[PATCH v3] i386: Update ___tls_get_addr to preserve vector registers
H.J. Lu
hjl.tools@gmail.com
Tue Jun 17 01:56:14 GMT 2025
On Tue, Jun 17, 2025 at 4:55 AM Adhemerval Zanella Netto
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 12/06/25 19:53, H.J. Lu wrote:
> > On Tue, Jun 10, 2025 at 8:01 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> On Tue, Jun 10, 2025, 7:47 PM H. Peter Anvin <hpa@zytor.com> wrote:
> >>>
> >>> On 2025-06-09 14:25, H.J. Lu wrote:
> >>>> On Mon, Jun 9, 2025 at 1:47 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>>>>
> >>>>> Compiler generates the following instruction sequence for dynamic TLS
> >>>>> access:
> >>>>>
> >>>>> leal tls_var@tlsgd(,%ebx,1), %eax
> >>>>> call ___tls_get_addr@PLT
> >>>>>
> >>>>> CALL instruction is transparent to compiler which assumes all registers,
> >>>>> except for EFLAGS, AX, CX, and DX, are unchanged after CALL. But
> >>>>> ___tls_get_addr is a normal function which doesn't preserve any vector
> >>>>> registers.
> >>>>>
> >>>>> 1. Rename the generic __tls_get_addr function to ___tls_get_addr_internal.
> >>>>> 2. Change ___tls_get_addr to a wrapper function with implementations for
> >>>>> FNSAVE, FXSAVE, XSAVE and XSAVEC to save and restore all vector registers.
> >>>>> 3. dl-tlsdesc-dynamic.h:
> >>>>>
> >>>
> >>> Would it not make more sense to build this functon with
> >>> -mgeneral-regs-only? There doesn't seem to be any reason for this
> >>> function to use vector registers, and that's a huge overhead.
> >>
> >>
> >> It won't work since that function calls other functions.
> >> In my test included in my patch, malloc is called, which uses vector registers.
> >
> > Here is the v3 patch. Changes are
> >
> > 1. Define DL_RUNTIME_RESOLVE_REALIGN_STACK in sysdeps/x86/sysdep.h.
> > 2. Add
> >
> > +ifneq (no,$(have-test-mtls-traditional))
> > CFLAGS-tst-tls23-mod.c += -mtls-dialect=$(have-test-mtls-traditional)
> > +endif
>
> On the weekly call during patchwork status, we noted that only the first
> version of this patch was registered [1].
>
> So I think it would be better to send possible newer versions in its own
> thread and as inline to 1. make patchwork to proper register and trigger
> CI (since this version also fixes the aarch64 regression on v1) and to
> make it review easier (since on some email client attachments are not
> readily added in the reply message).
>
> [1] https://patchwork.sourceware.org/project/glibc/patch/CAMe9rOrYHrH91_qTB5e4kdWxdgamaCf19BCaSeVpuzV0R=8i=A@mail.gmail.com/
>
> > > From 48ca104d680cdcc782e6ba26d4c0f4b146fb2e7f Mon Sep 17 00:00:00 2001
> > From: "H.J. Lu" <hjl.tools@gmail.com>
> > Date: Mon, 9 Jun 2025 05:22:10 +0800
> > Subject: [PATCH v3] i386: Update ___tls_get_addr to preserve vector registers
> >
> > Compiler generates the following instruction sequence for dynamic TLS
> > access:
> >
> > leal tls_var@tlsgd(,%ebx,1), %eax
> > call ___tls_get_addr@PLT
> >
> > CALL instruction is transparent to compiler which assumes all registers,
> > except for EFLAGS, AX, CX, and DX, are unchanged after CALL. But
> > ___tls_get_addr is a normal function which doesn't preserve any vector
> > registers.
>
> So if I understand correctly re-reading the TLS ABI documents, the
> ___tls_get_addr is the GNU variant that has a slight different calling
> convention than the double score __tls_get_addr (SUN variantion), where
> the GNU is as defined with __attribute__ ((regparam (1))). And that's
> why also x86_64 is not affected by this very issue (since it always
> used __tls_get_addr, which follows the usual ABI convention).
>
> Just a minor nit below (line too long), but the rest looks ok. There is
> not regression on aarch64, arm, or loongarch (all the other ABI that
> support TLS ABI variant).
>
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
> >
> > 1. Rename the generic __tls_get_addr function to ___tls_get_addr_internal.
> > 2. Change ___tls_get_addr to a wrapper function with implementations for
> > FNSAVE, FXSAVE, XSAVE and XSAVEC to save and restore all vector registers.
> > 3. dl-tlsdesc-dynamic.h has:
> >
> > _dl_tlsdesc_dynamic:
> > /* Like all TLS resolvers, preserve call-clobbered registers.
> > We need two scratch regs anyway. */
> > subl $32, %esp
> > cfi_adjust_cfa_offset (32)
> >
> > It is wrong to use
> >
> > movl %ebx, -28(%esp)
> > movl %esp, %ebx
> > cfi_def_cfa_register(%ebx)
> > ...
> > mov %ebx, %esp
> > cfi_def_cfa_register(%esp)
> > movl -28(%esp), %ebx
> >
> > to preserve EBX on stack. Fix it with:
> >
> > movl %ebx, 28(%esp)
> > movl %esp, %ebx
> > cfi_def_cfa_register(%ebx)
> > ...
> > mov %ebx, %esp
> > cfi_def_cfa_register(%esp)
> > movl 28(%esp), %ebx
> >
> > 4. Update _dl_tlsdesc_dynamic to call ___tls_get_addr_internal directly.
> > 5. Add have-test-mtls-traditional to compile tst-tls23-mod.c with
> > traditional TLS variant to verify the fix.
> > 6. Define DL_RUNTIME_RESOLVE_REALIGN_STACK in sysdeps/x86/sysdep.h.
