[v7,2/4] elf: Add a test for PT_LOAD segments with mixed p_align [BZ #28676]
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Commit Message
Add tst-p_alignmod1-edit to edit the copy of tst-alignmod3.so to reduce
p_align of the first PT_LOAD segment by half and verify that the shared
library is mapped with the maximum p_align of all PT_LOAD segments.
---
elf/Makefile | 18 ++++++
elf/tst-elf-edit.h | 126 +++++++++++++++++++++++++++++++++++++
elf/tst-p_align1.c | 27 ++++++++
elf/tst-p_alignmod1-edit.c | 34 ++++++++++
4 files changed, 205 insertions(+)
create mode 100644 elf/tst-elf-edit.h
create mode 100644 elf/tst-p_align1.c
create mode 100644 elf/tst-p_alignmod1-edit.c
Comments
On 03/01/2022 20:04, H.J. Lu wrote:
> Add tst-p_alignmod1-edit to edit the copy of tst-alignmod3.so to reduce
> p_align of the first PT_LOAD segment by half and verify that the shared
> library is mapped with the maximum p_align of all PT_LOAD segments.
> ---
> elf/Makefile | 18 ++++++
> elf/tst-elf-edit.h | 126 +++++++++++++++++++++++++++++++++++++
> elf/tst-p_align1.c | 27 ++++++++
> elf/tst-p_alignmod1-edit.c | 34 ++++++++++
> 4 files changed, 205 insertions(+)
> create mode 100644 elf/tst-elf-edit.h
> create mode 100644 elf/tst-p_align1.c
> create mode 100644 elf/tst-p_alignmod1-edit.c
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 883578ee36..9c831faac1 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -403,6 +403,13 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
> tst-dl_find_object-mod8 \
> tst-dl_find_object-mod9 \
>
> +ifeq (yes,$(build-shared))
> +tests += \
> + tst-p_alignmod1-edit \
> + tst-p_align1 \
> +
> +endif
> +
> # Most modules build with _ISOMAC defined, but those filtered out
> # depend on internal headers.
> modules-names-tests = $(filter-out ifuncmod% tst-tlsmod%,\
> @@ -2079,3 +2086,14 @@ CFLAGS-tst-dl_find_object-mod6.c += -funwind-tables
> CFLAGS-tst-dl_find_object-mod7.c += -funwind-tables
> CFLAGS-tst-dl_find_object-mod8.c += -funwind-tables
> CFLAGS-tst-dl_find_object-mod9.c += -funwind-tables
> +
> +$(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
> +
> +# Make a copy of tst-alignmod3.so and lower p_align of the first PT_LOAD
> +# segment.
> +$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod1-edit \
> + $(objpfx)tst-alignmod3.so
tst-alignmod3.so is only provided in the last patch, I think it would be better
to move to this patch as tst-alignmod-base and it instead by copying and changing
on each test.
> + rm -f $@
> + cp $(objpfx)tst-alignmod3.so $@
> + $(test-wrapper-env) $(run-program-env) $(rtld-prefix) \
> + $(objpfx)tst-p_alignmod1-edit $@
> diff --git a/elf/tst-elf-edit.h b/elf/tst-elf-edit.h
> new file mode 100644
> index 0000000000..ce98cf012c
> --- /dev/null
> +++ b/elf/tst-elf-edit.h
> @@ -0,0 +1,126 @@
> +/* Update p_align of the first PT_LOAD segment.
