[PATCH v13] elf: Support THP segment load with madvise enabled THP
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Fri Jun 19 14:05:34 GMT 2026
On 16/06/26 19:54, H.J. Lu wrote:
> Changes in v13:
>
> 1. Rename support get_thp_mode and get_thp_size to support_get_thp_mode and
> support_get_thp_size.
> 2. Update support_thp_work_madvise to return true for both always and
> madvise THP.
> 3. Update strace THP tests to run directly for --enable-hardcoded-path-in-tests.
> 4. Update _dl_segment_thp_eligible to check for PROT_READ.
> 5. Update strace THP tests to use "strace -X raw".
> 6. Define DL_MAP_DEFAULT_THP_PAGESIZE for x86-64, instead of x86.
>
> --
> 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. Define DL_MAP_DEFAULT_THP_PAGESIZE in hugepages.h and default it to 0.
> If DL_MAP_DEFAULT_THP_PAGESIZE is defined, assume kernel THP madvise mode.
> If kernel THP mode is always or never, there is an extra madvise call
> which has no impact. DL_MAP_DEFAULT_THP_PAGESIZE is defined for x86-64
> and 64-bit loongarch.
> 2. Update _dl_map_segment_align to support madvise THP mode. This fixes
> BZ #34079.
> 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. Set the maximum page alignment on THP tests to THP page size as the
> default maximum page alignment may be smaller than THP page size.
> 6. Add tests to verify that large executable PT_LOAD segments in
> executables 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. 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.
>
> NB: Some THP tests fail on arm due to limitations of arm32 kABI:
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=34096
>
> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
The patch looks go to me, just two small changes for support and suggestion
below. Ok with the changes.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> csu/libc-start.c | 6 +
> elf/dl-load.h | 3 +
> elf/dl-support.c | 6 +
> elf/rtld.c | 14 +-
> support/support_check_hugetlb.c | 64 +++++-
> support/support_check_hugetlb.h | 12 ++
> sysdeps/generic/dl-exec-post.h | 34 ++++
> sysdeps/generic/dl-load-post.h | 23 +++
> sysdeps/generic/hugepages.h | 19 +-
> sysdeps/generic/ldsodefs.h | 9 +
> sysdeps/unix/sysv/linux/Makefile | 187 +++++++++++++++++-
> sysdeps/unix/sysv/linux/arm/Makefile | 7 +
> sysdeps/unix/sysv/linux/dl-exec-post.h | 138 +++++++++++++
> sysdeps/unix/sysv/linux/dl-load-post.h | 42 ++++
> .../unix/sysv/linux/dl-map-segment-align.c | 34 +---
> .../unix/sysv/linux/dl-map-segment-align.h | 17 +-
> sysdeps/unix/sysv/linux/ldsodefs.h | 3 +
> sysdeps/unix/sysv/linux/loongarch/Makefile | 3 +
> .../{dl-map-segment-align.h => hugepages.h} | 4 +-
> sysdeps/unix/sysv/linux/strace-tst-thp.sh | 62 ++++++
> .../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 | 67 +++++++
> sysdeps/unix/sysv/linux/tst-thp-align.c | 123 +-----------
> sysdeps/unix/sysv/linux/x86_64/hugepages.h | 22 +++
> 29 files changed, 848 insertions(+), 174 deletions(-)
> create mode 100644 sysdeps/generic/dl-exec-post.h
> create mode 100644 sysdeps/generic/dl-load-post.h
> create mode 100644 sysdeps/unix/sysv/linux/dl-exec-post.h
> create mode 100644 sysdeps/unix/sysv/linux/dl-load-post.h
> rename sysdeps/unix/sysv/linux/loongarch/lp64/{dl-map-segment-align.h => hugepages.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/x86_64/hugepages.h
>
> diff --git a/csu/libc-start.c b/csu/libc-start.c
> index 03d770ef15..64ba0bc3a9 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),
> @@ -307,6 +308,11 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
> _dl_relocate_static_pie_ifunc ();
> ARCH_SETUP_IREL ();
>
> + /* This must run after the IFUNC relocations: _dl_executable_postprocess
> + may call IFUNC-resolved routines. */
> + struct link_map *main_map = _dl_get_dl_main_map ();
> + _dl_executable_postprocess (main_map, GL(dl_phdr), GL(dl_phnum));
> +
> /* Initialize libpthread if linked in. */
> if (__pthread_initialize_minimal != NULL)
> __pthread_initialize_minimal ();
Ok, and we can overcome it with dl-symbol-redir-ifunc.h if required.