> >
> > This fixes BZ #32996.
> >
> > Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> > ---
> > configure | 38 ++++++
> > configure.ac | 13 ++
> > elf/Makefile | 9 ++
> > elf/tst-tls23-mod.c | 32 +++++
> > elf/tst-tls23.c | 106 +++++++++++++++
> > .../dl-trampoline-save.h => elf/tst-tls23.h | 34 +++--
> > sysdeps/aarch64/preconfigure | 1 +
> > sysdeps/i386/Makefile | 7 +-
> > sysdeps/i386/dl-tls-get-addr.c | 68 ++++++++++
> > sysdeps/i386/dl-tls.h | 28 +---
> > sysdeps/i386/dl-tlsdesc-dynamic.h | 108 +--------------
> > sysdeps/i386/dl-tlsdesc.S | 17 ---
> > sysdeps/i386/tls-get-addr-wrapper.h | 126 ++++++++++++++++++
> > sysdeps/i386/tls-get-addr.S | 57 ++++++++
> > sysdeps/i386/tls-get-addr.h | 42 ++++++
> > sysdeps/loongarch/preconfigure | 1 +
> > sysdeps/loongarch/preconfigure.ac | 1 +
> > sysdeps/x86/Makefile | 8 ++
> > sysdeps/x86/sysdep.h | 23 ++++
> > sysdeps/x86/tst-tls23.c | 22 +++
> > sysdeps/x86/tst-tls23.h | 35 +++++
> > sysdeps/x86_64/dl-tlsdesc.S | 1 -
> > sysdeps/x86_64/dl-trampoline.S | 1 -
> > 23 files changed, 613 insertions(+), 165 deletions(-)
> > create mode 100644 elf/tst-tls23-mod.c
> > create mode 100644 elf/tst-tls23.c
> > rename sysdeps/x86_64/dl-trampoline-save.h => elf/tst-tls23.h (52%)
> > create mode 100644 sysdeps/i386/dl-tls-get-addr.c
> > create mode 100644 sysdeps/i386/tls-get-addr-wrapper.h
> > create mode 100644 sysdeps/i386/tls-get-addr.S
> > create mode 100644 sysdeps/i386/tls-get-addr.h
> > create mode 100644 sysdeps/x86/tst-tls23.c
> > create mode 100644 sysdeps/x86/tst-tls23.h
> >
> > diff --git a/configure b/configure
> > index efc9203dda..53f7d1fce8 100755
> > --- a/configure
> > +++ b/configure
> > @@ -4931,6 +4931,9 @@ with_fp_cond=1
> > # A preconfigure script may define another name to TLS descriptor variant
> > mtls_descriptor=gnu2
> >
> > +# A preconfigure script may define another name to traditional TLS variant
> > +mtls_traditional=gnu
> > +
> > if frags=`ls -d $srcdir/sysdeps/*/preconfigure 2> /dev/null`
> > then
> > { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for sysdeps preconfigure fragments" >&5
> > @@ -7490,6 +7493,41 @@ rm -f conftest*
> > config_vars="$config_vars
> > have-test-mtls-descriptor = $libc_cv_test_mtls_descriptor"
> >
> > +
> > +cat > conftest.c <<EOF
> > +$conftest_code
> > +EOF
> > +
> > +saved_CC="$CC"
> > +CC="$TEST_CC"
> > +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for traditional tls support in testing" >&5
> > +printf %s "checking for traditional tls support in testing... " >&6; }
> > +if test ${libc_cv_test_mtls_traditional+y}
> > +then :
> > + printf %s "(cached) " >&6
> > +else case e in #(
> > + e) if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fPIC -mtls-dialect=$mtls_traditional -nostdlib -nostartfiles -shared conftest.c -o conftest 1>&5'
> > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> > + (eval $ac_try) 2>&5
> > + ac_status=$?
> > + printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> > + test $ac_status = 0; }; }
> > + then
> > + libc_cv_test_mtls_traditional=$mtls_traditional
> > + else
> > + libc_cv_test_mtls_traditional=no
> > + fi ;;
> > +esac
> > +fi
> > +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_test_mtls_traditional" >&5
> > +printf "%s\n" "$libc_cv_test_mtls_traditional" >&6; }
> > +
> > +CC="$saved_CC"
> > +
> > +rm -f conftest*
> > +config_vars="$config_vars
> > +have-test-mtls-traditional = $libc_cv_test_mtls_traditional"
> > +
> > conftest_code="
> > void __foo (void)
> > {
> > diff --git a/configure.ac b/configure.ac
> > index 6d00b473e8..09d2ab721c 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -483,6 +483,9 @@ with_fp_cond=1
> > # A preconfigure script may define another name to TLS descriptor variant
> > mtls_descriptor=gnu2
> >
> > +# A preconfigure script may define another name to traditional TLS variant
> > +mtls_traditional=gnu
> > +
> > dnl Let sysdeps/*/preconfigure act here.
> > LIBC_PRECONFIGURE([$srcdir], [for sysdeps])
> >
> > @@ -1401,6 +1404,16 @@ LIBC_TRY_TEST_CC_COMMAND([for tls descriptor support],
> > LIBC_CONFIG_VAR([have-test-mtls-descriptor],
> > [$libc_cv_test_mtls_descriptor])
> >
> > +dnl Check if TEST_CC support traditional tls.
> > +LIBC_TRY_TEST_CC_COMMAND([for traditional tls support],
> > + [$conftest_code],
> > + [-fPIC -mtls-dialect=$mtls_traditional -nostdlib -nostartfiles -shared],
> > + libc_cv_test_mtls_traditional,
> > + [libc_cv_test_mtls_traditional=$mtls_traditional],
> > + [libc_cv_test_mtls_traditional=no])
> > +LIBC_CONFIG_VAR([have-test-mtls-traditional],
> > + [$libc_cv_test_mtls_traditional])
> > +
> > dnl clang emits an warning for a double alias redirection, to warn the
> > dnl original symbol is sed even when weak definition overrides it.