> + Copyright (C) 2021 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <stdio.h>
> +#include <stdbool.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <link.h>
> +#include <error.h>
> +#include <errno.h>
> +#include <sys/stat.h>
> +#include <sys/mman.h>
> +
> +const char *file_name;
> +
> +static size_t update_p_align (size_t);
> +
> +int
> +main (int argc, char ** argv)
> +{
> + if (argc != 2)
> + {
> + printf ("Usage: %s: file\n", argv[0]);
> + return 0;
> + }
> +
> + file_name = argv[1];
> + struct stat statbuf;
> + int errno_saved;
> +
> + if (stat (file_name, &statbuf) < 0)
> + error (1, errno, "%s: not exist", file_name);
> +
> + ElfW(Ehdr) *ehdr;
> +
> + if (statbuf.st_size < sizeof (*ehdr))
> + error (1, 0, "%s: too small", file_name);
> +
> + int fd = open (file_name, O_RDWR);
> + if (fd < 0)
> + error (1, errno, "%s: can't open", file_name);
> +
> + /* Map in the whole file. */
> + void *base = mmap (NULL, statbuf.st_size, PROT_READ | PROT_WRITE,
> + MAP_SHARED, fd, 0);
> + if (base == MAP_FAILED)
> + {
> + errno_saved = errno;
> + close (fd);
> + error (1, errno_saved, "%s: failed to map", file_name);
> + }
> +
> + ehdr = (ElfW(Ehdr) *) base;
> + if (ehdr->e_ident[EI_MAG0] != ELFMAG0
> + || ehdr->e_ident[EI_MAG1] != ELFMAG1
> + || ehdr->e_ident[EI_MAG2] != ELFMAG2
> + || ehdr->e_ident[EI_MAG3] != ELFMAG3)
> + {
> + close (fd);
> + error (1, 0, "%s: bad ELF header", file_name);
> + }
> +
> + if (ehdr->e_type != ET_DYN)
> + {
> + close (fd);
> + error (1, 0, "%s: not shared library", file_name);
> + }
> +
> + bool unsupported_class = true;
> + switch (ehdr->e_ident[EI_CLASS])
> + {
> + default:
> + break;
> +
> + case ELFCLASS32:
> + unsupported_class = __ELF_NATIVE_CLASS != 32;
> + break;
> +
> + case ELFCLASS64:
> + unsupported_class = __ELF_NATIVE_CLASS != 64;
> + break;
> + }
> +
> + if (unsupported_class)
> + {
> + close (fd);
> + error (1, 0, "%s: unsupported ELF class: %d",
> + file_name, ehdr->e_ident[EI_CLASS]);
> + }
> +
> + size_t phdr_size = sizeof (ElfW(Phdr)) * ehdr->e_phentsize;
> + if (statbuf.st_size < (ehdr->e_phoff + phdr_size))
> + {
> + close (fd);
> + error (1, 0, "%s: too small", file_name);
> + }
> +
> + ElfW(Phdr) *phdr = (ElfW(Phdr) *) (base + ehdr->e_phoff);
> + for (int i = 0; i < ehdr->e_phnum; i++, phdr++)
> + if (phdr->p_type == PT_LOAD)
> + {
> + /* Update p_align of the first PT_LOAD segment. */
> + phdr->p_align = update_p_align (phdr->p_align);
> + break;
> + }
> +
> + munmap (base, statbuf.st_size);
> + close (fd);
> +
> + return 0;
> +}
Look ok, although I think it would be simpler to build it once and use an
argument of how to change the alignment instead of build once binary
per test. I am not if it is worth to use libsupport here.
> diff --git a/elf/tst-p_align1.c b/elf/tst-p_align1.c
> new file mode 100644
> index 0000000000..cab9793220
> --- /dev/null
> +++ b/elf/tst-p_align1.c
> @@ -0,0 +1,27 @@
> +/* Check different alignments of PT_LOAD segments in a shared library.
> + Copyright (C) 2021 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/>. */
> +
> +extern int do_load_test (void);
The do_load_test is defined as returning void on elf/tst-alignmod3.c,
but it redefined here as returning 'int'. This is causing a failure
on aarch64.
Maybe it would better to move it to a proper header.
> +
> +static int
> +do_test (void)
> +{
> + return do_load_test ();
> +}
> +
> +#include <support/test-driver.c>
And I think 'is_aligned' from sysdeps/generic/tst-stack-align.h
seems to have the inverted semantic that makes things confusing
(elf/tst-alignmod3.c check if it is equal to 0 to actually check
if pointer is aligned).
