[PATCH v2 2/2] elf: Support THP segment load with madvise enabled THP
WANG Rui
wangrui@loongson.cn
Fri Apr 17 15:41:21 GMT 2026
On Fri, Apr 17, 2026 at 2:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Fri, Apr 17, 2026 at 12:11 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > The current THP segment load approach works only when THP is enabled
> > with always in the kernel. If THP is enabled with madvise in the
> > kernel, to enable THP segment load in an application, madvise should
> > be called with MADV_HUGEPAGE on all THP eligible PT_LOAD segments:
> >
> > 1. Remove _dl_map_segment_align. Call _dl_map_segment_adjust to adjust
> > alignments of PT_LOAD segments, which marks and aligns only THP eligible
> > PT_LOAD segments to THP page size when loading an object. This fixes
> > BZ #34079.
> > 2. Rename DL_MAP_DEFAULT_THP_PAGESIZE to DL_DEFAULT_THP_PAGESIZE. If
> > DL_DEFAULT_THP_PAGESIZE is defined, assume that THP is enabled with
> > madvise in the kernel. Otherwise, call __get_thp_size to get THP page
> > size and call __get_thp_mode to get THP mode.
> > 3. Call _dl_executable_postprocess in rtld_setup_main_map for dynamic
> > executables and in LIBC_START_MAIN for static executables, which calls
> > madvise with MADV_HUGEPAGE on all THP eligible PT_LOAD segments in
> > executable. This fixes BZ #34080 for both dynamic and static executables.
> > 4. Call _dl_postprocess_loadcmd_extra in _dl_postprocess_loadcmd, which
> > calls madvise with MADV_HUGEPAGE on all THP eligible PT_LOAD segments
> > when loading an object after they have been mapped in. This fixes
> > BZ #34080 for shared objects.
> > 5. Add tests to verify that large executable PT_LOAD segments in
> > executables and shared libraries are mapped at addresses aligned to THP
> > page size when the kernel is configured to use THP in "always" mode or
> > "madvise" mode by inspecting /proc/self/maps to check that the mapping
> > address is aligned to THP page size reported by the kernel [1]. Also
> > verify that madvise is called with MADV_HUGEPAGE when the glibc tunable
> > glibc.elf.thp=1 is used and madvise isn't called with MADV_HUGEPAGE when
> > the glibc tunable glibc.elf.thp=0 is used.
> >
> > Skip these tests if THP page size cannot be determined or if THP is not
> > enabled in "always" mode nor "madvise" mode.
> >
> > Quote WANG Rui <wangrui@loongson.cn>:
> >
> > From benchmarking a clang build of the Linux kernel on x86_64 with
> > your patch in THP madvise mode, I observed that iTLB misses were
> > reduced, similar to what we see in THP always mode.
> >
> > [1] This is developed by WANG Rui <wangrui@loongson.cn>.
> >
> > Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> > Co-developed-by: WANG Rui <wangrui@loongson.cn>
>
> Changes from v1:
>
> 1. Rebased against the v10 THP test patch from WANG Rui <wangrui@loongson.cn>.
> 2. Keep DL_MAP_DEFAULT_THP_PAGESIZE.
>
> --
> H.J.
> ---
> The current THP segment load approach works only when THP is enabled
> with always in the kernel. If THP is enabled with madvise in the
> kernel, to enable THP segment load in an application, madvise should
> be called with MADV_HUGEPAGE on all THP eligible PT_LOAD segments:
>
> 1. Remove _dl_map_segment_align. Call _dl_map_segment_adjust to adjust
> alignments of PT_LOAD segments, which marks and aligns only THP eligible
> PT_LOAD segments to THP page size when loading an object. This fixes
> BZ #34079.
> 2. Call _dl_executable_postprocess in rtld_setup_main_map for dynamic
> executables and in LIBC_START_MAIN for static executables, which calls
> madvise with MADV_HUGEPAGE on all THP eligible PT_LOAD segments in
> executable. This fixes BZ #34080 for both dynamic and static executables.
> 3. Call _dl_postprocess_loadcmd_extra in _dl_postprocess_loadcmd, which
> calls madvise with MADV_HUGEPAGE on all THP eligible PT_LOAD segments
> when loading an object after they have been mapped in. This fixes
> BZ #34080 for shared objects.
> 4. Add tests to verify that large executable PT_LOAD segments in
> executables and shared libraries are mapped at addresses aligned to THP
> page size when the kernel is configured to use THP in "always" mode or
> "madvise" mode by inspecting /proc/self/maps to check that the mapping
> address is aligned to THP page size reported by the kernel [1]. Also
> verify that madvise is called with MADV_HUGEPAGE when the glibc tunable
> glibc.elf.thp=1 is used and madvise isn't called with MADV_HUGEPAGE when
> the glibc tunable glibc.elf.thp=0 is used.
>
> Skip these tests if THP page size cannot be determined or if THP is not
> enabled in "always" mode nor "madvise" mode.
>
> Quote WANG Rui <wangrui@loongson.cn>:
>
> From benchmarking a clang build of the Linux kernel on x86_64 with
> your patch in THP madvise mode, I observed that iTLB misses were
> reduced, similar to what we see in THP always mode.
>
> [1] This is developed by WANG Rui <wangrui@loongson.cn>.