> > dnl It is a usual pattern for weak_alias, where multiple alias point to
>
> Ok.
>
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 362523ff11..05a78dc9a5 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -496,6 +496,7 @@ tests += \
> > tst-tls21 \
> > tst-tls22 \
> > tst-tls22-gnu2 \
> > + tst-tls23 \
> > tst-tlsalign \
> > tst-tlsalign-extern \
> > tst-tlsgap \
> > @@ -1023,6 +1024,7 @@ modules-names += \
> > tst-tls22-mod1-gnu2 \
> > tst-tls22-mod2 \
> > tst-tls22-mod2-gnu2 \
> > + tst-tls23-mod \
> > tst-tlsalign-lib \
> > tst-tlsgap-mod0 \
> > tst-tlsgap-mod1 \
> > @@ -3410,6 +3412,13 @@ tst-tls22-mod1-gnu2.so-no-z-defs = yes
> > tst-tls22-mod2.so-no-z-defs = yes
> > tst-tls22-mod2-gnu2.so-no-z-defs = yes
> >
> > +$(objpfx)tst-tls23: $(shared-thread-library)
> > +$(objpfx)tst-tls23.out: $(objpfx)tst-tls23-mod.so
> > +
> > +ifneq (no,$(have-test-mtls-traditional))
> > +CFLAGS-tst-tls23-mod.c += -mtls-dialect=$(have-test-mtls-traditional)
> > +endif
> > +
> > ifeq ($(have-test-cc-cflags-fsemantic-interposition),yes)
> > # Compiler may default to -fno-semantic-interposition. These modules
> > # must be compiled with -fsemantic-interposition.
>
> Ok.
>
> > diff --git a/elf/tst-tls23-mod.c b/elf/tst-tls23-mod.c
> > new file mode 100644
> > index 0000000000..3ee4c70e40
> > --- /dev/null
> > +++ b/elf/tst-tls23-mod.c
> > @@ -0,0 +1,32 @@
> > +/* DSO used by tst-tls23.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#include <tst-tls23.h>
> > +
> > +__thread struct tls tls_var0 __attribute__ ((visibility ("hidden")));
> > +
> > +struct tls *
> > +apply_tls (struct tls *p)
> > +{
> > + INIT_TLS_CALL ();
> > + BEFORE_TLS_CALL ();
> > + tls_var0 = *p;
> > + struct tls *ret = &tls_var0;
> > + AFTER_TLS_CALL ();
> > + return ret;
> > +}
> > diff --git a/elf/tst-tls23.c b/elf/tst-tls23.c
> > new file mode 100644
> > index 0000000000..afe594c067
> > --- /dev/null
> > +++ b/elf/tst-tls23.c
> > @@ -0,0 +1,106 @@
> > +/* Test that __tls_get_addr preserves caller-saved registers.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <http://www.gnu.org/licenses/>. */
> > +
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <dlfcn.h>
> > +#include <pthread.h>
> > +#include <support/xdlfcn.h>
> > +#include <support/xthread.h>
> > +#include <support/check.h>
> > +#include <support/test-driver.h>
> > +#include <tst-tls23.h>
> > +
> > +#ifndef IS_SUPPORTED
> > +# define IS_SUPPORTED() true
> > +#endif
> > +
> > +/* An architecture can define it to clobber caller-saved registers in
> > + malloc below to verify that __tls_get_addr won't change caller-saved
> > + registers. */
> > +#ifndef PREPARE_MALLOC
> > +# define PREPARE_MALLOC()
> > +#endif
> > +
> > +extern void * __libc_malloc (size_t);
> > +
> > +size_t malloc_counter = 0;
> > +
> > +void *
> > +malloc (size_t n)
> > +{
> > + PREPARE_MALLOC ();
> > + malloc_counter++;
> > + return __libc_malloc (n);
> > +}
> > +
> > +static void *mod;
> > +static const char *modname = "tst-tls23-mod.so";
> > +
> > +static void
> > +open_mod (void)
> > +{
> > + mod = xdlopen (modname, RTLD_LAZY);
> > + printf ("open %s\n", modname);
> > +}
> > +
> > +static void
> > +close_mod (void)
> > +{
> > + xdlclose (mod);
> > + mod = NULL;
> > + printf ("close %s\n", modname);
> > +}
> > +
> > +static void
> > +access_mod (const char *sym)
> > +{
> > + struct tls var = { -4, -4, -4, -4 };
> > + struct tls *(*f) (struct tls *) = xdlsym (mod, sym);
> > + /* Check that our malloc is called. */
> > + malloc_counter = 0;
> > + struct tls *p = f (&var);
> > + TEST_VERIFY (malloc_counter != 0);
> > + printf ("access %s: %s() = %p\n", modname, sym, p);
> > + TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > + ++(p->a);
> > +}
> > +
> > +static void *
> > +start (void *arg)
> > +{
> > + access_mod ("apply_tls");
> > + return arg;
> > +}
> > +
> > +static int
> > +do_test (void)
> > +{
> > + if (!IS_SUPPORTED ())
> > + return EXIT_UNSUPPORTED;
> > +
> > + open_mod ();
> > + pthread_t t = xpthread_create (NULL, start, NULL);
> > + xpthread_join (t);
> > + close_mod ();
> > +
> > + return 0;
> > +}
> > +
> > +#include <support/test-driver.c>
>
> Ok.
>
> > diff --git a/sysdeps/x86_64/dl-trampoline-save.h b/elf/tst-tls23.h
> > similarity index 52%
> > rename from sysdeps/x86_64/dl-trampoline-save.h
> > rename to elf/tst-tls23.h
> > index 761128d980..d0e734569c 100644
> > --- a/sysdeps/x86_64/dl-trampoline-save.h
> > +++ b/elf/tst-tls23.h
> > @@ -1,5 +1,5 @@
> > -/* x86-64 PLT trampoline register save macros.
