On Fri, Aug 26, 2016 at 01:58:03PM +1000, Nicholas Piggin wrote:
> On Mon, 22 Aug 2016 20:47:58 +1000
> Nicholas Piggin <npiggin@xxxxxxxxx> wrote:
>
> > On Fri, 19 Aug 2016 20:44:55 +1000
> > Nicholas Piggin <npiggin@xxxxxxxxx> wrote:
> >
> > > On Fri, 19 Aug 2016 10:37:00 +0200
> > > Michal Marek <mmarek@xxxxxxx> wrote:
> > >
> > > > On 2016-08-19 07:09, Stephen Rothwell wrote:
> >
> > [snip]
> >
> > > > >
> > > > > I may be missing something, but genksyms generates the crc's off the
> > > > > preprocessed C source code and we don't have any for the asm files ...
> > > >
> > > > Of course you are right. Which means that we are losing type information
> > > > for these exports for CONFIG_MODVERSIONS purposes. I guess it's
> > > > acceptable, since the asm functions are pretty basic and their
> > > > signatures do not change.
> > >
> > > I don't completely agree. It would be nice to have the functionality
> > > still there.
> > >
> > > What happens if you just run cmd_modversions on the as rule? It relies on
> > > !defined(__ASSEMBLY__), but we're feeding the result to genksyms, not as.
> > > It would require the header be included in the .S file and be protected for
> > > asm builds.
> >
> >
> > This seems like it *could* be made to work, but there's a few problems.
> >
> > - .h files are not made for C consumption. Matter of manually adding the
> > ifdef guards, which isn't terrible.
> >
> > - .S files do not all include their .h where the C declaration is. Also
> > will cause some churn but doable and maybe not completely unreasonable.
> >
> > - genksyms parser barfs when it hits the assembly of the .S file. Best
> > way to fix that seems just send the #include and EXPORT_SYMBOL lines
> > from the .S to the preprocessor. That's a bit of a rabbit hole too, with
> > some .S files being included, etc.
> >
> > I'm not sure what to do here. If nobody cares and we lose CRCs for .S
> > exports, then okay we can whitelist those relocs easily. If we don't want
> > to lose the functionality, the above might work but it's a bit intrusive
> > an is going to require another cycle of prep patches to go through arch
> > code first.
> >
> > Or suggestions for alternative approach?
>
> Here is a quick patch that I think should catch missing CRCs in
> architecture independent way. If we merge something like this, we
> can whitelist the symbols in arch/powerpc so people get steered to
> the right place.
>
> Powerpc seems to be the only one really catching this, and it's
> only as a side effect of a test run for CONFIG_RELOCATABLE kernels,
> which means version failures probably slipped through other archs.
>
> I'll clean it up, do some more testing, and submit it unless
> anybody dislikes it or has a better way to do it.
>
> Thanks,
> Nick
>
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 4b8ffd3..1efc454 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -609,6 +609,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
> {
> unsigned int crc;
> enum export export;
> + int is_crc = 0;
should that not be a bool here ?
>
> if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
> strncmp(symname, "__ksymtab", 9) == 0)
> @@ -618,6 +619,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
>
> /* CRC'd symbol */
> if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
> + is_crc = 1;
is_crc = true;
> crc = (unsigned int) sym->st_value;
> sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
> export);
thx!
hofrat
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