>
> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> Co-developed-by: WANG Rui <wangrui@loongson.cn>
> ---
> csu/libc-start.c | 4 +
> elf/dl-load.c | 10 +-
> elf/dl-load.h | 5 +
> elf/dl-support.c | 6 +
> elf/rtld.c | 17 +--
> sysdeps/generic/dl-exec-post.h | 34 +++++
> ...{dl-map-segment-align.h => dl-load-post.h} | 7 +-
> sysdeps/generic/dl-map-segment-adjust.h | 30 ++++
> sysdeps/generic/hugepages.h | 4 +-
> sysdeps/generic/ldsodefs.h | 11 ++
> sysdeps/unix/sysv/linux/Makefile | 124 +++++++++++++++-
> sysdeps/unix/sysv/linux/dl-exec-post.h | 95 +++++++++++++
> sysdeps/unix/sysv/linux/dl-load-post.h | 32 +++++
> .../unix/sysv/linux/dl-map-segment-adjust.c | 67 +++++++++
> ...egment-align.h => dl-map-segment-adjust.h} | 10 +-
> .../unix/sysv/linux/dl-map-segment-align.c | 55 --------
> sysdeps/unix/sysv/linux/ldsodefs.h | 3 +
> sysdeps/unix/sysv/linux/loongarch/Makefile | 3 +
> ...{dl-map-segment-align.h => dl-exec-post.h} | 4 +-
> sysdeps/unix/sysv/linux/strace-tst-thp.sh | 56 ++++++++
> .../unix/sysv/linux/tst-thp-1-no-s-code-pde.c | 19 +++
> .../sysv/linux/tst-thp-1-no-s-code-static.c | 19 +++
> sysdeps/unix/sysv/linux/tst-thp-1-no-s-code.c | 19 +++
> sysdeps/unix/sysv/linux/tst-thp-1-pde.c | 19 +++
> sysdeps/unix/sysv/linux/tst-thp-1-static.c | 19 +++
> sysdeps/unix/sysv/linux/tst-thp-1.c | 28 ++++
> sysdeps/unix/sysv/linux/tst-thp-align-check.h | 132 ++++++++++++++++++
> sysdeps/unix/sysv/linux/tst-thp-align.c | 36 +++++
> sysdeps/unix/sysv/linux/tst-thp-size-mod.S | 24 ++++
> sysdeps/unix/sysv/linux/x86/dl-exec-post.h | 22 +++
> 30 files changed, 829 insertions(+), 85 deletions(-)
> create mode 100644 sysdeps/generic/dl-exec-post.h
> rename sysdeps/generic/{dl-map-segment-align.h => dl-load-post.h} (83%)
> create mode 100644 sysdeps/generic/dl-map-segment-adjust.h
> create mode 100644 sysdeps/unix/sysv/linux/dl-exec-post.h
> create mode 100644 sysdeps/unix/sysv/linux/dl-load-post.h
> create mode 100644 sysdeps/unix/sysv/linux/dl-map-segment-adjust.c
> rename sysdeps/unix/sysv/linux/{dl-map-segment-align.h => dl-map-segment-adjust.h} (79%)
> delete mode 100644 sysdeps/unix/sysv/linux/dl-map-segment-align.c
> rename sysdeps/unix/sysv/linux/loongarch/lp64/{dl-map-segment-align.h => dl-exec-post.h} (90%)
> create mode 100644 sysdeps/unix/sysv/linux/strace-tst-thp.sh
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-pde.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-static.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-1-no-s-code.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-1-pde.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-1-static.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-1.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-align-check.h
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-align.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-thp-size-mod.S
> create mode 100644 sysdeps/unix/sysv/linux/x86/dl-exec-post.h
>
> diff --git a/csu/libc-start.c b/csu/libc-start.c
> index 1c58561bce..be60831a42 100644
> --- a/csu/libc-start.c
> +++ b/csu/libc-start.c
> @@ -205,6 +205,7 @@ call_fini (void *unused)
> #endif /* !SHARED */
>
> #include <libc-start.h>
> +#include <dl-exec-post.h>
>
> STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
> MAIN_AUXVEC_DECL),
> @@ -305,6 +306,9 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
> __pointer_chk_guard_local = pointer_chk_guard;
> # endif
>
> + struct link_map *main_map = _dl_get_dl_main_map ();
> + _dl_executable_postprocess (main_map, GL(dl_phdr), GL(dl_phnum));
> +
> #endif /* !SHARED */
>
> /* Register the destructor of the dynamic linker if there is any. */
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index 48575fff06..800b7ca1a6 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
> @@ -71,7 +71,7 @@ struct filebuf
> #include <dl-dst.h>
> #include <dl-load.h>
> #include <dl-map-segments.h>
> -#include <dl-map-segment-align.h>
> +#include <dl-map-segment-adjust.h>
> #include <dl-unmap-segments.h>
> #include <dl-machine-reject-phdr.h>
> #include <dl-prop.h>
> @@ -1173,8 +1173,8 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
> /* Optimize a common case. */
> c->prot = pf_to_prot (ph->p_flags);
>
> - /* Architecture-specific adjustment of segment alignment. */
> - p_align_max = _dl_map_segment_align (c, p_align_max);
> + /* Initialize flags. */
> + c->flags = 0;
> break;
>
> case PT_TLS:
> @@ -1229,9 +1229,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
> goto lose;
> }
>
> - /* Align all PT_LOAD segments to the maximum p_align. */
> - for (size_t i = 0; i < nloadcmds; i++)
> - loadcmds[i].mapalign = p_align_max;
> + _dl_map_segment_adjust (loadcmds, &nloadcmds, p_align_max);
>
> /* dlopen of an executable is not valid because it is not possible
> to perform proper relocations, handle static TLS, or run the
> diff --git a/elf/dl-load.h b/elf/dl-load.h
> index 897c4034c5..55edf0323c 100644
> --- a/elf/dl-load.h
> +++ b/elf/dl-load.h
> @@ -78,8 +78,11 @@ struct loadcmd
> ElfW(Addr) mapstart, mapend, dataend, allocend, mapalign;
> ElfW(Off) mapoff;
> int prot; /* PROT_* bits. */
> + /* May be used by _dl_postprocess_loadcmd_extra. */
> + unsigned int flags;
> };
>
> +#include <dl-load-post.h>
>
> /* This is a subroutine of _dl_map_segments. It should be called for each
> load command, some time after L->l_addr has been set correctly. It is
> @@ -95,6 +98,8 @@ _dl_postprocess_loadcmd (struct link_map *l, const ElfW(Ehdr) *header,
> /* Found the program header in this segment. */
> l->l_phdr = (void *) (uintptr_t) (c->mapstart + header->e_phoff
> - c->mapoff);
> +
> + _dl_postprocess_loadcmd_extra (l, c);
> }
>
>
> diff --git a/elf/dl-support.c b/elf/dl-support.c
