Re: [musl] [RFC v2 0/2] xtensa FDPIC port

[Max Filippov <jcmvbkbc@gmail.com>]

On Thu, Mar 28, 2024 at 4:00 PM Rich Felker <dalias@libc.org> wrote:
> On Thu, Mar 28, 2024 at 01:03:17PM -0700, Max Filippov wrote:
> > functional/dlopen fails with the
> >   src/functional/dlopen.c:39: dlsym main failed: (null)
> > There's no failure in the dlsym call, but the pointers don't match.
>
> Is this something related to canonical function descriptors? Is it
> musl's fault or a bug in the tooling? I suspect the latter.

Yes, dlsym() returns the pointer into def.dso->funcdescs,
but (void *)main returns the pointer to the canonical function
descriptor. I understand that the linker must use the
R_XTENSA_FUNCDESC relocation for the locally defined
global symbol instead of the .rofixup entries.

> > functional/ and regression/ pthread-related failures are expected
> > because the robust list functions are not available in the linux-user
> > mode. These particular tests pass in full system emulation.
> >
> > math tests fail with ULP differences.
> >
> > I have also added the following changes to the abi tests to fix the
> > build:
> >
> > diff --git a/src/api/sys_sem.c b/src/api/sys_sem.c
> > index a473cad0a2aa..bd4df9a4fe70 100644
> > --- a/src/api/sys_sem.c
> > +++ b/src/api/sys_sem.c
> > @@ -18,7 +18,11 @@ C(SETALL)
> >  {
> >  struct semid_ds x;
> >  F(struct ipc_perm,sem_perm)
> > +#ifdef __xtensa__
> > +F(unsigned long, sem_nsems)
> > +#else
> >  F(unsigned short, sem_nsems)
> > +#endif
>
> This is invalid and indicates an error in the port; the whole point of
> the tests is to catch that so it can be fixed. POSIX requires

I must have misinterpreted that. Will fix it.

> sem_nsems to have type unsigned short. I believe Linux has this wrong
> on some (most? all?) archs and we just fix it by replacing the rest
> with padding.

-- 
Thanks.
-- Max