> diff --git a/elf/dl-load.h b/elf/dl-load.h
> index 80ae5db4b3..84b82e183d 100644
> --- a/elf/dl-load.h
> +++ b/elf/dl-load.h
> @@ -112,6 +112,7 @@ struct loadcmd
> int prot; /* PROT_* bits. */
> };
>
> +#include <dl-load-post.h>
>
> /* Iterator for program header segments. Initialize with
> _dl_pt_load_iterator_init, then either walk PT_LOAD segments via
> @@ -215,6 +216,8 @@ _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);
> }
>
>
Ok.
> diff --git a/elf/dl-support.c b/elf/dl-support.c
> index 0508d6113b..b57fd74670 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
> +enum dl_elf_thp_control_t _dl_elf_thp_control;
> +enum thp_mode_t _dl_thp_mode;
> +size_t _dl_elf_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. */
Ok.
> diff --git a/elf/rtld.c b/elf/rtld.c
> index 12e1b4dd71..57f829cff2 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>
>
> @@ -1209,14 +1210,8 @@ 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 +1584,9 @@ 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);
Ok.
> diff --git a/support/support_check_hugetlb.c b/support/support_check_hugetlb.c
> index c73946c894..202f1a7933 100644
> --- a/support/support_check_hugetlb.c
> +++ b/support/support_check_hugetlb.c
> @@ -27,23 +27,67 @@
> #include <support/support_check_hugetlb.h>
> #include <support/check.h>
>
> -bool
> -support_thp_work_madvise (void)
> +enum thp_mode_t
> +support_get_thp_mode (void)
> {
> - int fd = open ("/sys/kernel/mm/transparent_hugepage/enabled", O_RDONLY);
> + int fd = open ("/sys/kernel/mm/transparent_hugepage/enabled",
> + O_RDONLY, 0);
> if (fd == -1)
> - return false;
> + return thp_mode_not_supported;
>
> -#define MODE_MADVISE "always [madvise] never\n"
> -#define MODE_ALWAYS "[always] madvise never\n"
> + 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_MADVISE)];
> + char str[sizeof(mode_always)];
> ssize_t s = read (fd, str, sizeof (str));
> close (fd);
> - if (s != sizeof (str) - 1)
> - return false;
> + if (s >= sizeof str || s < 0)
I think it should be:
if (s < 0 || s >= sizeof str)
to avoid 's' being promoted to size_t and make the second check ineffective.
> + return thp_mode_not_supported;
> str[s] = '\0';
> - return strcmp (str, MODE_MADVISE) == 0 || strcmp (str, MODE_ALWAYS) == 0;
> +
> + 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;
> +}
> +
> +unsigned long int
> +support_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;
> +}
> +
> +bool
> +support_thp_work_madvise (void)
> +{
> + enum thp_mode_t mode = support_get_thp_mode ();
> + return mode == thp_mode_always || mode == thp_mode_madvise;
> }
>
> bool
Ok.