> > - Copyright (C) 2024-2025 Free Software Foundation, Inc.
> > +/* Test that __tls_get_addr preserves caller-saved registers.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > This file is part of the GNU C Library.
> >
> > The GNU C Library is free software; you can redistribute it and/or
> > @@ -16,19 +16,25 @@
> > License along with the GNU C Library; if not, see
> > <https://www.gnu.org/licenses/>. */
> >
> > -#ifndef DL_STACK_ALIGNMENT
> > -/* Due to GCC bug:
> > +#include <stdint.h>
> >
> > - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> > +struct tls
> > +{
> > + int64_t a, b, c, d;
> > +};
> >
> > - __tls_get_addr may be called with 8-byte stack alignment. Although
> > - this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> > - that stack will be always aligned at 16 bytes. */
> > -# define DL_STACK_ALIGNMENT 8
> > +extern struct tls *apply_tls (struct tls *);
> > +
> > +/* An architecture can define them to verify that caller-saved registers
> > + aren't changed by __tls_get_addr. */
> > +#ifndef INIT_TLS_CALL
> > +# define INIT_TLS_CALL()
> > +#endif
> > +
> > +#ifndef BEFORE_TLS_CALL
> > +# define BEFORE_TLS_CALL()
> > #endif
> >
> > -/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> > - stack to 16 bytes before calling _dl_fixup. */
> > -#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> > - (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> > - || 16 > DL_STACK_ALIGNMENT)
> > +#ifndef AFTER_TLS_CALL
> > +# define AFTER_TLS_CALL()
> > +#endif
>
> Ok.
>
> > diff --git a/sysdeps/aarch64/preconfigure b/sysdeps/aarch64/preconfigure
> > index 19657b627b..e1b772c586 100644
> > --- a/sysdeps/aarch64/preconfigure
> > +++ b/sysdeps/aarch64/preconfigure
> > @@ -3,5 +3,6 @@ aarch64*)
> > base_machine=aarch64
> > machine=aarch64
> > mtls_descriptor=desc
> > + mtls_traditional=trad
> > ;;
> > esac
> > diff --git a/sysdeps/i386/Makefile b/sysdeps/i386/Makefile
> > index a2e8c0b128..87f113eca1 100644
> > --- a/sysdeps/i386/Makefile
> > +++ b/sysdeps/i386/Makefile
> > @@ -30,7 +30,12 @@ stack-align-test-flags += -malign-double
> > endif
> >
> > ifeq ($(subdir),elf)
> > -sysdep-dl-routines += tlsdesc dl-tlsdesc
> > +sysdep-dl-routines += \
> > + dl-tls-get-addr \
> > + dl-tlsdesc \
> > + tls-get-addr \
> > + tlsdesc \
> > +# sysdep-dl-routines
> >
> > tests += tst-audit3
> > modules-names += tst-auditmod3a tst-auditmod3b
>
> I think you can move dl-tlsdesc, tls-get-addr, and tlsdesc to sysdep/x86/Makefile.
Fixed.
> > diff --git a/sysdeps/i386/dl-tls-get-addr.c b/sysdeps/i386/dl-tls-get-addr.c
> > new file mode 100644
> > index 0000000000..c97e5c57be
> > --- /dev/null
> > +++ b/sysdeps/i386/dl-tls-get-addr.c
> > @@ -0,0 +1,68 @@
> > +/* Ifunc selector for ___tls_get_addr.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#ifdef SHARED
> > +# define ___tls_get_addr __redirect____tls_get_addr
> > +# include <dl-tls.h>
> > +# undef ___tls_get_addr
> > +# undef __tls_get_addr
> > +
> > +# define SYMBOL_NAME ___tls_get_addr
> > +# include <init-arch.h>
> > +
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (fnsave) attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (fxsave) attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (xsave) attribute_hidden;
> > +extern __typeof (REDIRECT_NAME) OPTIMIZE (xsavec) attribute_hidden;
> > +
> > +static inline void *
> > +IFUNC_SELECTOR (void)
> > +{
> > + const struct cpu_features* cpu_features = __get_cpu_features ();
> > +
> > + if (cpu_features->xsave_state_size != 0)
> > + {
> > + if (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))
> > + return OPTIMIZE (xsavec);
> > + else
> > + return OPTIMIZE (xsave);
> > + }
> > + else if (CPU_FEATURE_USABLE_P (cpu_features, FXSR))
> > + return OPTIMIZE (fxsave);
> > + return OPTIMIZE (fnsave);
> > +}
> > +
> > +libc_ifunc_redirected (__redirect____tls_get_addr, ___tls_get_addr,
> > + IFUNC_SELECTOR ());
> > +
> > +/* The special thing about the x86 TLS ABI is that we have two
> > + variants of the __tls_get_addr function with different calling
> > + conventions. The GNU version, which we are mostly concerned here,
> > + takes the parameter in a register. The name is changed by adding
> > + an additional underscore at the beginning. The Sun version uses
> > + the normal calling convention. */
> > +
> > +rtld_hidden_proto (___tls_get_addr)
> > +rtld_hidden_def (___tls_get_addr)
> > +
> > +void *
> > +__tls_get_addr (tls_index *ti)
> > +{
> > + return ___tls_get_addr (ti);
> > +}
> > +#endif
>
> Ok.
