b/include/linux/module.h
> > index 3a19c79..9b46256 100644
> > --- a/include/linux/module.h
> > +++ b/include/linux/module.h
> > @@ -425,6 +425,14 @@ struct module {
> >
> > /* Notes attributes */
> > struct module_notes_attrs *notes_attrs;
> > +
> > + /* Elf information (optionally saved) */
> > + Elf_Ehdr *hdr;
>
> I would rename "hdr" to "elf_hdr" to make its purpose clearer.
>
> > + Elf_Shdr *sechdrs;
> > + char *secstrings;
>
> Probably a good idea to add underscores to the names ("sec_hdrs" and
> "sec_strings") to be consistent with most of the other fields in the
> struct.
We should keep the names in sync with struct load_info.
> > + struct {
> > + unsigned int sym, str, mod, vers, info, pcpu;
> > + } index;
>
> I might be contradicting myself from what I said before. But I'm
> thinking we should put all these fields inside a CONFIG_LIVEPATCH ifdef.
> Then below, there could be two versions of copy_module_elf(), the real
> one for LIVEPATCH and and an empty one for !LIVEPATCH. And the same
> story for free_module_elf().
Yes, I would hide these fields for !LIVEPATCH.
Best Regards,
Petr
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