> diff --git a/support/support_check_hugetlb.h b/support/support_check_hugetlb.h
> index 2c5f5cb80c..6f55405c27 100644
> --- a/support/support_check_hugetlb.h
> +++ b/support/support_check_hugetlb.h
> @@ -21,6 +21,10 @@
>
> #include <stdbool.h>
> #include <sys/cdefs.h>
> +#undef attribute_hidden
> +#define attribute_hidden
> +#include <hugepages.h> /* For enum thp_mode_t. */
> +#undef attribute_hidden
>
> __BEGIN_DECLS
>
> @@ -43,6 +47,14 @@ bool support_hugepages_reserved (void);
> so it is safe to call unconditionally. */
> void support_check_malloc_hugetlb (void);
>
> +/* Returns Transparent Huge Pages (THP) mode from
> + /sys/kernel/mm/transparent_hugepage/enabled. */
> +extern enum thp_mode_t support_get_thp_mode (void);
> +
> +/* Returns Transparent Huge Pages (THP) page size from
> + /sys/kernel/mm/transparent_hugepage/hpage_pmd_size. */
> +extern unsigned long int support_get_thp_size (void);
> +
> __END_DECLS
>
> #endif /* SUPPORT_SUPPORT_CHECK_HUGETLB_H */
I think it would be better to add a support only thp_mode_t like definition.
I recall Florian some time ago maintained a libsupport external project, and
this makes it hard to keep them in sync.
> 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
> +}
Ok.
> diff --git a/sysdeps/generic/dl-load-post.h b/sysdeps/generic/dl-load-post.h
> new file mode 100644
> index 0000000000..1a6d205e33
> --- /dev/null
> +++ b/sysdeps/generic/dl-load-post.h
> @@ -0,0 +1,23 @@
> +/* _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.
> +
> + 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_postprocess_loadcmd_extra (struct link_map *l, const struct loadcmd *c)
> +{
> +}
Ok.
> diff --git a/sysdeps/generic/hugepages.h b/sysdeps/generic/hugepages.h
> index 5fc9b5c8de..8e54661527 100644
> --- a/sysdeps/generic/hugepages.h
> +++ b/sysdeps/generic/hugepages.h
> @@ -21,15 +21,26 @@
>
> #include <stddef.h>
>
> +/* The THP segment load control mode. */
> +enum dl_elf_thp_control_t
> +{
> + /* To be enabled or disabled by GLIBC_TUNABLES. */
> + dl_elf_thp_control_default = 0,
> + /* Enabled by GLIBC_TUNABLES=glibc.elf.thp=1. */
> + dl_elf_thp_control_enabled,
> + /* Disabled by GLIBC_TUNABLES=glibc.elf.thp=0. */
> + dl_elf_thp_control_disabled
> +};
> +
> /* Return the default transparent huge page size. */
> 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;
> @@ -45,6 +56,10 @@ void __get_hugepage_config (size_t requested, size_t *pagesize, int *flags)
> # define MALLOC_DEFAULT_THP_PAGESIZE 0
> #endif
>
> +#ifndef DL_MAP_DEFAULT_THP_PAGESIZE
> +# define DL_MAP_DEFAULT_THP_PAGESIZE 0
> +#endif
> +
> #ifndef MAX_THP_PAGESIZE
> # define MAX_THP_PAGESIZE (32 * 1024 * 1024)
> #endif
Ok.
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 24529db8a1..f94247ad9f 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 +478,14 @@ 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. */
> + EXTERN enum dl_elf_thp_control_t _dl_elf_thp_control;
> + /* The kernel THP mode. */
> + EXTERN enum thp_mode_t _dl_thp_mode;
> + /* Page size used for THP segment load. */
> + EXTERN size_t _dl_elf_thp_pagesize;
> +#endif
> #ifdef SHARED
> };
> # define __rtld_global_attribute__
Ok.