>
> > diff --git a/sysdeps/i386/dl-tls.h b/sysdeps/i386/dl-tls.h
> > index f453931d78..ef605c5b0d 100644
> > --- a/sysdeps/i386/dl-tls.h
> > +++ b/sysdeps/i386/dl-tls.h
> > @@ -37,34 +37,14 @@ typedef struct dl_tls_index
> > /* This is the prototype for the GNU version. */
> > extern void *___tls_get_addr (tls_index *ti)
> > __attribute__ ((__regparm__ (1)));
> > -extern void *___tls_get_addr_internal (tls_index *ti)
> > - __attribute__ ((__regparm__ (1))) attribute_hidden;
> > -
> > # if IS_IN (rtld)
> > -/* The special thing about the x86 TLS ABI is that we have two
> > - variants of the __tls_get_addr function with different calling
> > - conventions. The GNU version, which we are mostly concerned here,
> > - takes the parameter in a register. The name is changed by adding
> > - an additional underscore at the beginning. The Sun version uses
> > - the normal calling convention. */
> > -void *
> > -__tls_get_addr (tls_index *ti)
> > -{
> > - return ___tls_get_addr_internal (ti);
> > -}
> > -
> > -
> > /* Prepare using the definition of __tls_get_addr in the generic
> > version of this file. */
> > -# define __tls_get_addr __attribute__ ((__regparm__ (1))) ___tls_get_addr
> > -strong_alias (___tls_get_addr, ___tls_get_addr_internal)
> > -rtld_hidden_proto (___tls_get_addr)
> > -rtld_hidden_def (___tls_get_addr)
> > -#else
> > -
> > +# define __tls_get_addr \
> > + __attribute__ ((__regparm__ (1))) ___tls_get_addr_internal
> > +# else
> > /* Users should get the better interface. */
> > -# define __tls_get_addr ___tls_get_addr
> > -
> > +# define __tls_get_addr ___tls_get_addr
> > # endif
> > #endif
> >
>
> Ok.
>
> > diff --git a/sysdeps/i386/dl-tlsdesc-dynamic.h b/sysdeps/i386/dl-tlsdesc-dynamic.h
> > index 6aec06d15c..be9ecd659b 100644
> > --- a/sysdeps/i386/dl-tlsdesc-dynamic.h
> > +++ b/sysdeps/i386/dl-tlsdesc-dynamic.h
> > @@ -16,34 +16,6 @@
> > License along with the GNU C Library; if not, see
> > <https://www.gnu.org/licenses/>. */
> >
> > -#undef REGISTER_SAVE_AREA
> > -
> > -#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
> > -# error STATE_SAVE_ALIGNMENT must be multiple of 16
> > -#endif
> > -
> > -#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > -# ifdef USE_FNSAVE
> > -# error USE_FNSAVE shouldn't be defined
> > -# endif
> > -# ifdef USE_FXSAVE
> > -/* Use fxsave to save all registers. */
> > -# define REGISTER_SAVE_AREA 512
> > -# endif
> > -#else
> > -# ifdef USE_FNSAVE
> > -/* Use fnsave to save x87 FPU stack registers. */
> > -# define REGISTER_SAVE_AREA 108
> > -# else
> > -# ifndef USE_FXSAVE
> > -# error USE_FXSAVE must be defined
> > -# endif
> > -/* Use fxsave to save all registers. Add 12 bytes to align the stack
> > - to 16 bytes. */
> > -# define REGISTER_SAVE_AREA (512 + 12)
> > -# endif
> > -#endif
> > -
> > .hidden _dl_tlsdesc_dynamic
> > .global _dl_tlsdesc_dynamic
> > .type _dl_tlsdesc_dynamic,@function
> > @@ -104,85 +76,7 @@ _dl_tlsdesc_dynamic:
> > ret
> > .p2align 4,,7
> > 2:
> > - cfi_adjust_cfa_offset (32)
> > -#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > - movl %ebx, -28(%esp)
> > - movl %esp, %ebx
> > - cfi_def_cfa_register(%ebx)
> > - and $-STATE_SAVE_ALIGNMENT, %esp
> > -#endif
> > -#ifdef REGISTER_SAVE_AREA
> > - subl $REGISTER_SAVE_AREA, %esp
> > -# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> > - cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> > -# endif
> > -#else
> > -# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> > -# error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
> > -# endif
> > - /* Allocate stack space of the required size to save the state. */
> > - LOAD_PIC_REG (cx)
> > - subl RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
> > -#endif
> > -#ifdef USE_FNSAVE
> > - fnsave (%esp)
> > -#elif defined USE_FXSAVE
> > - fxsave (%esp)
> > -#else
> > - /* Save the argument for ___tls_get_addr in EAX. */
> > - movl %eax, %ecx
> > - movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > - xorl %edx, %edx
> > - /* Clear the XSAVE Header. */
> > -# ifdef USE_XSAVE
> > - movl %edx, (512)(%esp)
> > - movl %edx, (512 + 4 * 1)(%esp)
> > - movl %edx, (512 + 4 * 2)(%esp)
> > - movl %edx, (512 + 4 * 3)(%esp)
> > -# endif
> > - movl %edx, (512 + 4 * 4)(%esp)
> > - movl %edx, (512 + 4 * 5)(%esp)
> > - movl %edx, (512 + 4 * 6)(%esp)
> > - movl %edx, (512 + 4 * 7)(%esp)
> > - movl %edx, (512 + 4 * 8)(%esp)
> > - movl %edx, (512 + 4 * 9)(%esp)
> > - movl %edx, (512 + 4 * 10)(%esp)
> > - movl %edx, (512 + 4 * 11)(%esp)
> > - movl %edx, (512 + 4 * 12)(%esp)
> > - movl %edx, (512 + 4 * 13)(%esp)
> > - movl %edx, (512 + 4 * 14)(%esp)
> > - movl %edx, (512 + 4 * 15)(%esp)
> > -# ifdef USE_XSAVE
> > - xsave (%esp)
> > -# else
> > - xsavec (%esp)
> > -# endif
> > - /* Restore the argument for ___tls_get_addr in EAX. */
> > - movl %ecx, %eax
> > -#endif
> > - call HIDDEN_JUMPTARGET (___tls_get_addr)
> > - /* Get register content back. */
> > -#ifdef USE_FNSAVE
> > - frstor (%esp)
> > -#elif defined USE_FXSAVE
> > - fxrstor (%esp)
> > -#else
> > - /* Save and retore ___tls_get_addr return value stored in EAX. */
> > - movl %eax, %ecx
> > - movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > - xorl %edx, %edx
> > - xrstor (%esp)
> > - movl %ecx, %eax
> > -#endif
> > -#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > - mov %ebx, %esp
> > - cfi_def_cfa_register(%esp)
> > - movl -28(%esp), %ebx
> > - cfi_restore(%ebx)
> > -#else
> > - addl $REGISTER_SAVE_AREA, %esp
> > - cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> > -#endif
> > +#include "tls-get-addr-wrapper.h"
> > jmp 1b
> > cfi_endproc
> > .size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
>
> Ok.