> index 0508d6113b..420e418b40 100644
> --- a/elf/dl-support.c
> +++ b/elf/dl-support.c
> @@ -179,6 +179,12 @@ int _dl_stack_cache_lock;
> #endif
> struct dl_scope_free_list *_dl_scope_free_list;
>
> +#ifdef HAVE_THP
> +int _dl_thp_control = -1;
> +enum thp_mode_t _dl_thp_mode;
> +size_t _dl_thp_pagesize;
> +#endif
> +
> #ifdef NEED_DL_SYSINFO
> /* Needed for improved syscall handling on at least x86/Linux. NB: Don't
> initialize it here to avoid RELATIVE relocation in static PIE. */
> diff --git a/elf/rtld.c b/elf/rtld.c
> index e926ec73e4..fe8d6f87e3 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -52,6 +52,7 @@
> #include <dl-find_object.h>
> #include <dl-audit-check.h>
> #include <dl-call_tls_init_tp.h>
> +#include <dl-exec-post.h>
>
> #include <assert.h>
>
> @@ -323,6 +324,9 @@ struct rtld_global _rtld_global =
> /* Generally the default presumption without further information is an
> * executable stack but this is not true for all platforms. */
> ._dl_stack_prot_flags = DEFAULT_STACK_PROT_PERMS,
> +#ifdef HAVE_THP
> + ._dl_thp_control = -1,
> +#endif
> #ifdef _LIBC_REENTRANT
> ._dl_load_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
> ._dl_load_write_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
> @@ -1209,14 +1213,8 @@ rtld_setup_main_map (struct link_map *main_map)
> main_map->l_relro_size = ph->p_memsz;
> break;
> }
> - /* Process program headers again, but scan them backwards since
> - PT_GNU_PROPERTY is close to the end of program headers. */
> - for (const ElfW(Phdr) *ph = &phdr[phnum]; ph != phdr; --ph)
> - if (ph[-1].p_type == PT_GNU_PROPERTY)
> - {
> - _dl_process_pt_gnu_property (main_map, -1, &ph[-1]);
> - break;
> - }
> +
> + _dl_executable_postprocess (main_map, phdr, phnum);
>
> /* Adjust the address of the TLS initialization image in case
> the executable is actually an ET_DYN object. */
> @@ -1589,6 +1587,9 @@ dl_main (const ElfW(Phdr) *phdr,
> {
> RTLD_TIMING_VAR (start);
> rtld_timer_start (&start);
> +#ifdef HAVE_THP
> + _dl_get_thp_config ();
> +#endif
> _dl_map_object (NULL, rtld_progname, lt_executable, 0,
> __RTLD_OPENEXEC, LM_ID_BASE);
> rtld_timer_stop (&load_time, start);
> diff --git a/sysdeps/generic/dl-exec-post.h b/sysdeps/generic/dl-exec-post.h
> new file mode 100644
> index 0000000000..f5dcdc093a
> --- /dev/null
> +++ b/sysdeps/generic/dl-exec-post.h
> @@ -0,0 +1,34 @@
> +/* _dl_executable_postprocess. Generic version.
> + Copyright (C) 2026 Free Software Foundation, Inc.
> + Copyright The GNU Toolchain Authors.
> + 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/>. */
> +
> +static inline void
> +_dl_executable_postprocess (struct link_map *main_map,
> + const ElfW(Phdr) *phdr, ElfW(Word) phnum)
> +{
> +#ifdef SHARED
> + /* Process program headers again, but scan them backwards since
> + PT_GNU_PROPERTY is close to the end of program headers. */
> + for (const ElfW(Phdr) *ph = &phdr[phnum]; ph != phdr; --ph)
> + if (ph[-1].p_type == PT_GNU_PROPERTY)
> + {
> + _dl_process_pt_gnu_property (main_map, -1, &ph[-1]);
> + break;
> + }
> +#endif
> +}
> diff --git a/sysdeps/generic/dl-map-segment-align.h b/sysdeps/generic/dl-load-post.h
> similarity index 83%
> rename from sysdeps/generic/dl-map-segment-align.h
> rename to sysdeps/generic/dl-load-post.h
> index f4a671f25f..bfaad8ea7c 100644
> --- a/sysdeps/generic/dl-map-segment-align.h
> +++ b/sysdeps/generic/dl-load-post.h
> @@ -1,4 +1,4 @@
> -/* _dl_map_segment_align. Generic version.
> +/* _dl_postprocess_loadcmd_extra. Generic version.
> Copyright (C) 2026 Free Software Foundation, Inc.
> Copyright The GNU Toolchain Authors.
> This file is part of the GNU C Library.
> @@ -19,8 +19,7 @@
>
> #include <dl-load.h>
>
> -static inline ElfW(Addr)
> -_dl_map_segment_align (const struct loadcmd *c, ElfW(Addr) p_align_max)
> +static inline void
> +_dl_postprocess_loadcmd_extra (struct link_map *l, const struct loadcmd *c)
> {
> - return p_align_max;
> }
> diff --git a/sysdeps/generic/dl-map-segment-adjust.h b/sysdeps/generic/dl-map-segment-adjust.h
> new file mode 100644
> index 0000000000..b48057ec26
> --- /dev/null
> +++ b/sysdeps/generic/dl-map-segment-adjust.h
> @@ -0,0 +1,30 @@
> +/* _dl_map_segment_adjust. Generic version.
> + Copyright (C) 2026 Free Software Foundation, Inc.
> + Copyright The GNU Toolchain Authors.
> + 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 <dl-load.h>
> +
> +static inline void
> +_dl_map_segment_adjust (struct loadcmd *load_cmds,
> + size_t *n_load_cmds, ElfW(Addr) p_align_max)
> +{
> + /* Align all PT_LOAD segments to the maximum p_align. */
> + size_t n = *n_load_cmds;
> + for (size_t i = 0; i < n; i++)
> + load_cmds[i].mapalign = p_align_max;
> +}
> diff --git a/sysdeps/generic/hugepages.h b/sysdeps/generic/hugepages.h
> index 5fc9b5c8de..df9ec4920b 100644
> --- a/sysdeps/generic/hugepages.h
> +++ b/sysdeps/generic/hugepages.h
> @@ -26,10 +26,10 @@ unsigned long int __get_thp_size (void) attribute_hidden;
>
> enum thp_mode_t
> {
> + thp_mode_not_supported = 0,
> thp_mode_always,
> thp_mode_madvise,
> - thp_mode_never,
> - thp_mode_not_supported
> + thp_mode_never
> };
>
> enum thp_mode_t __get_thp_mode (void) attribute_hidden;
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 15c4659853..36f2e88ae4 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -39,6 +39,7 @@
> #include <libc-lock.h>
> #include <hp-timing.h>
> #include <list_t.h>
> +#include <hugepages.h>
>
> __BEGIN_DECLS
>
> @@ -477,6 +478,16 @@ struct rtld_global
> EXTERN struct __pthread **_dl_pthread_threads;
> __mach_rwlock_define (EXTERN, _dl_pthread_threads_lock)
> #endif
> +#ifdef HAVE_THP
> + /* The THP segment load control:
> + > 0: Enabled by GLIBC_TUNABLES=glibc.elf.thp=1.
