[v8,2/4] elf: Add a test for PT_LOAD segments with mixed p_align [BZ #28676]

  Add tst-p_alignmod1-edit to edit the copy of tst-p_alignmod-base.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               |  16 +++++
 elf/tst-elf-edit.h         | 126 +++++++++++++++++++++++++++++++++++++
 elf/tst-p_align.h          |  20 ++++++
 elf/tst-p_align1.c         |  27 ++++++++
 elf/tst-p_alignmod-base.c  |  41 ++++++++++++
 elf/tst-p_alignmod1-edit.c |  34 ++++++++++
 6 files changed, 264 insertions(+)
 create mode 100644 elf/tst-elf-edit.h
 create mode 100644 elf/tst-p_align.h
 create mode 100644 elf/tst-p_align1.c
 create mode 100644 elf/tst-p_alignmod-base.c
 create mode 100644 elf/tst-p_alignmod1-edit.c
  

On 18/01/2022 18:57, H.J. Lu wrote:
> Add tst-p_alignmod1-edit to edit the copy of tst-p_alignmod-base.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               |  16 +++++
>  elf/tst-elf-edit.h         | 126 +++++++++++++++++++++++++++++++++++++
>  elf/tst-p_align.h          |  20 ++++++
>  elf/tst-p_align1.c         |  27 ++++++++
>  elf/tst-p_alignmod-base.c  |  41 ++++++++++++
>  elf/tst-p_alignmod1-edit.c |  34 ++++++++++
>  6 files changed, 264 insertions(+)
>  create mode 100644 elf/tst-elf-edit.h
>  create mode 100644 elf/tst-p_align.h
>  create mode 100644 elf/tst-p_align1.c
>  create mode 100644 elf/tst-p_alignmod-base.c
>  create mode 100644 elf/tst-p_alignmod1-edit.c
> 
> diff --git a/elf/Makefile b/elf/Makefile
> index 692a65b061..94ebcab1fa 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -412,6 +412,8 @@ tests += \
>    tst-nodelete-opened \
>    tst-noload \
>    tst-null-argv \
> +  tst-p_alignmod1-edit \
> +  tst-p_align1 \
>    tst-relsort1 \
>    tst-ro-dynamic \
>    tst-rtld-run-static \
> @@ -728,6 +730,7 @@ modules-names = \
>    tst-nodelete-dlclose-plugin \
>    tst-nodelete-opened-lib \
>    tst-null-argv-lib \
> +  tst-p_alignmod-base \
>    tst-relsort1mod1 \
>    tst-relsort1mod2 \
>    tst-ro-dynamic-mod \
> @@ -2578,3 +2581,16 @@ 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_alignmod-base.so: $(libsupport)
> +
> +$(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
> +
> +# Make a copy of tst-p_alignmod-base.so and lower p_align of the first
> +# PT_LOAD segment.
> +$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod1-edit \
> +			     $(objpfx)tst-p_alignmod-base.so
> +	rm -f $@
> +	cp $(objpfx)tst-p_alignmod-base.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..b764e78933
> --- /dev/null
> +++ b/elf/tst-elf-edit.h
> @@ -0,0 +1,126 @@
> +/* Update p_align of the first PT_LOAD segment.
> +   Copyright (C) 2022 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;
> +}
> diff --git a/elf/tst-p_align.h b/elf/tst-p_align.h
> new file mode 100644
> index 0000000000..cef92330fb
> --- /dev/null
> +++ b/elf/tst-p_align.h
> @@ -0,0 +1,20 @@
> +/* Prototypes to check different alignments of PT_LOAD segments in
> +   a shared library.
> +   Copyright (C) 2022 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);
> diff --git a/elf/tst-p_align1.c b/elf/tst-p_align1.c
> new file mode 100644
> index 0000000000..961c7fbbf1
> --- /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) 2022 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-p_align.h"
> +
> +static int
> +do_test (void)
> +{
> +  return do_load_test ();
> +}
> +
> +#include <support/test-driver.c>

I am seeing a failure with GNU ld (GNU Binutils) 2.37.20220112:

$ make test t=elf/tst-p_align1
[...]
FAIL: elf/tst-p_align1
original exit status 1
foo: 0x7fdddbecb000
error: tst-p_alignmod-base.c:39: not true: is_aligned_p (&foo, ALIGN)
error: 1 test failures

Without -Wl,-z,max-page-size=0x200000 the tst-p_alignmod-base.so is still
0x1000:

$ readelf -l elf/tst-p_alignmod-base.so 
[...]
Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000000000000 0x0000000000000000 0x0000000000000000
                 0x0000000000000998 0x0000000000000998  R      0x1000
  LOAD           0x0000000000001000 0x0000000000001000 0x0000000000001000
                 0x0000000000000589 0x0000000000000589  R E    0x1000
  LOAD           0x0000000000002000 0x0000000000002000 0x0000000000002000
                 0x00000000000003f8 0x00000000000003f8  R      0x1000
  LOAD           0x0000000000002df0 0x0000000000003df0 0x0000000000003df0
                 0x0000000000000288 0x0000000000000288  RW     0x1000
  LOAD           0x0000000000200000 0x0000000000200000 0x0000000000200000
                 0x0000000000200004 0x0000000000200018  RW     0x1000
[...]