Maybe it would be better to return bool and 'true' if the pointer
is indeed aligned (similar to what IS_ALIGNED/PTR_IS_ALIGNED
internal macros do).
bool
__attribute__ ((weak, noclone, noinline))
is_aligned (void *p, int align)
{
return (((uintptr_t) p) & (align - 1)) == 0;
}
> diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
> new file mode 100644
> index 0000000000..2aa0e7ccdd
> --- /dev/null
> +++ b/elf/tst-p_alignmod1-edit.c
> @@ -0,0 +1,34 @@
> +/* Reduce p_align of the first PT_LOAD segment by half.
> + Copyright (C) 2021 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include "tst-elf-edit.h"
> +
> +/* Reduce p_align by half. */
> +
> +static size_t
> +update_p_align (size_t p_align)
> +{
> + size_t pagesize = sysconf (_SC_PAGESIZE);
> + size_t new_p_align = p_align >> 1;
> +
> + if (new_p_align < pagesize)
> + error (1, 0, "%s: new p_align (0x%zx) < page size (0x%zx)",
> + file_name, new_p_align, pagesize);
> +
> + return new_p_align;
> +}
On Tue, Jan 18, 2022 at 8:26 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 03/01/2022 20:04, H.J. Lu wrote:
> > Add tst-p_alignmod1-edit to edit the copy of tst-alignmod3.so to reduce
> > p_align of the first PT_LOAD segment by half and verify that the shared
> > library is mapped with the maximum p_align of all PT_LOAD segments.
> > ---
> > elf/Makefile | 18 ++++++
> > elf/tst-elf-edit.h | 126 +++++++++++++++++++++++++++++++++++++
> > elf/tst-p_align1.c | 27 ++++++++
> > elf/tst-p_alignmod1-edit.c | 34 ++++++++++
> > 4 files changed, 205 insertions(+)
> > create mode 100644 elf/tst-elf-edit.h
> > create mode 100644 elf/tst-p_align1.c
> > create mode 100644 elf/tst-p_alignmod1-edit.c
> >
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 883578ee36..9c831faac1 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -403,6 +403,13 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
> > tst-dl_find_object-mod8 \
> > tst-dl_find_object-mod9 \
> >
> > +ifeq (yes,$(build-shared))
> > +tests += \
> > + tst-p_alignmod1-edit \
> > + tst-p_align1 \
> > +
> > +endif
> > +
> > # Most modules build with _ISOMAC defined, but those filtered out
> > # depend on internal headers.
> > modules-names-tests = $(filter-out ifuncmod% tst-tlsmod%,\
> > @@ -2079,3 +2086,14 @@ CFLAGS-tst-dl_find_object-mod6.c += -funwind-tables
> > CFLAGS-tst-dl_find_object-mod7.c += -funwind-tables
> > CFLAGS-tst-dl_find_object-mod8.c += -funwind-tables
> > CFLAGS-tst-dl_find_object-mod9.c += -funwind-tables
> > +
> > +$(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
> > +
> > +# Make a copy of tst-alignmod3.so and lower p_align of the first PT_LOAD
> > +# segment.
> > +$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod1-edit \
> > + $(objpfx)tst-alignmod3.so
>
> tst-alignmod3.so is only provided in the last patch, I think it would be better
> to move to this patch as tst-alignmod-base, not and it instead by copying and changing
> on each test.
It is tst-alignmod3.so, not tst-p_alignmod3.so. In any case, I added
tst-p_alignmod-base.so.
> > + rm -f $@
> > + cp $(objpfx)tst-alignmod3.so $@
> > + $(test-wrapper-env) $(run-program-env) $(rtld-prefix) \
> > + $(objpfx)tst-p_alignmod1-edit $@
> > diff --git a/elf/tst-elf-edit.h b/elf/tst-elf-edit.h
> > new file mode 100644
> > index 0000000000..ce98cf012c
> > --- /dev/null
> > +++ b/elf/tst-elf-edit.h
> > @@ -0,0 +1,126 @@
> > +/* Update p_align of the first PT_LOAD segment.