>
> > diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
> > index c080993a60..c914ca4220 100644
> > --- a/sysdeps/i386/dl-tlsdesc.S
> > +++ b/sysdeps/i386/dl-tlsdesc.S
> > @@ -22,23 +22,6 @@
> > #include <features-offsets.h>
> > #include "tlsdesc.h"
> >
> > -#ifndef DL_STACK_ALIGNMENT
> > -/* Due to GCC bug:
> > -
> > - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> > -
> > - __tls_get_addr may be called with 4-byte stack alignment. Although
> > - this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> > - that stack will be always aligned at 16 bytes. */
> > -# define DL_STACK_ALIGNMENT 4
> > -#endif
> > -
> > -/* True if _dl_tlsdesc_dynamic should align stack for STATE_SAVE or align
> > - stack to MINIMUM_ALIGNMENT bytes before calling ___tls_get_addr. */
> > -#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> > - (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> > - || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
> > -
> > .text
> >
> > /* This function is used to compute the TP offset for symbols in
>
>
> Ok.
>
> > diff --git a/sysdeps/i386/tls-get-addr-wrapper.h b/sysdeps/i386/tls-get-addr-wrapper.h
> > new file mode 100644
> > index 0000000000..cb05c6d1c5
> > --- /dev/null
> > +++ b/sysdeps/i386/tls-get-addr-wrapper.h
> > @@ -0,0 +1,126 @@
> > +/* Wrapper of i386 ___tls_get_addr to save and restore vector registers.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#undef REGISTER_SAVE_AREA
> > +
> > +#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
> > +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> > +#endif
> > +
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +# ifdef USE_FNSAVE
> > +# error USE_FNSAVE shouldn't be defined
> > +# endif
> > +# ifdef USE_FXSAVE
> > +/* Use fxsave to save all registers. */
> > +# define REGISTER_SAVE_AREA 512
> > +# endif
> > +#else
> > +# ifdef USE_FNSAVE
> > +/* Use fnsave to save x87 FPU stack registers. */
> > +# define REGISTER_SAVE_AREA 108
> > +# else
> > +# ifndef USE_FXSAVE
> > +# error USE_FXSAVE must be defined
> > +# endif
> > +/* Use fxsave to save all registers. Add 12 bytes to align the stack
> > + to 16 bytes. */
> > +# define REGISTER_SAVE_AREA (512 + 12)
> > +# endif
> > +#endif
> > +
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > + movl %ebx, 28(%esp)
> > + movl %esp, %ebx
> > + cfi_def_cfa_register(%ebx)
> > + and $-STATE_SAVE_ALIGNMENT, %esp
> > +#endif
> > +#ifdef REGISTER_SAVE_AREA
> > + subl $REGISTER_SAVE_AREA, %esp
> > +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> > + cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> > +# endif
> > +#else
> > +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +# error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
> > +# endif
> > + /* Allocate stack space of the required size to save the state. */
> > + LOAD_PIC_REG (cx)
> > + subl RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
>
> Line too long.
Fixed.
> > +#endif
> > +#ifdef USE_FNSAVE
> > + fnsave (%esp)
> > +#elif defined USE_FXSAVE
> > + fxsave (%esp)
> > +#else
> > + /* Save the argument for ___tls_get_addr in EAX. */
> > + movl %eax, %ecx
> > + movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > + xorl %edx, %edx
> > + /* Clear the XSAVE Header. */
> > +# ifdef USE_XSAVE
> > + movl %edx, (512)(%esp)
> > + movl %edx, (512 + 4 * 1)(%esp)
> > + movl %edx, (512 + 4 * 2)(%esp)
> > + movl %edx, (512 + 4 * 3)(%esp)
> > +# endif
> > + movl %edx, (512 + 4 * 4)(%esp)
> > + movl %edx, (512 + 4 * 5)(%esp)
> > + movl %edx, (512 + 4 * 6)(%esp)
> > + movl %edx, (512 + 4 * 7)(%esp)
> > + movl %edx, (512 + 4 * 8)(%esp)
> > + movl %edx, (512 + 4 * 9)(%esp)
> > + movl %edx, (512 + 4 * 10)(%esp)
> > + movl %edx, (512 + 4 * 11)(%esp)
> > + movl %edx, (512 + 4 * 12)(%esp)
> > + movl %edx, (512 + 4 * 13)(%esp)
> > + movl %edx, (512 + 4 * 14)(%esp)
> > + movl %edx, (512 + 4 * 15)(%esp)
> > +# ifdef USE_XSAVE
> > + xsave (%esp)
> > +# else
> > + xsavec (%esp)
> > +# endif
> > + /* Restore the argument for ___tls_get_addr in EAX. */
> > + movl %ecx, %eax
> > +#endif
> > + call ___tls_get_addr_internal
> > + /* Get register content back. */
> > +#ifdef USE_FNSAVE
> > + frstor (%esp)
> > +#elif defined USE_FXSAVE
> > + fxrstor (%esp)
> > +#else
> > + /* Save and retore ___tls_get_addr return value stored in EAX. */
> > + movl %eax, %ecx
> > + movl $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > + xorl %edx, %edx
> > + xrstor (%esp)
> > + movl %ecx, %eax
> > +#endif
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > + mov %ebx, %esp
> > + cfi_def_cfa_register(%esp)
> > + movl 28(%esp), %ebx
> > + cfi_restore(%ebx)
> > +#else
> > + addl $REGISTER_SAVE_AREA, %esp
> > + cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> > +#endif
> > +
> > +#undef STATE_SAVE_ALIGNMENT
>
> Ok.
