From 573456a931b6dc23dfe3da1e42d88a0bc0fbba7d Mon Sep 17 00:00:00 2001 From: Ed Maste Date: Fri, 23 Oct 2020 16:35:23 +0000 Subject: [PATCH] libelf: add compression header support GNU and Oracle libelf implementations added support for section compression, intended to reduce the size of DWARF debug info (which might be an order of magnitude larger than the code). There are two compressed ELF section formats: 1. Old GNU - sections are renmaed to start with 'z'. Section contains a magic number, uncompressed size, and compressed data. 2. Oracle and New GNU - compressed sections use the SHF_COMPRESSED flag. The compression header contains the compression type, uncompressed size, and uncompressed alignment. The second style is preferred and this change implements only that one. Submitted by: Tiger Gao Reviewed by: markj MFC after: 2 weeks Relnotes: Yes Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D24566 --- contrib/elftoolchain/libelf/Version.map | 9 +- contrib/elftoolchain/libelf/_libelf.h | 1 + contrib/elftoolchain/libelf/gelf.3 | 6 +- contrib/elftoolchain/libelf/gelf.h | 2 + contrib/elftoolchain/libelf/gelf_chdr.c | 82 +++++++++++++++ contrib/elftoolchain/libelf/gelf_getchdr.3 | 117 +++++++++++++++++++++ contrib/elftoolchain/libelf/libelf.h | 5 + contrib/elftoolchain/libelf/libelf_chdr.c | 104 ++++++++++++++++++ lib/libelf/Makefile | 2 + 9 files changed, 326 insertions(+), 2 deletions(-) create mode 100644 contrib/elftoolchain/libelf/gelf_chdr.c create mode 100644 contrib/elftoolchain/libelf/gelf_getchdr.3 create mode 100644 contrib/elftoolchain/libelf/libelf_chdr.c diff --git a/contrib/elftoolchain/libelf/Version.map b/contrib/elftoolchain/libelf/Version.map index e71a59197d0d..3d54bcb90aaa 100644 --- a/contrib/elftoolchain/libelf/Version.map +++ b/contrib/elftoolchain/libelf/Version.map @@ -91,6 +91,13 @@ global: gelf_update_symshndx; gelf_xlatetof; gelf_xlatetom; +}; + +R1.1 { +global: + elf32_getchdr; + elf64_getchdr; + gelf_getchdr; local: *; -}; +} R1.0; diff --git a/contrib/elftoolchain/libelf/_libelf.h b/contrib/elftoolchain/libelf/_libelf.h index 1a70d13886d5..ef1f31a39d61 100644 --- a/contrib/elftoolchain/libelf/_libelf.h +++ b/contrib/elftoolchain/libelf/_libelf.h @@ -220,6 +220,7 @@ size_t _libelf_fsize(Elf_Type _t, int _elfclass, unsigned int _version, size_t count); _libelf_translator_function *_libelf_get_translator(Elf_Type _t, int _direction, int _elfclass, int _elfmachine); +void *_libelf_getchdr(Elf_Scn *_e, int _elfclass); void *_libelf_getphdr(Elf *_e, int _elfclass); void *_libelf_getshdr(Elf_Scn *_scn, int _elfclass); void _libelf_init_elf(Elf *_e, Elf_Kind _kind); diff --git a/contrib/elftoolchain/libelf/gelf.3 b/contrib/elftoolchain/libelf/gelf.3 index d703c1b3f65e..d77fd1083d0b 100644 --- a/contrib/elftoolchain/libelf/gelf.3 +++ b/contrib/elftoolchain/libelf/gelf.3 @@ -23,7 +23,7 @@ .\" .\" $Id: gelf.3 3743 2019-06-12 19:36:30Z jkoshy $ .