> > + Copyright (C) 2021 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#include <stdio.h>
> > +#include <stdbool.h>
> > +#include <unistd.h>
> > +#include <fcntl.h>
> > +#include <link.h>
> > +#include <error.h>
> > +#include <errno.h>
> > +#include <sys/stat.h>
> > +#include <sys/mman.h>
> > +
> > +const char *file_name;
> > +
> > +static size_t update_p_align (size_t);
> > +
> > +int
> > +main (int argc, char ** argv)
> > +{
> > + if (argc != 2)
> > + {
> > + printf ("Usage: %s: file\n", argv[0]);
> > + return 0;
> > + }
> > +
> > + file_name = argv[1];
> > + struct stat statbuf;
> > + int errno_saved;
> > +
> > + if (stat (file_name, &statbuf) < 0)
> > + error (1, errno, "%s: not exist", file_name);
> > +
> > + ElfW(Ehdr) *ehdr;
> > +
> > + if (statbuf.st_size < sizeof (*ehdr))
> > + error (1, 0, "%s: too small", file_name);
> > +
> > + int fd = open (file_name, O_RDWR);
> > + if (fd < 0)
> > + error (1, errno, "%s: can't open", file_name);
> > +
> > + /* Map in the whole file. */
> > + void *base = mmap (NULL, statbuf.st_size, PROT_READ | PROT_WRITE,
> > + MAP_SHARED, fd, 0);
> > + if (base == MAP_FAILED)
> > + {
> > + errno_saved = errno;
> > + close (fd);
> > + error (1, errno_saved, "%s: failed to map", file_name);
> > + }
> > +
> > + ehdr = (ElfW(Ehdr) *) base;
> > + if (ehdr->e_ident[EI_MAG0] != ELFMAG0
> > + || ehdr->e_ident[EI_MAG1] != ELFMAG1
> > + || ehdr->e_ident[EI_MAG2] != ELFMAG2
> > + || ehdr->e_ident[EI_MAG3] != ELFMAG3)
> > + {
> > + close (fd);
> > + error (1, 0, "%s: bad ELF header", file_name);
> > + }
> > +
> > + if (ehdr->e_type != ET_DYN)
> > + {
> > + close (fd);
> > + error (1, 0, "%s: not shared library", file_name);
> > + }
> > +
> > + bool unsupported_class = true;
> > + switch (ehdr->e_ident[EI_CLASS])
> > + {
> > + default:
> > + break;
> > +
> > + case ELFCLASS32:
> > + unsupported_class = __ELF_NATIVE_CLASS != 32;
> > + break;
> > +
> > + case ELFCLASS64:
> > + unsupported_class = __ELF_NATIVE_CLASS != 64;
> > + break;
> > + }
> > +
> > + if (unsupported_class)
> > + {
> > + close (fd);
> > + error (1, 0, "%s: unsupported ELF class: %d",
> > + file_name, ehdr->e_ident[EI_CLASS]);
> > + }
> > +
> > + size_t phdr_size = sizeof (ElfW(Phdr)) * ehdr->e_phentsize;
> > + if (statbuf.st_size < (ehdr->e_phoff + phdr_size))
> > + {
> > + close (fd);
> > + error (1, 0, "%s: too small", file_name);
> > + }
> > +
> > + ElfW(Phdr) *phdr = (ElfW(Phdr) *) (base + ehdr->e_phoff);
> > + for (int i = 0; i < ehdr->e_phnum; i++, phdr++)
> > + if (phdr->p_type == PT_LOAD)
> > + {
> > + /* Update p_align of the first PT_LOAD segment. */
> > + phdr->p_align = update_p_align (phdr->p_align);
> > + break;
> > + }
> > +
> > + munmap (base, statbuf.st_size);
> > + close (fd);
> > +
> > + return 0;
> > +}
>
> Look ok, although I think it would be simpler to build it once and use an
> argument of how to change the alignment instead of build once binary
> per test. I am not if it is worth to use libsupport here.