>
> > diff --git a/sysdeps/i386/tls-get-addr.S b/sysdeps/i386/tls-get-addr.S
> > new file mode 100644
> > index 0000000000..9b5d6532fc
> > --- /dev/null
> > +++ b/sysdeps/i386/tls-get-addr.S
> > @@ -0,0 +1,57 @@
> > +/* Thread-local storage handling in the ELF dynamic linker. i386 version.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#include <sysdep.h>
> > +#include <tls.h>
> > +#include <cpu-features-offsets.h>
> > +#include <features-offsets.h>
> > +
> > + .text
> > +#ifdef SHARED
> > +# define USE_FNSAVE
> > +# define MINIMUM_ALIGNMENT 4
> > +# define STATE_SAVE_ALIGNMENT 4
> > +# define ___tls_get_addr _____tls_get_addr_fnsave
> > +# include "tls-get-addr.h"
> > +# undef ___tls_get_addr
> > +# undef MINIMUM_ALIGNMENT
> > +# undef USE_FNSAVE
> > +
> > +# define MINIMUM_ALIGNMENT 16
> > +
> > +# define USE_FXSAVE
> > +# define STATE_SAVE_ALIGNMENT 16
> > +# define ___tls_get_addr _____tls_get_addr_fxsave
> > +# include "tls-get-addr.h"
> > +# undef ___tls_get_addr
> > +# undef USE_FXSAVE
> > +
> > +# define USE_XSAVE
> > +# define STATE_SAVE_ALIGNMENT 64
> > +# define ___tls_get_addr _____tls_get_addr_xsave
> > +# include "tls-get-addr.h"
> > +# undef ___tls_get_addr
> > +# undef USE_XSAVE
> > +
> > +# define USE_XSAVEC
> > +# define STATE_SAVE_ALIGNMENT 64
> > +# define ___tls_get_addr _____tls_get_addr_xsavec
> > +# include "tls-get-addr.h"
> > +# undef ___tls_get_addr
> > +# undef USE_XSAVEC
> > +#endif /* SHARED */
>
> Ok.
>
> > diff --git a/sysdeps/i386/tls-get-addr.h b/sysdeps/i386/tls-get-addr.h
> > new file mode 100644
> > index 0000000000..1825798724
> > --- /dev/null
> > +++ b/sysdeps/i386/tls-get-addr.h
> > @@ -0,0 +1,42 @@
> > +/* Thread-local storage handling in the ELF dynamic linker. i386 version.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > + .hidden ___tls_get_addr
> > + .global ___tls_get_addr
> > + .type ___tls_get_addr,@function
> > +
> > + /* This function is a wrapper of ___tls_get_addr_internal to
> > + preserve caller-saved vector registers. */
> > +
> > + cfi_startproc
> > + .align 16
> > +___tls_get_addr:
> > + /* Like all TLS resolvers, preserve call-clobbered registers.
> > + We need two scratch regs anyway. */
> > + subl $32, %esp
> > + cfi_adjust_cfa_offset (32)
> > + movl %ecx, 20(%esp)
> > + movl %edx, 24(%esp)
> > +#include "tls-get-addr-wrapper.h"
> > + movl 20(%esp), %ecx
> > + movl 24(%esp), %edx
> > + addl $32, %esp
> > + cfi_adjust_cfa_offset (-32)
> > + ret
> > + cfi_endproc
> > + .size ___tls_get_addr, .-___tls_get_addr
>
> Ok.
>
> > diff --git a/sysdeps/loongarch/preconfigure b/sysdeps/loongarch/preconfigure
> > index 0d1e9ed8df..6726ab8302 100644
> > --- a/sysdeps/loongarch/preconfigure
> > +++ b/sysdeps/loongarch/preconfigure
> > @@ -44,6 +44,7 @@ loongarch*)
> >
> > base_machine=loongarch
> > mtls_descriptor=desc
> > + mtls_traditional=trad
> > ;;
> > esac
> >
> > diff --git a/sysdeps/loongarch/preconfigure.ac b/sysdeps/loongarch/preconfigure.ac
> > index df07dbf41f..56402261df 100644
> > --- a/sysdeps/loongarch/preconfigure.ac
> > +++ b/sysdeps/loongarch/preconfigure.ac
> > @@ -42,6 +42,7 @@ loongarch*)
> >
> > base_machine=loongarch
> > mtls_descriptor=desc
> > + mtls_traditional=trad
> > ;;
> > esac
> >
>
> Ok.
>
> > diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> > index 01b0192ddf..9ff00717ce 100644
> > --- a/sysdeps/x86/Makefile
> > +++ b/sysdeps/x86/Makefile
> > @@ -113,6 +113,14 @@ $(objpfx)tst-gnu2-tls2-x86-noxsavexsavec.out: \
> > $(objpfx)tst-gnu2-tls2mod0.so \
> > $(objpfx)tst-gnu2-tls2mod1.so \
> > $(objpfx)tst-gnu2-tls2mod2.so
> > +
> > +CFLAGS-tst-tls23.c += -msse2
> > +CFLAGS-tst-tls23-mod.c += -msse2 -mtune=haswell
> > +
> > +LDFLAGS-tst-tls23 += -rdynamic
> > +tst-tls23-mod.so-no-z-defs = yes
> > +
> > +$(objpfx)tst-tls23-mod.so: $(libsupport)
> > endif
> >
> > ifeq ($(subdir),math)
>
> Ok.