> + 0: Disabled by GLIBC_TUNABLES=glibc.elf.thp=0.
> + < 0: To be enabled or disabled by GLIBC_TUNABLES. */
I think we need to treat THP-always and THP-madvise differently. For
always, it seems reasonable to let an architecture enable
`glibc.elf.thp` by default. But for madvise, it should be opt-in only.
> + EXTERN int _dl_thp_control;
> +
> + EXTERN enum thp_mode_t _dl_thp_mode;
> + EXTERN size_t _dl_thp_pagesize;
> +#endif
> #ifdef SHARED
> };
> # define __rtld_global_attribute__
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index b06afbdeaa..41d321c564 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -673,7 +673,7 @@ endif
>
> ifeq ($(subdir),elf)
> dl-routines += \
> - dl-map-segment-align \
> + dl-map-segment-adjust \
> dl-rseq-symbols \
> # dl-routines
>
> @@ -698,13 +698,19 @@ $(objpfx)pldd: $(objpfx)xmalloc.o
> tests += \
> tst-rseq-tls-range \
> tst-rseq-tls-range-4096 \
> + tst-thp-1 \
> + tst-thp-1-pde \
> + tst-thp-1-static \
> + tst-thp-align \
> # tests
> tests-static += \
> tst-rseq-tls-range-4096-static \
> tst-rseq-tls-range-static \
> + tst-thp-1-static \
> # tests-static
> modules-names += \
> tst-rseq-tls-range-mod \
> + tst-thp-size-mod \
> # modules-names
> CFLAGS-tst-rseq-tls-range.c += -DMAIN_TLS_ALIGN=4
> CFLAGS-tst-rseq-tls-range-4096.c += -DMAIN_TLS_ALIGN=4096
> @@ -724,6 +730,122 @@ tests-special += \
> $(objpfx)tst-nolink-libc-2.out \
> # tests-special
> endif
> +
> +ifndef THP-PAGE-SIZE
> +# Align PT_LOAD segments in THP tests to THP page size so that kernel will
> +# map PIE to the address aligned to THP page size. Default THP page size
> +# to 2MB which can be overridden in Makefile in subdirectories.
> +THP-PAGE-SIZE = 0x200000
> +endif
> +
> +THP-PAGE-SIZE-LDFLAGS = -Wl,-z,max-page-size=$(THP-PAGE-SIZE)
> +
> +LDFLAGS-tst-thp-size-mod.so = $(THP-PAGE-SIZE-LDFLAGS)
> +tst-thp-align-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +$(objpfx)tst-thp-align.out: $(objpfx)tst-thp-size-mod.so
> +
> +ifeq ($(have-separate-code),yes)
> +tests += \
> + tst-thp-1-no-s-code \
> + tst-thp-1-no-s-code-pde \
> + tst-thp-1-no-s-code-static \
> +# tests
> +tests-static += \
> + tst-thp-1-no-s-code-static \
> +# tests-static
> +
> +LDFLAGS-tst-thp-1 = -Wl,-z,separate-code $(THP-PAGE-SIZE-LDFLAGS)
> +LDFLAGS-tst-thp-1-pde = -Wl,-z,separate-code $(THP-PAGE-SIZE-LDFLAGS)
> +LDFLAGS-tst-thp-1-static = -Wl,-z,separate-code $(THP-PAGE-SIZE-LDFLAGS)
> +LDFLAGS-tst-thp-1-no-s-code = -Wl,-z,noseparate-code \
> + $(THP-PAGE-SIZE-LDFLAGS)
> +LDFLAGS-tst-thp-1-no-s-code-pde = -Wl,-z,noseparate-code \
> + $(THP-PAGE-SIZE-LDFLAGS)
> +LDFLAGS-tst-thp-1-no-s-code-static = -Wl,-z,noseparate-code \
> + $(THP-PAGE-SIZE-LDFLAGS)
> +
> +$(objpfx)tst-thp-1-no-s-code: $(objpfx)tst-thp-size-mod.o
> +$(objpfx)tst-thp-1-no-s-code-pde: $(objpfx)tst-thp-size-mod.o
> +$(objpfx)tst-thp-1-no-s-code-static: $(objpfx)tst-thp-size-mod.o
> +
> +tst-thp-1-no-s-code-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-no-s-code-pde-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-no-s-code-static-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +
> +tst-thp-1-no-s-code-pde-no-pie = yes
> +endif
> +
> +tst-thp-1-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-pde-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-static-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +
> +$(objpfx)tst-thp-1: $(objpfx)tst-thp-size-mod.o
> +$(objpfx)tst-thp-1-pde: $(objpfx)tst-thp-size-mod.o
> +$(objpfx)tst-thp-1-static: $(objpfx)tst-thp-size-mod.o
> +
> +tst-thp-1-pde-no-pie = yes
> +
> +thp-kernel-status = $(shell grep madvise /sys/kernel/mm/transparent_hugepage/enabled)
> +# Verify that madvise is called with MADV_HUGEPAGE when THP is enabled
> +# under madvise THP kernel.