This can be more flexible than an argument. I prefer to keep
it ASIS.
> > diff --git a/elf/tst-p_align1.c b/elf/tst-p_align1.c
> > new file mode 100644
> > index 0000000000..cab9793220
> > --- /dev/null
> > +++ b/elf/tst-p_align1.c
> > @@ -0,0 +1,27 @@
> > +/* Check different alignments of PT_LOAD segments in a shared library.
> > + Copyright (C) 2021 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/>. */
> > +
> > +extern int do_load_test (void);
>
> The do_load_test is defined as returning void on elf/tst-alignmod3.c,
> but it redefined here as returning 'int'. This is causing a failure
> on aarch64.
>
> Maybe it would better to move it to a proper header.
Done.
> > +
> > +static int
> > +do_test (void)
> > +{
> > + return do_load_test ();
> > +}
> > +
> > +#include <support/test-driver.c>
>
> And I think 'is_aligned' from sysdeps/generic/tst-stack-align.h
> seems to have the inverted semantic that makes things confusing
> (elf/tst-alignmod3.c check if it is equal to 0 to actually check
> if pointer is aligned).
>
> Maybe it would be better to return bool and 'true' if the pointer
> is indeed aligned (similar to what IS_ALIGNED/PTR_IS_ALIGNED
> internal macros do).
Fixed.
> bool
> __attribute__ ((weak, noclone, noinline))
> is_aligned (void *p, int align)
> {
> return (((uintptr_t) p) & (align - 1)) == 0;
> }
>
> > diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
> > new file mode 100644
> > index 0000000000..2aa0e7ccdd
> > --- /dev/null
> > +++ b/elf/tst-p_alignmod1-edit.c
> > @@ -0,0 +1,34 @@
> > +/* Reduce p_align of the first PT_LOAD segment by half.
> > + Copyright (C) 2021 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <https://www.gnu.org/licenses/>. */
> > +
> > +#include "tst-elf-edit.h"
> > +
> > +/* Reduce p_align by half. */
> > +
> > +static size_t
> > +update_p_align (size_t p_align)
> > +{
> > + size_t pagesize = sysconf (_SC_PAGESIZE);
> > + size_t new_p_align = p_align >> 1;
> > +
> > + if (new_p_align < pagesize)
> > + error (1, 0, "%s: new p_align (0x%zx) < page size (0x%zx)",
> > + file_name, new_p_align, pagesize);
> > +
> > + return new_p_align;
> > +}
Thanks.
@@ -403,6 +403,13 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-dl_find_object-mod8 \
tst-dl_find_object-mod9 \
+ifeq (yes,$(build-shared))
+tests += \
+ tst-p_alignmod1-edit \
+ tst-p_align1 \
+
+endif
+
# Most modules build with _ISOMAC defined, but those filtered out
# depend on internal headers.
modules-names-tests = $(filter-out ifuncmod% tst-tlsmod%,\
@@ -2079,3 +2086,14 @@ CFLAGS-tst-dl_find_object-mod6.c += -funwind-tables
CFLAGS-tst-dl_find_object-mod7.c += -funwind-tables
CFLAGS-tst-dl_find_object-mod8.c += -funwind-tables
CFLAGS-tst-dl_find_object-mod9.c += -funwind-tables
+
+$(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
+
+# Make a copy of tst-alignmod3.so and lower p_align of the first PT_LOAD
+# segment.