I think you will need to use the same strategy from tst-align3 to force the
maximum alignment:

diff --git a/elf/Makefile b/elf/Makefile
index 94ebcab1fa..cdb41c686e 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -2583,6 +2583,7 @@ CFLAGS-tst-dl_find_object-mod8.c += -funwind-tables
 CFLAGS-tst-dl_find_object-mod9.c += -funwind-tables
 
 $(objpfx)tst-p_alignmod-base.so: $(libsupport)
+LDFLAGS-tst-p_alignmod-base.so += -Wl,-z,max-page-size=0x200000
 
 $(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
 
diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
index cdb453e696..06d9c636fd 100644
--- a/elf/tst-p_alignmod1-edit.c
+++ b/elf/tst-p_alignmod1-edit.c
@@ -23,12 +23,5 @@
 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;
+  return p_align >> 1;
 }

The rest looks ok.

> diff --git a/elf/tst-p_alignmod-base.c b/elf/tst-p_alignmod-base.c
> new file mode 100644
> index 0000000000..0fc1b75523
> --- /dev/null
> +++ b/elf/tst-p_alignmod-base.c
> @@ -0,0 +1,41 @@
> +/* Check alignment of PT_LOAD segment in a shared library.
> +   Copyright (C) 2022 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 <stdint.h>
> +#include <support/check.h>
> +#include <tst-file-align.h>
> +#include "tst-p_align.h"
> +
> +int foo __attribute__ ((aligned (ALIGN))) = 1;
> +
> +bool
> +__attribute__ ((weak, noclone, noinline))
> +is_aligned_p (void *p, int align)
> +{
> +  return (((uintptr_t) p) & (align - 1)) == 0;
> +}
> +
> +int
> +do_load_test (void)
> +{
> +  printf ("foo: %p\n", &foo);
> +  TEST_VERIFY (is_aligned_p (&foo, ALIGN));
> +  return 0;
> +}
> diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
> new file mode 100644
> index 0000000000..cdb453e696
> --- /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) 2022 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 Fri, Jan 21, 2022 at 12:00 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
> On 18/01/2022 18:57, H.J. Lu wrote:
> > Add tst-p_alignmod1-edit to edit the copy of tst-p_alignmod-base.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               |  16 +++++
> >  elf/tst-elf-edit.h         | 126 +++++++++++++++++++++++++++++++++++++
> >  elf/tst-p_align.h          |  20 ++++++
> >  elf/tst-p_align1.c         |  27 ++++++++
> >  elf/tst-p_alignmod-base.c  |  41 ++++++++++++
> >  elf/tst-p_alignmod1-edit.c |  34 ++++++++++
> >  6 files changed, 264 insertions(+)
> >  create mode 100644 elf/tst-elf-edit.h
> >  create mode 100644 elf/tst-p_align.h
> >  create mode 100644 elf/tst-p_align1.c
> >  create mode 100644 elf/tst-p_alignmod-base.c
> >  create mode 100644 elf/tst-p_alignmod1-edit.c
> >
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 692a65b061..94ebcab1fa 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -412,6 +412,8 @@ tests += \
> >    tst-nodelete-opened \
> >    tst-noload \
> >    tst-null-argv \
> > +  tst-p_alignmod1-edit \
> > +  tst-p_align1 \
> >    tst-relsort1 \
> >    tst-ro-dynamic \
> >    tst-rtld-run-static \
> > @@ -728,6 +730,7 @@ modules-names = \
> >    tst-nodelete-dlclose-plugin \
> >    tst-nodelete-opened-lib \
> >    tst-null-argv-lib \
> > +  tst-p_alignmod-base \
> >    tst-relsort1mod1 \
> >    tst-relsort1mod2 \
> >    tst-ro-dynamic-mod \
> > @@ -2578,3 +2581,16 @@ 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_alignmod-base.so: $(libsupport)
> > +
> > +$(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
> > +
> > +# Make a copy of tst-p_alignmod-base.so and lower p_align of the first
> > +# PT_LOAD segment.
> > +$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod1-edit \
> > +                          $(objpfx)tst-p_alignmod-base.so
> > +     rm -f $@
> > +     cp $(objpfx)tst-p_alignmod-base.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..b764e78933
> > --- /dev/null
> > +++ b/elf/tst-elf-edit.h
> > @@ -0,0 +1,126 @@
> > +/* Update p_align of the first PT_LOAD segment.
> > +   Copyright (C) 2022 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;
> > +}
> > diff --git a/elf/tst-p_align.h b/elf/tst-p_align.h
> > new file mode 100644
> > index 0000000000..cef92330fb
> > --- /dev/null
> > +++ b/elf/tst-p_align.h
> > @@ -0,0 +1,20 @@
> > +/* Prototypes to check different alignments of PT_LOAD segments in
> > +   a shared library.
> > +   Copyright (C) 2022 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);
> > diff --git a/elf/tst-p_align1.c b/elf/tst-p_align1.c
> > new file mode 100644
> > index 0000000000..961c7fbbf1
> > --- /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) 2022 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-p_align.h"
> > +
> > +static int
> > +do_test (void)
> > +{
> > +  return do_load_test ();
> > +}
> > +
> > +#include <support/test-driver.c>
>
> I am seeing a failure with GNU ld (GNU Binutils) 2.37.20220112:
>
> $ make test t=elf/tst-p_align1
> [...]
> FAIL: elf/tst-p_align1
> original exit status 1
> foo: 0x7fdddbecb000
> error: tst-p_alignmod-base.c:39: not true: is_aligned_p (&foo, ALIGN)
> error: 1 test failures
>
> Without -Wl,-z,max-page-size=0x200000 the tst-p_alignmod-base.so is still
> 0x1000:
>
> $ readelf -l elf/tst-p_alignmod-base.so
> [...]
> Program Headers:
>   Type           Offset             VirtAddr           PhysAddr
>                  FileSiz            MemSiz              Flags  Align
>   LOAD           0x0000000000000000 0x0000000000000000 0x0000000000000000
>                  0x0000000000000998 0x0000000000000998  R      0x1000
>   LOAD           0x0000000000001000 0x0000000000001000 0x0000000000001000
>                  0x0000000000000589 0x0000000000000589  R E    0x1000
>   LOAD           0x0000000000002000 0x0000000000002000 0x0000000000002000
>                  0x00000000000003f8 0x00000000000003f8  R      0x1000
>   LOAD           0x0000000000002df0 0x0000000000003df0 0x0000000000003df0
>                  0x0000000000000288 0x0000000000000288  RW     0x1000
>   LOAD           0x0000000000200000 0x0000000000200000 0x0000000000200000
>                  0x0000000000200004 0x0000000000200018  RW     0x1000
> [...]
>
> I think you will need to use the same strategy from tst-align3 to force the
> maximum alignment:
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 94ebcab1fa..cdb41c686e 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -2583,6 +2583,7 @@ CFLAGS-tst-dl_find_object-mod8.c += -funwind-tables
>  CFLAGS-tst-dl_find_object-mod9.c += -funwind-tables
>
>  $(objpfx)tst-p_alignmod-base.so: $(libsupport)
> +LDFLAGS-tst-p_alignmod-base.so += -Wl,-z,max-page-size=0x200000