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 63e7046cb3..2462cdbc7c 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -698,11 +698,15 @@ $(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 \
> @@ -712,15 +716,12 @@ CFLAGS-tst-rseq-tls-range.c += -DMAIN_TLS_ALIGN=4
> CFLAGS-tst-rseq-tls-range-4096.c += -DMAIN_TLS_ALIGN=4096
> CFLAGS-tst-rseq-tls-range-static.c += -DMAIN_TLS_ALIGN=4
> CFLAGS-tst-rseq-tls-range-4096-static.c += -DMAIN_TLS_ALIGN=4096
> -LDFLAGS-tst-thp-size-mod.so += -Wl,-z,noseparate-code
> $(objpfx)tst-rseq-tls-range.out: $(objpfx)tst-rseq-tls-range-mod.so
> $(objpfx)tst-rseq-tls-range-4096.out: $(objpfx)tst-rseq-tls-range-mod.so
> $(objpfx)tst-rseq-tls-range-static.out: $(objpfx)tst-rseq-tls-range-mod.so
> $(objpfx)tst-rseq-tls-range-4096-static.out: $(objpfx)tst-rseq-tls-range-mod.so
> -$(objpfx)tst-thp-align.out: $(objpfx)tst-thp-size-mod.so
> tst-rseq-tls-range-static-ENV = LD_LIBRARY_PATH=$(objpfx):$(common-objpfx)
> tst-rseq-tls-range-4096-static-ENV = LD_LIBRARY_PATH=$(objpfx):$(common-objpfx)
> -tst-thp-align-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
>
> test-internal-extras += tst-nolink-libc
> ifeq ($(run-built-tests),yes)
> @@ -729,6 +730,186 @@ 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)
> +
> +# -Wl,-z,max-page-size=$(THP-PAGE-SIZE) alone doesn't work for PDE when
> +# text-segment address is lower than the maximum page size:
> +# https://sourceware.org/bugzilla/show_bug.cgi?id=34184
> +ifneq (,$(load-address-ldflag))
> +LOAD-THP-ADDRESS-LDFLAGS = $(load-address-ldflag)=$(THP-PAGE-SIZE)
> +endif
> +
> +LDFLAGS-tst-thp-size-mod.so = -Wl,-z,noseparate-code \
> + $(THP-PAGE-SIZE-LDFLAGS)
> +tst-thp-align-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +$(objpfx)tst-thp-align.out: $(objpfx)tst-thp-size-mod.so
> +
> +tests += \
> + tst-thp-1-no-s-code \
> + tst-thp-1-no-s-code-pde \
> + tst-thp-1-no-s-code-static \
> +# tests
> +tests-static += \
> + tst-thp-1-no-s-code-static \
> +# tests-static
> +
> +ifeq (yes,$(with-lld))
> +# -z noseparate-code is a nop for lld. It doesn't create an executable
> +# segment placed at 0 file offset.
> +test-xfail-tst-thp-1-no-s-code = yes
> +test-xfail-tst-thp-1-no-s-code-pde = yes
> +test-xfail-tst-thp-1-no-s-code-static = yes
> +endif
> +
> +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) \
> + $(LOAD-THP-ADDRESS-LDFLAGS)
> +LDFLAGS-tst-thp-1-static = -Wl,-z,separate-code $(THP-PAGE-SIZE-LDFLAGS)
> +ifneq (yes,$(enable-static-pie))
> +LDFLAGS-tst-thp-1-static += $(LOAD-THP-ADDRESS-LDFLAGS)
> +endif
> +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) \
> + $(LOAD-THP-ADDRESS-LDFLAGS)
> +LDFLAGS-tst-thp-1-no-s-code-static = -Wl,-z,noseparate-code \
> + $(THP-PAGE-SIZE-LDFLAGS)
> +ifneq (yes,$(enable-static-pie))
> +LDFLAGS-tst-thp-1-no-s-code-static += $(LOAD-THP-ADDRESS-LDFLAGS)
> +endif
> +
> +$(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: $(objpfx)tst-thp-size-mod.o
> +
> +tst-thp-1-no-s-code-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-no-s-code-pde-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-no-s-code-static-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +
> +tst-thp-1-no-s-code-pde-no-pie = yes
> +
> +tst-thp-1-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-pde-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +tst-thp-1-static-ENV = GLIBC_TUNABLES=glibc.elf.thp=1
> +
> +$(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: $(objpfx)tst-thp-size-mod.o
> +
> +tst-thp-1-pde-no-pie = yes
> +
> +# Don't run strace tests for cross-compiling.
