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([2804:431:c7cb:989a:419b:3fe6:8885:ab23]) by smtp.gmail.com with ESMTPSA id h26sm2223407otk.55.2022.01.18.08.26.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Jan 2022 08:26:02 -0800 (PST) Message-ID: <5d0957aa-5128-601e-fece-837cdc6e6a20@linaro.org> Date: Tue, 18 Jan 2022 13:25:59 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v7 2/4] elf: Add a test for PT_LOAD segments with mixed p_align [BZ #28676] Content-Language: en-US To: "H.J. Lu" , libc-alpha@sourceware.org Cc: Florian Weimer References: <20220103230433.1907240-1-hjl.tools@gmail.com> <20220103230433.1907240-3-hjl.tools@gmail.com> From: Adhemerval Zanella In-Reply-To: <20220103230433.1907240-3-hjl.tools@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-12.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Jan 2022 16:26:06 -0000 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 > + . */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +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 > + . */ > + > +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 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 > + . */ > + > +#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; > +}