>
> > diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> > index c3c73e75dd..b8e963b654 100644
> > --- a/sysdeps/x86/sysdep.h
> > +++ b/sysdeps/x86/sysdep.h
> > @@ -183,6 +183,29 @@
> >
> > #define atom_text_section .section ".text.atom", "ax"
> >
> > +#ifndef DL_STACK_ALIGNMENT
> > +/* Due to GCC bug:
> > +
> > + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> > +
> > + __tls_get_addr may be called with 8-byte/4-byte stack alignment.
> > + Although this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't
> > + assume that stack will be always aligned at 16 bytes. */
> > +# ifdef __x86_64__
> > +# define DL_STACK_ALIGNMENT 8
> > +# define MINIMUM_ALIGNMENT 16
> > +# else
> > +# define DL_STACK_ALIGNMENT 4
> > +# endif
> > +#endif
> > +
> > +/* True if _dl_runtime_resolve/_dl_tlsdesc_dynamic should align stack for
> > + STATE_SAVE or align stack to MINIMUM_ALIGNMENT bytes before calling
> > + _dl_fixup/__tls_get_addr. */
> > +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> > + (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> > + || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
> > +
> > #endif /* __ASSEMBLER__ */
> >
> > #endif /* _X86_SYSDEP_H */
>
> Ok.
>
> > diff --git a/sysdeps/x86/tst-tls23.c b/sysdeps/x86/tst-tls23.c
> > new file mode 100644
> > index 0000000000..6130d91cf8
> > --- /dev/null
> > +++ b/sysdeps/x86/tst-tls23.c
> > @@ -0,0 +1,22 @@
> > +#ifndef __x86_64__
> > +#include <sys/platform/x86.h>
> > +
> > +#define IS_SUPPORTED() CPU_FEATURE_ACTIVE (SSE2)
> > +#endif
> > +
> > +/* Set XMM0...XMM7 to all 1s. */
> > +#define PREPARE_MALLOC() \
> > +{ \
> > + asm volatile ("pcmpeqd %%xmm0, %%xmm0" : : : "xmm0" ); \
> > + asm volatile ("pcmpeqd %%xmm1, %%xmm1" : : : "xmm1" ); \
> > + asm volatile ("pcmpeqd %%xmm2, %%xmm2" : : : "xmm2" ); \
> > + asm volatile ("pcmpeqd %%xmm3, %%xmm3" : : : "xmm3" ); \
> > + asm volatile ("pcmpeqd %%xmm4, %%xmm4" : : : "xmm4" ); \
> > + asm volatile ("pcmpeqd %%xmm5, %%xmm5" : : : "xmm5" ); \
> > + asm volatile ("pcmpeqd %%xmm6, %%xmm6" : : : "xmm6" ); \
> > + asm volatile ("pcmpeqd %%xmm7, %%xmm7" : : : "xmm7" ); \
> > +}
> > +
> > +#include <elf/tst-tls23.c>
> > +
> > +v2di v1, v2, v3;
> > diff --git a/sysdeps/x86/tst-tls23.h b/sysdeps/x86/tst-tls23.h
> > new file mode 100644
> > index 0000000000..21cee4ca07
> > --- /dev/null
> > +++ b/sysdeps/x86/tst-tls23.h
> > @@ -0,0 +1,35 @@
> > +/* Test that __tls_get_addr preserves XMM registers.
> > + Copyright (C) 2025 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#include <support/check.h>
> > +
> > +typedef long long v2di __attribute__((vector_size(16)));
> > +extern v2di v1, v2, v3;
> > +
> > +#define BEFORE_TLS_CALL() \
> > + v1 = __extension__(v2di){0, 0}; \
> > + v2 = __extension__(v2di){0, 0};
> > +
> > +#define AFTER_TLS_CALL() \
> > + v3 = __extension__(v2di){0, 0}; \
> > + asm volatile ("" : "+x" (v3)); \
> > + union { v2di x; long long a[2]; } u; \
> > + u.x = v3; \
> > + TEST_VERIFY_EXIT (u.a[0] == 0 && u.a[1] == 0);
> > +
> > +#include <elf/tst-tls23.h>
> > diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
> > index d1bb125560..9a55fc52bb 100644
> > --- a/sysdeps/x86_64/dl-tlsdesc.S
> > +++ b/sysdeps/x86_64/dl-tlsdesc.S
> > @@ -22,7 +22,6 @@
> > #include <features-offsets.h>
> > #include <isa-level.h>
> > #include "tlsdesc.h"
> > -#include "dl-trampoline-save.h"
> >
> > /* Area on stack to save and restore registers used for parameter
> > passing when calling _dl_tlsdesc_dynamic. */
> > diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
> > index a055722e64..ac85f96794 100644
> > --- a/sysdeps/x86_64/dl-trampoline.S
> > +++ b/sysdeps/x86_64/dl-trampoline.S
> > @@ -22,7 +22,6 @@
> > #include <features-offsets.h>
> > #include <link-defines.h>
> > #include <isa-level.h>
> > -#include "dl-trampoline-save.h"
> >
> > /* Area on stack to save and restore registers used for parameter
> > passing when calling _dl_fixup. */
> > --
> > 2.49.0
> >
>
The v4 patch is at
https://patchwork.sourceware.org/project/glibc/patch/CAMe9rOoaJ3RxjAiJev7utpWR33+1Tt_2nP7ys7tXMK57OSRRAQ@mail.gmail.com/
https://sourceware.org/pipermail/libc-alpha/2025-June/167782.html
--
H.J.
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