> +ifeq (no,$(cross-compiling))
> +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 \
> + $(objpfx)strace-tst-thp-align-default.out \
> + $(objpfx)strace-tst-thp-align-disabled.out \
> + $(objpfx)strace-tst-thp-align-enabled.out \
> +# tests-special
> +
> +ifeq (yes,$(build-hardcoded-path-in-tests))
> +strace-test-via-rtld-prefix =
> +else
> +strace-test-via-rtld-prefix = $(rtld-prefix)
> +endif
> +
> +$(objpfx)strace-tst-thp-1-enabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-1
> + $(SHELL) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + $(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) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + $(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) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + $(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) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + $(objpfx)tst-thp-1-pde > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-static-enabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh \
> + $(objpfx)tst-thp-1-static
> + $(SHELL) $< '' '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + $(objpfx)tst-thp-1-static > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-1-static-disabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh \
> + $(objpfx)tst-thp-1-static
> + $(SHELL) $< '' '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + $(objpfx)tst-thp-1-static > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-align-default.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-align
> + $(SHELL) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' '$(run-program-env)' \
> + $(objpfx)tst-thp-align > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-align-enabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-align
> + $(SHELL) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=1' \
> + $(objpfx)tst-thp-align > $@; \
> + $(evaluate-test)
> +
> +$(objpfx)strace-tst-thp-align-disabled.out: \
> + $(..)sysdeps/unix/sysv/linux/strace-tst-thp.sh $(objpfx)ld.so \
> + $(objpfx)tst-thp-align
> + $(SHELL) $< '$(strace-test-via-rtld-prefix)' \
> + '$(test-wrapper-env)' \
> + '$(run-program-env) GLIBC_TUNABLES=glibc.elf.thp=0' \
> + $(objpfx)tst-thp-align > $@; \
> + $(evaluate-test)
> +endif # [madvise]
> +endif # $(cross-compiling)
> endif # $(subdir) == elf
>
> ifeq ($(subdir),rt)
Ok.
> diff --git a/sysdeps/unix/sysv/linux/arm/Makefile b/sysdeps/unix/sysv/linux/arm/Makefile
> index e73ce4f811..428949fefd 100644
> --- a/sysdeps/unix/sysv/linux/arm/Makefile
> +++ b/sysdeps/unix/sysv/linux/arm/Makefile
> @@ -3,6 +3,13 @@ sysdep-rtld-routines += aeabi_read_tp libc-do-syscall
> # The test uses INTERNAL_SYSCALL_CALL. In thumb mode, this uses
> # an undefined reference to __libc_do_syscall.
> CFLAGS-tst-nolink-libc.c += -marm
> +
> +ifeq (yes,$(enable-static-pie))
> +# These static PIE tests fail on arm due to limitations of arm32 kABI:
> +# https://sourceware.org/bugzilla/show_bug.cgi?id=34096
> +test-xfail-tst-thp-1-no-s-code-static = yes
> +test-xfail-tst-thp-1-static = yes
> +endif
> endif
>
> ifeq ($(subdir),misc)
Ok.
> 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..788e427d06
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/dl-exec-post.h
> @@ -0,0 +1,138 @@
> +/* _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_GET_FULL (glibc, elf, thp, int32_t, NULL) == 0)
> + GL(dl_elf_thp_control) = dl_elf_thp_control_disabled;
> + else
> + GL(dl_elf_thp_control) = dl_elf_thp_control_enabled;
> +
> + /* Return if the tunable is not set or THP is disabled by the
> + tunable. */
> + if (GL(dl_elf_thp_control) == dl_elf_thp_control_disabled)
> + return;
> +
> + _Static_assert (DL_MAP_DEFAULT_THP_PAGESIZE <= MAX_THP_PAGESIZE,
> + "DL_MAP_DEFAULT_THP_PAGESIZE <= MAX_THP_PAGESIZE");
Minor suggestion: replace with verify (...).
> +
> + /* 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 non-zero, assume THP mode is madvise and always call madvise.