> +ifneq ($(findstring [madvise],$(thp-kernel-status)),)
> +tests-special += \
> + $(objpfx)strace-tst-thp-1-disabled.out \
> + $(objpfx)strace-tst-thp-1-enabled.out \
> + $(objpfx)strace-tst-thp-1-pde-disabled.out \
> + $(objpfx)strace-tst-thp-1-pde-enabled.out \
> + $(objpfx)strace-tst-thp-1-static-disabled.out \
> + $(objpfx)strace-tst-thp-1-static-enabled.out \
> +# tests-special
> +
> +$(objpfx)strace-tst-thp-1-enabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1
> + $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + '$(rpath-link)' $(objpfx)tst-thp-1 > $@;
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-disabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1
> + $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + '$(rpath-link)' $(objpfx)tst-thp-1 > $@;
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-pde-enabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1-pde
> + $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + '$(rpath-link)' $(objpfx)tst-thp-1-pde > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-pde-disabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1-pde
> + $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + '$(rpath-link)' $(objpfx)tst-thp-1-pde > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-static-enabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1-static
> + $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + '$(rpath-link)' $(objpfx)tst-thp-1-static > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-static-disabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1-static
> + $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + '$(rpath-link)' $(objpfx)tst-thp-1-static > $@; \
> + $(evaluate-test)
> +endif
> endif # $(subdir) == elf
>
> ifeq ($(subdir),rt)
> diff --git a/sysdeps/unix/sysv/linux/dl-exec-post.h b/sysdeps/unix/sysv/linux/dl-exec-post.h
> new file mode 100644
> index 0000000000..1ef1f6556e
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/dl-exec-post.h
> @@ -0,0 +1,95 @@
> +/* _dl_executable_postprocess. Linux version.
> + Copyright (C) 2026 Free Software Foundation, Inc.
> + Copyright The GNU Toolchain Authors.
> + 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/>. */
> +
> +static inline void
> +_dl_get_thp_config (void)
> +{
> + /* Check if there is GLIBC_TUNABLES=glibc.elf.thp=[0|1]. */
> + if (TUNABLE_IS_INITIALIZED_FULL (glibc, elf, thp))
> + GL(dl_thp_control) = TUNABLE_GET_FULL (glibc, elf, thp, int32_t,
> + NULL);
> +
> + /* Return if THP is disabled by GLIBC_TUNABLES=glibc.elf.thp=0. */
> + if (GL(dl_thp_control) == 0)
> + return;
> +
> +#ifdef DL_MAP_DEFAULT_THP_PAGESIZE
> + /* NB: Accessing /sys/kernel/mm files is quite expensive and the file
> + may not be accessible in containers. If DL_MAP_DEFAULT_THP_PAGESIZE
> + is defined, assume THP mode is madvise and always call madvise.
> + Since madvise is a fast systemcall, it adds only a small overhead
> + compared to the cost of accessing /sys/kernel/mm files. */
> + GL(dl_thp_pagesize) = DL_MAP_DEFAULT_THP_PAGESIZE;
> + GL(dl_thp_mode) = thp_mode_madvise;
> +#else
> + GL(dl_thp_pagesize) = __get_thp_size ();
> + GL(dl_thp_mode) = __get_thp_mode ();
> +#endif
> +}
> +
> +static inline void
> +_dl_executable_postprocess (struct link_map *main_map,
> + const ElfW(Phdr) *phdr, ElfW(Word) phnum)
> +{
> + if (GL(dl_thp_control) == -1)
> + _dl_get_thp_config ();
> +
> + /* NB: In static executable, PT_GNU_PROPERTY is processed in target
> + libc-start.h if it is needed by target. When ld.so is used, if
> + a target doesn't need PT_GNU_PROPERTY, _dl_process_pt_gnu_property
> + is an empty function. */
> +#ifdef SHARED
> + /* Process program headers again, but scan them backwards since
> + PT_GNU_PROPERTY is close to the end of program headers. */
> + for (const ElfW(Phdr) *ph = &phdr[phnum]; ph != phdr; --ph)
> + if (ph[-1].p_type == PT_GNU_PROPERTY)
> + {
> + _dl_process_pt_gnu_property (main_map, -1, &ph[-1]);
> + break;
> + }
> +#endif
> +
> + /* Return if THP segment load isn't enabled. */
> + if (GL(dl_thp_control) <= 0)
> + return;
> +
> +#ifndef DL_MAP_DEFAULT_THP_PAGESIZE
> + /* NB: If DL_MAP_DEFAULT_THP_PAGESIZE is defined, dl_thp_mode is always
> + set to thp_mode_madvise. */
> + if (GL(dl_thp_mode) != thp_mode_madvise)
> + return;
> +#endif
> +
> + /* When we get here, the main executable have been mapped in. Call
> + madvise with MADV_HUGEPAGE for all THP eligible PT_LOAD segments. */
> +
> + const ElfW(Phdr) *ph;
> +
> + size_t thp_pagesize = GL(dl_thp_pagesize);
> +
> + /* Call __madvise if offset and address of the PT_LOAD segment are
> + aligned to THP page size and it is read-only. */
> + for (ph = phdr; ph < &phdr[phnum]; ++ph)
> + if (ph->p_type == PT_LOAD
> + && ph->p_memsz >= thp_pagesize
> + && ((ph->p_vaddr | ph->p_offset) & (thp_pagesize - 1)) == 0
> + && (ph->p_flags & (PF_W | PF_R)) == PF_R)
> + __madvise ((void *) (main_map->l_addr + ph->p_vaddr),
> + ph->p_memsz, MADV_HUGEPAGE);
> +}
> diff --git a/sysdeps/unix/sysv/linux/dl-load-post.h b/sysdeps/unix/sysv/linux/dl-load-post.h
> new file mode 100644
> index 0000000000..b3c4e16bb7
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/dl-load-post.h
> @@ -0,0 +1,32 @@
> +/* _dl_postprocess_loadcmd_extra. Linux version.
> + Copyright (C) 2026 Free Software Foundation, Inc.
> + Copyright The GNU Toolchain Authors.
> + 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/>. */
> +
> +/* Bits in the flags field of struct loadcmd. */
> +#define LOADCMD_POST_MADVISE_THP (0x1 << 0)
> +
> +/* After L has been mapped in, call madvise with MADV_HUGEPAGE if L is
> + THP eligible. */
> +
> +static inline void
> +_dl_postprocess_loadcmd_extra (struct link_map *l, const struct loadcmd *c)
> +{
> + if ((c->flags & LOADCMD_POST_MADVISE_THP) != 0)
> + __madvise ((void *) (l->l_addr + c->mapstart),
> + c->mapend - c->mapstart, MADV_HUGEPAGE);
> +}
> diff --git a/sysdeps/unix/sysv/linux/dl-map-segment-adjust.c b/sysdeps/unix/sysv/linux/dl-map-segment-adjust.c
> new file mode 100644
> index 0000000000..90c8ea92fe
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/dl-map-segment-adjust.c
> @@ -0,0 +1,67 @@
> +/* _dl_map_segment_adjust. Linux version.
