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Message-ID: <CAORiPTNM7a=QhWNP4NUd0KDNLOubmG0KmGaBWQm2ssrs5CCz7g@mail.gmail.com>
Date: Sun, 24 Aug 2025 11:25:25 +0200
From: Tomáš Hulata <hulata@...art.tech>
To: musl@...ts.openwall.com
Cc: Rich Felker <dalias@...c.org>
Subject: Re: [PATCH v3] vdso: add support for GNU hash tables

It would be great to get it included, but it's up to you. I'm going to
use a fork till it is not released.
Thanks

Best Regards
Tomáš Hulata
[ SysArt / Pixel Federation ]

On Sun, Aug 24, 2025 at 4:26 AM Rich Felker <dalias@...c.org> wrote:
>
> On Sat, Aug 23, 2025 at 12:54:04AM +0200, tombo wrote:
> > Hi Rich, thanks for the review. Hopefully this version addresses all the points.
> >
> > ---
> >  src/internal/vdso.c | 28 ++++++++++++++++++++++++++--
> >  1 file changed, 26 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/internal/vdso.c b/src/internal/vdso.c
> > index d46d3228..2b6e1ae2 100644
> > --- a/src/internal/vdso.c
> > +++ b/src/internal/vdso.c
> > @@ -40,6 +40,24 @@ static int checkver(Verdef *def, int vsym, const char *vername, char *strings)
> >  #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON)
> >  #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
> >
> > +static size_t count_syms_gnu(uint32_t *gh)
> > +{
> > +     size_t nsym, i;
> > +     uint32_t *buckets = gh + 4 + (gh[2]*sizeof(size_t)/4);
> > +     uint32_t *hashval;
> > +     for (i = nsym = 0; i < gh[0]; i++) {
> > +             if (buckets[i] > nsym)
> > +                     nsym = buckets[i];
> > +     }
> > +     if (nsym) {
> > +             hashval = buckets + gh[0] + (nsym - gh[1]);
> > +             do nsym++;
> > +             while (!(*hashval++ & 1));
> > +     }
> > +     return nsym;
> > +}
> > +
> > +
> >  void *__vdsosym(const char *vername, const char *name)
> >  {
> >       size_t i;
> > @@ -60,6 +78,7 @@ void *__vdsosym(const char *vername, const char *name)
> >       char *strings = 0;
> >       Sym *syms = 0;
> >       Elf_Symndx *hashtab = 0;
> > +     uint32_t *ghashtab = 0;
> >       uint16_t *versym = 0;
> >       Verdef *verdef = 0;
> >
> > @@ -69,15 +88,20 @@ void *__vdsosym(const char *vername, const char *name)
> >               case DT_STRTAB: strings = p; break;
> >               case DT_SYMTAB: syms = p; break;
> >               case DT_HASH: hashtab = p; break;
> > +             case DT_GNU_HASH: ghashtab = p; break;
> >               case DT_VERSYM: versym = p; break;
> >               case DT_VERDEF: verdef = p; break;
> >               }
> >       }
> >
> > -     if (!strings || !syms || !hashtab) return 0;
> > +     if (!strings || !syms) return 0;
> >       if (!verdef) versym = 0;
> > +     size_t nsym = 0;
> > +
> > +     if (hashtab) nsym = hashtab[1];
> > +     else if (ghashtab) nsym = count_syms_gnu(ghashtab);
> >
> > -     for (i=0; i<hashtab[1]; i++) {
> > +     for (i=0; i<nsym; i++) {
> >               if (!(1<<(syms[i].st_info&0xf) & OK_TYPES)) continue;
> >               if (!(1<<(syms[i].st_info>>4) & OK_BINDS)) continue;
> >               if (!syms[i].st_shndx) continue;
> > --
> > 2.46.0
>
> Thanks! I don't see anything obviously wrong with this. I'll take a
> more detailed look over it soon. Are you hoping to get it included in
> this release cycle?
>
> Rich

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