From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Cc: Florian Weimer <fweimer@redhat.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Subject: [PATCH v7 2/4] elf: Add a test for PT_LOAD segments with mixed p_align [BZ #28676]
Date: Mon, 3 Jan 2022 15:04:31 -0800 [thread overview]
Message-ID: <20220103230433.1907240-3-hjl.tools@gmail.com> (raw)
In-Reply-To: <20220103230433.1907240-1-hjl.tools@gmail.com>
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
+ 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;
+}
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);
+
+static int
+do_test (void)
+{
+ return do_load_test ();
+}
+
+#include <support/test-driver.c>
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;
+}
--
2.33.1
next prev parent reply other threads:[~2022-01-03 23:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-03 23:04 [PATCH v7 0/4] Properly align all PT_LOAD segments with tests H.J. Lu
2022-01-03 23:04 ` [PATCH v7 1/4] elf: Properly align all PT_LOAD segments [BZ #28676] H.J. Lu
2022-01-18 17:48 ` Adhemerval Zanella
2022-01-18 21:46 ` H.J. Lu
2022-01-03 23:04 ` H.J. Lu [this message]
2022-01-18 16:25 ` [PATCH v7 2/4] elf: Add a test for PT_LOAD segments with mixed p_align " Adhemerval Zanella
2022-01-18 21:53 ` H.J. Lu
2022-01-03 23:04 ` [PATCH v7 3/4] elf: Add a test for PT_LOAD segments with p_align == 1 [BZ #28688] H.J. Lu
2022-01-18 16:32 ` Adhemerval Zanella
2022-01-18 16:36 ` Adhemerval Zanella
2022-01-18 21:55 ` H.J. Lu
2022-01-03 23:04 ` [PATCH v7 4/4] elf: Add a test for PT_LOAD segments with invalid p_align " H.J. Lu
2022-01-18 18:05 ` Adhemerval Zanella
2022-01-18 21:50 ` H.J. Lu
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