> + Copyright (C) 2026 Free Software Foundation, Inc.
> + Copyright The GNU Toolchain Authors.
> + 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 <ldsodefs.h>
> +#include <dl-map-segment-adjust.h>
> +
> +/* Set the mapalign field in entries in LOAD_CMDS to align PT_LOAD
> + segments for THP. P_ALIGN_MAX is the maximum p_align value in all
> + PT_LOAD segments. */
> +
> +void
> +_dl_map_segment_adjust (struct loadcmd *load_cmds, size_t *n_load_cmds,
> + ElfW(Addr) p_align_max)
size_t n_load_cmds?
> +{
> + size_t n = *n_load_cmds;
> + size_t i;
> + enum thp_mode_t thp_mode = GL(dl_thp_mode);
> + size_t thp_pagesize = GL(dl_thp_pagesize);
> + struct loadcmd *c = load_cmds;
> +
> + if (n == 0)
> + return;
> +
> + /* We cap the huge page size at MAX_THP_PAGESIZE to avoid over-aligning
> + on systems with very large normal pages (like 64K pages with 512M
> + huge pages). */
> + if (GL(dl_thp_control) <= 0
> + || p_align_max >= thp_pagesize
> + || !(thp_mode == thp_mode_always || thp_mode == thp_mode_madvise))
Missing a check for MAX_THP_PAGESIZE?
> + {
> + for (i = 0; i < n; i++, c++)
> + c->mapalign = p_align_max;
> + return;
> + }
> +
> + /* Set the mapalign field to THP page size only if offset and address
> + of the segment are aligned to THP page size, it is read-only and
> + its size >= THP page size. It helps improve THP eligibility and
> + reduces TLB pressure. */
> + for (i = 0; i < n; i++, c++)
> + if (((c->mapstart | c->mapoff) & (thp_pagesize - 1)) == 0
> + && (c->mapend - c->mapstart) >= thp_pagesize
> + && (c->prot & PROT_WRITE) == 0)
> + {
> + c->mapalign = thp_pagesize;
> + if (thp_mode == thp_mode_madvise)
> + c->flags = LOADCMD_POST_MADVISE_THP;
> + }
> + else
> + c->mapalign = p_align_max;
> +}
> diff --git a/sysdeps/unix/sysv/linux/dl-map-segment-align.h b/sysdeps/unix/sysv/linux/dl-map-segment-adjust.h
> similarity index 79%
> rename from sysdeps/unix/sysv/linux/dl-map-segment-align.h
> rename to sysdeps/unix/sysv/linux/dl-map-segment-adjust.h
Why rename this hook?
> index d9b05181b7..2fbfc66d48 100644
> --- a/sysdeps/unix/sysv/linux/dl-map-segment-align.h
> +++ b/sysdeps/unix/sysv/linux/dl-map-segment-adjust.h
> @@ -1,4 +1,4 @@
> -/* _dl_map_segment_align. Linux version.
> +/* _dl_map_segment_adjust. Linux version.
> Copyright (C) 2026 Free Software Foundation, Inc.
> Copyright The GNU Toolchain Authors.
> This file is part of the GNU C Library.
> @@ -19,9 +19,5 @@
>
> #include <dl-load.h>
>
> -#ifndef DL_MAP_DEFAULT_THP_PAGESIZE
> -# define DL_MAP_DEFAULT_THP_PAGESIZE 0
> -#endif
> -
> -extern ElfW (Addr) _dl_map_segment_align
> - (const struct loadcmd *, ElfW (Addr)) attribute_hidden;
> +extern void _dl_map_segment_adjust
> + (struct loadcmd *, size_t *, ElfW(Addr)) attribute_hidden;
> diff --git a/sysdeps/unix/sysv/linux/dl-map-segment-align.c b/sysdeps/unix/sysv/linux/dl-map-segment-align.c
> deleted file mode 100644
> index a39e74d91b..0000000000
> --- a/sysdeps/unix/sysv/linux/dl-map-segment-align.c
> +++ /dev/null
> @@ -1,55 +0,0 @@
> -/* _dl_map_segment_align. Linux version.
> - Copyright (C) 2026 Free Software Foundation, Inc.
> - Copyright The GNU Toolchain Authors.
> - 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 <dl-map-segment-align.h>
> -#include <dl-tunables.h>
> -#include <hugepages.h>
> -
> -ElfW (Addr)
> -_dl_map_segment_align (const struct loadcmd *c, ElfW (Addr) p_align_max)
> -{
> - static enum thp_mode_t thp_mode = thp_mode_not_supported;
> - static unsigned long int thp_pagesize;
> -
> - if (TUNABLE_GET (glibc, elf, thp, int32_t, NULL) == 0)
> - return p_align_max;
> -
> - if (__glibc_unlikely (thp_mode == thp_mode_not_supported
> - || thp_pagesize == 0))
> - {
> - unsigned long int default_thp_pagesize = DL_MAP_DEFAULT_THP_PAGESIZE;
> - thp_mode = default_thp_pagesize ? thp_mode_always : __get_thp_mode ();
> - thp_pagesize = default_thp_pagesize ? : __get_thp_size ();
> - }
> -
> - /* Aligning load segments that are large enough to the PMD size helps
> - improve THP eligibility and reduces TLB pressure.
