[2.38 PATCH] x86-64: Don't use SSE resolvers for ISA level 3 or above

[H.J. Lu]

On Thu, Feb 29, 2024 at 1:58 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Wed, Feb 28, 2024 at 11:51 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > When glibc is built with ISA level 3 or above enabled, SSE resolvers
> > aren't available and glibc fails to build:
> >
> > ld: .../elf/librtld.os: in function `init_cpu_features':
> > .../elf/../sysdeps/x86/cpu-features.c:1200:(.text+0x1445f): undefined reference to `_dl_runtime_resolve_fxsave'
> > ld: .../elf/librtld.os: relocation R_X86_64_PC32 against undefined hidden symbol `_dl_runtime_resolve_fxsave' can not be used when making a shared object
> > /usr/local/bin/ld: final link failed: bad value
> >
> > For ISA level 3 or above, don't use _dl_runtime_resolve_fxsave nor
> > _dl_tlsdesc_dynamic_fxsave and also exclude _dl_tlsdesc_dynamic_fxsave.
> >
> > This fixes BZ #31429.
> > ---
> >  sysdeps/x86/cpu-features.c  | 17 +++++++++++------
> >  sysdeps/x86_64/dl-tlsdesc.S | 15 +++++++++------
> >  2 files changed, 20 insertions(+), 12 deletions(-)
> >
> > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> > index d71e8d3d2e..e7c7ece462 100644
> > --- a/sysdeps/x86/cpu-features.c
> > +++ b/sysdeps/x86/cpu-features.c
> > @@ -18,6 +18,7 @@
> >
> >  #include <dl-hwcap.h>
> >  #include <libc-pointer-arith.h>
> > +#include <isa-level.h>
> >  #include <get-isa-level.h>
> >  #include <cacheinfo.h>
> >  #include <dl-cacheinfo.h>
> > @@ -1195,7 +1196,9 @@ no_cpuid:
> >                TUNABLE_CALLBACK (set_x86_shstk));
> >  #endif
> >
> > +#if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
> >    if (GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> > +#endif
> >      {
> >        if (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))
> >         {
> > @@ -1216,22 +1219,24 @@ no_cpuid:
> >  #endif
> >         }
> >      }
> > +#if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
> >    else
> >      {
> > -#ifdef __x86_64__
> > +# ifdef __x86_64__
> >        GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_fxsave;
> > -# ifdef SHARED
> > +#  ifdef SHARED
> >        GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> > -# endif
> > -#else
> > -# ifdef SHARED
> > +#  endif
> > +# else
> > +#  ifdef SHARED
> >        if (CPU_FEATURE_USABLE_P (cpu_features, FXSR))
> >         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> >        else
> >         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fnsave;
> > +#  endif
> >  # endif
> > -#endif
> >      }
> > +#endif
> >
> >  #ifdef SHARED
> >  # ifdef __x86_64__
> > diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
> > index ea69f5223a..057a10862a 100644
> > --- a/sysdeps/x86_64/dl-tlsdesc.S
> > +++ b/sysdeps/x86_64/dl-tlsdesc.S
> > @@ -20,6 +20,7 @@
> >  #include <tls.h>
> >  #include <cpu-features-offsets.h>
> >  #include <features-offsets.h>
> > +#include <isa-level.h>
> >  #include "tlsdesc.h"
> >  #include "dl-trampoline-save.h"
> >
> > @@ -79,12 +80,14 @@ _dl_tlsdesc_undefweak:
> >         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
> >
> >  #ifdef SHARED
> > -# define USE_FXSAVE
> > -# define STATE_SAVE_ALIGNMENT  16
> > -# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> > -# include "dl-tlsdesc-dynamic.h"
> > -# undef _dl_tlsdesc_dynamic
> > -# undef USE_FXSAVE
> > +# if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
> > +#  define USE_FXSAVE
> > +#  define STATE_SAVE_ALIGNMENT 16
> > +#  define _dl_tlsdesc_dynamic  _dl_tlsdesc_dynamic_fxsave
> > +#  include "dl-tlsdesc-dynamic.h"
> > +#  undef _dl_tlsdesc_dynamic
> > +#  undef USE_FXSAVE
> > +# endif
> >
> >  # define USE_XSAVE
> >  # define STATE_SAVE_ALIGNMENT  64
> > --
> > 2.43.2
> >
>
> LGTM.
> Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

I am backporting it to 2.38 branch.


--
H.J.