+$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod1-edit \
+ $(objpfx)tst-alignmod3.so
+ rm -f $@
+ cp $(objpfx)tst-alignmod3.so $@
+ $(test-wrapper-env) $(run-program-env) $(rtld-prefix) \
+ $(objpfx)tst-p_alignmod1-edit $@
new file mode 100644
@@ -0,0 +1,126 @@
+/* Update p_align of the first PT_LOAD segment.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <link.h>
+#include <error.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+const char *file_name;
+
+static size_t update_p_align (size_t);
+
+int
+main (int argc, char ** argv)
+{
+ if (argc != 2)
+ {
+ printf ("Usage: %s: file\n", argv[0]);
+ return 0;
+ }
+
+ file_name = argv[1];
+ struct stat statbuf;
+ int errno_saved;
+
+ if (stat (file_name, &statbuf) < 0)
+ error (1, errno, "%s: not exist", file_name);
+
+ ElfW(Ehdr) *ehdr;
+
+ if (statbuf.st_size < sizeof (*ehdr))
+ error (1, 0, "%s: too small", file_name);
+
+ int fd = open (file_name, O_RDWR);
+ if (fd < 0)
+ error (1, errno, "%s: can't open", file_name);
+
+ /* Map in the whole file. */
+ void *base = mmap (NULL, statbuf.st_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED, fd, 0);
+ if (base == MAP_FAILED)
+ {
+ errno_saved = errno;
+ close (fd);
+ error (1, errno_saved, "%s: failed to map", file_name);
+ }
+
+ ehdr = (ElfW(Ehdr) *) base;
+ if (ehdr->e_ident[EI_MAG0] != ELFMAG0
+ || ehdr->e_ident[EI_MAG1] != ELFMAG1
+ || ehdr->e_ident[EI_MAG2] != ELFMAG2
+ || ehdr->e_ident[EI_MAG3] != ELFMAG3)
+ {
+ close (fd);
+ error (1, 0, "%s: bad ELF header", file_name);
+ }
+
+ if (ehdr->e_type != ET_DYN)
+ {
+ close (fd);
+ error (1, 0, "%s: not shared library", file_name);
+ }
+
+ bool unsupported_class = true;
+ switch (ehdr->e_ident[EI_CLASS])
+ {
+ default:
+ break;
+
+ case ELFCLASS32:
+ unsupported_class = __ELF_NATIVE_CLASS != 32;
+ break;
+
+ case ELFCLASS64:
+ unsupported_class = __ELF_NATIVE_CLASS != 64;
+ break;
+ }
+
+ if (unsupported_class)
+ {
+ close (fd);
+ error (1, 0, "%s: unsupported ELF class: %d",
+ file_name, ehdr->e_ident[EI_CLASS]);
+ }
+
+ size_t phdr_size = sizeof (ElfW(Phdr)) * ehdr->e_phentsize;
+ if (statbuf.st_size < (ehdr->e_phoff + phdr_size))
+ {
+ close (fd);
+ error (1, 0, "%s: too small", file_name);
+ }
+
+ ElfW(Phdr) *phdr = (ElfW(Phdr) *) (base + ehdr->e_phoff);
+ for (int i = 0; i < ehdr->e_phnum; i++, phdr++)
+ if (phdr->p_type == PT_LOAD)
+ {
+ /* Update p_align of the first PT_LOAD segment. */
+ phdr->p_align = update_p_align (phdr->p_align);
+ break;
+ }
+
+ munmap (base, statbuf.st_size);
+ close (fd);
+
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,27 @@
+/* Check different alignments of PT_LOAD segments in a shared library.
+ Copyright (C) 2021 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/>. */
+
+extern int do_load_test (void);
+
+static int
+do_test (void)
+{
+ return do_load_test ();
+}
+
+#include <support/test-driver.c>
new file mode 100644
@@ -0,0 +1,34 @@
+/* Reduce p_align of the first PT_LOAD segment by half.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include "tst-elf-edit.h"
+
+/* Reduce p_align by half. */
+
+static size_t
+update_p_align (size_t p_align)
+{
+ size_t pagesize = sysconf (_SC_PAGESIZE);
+ size_t new_p_align = p_align >> 1;
+
+ if (new_p_align < pagesize)
+ error (1, 0, "%s: new p_align (0x%zx) < page size (0x%zx)",
+ file_name, new_p_align, pagesize);
+
+ return new_p_align;
+}