> - We cap the huge page size at MAX_THP_PAGESIZE to avoid over-aligning
> - on systems with very large normal pages (like 64K pages with 512M
> - huge pages). */
> - if (thp_mode == thp_mode_always
> - && thp_pagesize <= MAX_THP_PAGESIZE
> - && ((c->mapstart | c->mapoff) & (thp_pagesize - 1)) == 0
> - && (c->mapend - c->mapstart) >= thp_pagesize
> - && p_align_max < thp_pagesize
> - && (c->prot & PROT_WRITE) == 0)
> - return thp_pagesize;
> -
> - return p_align_max;
> -}
> diff --git a/sysdeps/unix/sysv/linux/ldsodefs.h b/sysdeps/unix/sysv/linux/ldsodefs.h
> index c63b649432..e39d9afe34 100644
> --- a/sysdeps/unix/sysv/linux/ldsodefs.h
> +++ b/sysdeps/unix/sysv/linux/ldsodefs.h
> @@ -21,6 +21,9 @@
> /* We have the auxiliary vector. */
> #define HAVE_AUX_VECTOR
>
> +/* We have transparent huge page. */
> +#define HAVE_THP
> +
> /* Get the real definitions. */
> #include_next <ldsodefs.h>
>
> diff --git a/sysdeps/unix/sysv/linux/loongarch/Makefile b/sysdeps/unix/sysv/linux/loongarch/Makefile
> index 0d5f087862..d5beb62440 100644
> --- a/sysdeps/unix/sysv/linux/loongarch/Makefile
> +++ b/sysdeps/unix/sysv/linux/loongarch/Makefile
> @@ -12,3 +12,6 @@ abi-ilp32s-condition := __WORDSIZE == 32 && defined __loongarch_soft_float
> abi-ilp32d-condition := __WORDSIZE == 32 && defined __loongarch_double_float
> abi-lp64s-condition := __WORDSIZE == 64 && defined __loongarch_soft_float
> abi-lp64d-condition := __WORDSIZE == 64 && defined __loongarch_double_float
> +
> +# Align THP tests to 32MB.
> +THP-PAGE-SIZE = 0x2000000
> diff --git a/sysdeps/unix/sysv/linux/loongarch/lp64/dl-map-segment-align.h b/sysdeps/unix/sysv/linux/loongarch/lp64/dl-exec-post.h
> similarity index 90%
> rename from sysdeps/unix/sysv/linux/loongarch/lp64/dl-map-segment-align.h
> rename to sysdeps/unix/sysv/linux/loongarch/lp64/dl-exec-post.h
> index c51ee4ac47..fbc58d662c 100644
> --- a/sysdeps/unix/sysv/linux/loongarch/lp64/dl-map-segment-align.h
> +++ b/sysdeps/unix/sysv/linux/loongarch/lp64/dl-exec-post.h
> @@ -1,4 +1,4 @@
> -/* _dl_map_segment_align. LoongArch64 Linux version.
> +/* DL_MAP_DEFAULT_THP_PAGESIZE. LoongArch64 Linux version.
> Copyright (C) 2026 Free Software Foundation, Inc.
> Copyright The GNU Toolchain Authors.
> This file is part of the GNU C Library.
> @@ -19,4 +19,4 @@
>
> #define DL_MAP_DEFAULT_THP_PAGESIZE (32 * 1024 * 1024)
>
> -#include_next <dl-map-segment-align.h>
> +#include_next <dl-exec-post.h>
> diff --git a/sysdeps/unix/sysv/linux/strace-tst-thp.sh b/sysdeps/unix/sysv/linux/strace-tst-thp.sh
> new file mode 100644
> index 0000000000..8903717fd4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/strace-tst-thp.sh
> @@ -0,0 +1,56 @@
> +#!/bin/sh
> +# Run THP test under strace to verify control of the THP segment load.
> +# Copyright (C) 2026 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/>.
> +
> +set -e
> +
> +rtld="$1"
> +test_wrapper_env="$2"
> +run_program_env="$3"
> +library_path="$4"
> +test_prog="$5"
> +
> +# Test whether strace is available in the test environment. If not, skip
> +# the test.
> +${test_wrapper_env} ${run_program_env} \
> + /bin/sh -c "command -v strace" || exit 77
> +
> +# Finally the actual test inside the test environment, using the just
> +# build ld.so and new libraries to run the THP test under strace.
> +if /bin/sh -c \
> + "${test_wrapper_env} ${run_program_env} strace ${rtld} \
> + --library-path ${library_path} ${test_prog} 2>&1 \
> + | grep -E \"madvise(.*, MADV_HUGEPAGE)\""; then
> + case x"${run_program_env}" in
> + *glibc.elf.thp=1*)
> + exit 0
> + ;;
> + *)
> + exit 1
> + ;;
> + esac
> +else
> + case x"${run_program_env}" in
> + *glibc.elf.thp=0*)
> + exit 0
> + ;;
> + *)
> + exit 1
> + ;;
> + esac
> +fi
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-pde.c b/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-pde.c
> new file mode 100644
> index 0000000000..3fd01e9bfe
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-pde.c
> @@ -0,0 +1,19 @@
> +/* Test PDE with THP segment load linked with -Wl,-z,noseparate-code.
> + Copyright (C) 2026 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 "tst-thp-1.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-static.c b/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-static.c
> new file mode 100644
> index 0000000000..d0ae0f1ff0
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code-static.c
> @@ -0,0 +1,19 @@
> +/* Test static with THP segment load linked with -Wl,-z,noseparate-code.
> + Copyright (C) 2026 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 "tst-thp-1.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code.c b/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code.c
> new file mode 100644
> index 0000000000..5eb1e005ed
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-1-no-s-code.c
> @@ -0,0 +1,19 @@
> +/* Test THP segment load linked with -Wl,-z,noseparate-code.
> + Copyright (C) 2026 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 "tst-thp-1.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-1-pde.c b/sysdeps/unix/sysv/linux/tst-thp-1-pde.c
> new file mode 100644
> index 0000000000..d854dd43da
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-1-pde.c
> @@ -0,0 +1,19 @@
> +/* Test PDE with THP segment load linked with -Wl,-z,separate-code.
> + Copyright (C) 2026 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 "tst-thp-1.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-1-static.c b/sysdeps/unix/sysv/linux/tst-thp-1-static.c
> new file mode 100644
> index 0000000000..66d7e12954
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-1-static.c
> @@ -0,0 +1,19 @@
> +/* Test static with THP segment load linked with -Wl,-z,separate-code.
> + Copyright (C) 2026 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 "tst-thp-1.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-1.c b/sysdeps/unix/sysv/linux/tst-thp-1.c
> new file mode 100644
> index 0000000000..49eea7069c
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-1.c
> @@ -0,0 +1,28 @@
> +/* Test THP segment load linked with -Wl,-z,separate-code.