> + Since madvise is a fast system call, it adds only a small overhead
> + compared to the cost of accessing /sys/kernel/mm files. */
> + if (DL_MAP_DEFAULT_THP_PAGESIZE != 0)
> + {
> + GL(dl_elf_thp_pagesize) = DL_MAP_DEFAULT_THP_PAGESIZE;
> + GL(dl_thp_mode) = thp_mode_madvise;
> + }
> + else
> + {
> + GL(dl_thp_mode) = __get_thp_mode ();
> + if (GL(dl_thp_mode) == thp_mode_always
> + || GL(dl_thp_mode) == thp_mode_madvise)
> + {
> + GL(dl_elf_thp_pagesize) = __get_thp_size ();
> + /* 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_elf_thp_pagesize) > MAX_THP_PAGESIZE)
> + GL(dl_elf_thp_pagesize) = 0;
> + }
> + else
> + GL(dl_elf_thp_pagesize) = 0;
> +
> + if (GL(dl_elf_thp_pagesize) == 0)
> + {
> + GL(dl_elf_thp_control) = dl_elf_thp_control_disabled;
> + GL(dl_thp_mode) = thp_mode_not_supported;
> + }
> + }
> +}
> +
> +static inline void
> +_dl_executable_postprocess (struct link_map *main_map,
> + const ElfW(Phdr) *phdr, ElfW(Word) phnum)
> +{
> + /* 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
> +
> + /* If THP state was not yet initialized, the main executable was mapped
> + by the kernel; in that case this function is the only place that can
> + apply MADV_HUGEPAGE to the main executable's segments. Otherwise,
> + _dl_get_thp_config has already run earlier in dl_main and
> + _dl_map_segments has just mapped the main executable, so
> + _dl_postprocess_loadcmd_extra has already done the madvise pass; do
> + not repeat it here. */
> + if (GL(dl_elf_thp_control) != dl_elf_thp_control_default)
> + return;
> +
> + _dl_get_thp_config ();
> +
> + /* Return if THP segment load isn't enabled. */
> + if (GL(dl_elf_thp_control) != dl_elf_thp_control_enabled)
> + return;
> +
> + /* NB: If DL_MAP_DEFAULT_THP_PAGESIZE is non-zero, dl_thp_mode is set
> + to thp_mode_madvise. */
> + if (DL_MAP_DEFAULT_THP_PAGESIZE == 0
> + && GL(dl_thp_mode) != thp_mode_madvise)
> + return;
> +
> + /* 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_elf_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)
> + {
> + int ret = __madvise ((void *) (main_map->l_addr + ph->p_vaddr),
> + ph->p_memsz, MADV_HUGEPAGE);
> + if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
> + _dl_debug_printf ("\
> +madvise (0x%0*lx, 0x%0*lx, MADV_HUGEPAGE) returns %d\n",
> +(int) sizeof (void *) * 2,
> +(unsigned long int) (main_map->l_addr + ph->p_vaddr),
> +(int) sizeof (void *) * 2,
> +(unsigned long int) ph->p_memsz,
> +ret);
> + }
> +}
Ok.
> 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..741c4ddcb1
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/dl-load-post.h
> @@ -0,0 +1,42 @@
> +/* _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/>. */
> +
> +static bool _dl_segment_thp_eligible (const struct loadcmd *, size_t);
> +
> +/* After L has been mapped in, call madvise with MADV_HUGEPAGE for THP
> + madvise mode if L is THP eligible. */
> +
> +static inline void
> +_dl_postprocess_loadcmd_extra (struct link_map *l, const struct loadcmd *c)
> +{
> + if (GL(dl_thp_mode) == thp_mode_madvise
> + && _dl_segment_thp_eligible (c, GL(dl_elf_thp_pagesize)))
> + {
> + int ret = __madvise ((void *) (l->l_addr + c->mapstart),
> + c->mapend - c->mapstart, MADV_HUGEPAGE);
> + if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
> + _dl_debug_printf ("\
> + madvise (0x%0*lx, 0x%0*lx, MADV_HUGEPAGE) returns %d\n",
> + (int) sizeof (void *) * 2,
> + (unsigned long int) (l->l_addr + c->mapstart),
> + (int) sizeof (void *) * 2,
> + (unsigned long int) (c->mapend - c->mapstart),
> + ret);
> + }
> +}
Ok.
