Re: [PATCH modules 1/2] module: allow arch overrides for .exit section names

[Matthias Schiffer]

On Thu, 2019-06-06 at 17:09 +0200, Jessica Yu wrote:
> +++ Matthias Schiffer [03/06/19 12:57 +0200]:
> > Some archs like ARM store unwind information for .exit.text in
> > sections
> > with unusual names. As this unwind information refers to
> > .exit.text, it
> > must not be loaded when .exit.text is not loaded (when
> > CONFIG_MODULE_UNLOAD
> > is unset); otherwise, loading a module can fail due to relocation
> > failures.
> > 
> > Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx
> > >
> > ---
> > include/linux/moduleloader.h | 8 ++++++++
> > kernel/module.c              | 2 +-
> > 2 files changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/moduleloader.h
> > b/include/linux/moduleloader.h
> > index 31013c2effd3..cddbd85fb659 100644
> > --- a/include/linux/moduleloader.h
> > +++ b/include/linux/moduleloader.h
> > @@ -5,6 +5,7 @@
> > 
> > #include <linux/module.h>
> > #include <linux/elf.h>
> > +#include <linux/string.h>
> > 
> > /* These may be implemented by architectures that need to hook into
> > the
> >  * module loader code.  Architectures that don't need to do
> > anything special
> > @@ -93,4 +94,11 @@ void module_arch_freeing_init(struct module
> > *mod);
> > #define MODULE_ALIGN PAGE_SIZE
> > #endif
> > 
> > +#ifndef HAVE_ARCH_MODULE_EXIT_SECTION
> > +static inline bool module_exit_section(const char *name)
> > +{
> > +	return strstarts(name, ".exit");
> > +}
> > +#endif
> > +
> 
> Hi Matthias,
> 
> For sake of consistency, could we implement this as an arch-
> overridable
> __weak symbol like the rest of the module arch-overrides in
> moduleloader.h?

Fine with me - making such a tiny function inlineable just seemed more
appropriate to me. I can send a v2 tomorrow.


> 
> > #endif
> > diff --git a/kernel/module.c b/kernel/module.c
> > index 6e6712b3aaf5..e8e4cd0a471f 100644
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
> > @@ -2924,7 +2924,7 @@ static int rewrite_section_headers(struct
> > load_info *info, int flags)
> > 
> > #ifndef CONFIG_MODULE_UNLOAD
> > 		/* Don't load .exit sections */
> > -		if (strstarts(info->secstrings+shdr->sh_name, ".exit"))
> > +		if (module_exit_section(info->secstrings+shdr-
> > >sh_name))
> > 			shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
> > #endif
> > 	}
> > -- 
> > 2.17.1
> >