> + Copyright (C) 2026 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 "tst-thp-align-check.h"
> +
> +static int
> +do_test (void)
> +{
> + check_align ("tst-thp-1");
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-align-check.h b/sysdeps/unix/sysv/linux/tst-thp-align-check.h
> new file mode 100644
> index 0000000000..bcb50c96f8
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-align-check.h
> @@ -0,0 +1,132 @@
> +/* Test the THP compatible alignment of PT_LOAD segments.
> +
> + Copyright (C) 2026 Free Software Foundation, Inc.
> +
> + 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 <fcntl.h>
> +#include <stdint.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <intprops.h>
> +#include <inttypes.h>
> +#include <support/check.h>
> +#include <support/xstdio.h>
> +#include <support/xunistd.h>
> +#define attribute_hidden
> +#include <hugepages.h> /* For enum thp_mode_t and MAX_THP_PAGESIZE. */
> +#undef attribute_hidden
> +
> +static unsigned long int
> +get_thp_size (void)
> +{
> + int fd = open ("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size",
> + O_RDONLY, 0);
> + if (fd == -1)
> + return 0;
> +
> + char str[INT_BUFSIZE_BOUND (unsigned long int)];
> + ssize_t s = read (fd, str, sizeof (str));
> + close (fd);
> + if (s < 0)
> + return 0;
> +
> + unsigned long int r = 0;
> + for (ssize_t i = 0; i < s; i++)
> + {
> + if (str[i] == '\n')
> + break;
> + r *= 10;
> + r += str[i] - '0';
> + }
> + return r;
> +}
> +
> +static enum thp_mode_t
> +get_thp_mode (void)
> +{
> + int fd = open ("/sys/kernel/mm/transparent_hugepage/enabled", O_RDONLY, 0);
> + if (fd == -1)
> + return thp_mode_not_supported;
> +
> + static const char mode_always[] = "[always] madvise never\n";
> + static const char mode_madvise[] = "always [madvise] never\n";
> + static const char mode_never[] = "always madvise [never]\n";
> +
> + char str[sizeof(mode_always)];
> + ssize_t s = read (fd, str, sizeof (str));
> + if (s >= sizeof str || s < 0)
> + return thp_mode_not_supported;
> + str[s] = '\0';
> + close (fd);
> +
> + if (s == sizeof (mode_always) - 1)
> + {
> + if (strcmp (str, mode_always) == 0)
> + return thp_mode_always;
> + else if (strcmp (str, mode_madvise) == 0)
> + return thp_mode_madvise;
> + else if (strcmp (str, mode_never) == 0)
> + return thp_mode_never;
> + }
> + return thp_mode_not_supported;
> +}
> +
> +static void
> +check_align (const char *name)
> +{
> + unsigned long int thp_size = get_thp_size ();
> + enum thp_mode_t thp_mode = get_thp_mode ();
> +
> + if (thp_size == 0)
> + {
> + FAIL_UNSUPPORTED ("unable to get THP size.\n");
> + return;
> + }
> +
> + if (thp_size > MAX_THP_PAGESIZE)
> + {
> + FAIL_UNSUPPORTED ("THP size exceeds MAX_THP_PAGESIZE.\n");
> + return;
> + }
> +
> + if (thp_mode != thp_mode_always && thp_mode != thp_mode_madvise)
> + {
> + FAIL_UNSUPPORTED ("THP mode is not always nor madvise.\n");
> + return;
> + }
> +
> + FILE *f = xfopen ("/proc/self/maps", "r");
> + char *line = NULL;
> + size_t len;
> +
> + while (xgetline (&line, &len, f))
> + {
> + uintptr_t from, to;
> + char *prot = NULL, *path = NULL;
> + int r = sscanf (line, "%" SCNxPTR "-%" SCNxPTR "%ms%*s%*s%*s%ms",
> + &from, &to, &prot, &path);
> +
> + TEST_VERIFY (r == 3 || r == 4);
> +
> + if (strstr (prot, "x") && strstr (path, name))
> + TEST_COMPARE (from % thp_size, 0);
> +
> + free (path);
> + }
> +
> + free (line);
> + xfclose (f);
> +}
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-align.c b/sysdeps/unix/sysv/linux/tst-thp-align.c
> new file mode 100644
> index 0000000000..2e44109ba6
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-align.c
> @@ -0,0 +1,36 @@
> +/* Test the THP compatible alignment of PT_LOAD segments.
> +
> + Copyright (C) 2026 Free Software Foundation, Inc.
> +
> + 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/xdlfcn.h>
> +#include "tst-thp-align-check.h"
> +
> +#define THP_SIZE_MOD_NAME "tst-thp-size-mod.so"
> +
> +static int
> +do_test (void)
> +{
> + void *dl;
> +
> + dl = xdlopen (THP_SIZE_MOD_NAME, RTLD_NOW);
> + check_align (THP_SIZE_MOD_NAME);
> + xdlclose (dl);
> +
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-size-mod.S b/sysdeps/unix/sysv/linux/tst-thp-size-mod.S
> new file mode 100644
> index 0000000000..add66dfb52
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-size-mod.S
> @@ -0,0 +1,24 @@
> +/* A module that provides THP code size for testing.
> +
> + Copyright (C) 2026 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/>. */
> +
> +/* Create a 32MB text section to enable transparent huge page load. */
> + .text
> + .globl thp_size
> +thp_size:
> + .space 32 * 1024 * 1024
> diff --git a/sysdeps/unix/sysv/linux/x86/dl-exec-post.h b/sysdeps/unix/sysv/linux/x86/dl-exec-post.h
> new file mode 100644
> index 0000000000..0fa0b5e0e5
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/x86/dl-exec-post.h
> @@ -0,0 +1,22 @@
> +/* DL_MAP_DEFAULT_THP_PAGESIZE. Linux/x86 version.
> + Copyright (C) 2026 Free Software Foundation, Inc.
> + Copyright The GNU Toolchain Authors.
> + 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/>. */
> +
> +#define DL_MAP_DEFAULT_THP_PAGESIZE (2 * 1024 * 1024)
> +
> +#include_next <dl-exec-post.h>
> --
> 2.53.0
>
Thanks,
Rui
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