> diff --git a/sysdeps/unix/sysv/linux/dl-map-segment-align.c b/sysdeps/unix/sysv/linux/dl-map-segment-align.c
> index a39e74d91b..c062ba0c58 100644
> --- a/sysdeps/unix/sysv/linux/dl-map-segment-align.c
> +++ b/sysdeps/unix/sysv/linux/dl-map-segment-align.c
> @@ -17,38 +17,24 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> +#include <ldsodefs.h>
> #include <dl-map-segment-align.h>
> -#include <dl-tunables.h>
> -#include <hugepages.h>
> +
> +/* Return the alignment of the PT_LOAD segment for THP. P_ALIGN_MAX is
> + the maximum p_align value in the PT_LOAD segment. */
>
> 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;
> + size_t thp_pagesize = GL(dl_elf_thp_pagesize);
>
> - if (TUNABLE_GET (glibc, elf, thp, int32_t, NULL) == 0)
> + if (GL(dl_elf_thp_control) != dl_elf_thp_control_enabled
> + || p_align_max >= thp_pagesize)
> 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 true if the segment is THP eligible. It helps improve THP
> + eligibility and reduces TLB pressure. */
> + if (_dl_segment_thp_eligible (c, thp_pagesize))
> return thp_pagesize;
>
> return p_align_max;
Ok.
> diff --git a/sysdeps/unix/sysv/linux/dl-map-segment-align.h b/sysdeps/unix/sysv/linux/dl-map-segment-align.h
> index d9b05181b7..9a7fc3a10e 100644
> --- a/sysdeps/unix/sysv/linux/dl-map-segment-align.h
> +++ b/sysdeps/unix/sysv/linux/dl-map-segment-align.h
> @@ -19,9 +19,18 @@
>
> #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;
> +
> +/* Return true only if the loadcmd C is THP eligible with THP page size
> + THP_PAGESIZE, which means that it is read-only, its size >= THP page
> + size, its offset and address of the loadcmd C are aligned to THP page
> + size. */
> +
> +static inline bool
> +_dl_segment_thp_eligible (const struct loadcmd *c, size_t thp_pagesize)
> +{
> + return ((c->prot & (PROT_WRITE | PROT_READ)) == PROT_READ
> + && (c->mapend - c->mapstart) >= thp_pagesize
> + && ((c->mapstart | c->mapoff) & (thp_pagesize - 1)) == 0);
> +}
Ok.
> 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>
>
Ok.
> 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
Ok.
> diff --git a/sysdeps/unix/sysv/linux/loongarch/lp64/dl-map-segment-align.h b/sysdeps/unix/sysv/linux/loongarch/lp64/hugepages.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/hugepages.h
> index c51ee4ac47..30252a9b86 100644
> --- a/sysdeps/unix/sysv/linux/loongarch/lp64/dl-map-segment-align.h
> +++ b/sysdeps/unix/sysv/linux/loongarch/lp64/hugepages.h
> @@ -1,4 +1,4 @@
> -/* _dl_map_segment_align. LoongArch64 Linux version.
> +/* Huge Page support. 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 <hugepages.h>
Ok.
> 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..bff7d3e7a0
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/strace-tst-thp.sh
> @@ -0,0 +1,62 @@
> +#!/bin/bash
> +# 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"
> +test_prog="$4"
> +
> +cmd="${test_wrapper_env} ${run_program_env} strace -X raw ${rtld} ${test_prog}"
> +
> +TIMEOUTFACTOR=${TIMEOUTFACTOR:-1}
> +
> +case x"${run_program_env}" in
> +*glibc.elf.thp=1*)
> + strace_expected=yes
> + ;;
> +*)
> + strace_expected=no
> + ;;
> +esac
> +
> +# Verify strace is not just present, but works in this environment. If
> +# not, skip the test.