Fixed.

>  $(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
>
> diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
> index cdb453e696..06d9c636fd 100644
> --- a/elf/tst-p_alignmod1-edit.c
> +++ b/elf/tst-p_alignmod1-edit.c
> @@ -23,12 +23,5 @@
>  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;
> +  return p_align >> 1;
>  }

Fixed.

I sent out the v9 patch.

> The rest looks ok.
>
> > diff --git a/elf/tst-p_alignmod-base.c b/elf/tst-p_alignmod-base.c
> > new file mode 100644
> > index 0000000000..0fc1b75523
> > --- /dev/null
> > +++ b/elf/tst-p_alignmod-base.c
> > @@ -0,0 +1,41 @@
> > +/* Check alignment of PT_LOAD segment in a shared library.
> > +   Copyright (C) 2022 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 <stdint.h>
> > +#include <support/check.h>
> > +#include <tst-file-align.h>
> > +#include "tst-p_align.h"
> > +
> > +int foo __attribute__ ((aligned (ALIGN))) = 1;
> > +
> > +bool
> > +__attribute__ ((weak, noclone, noinline))
> > +is_aligned_p (void *p, int align)
> > +{
> > +  return (((uintptr_t) p) & (align - 1)) == 0;
> > +}
> > +
> > +int
> > +do_load_test (void)
> > +{
> > +  printf ("foo: %p\n", &foo);
> > +  TEST_VERIFY (is_aligned_p (&foo, ALIGN));
> > +  return 0;
> > +}
> > diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
> > new file mode 100644
> > index 0000000000..cdb453e696
> > --- /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) 2022 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;
> > +}