> +/bin/sh -c \
> + "${test_wrapper_env} ${run_program_env} \
> + strace -X raw -e trace=none -- /bin/true" > /dev/null 2>&1 || 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 \
> + "timeout -k 4 $((3*$TIMEOUTFACTOR)) ${cmd} --direct 2>&1 \
> + | grep -E \"madvise\(0x[0-9a-f]+, [0-9]+, 0xe)\""; then
> + if test ${strace_expected} = yes; then
> + exit 0
> + else
> + exit 1
> + fi
> +else
> + if test ${strace_expected} = no; then
> + exit 0
> + else
> + exit 1
> + fi
> +fi
Ok.
> 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>
Ok.
> 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..c71ac887d1
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-thp-align-check.h
> @@ -0,0 +1,67 @@
> +/* 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/support_check_hugetlb.h>
> +#include <support/check.h>
> +#include <support/xstdio.h>
> +#include <support/xunistd.h>
> +
> +static void
> +check_align (const char *name)
> +{
> + unsigned long int thp_size = support_get_thp_size ();
> + enum thp_mode_t thp_mode = support_get_thp_mode ();
> +
> + if (thp_size == 0)
> + FAIL_UNSUPPORTED ("unable to get THP size.\n");
> +
> + if (thp_size > MAX_THP_PAGESIZE)
> + FAIL_UNSUPPORTED ("THP size exceeds MAX_THP_PAGESIZE.\n");
> +
> + if (thp_mode != thp_mode_always && thp_mode != thp_mode_madvise)
> + FAIL_UNSUPPORTED ("THP mode is not always nor madvise.\n");
> +
> + 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 (path != NULL && strstr (prot, "x") && strstr (path, name))
> + TEST_COMPARE (from % thp_size, 0);
> +
> + free (prot);
> + free (path);
> + }
> +
> + free (line);
> + xfclose (f);
> +}
Ok.
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-align.c b/sysdeps/unix/sysv/linux/tst-thp-align.c
> index 0b3f18e000..2e44109ba6 100644
> --- a/sysdeps/unix/sysv/linux/tst-thp-align.c
> +++ b/sysdeps/unix/sysv/linux/tst-thp-align.c
> @@ -16,129 +16,10 @@
> 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/xdlfcn.h>
> -#include <support/xstdio.h>
> -#include <support/xunistd.h>
> +#include "tst-thp-align-check.h"
>
> #define THP_SIZE_MOD_NAME "tst-thp-size-mod.so"
> -#define MAX_THP_PAGESIZE (32 * 1024 * 1024)
> -
> -enum thp_mode_t
> -{
> - thp_mode_always,
> - thp_mode_madvise,
> - thp_mode_never,
> - thp_mode_not_supported
> -};
> -
> -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 (void)
> -{
> - 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)
> - {
> - FAIL_UNSUPPORTED ("THP mode is not always.\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, THP_SIZE_MOD_NAME))
> - TEST_COMPARE (from % thp_size, 0);
> -
> - free (path);
> - }
> -
> - free (line);
> - xfclose (f);
> -}
>
> static int
> do_test (void)
> @@ -146,7 +27,7 @@ do_test (void)
> void *dl;
>
> dl = xdlopen (THP_SIZE_MOD_NAME, RTLD_NOW);
> - check_align ();
> + check_align (THP_SIZE_MOD_NAME);
> xdlclose (dl);
>
> return 0;
Ok.
> diff --git a/sysdeps/unix/sysv/linux/x86_64/hugepages.h b/sysdeps/unix/sysv/linux/x86_64/hugepages.h
> new file mode 100644
> index 0000000000..74a3833842
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/x86_64/hugepages.h
> @@ -0,0 +1,22 @@
> +/* Huge Page support. Linux/x86-64 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 <hugepages.h>
Ok.
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