\" -.Dd June 12, 2019 +.Dd October 23, 2020 .Dt GELF 3 .Os .Sh NAME @@ -45,6 +45,8 @@ The GElf API defines the following class-independent data structures: .Bl -tag -width GElf_Sxword .It Vt GElf_Addr A representation of ELF addresses. +.It Vt GElf_Chdr +A class-independent representation of an ELF Compression Header. .It Vt GElf_Dyn A class-independent representation of ELF .Sy .dynamic @@ -144,6 +146,8 @@ native representation. .El .It "Retrieving ELF Data" .Bl -tag -compact -width indent +.It Fn gelf_getchdr +Retrieve an ELF Compression Header from the underlying ELF descriptor. .It Fn gelf_getdyn Retrieve an ELF .Sy .dynamic diff --git a/contrib/elftoolchain/libelf/gelf.h b/contrib/elftoolchain/libelf/gelf.h index 6eae0a5f27f5..87f272d56204 100644 --- a/contrib/elftoolchain/libelf/gelf.h +++ b/contrib/elftoolchain/libelf/gelf.h @@ -39,6 +39,7 @@ typedef Elf64_Sxword GElf_Sxword; /* Signed long words (64 bit) */ typedef Elf64_Word GElf_Word; /* Unsigned words (32 bit) */ typedef Elf64_Xword GElf_Xword; /* Unsigned long words (64 bit) */ +typedef Elf64_Chdr GElf_Chdr; /* Compressed section header */ typedef Elf64_Dyn GElf_Dyn; /* ".dynamic" section entries */ typedef Elf64_Ehdr GElf_Ehdr; /* ELF header */ typedef Elf64_Phdr GElf_Phdr; /* Program header */ @@ -73,6 +74,7 @@ extern "C" { long gelf_checksum(Elf *_elf); size_t gelf_fsize(Elf *_elf, Elf_Type _type, size_t _count, unsigned int _version); +GElf_Chdr *gelf_getchdr(Elf_Scn *_scn, GElf_Chdr *_dst); int gelf_getclass(Elf *_elf); GElf_Dyn *gelf_getdyn(Elf_Data *_data, int _index, GElf_Dyn *_dst); GElf_Ehdr *gelf_getehdr(Elf *_elf, GElf_Ehdr *_dst); diff --git a/contrib/elftoolchain/libelf/gelf_chdr.c b/contrib/elftoolchain/libelf/gelf_chdr.c new file mode 100644 index 000000000000..9f4f9a699a2a --- /dev/null +++ b/contrib/elftoolchain/libelf/gelf_chdr.c @@ -0,0 +1,82 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2020 The FreeBSD Foundation + * + * This software was developed by Tiger Gao under sponsorship from + * the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include +#include +#include +#include +#include + +#include "_libelf.h" + +Elf32_Chdr * +elf32_getchdr(Elf_Scn *s) +{ + return (_libelf_getchdr(s, ELFCLASS32)); +} + +Elf64_Chdr * +elf64_getchdr(Elf_Scn *s) +{ + return (_libelf_getchdr(s, ELFCLASS64)); +} + +GElf_Chdr * +gelf_getchdr(Elf_Scn *s, GElf_Chdr *d) +{ + int ec; + void *ch; + Elf32_Chdr *ch32; + Elf64_Chdr *ch64; + + if (d == NULL) { + LIBELF_SET_ERROR(ARGUMENT, 0); + return (NULL); + } + + if ((ch = _libelf_getchdr(s, ELFCLASSNONE)) == NULL) + return (NULL); + + ec = s->s_elf->e_class; + assert(ec == ELFCLASS32 || ec == ELFCLASS64); + + if (ec == ELFCLASS32) { + ch32 = (Elf32_Chdr *)ch; + + d->ch_type = (Elf64_Word)ch32->ch_type; + d->ch_size = (Elf64_Xword)ch32->ch_size; + d->ch_addralign = (Elf64_Xword)ch32->ch_addralign; + } else { + ch64 = (Elf64_Chdr *)ch; + *d = *ch64; + } + + return (d); +} diff --git a/contrib/elftoolchain/libelf/gelf_getchdr.3 b/contrib/elftoolchain/libelf/gelf_getchdr.3 new file mode 100644 index 000000000000..fde9179af3a1 --- /dev/null +++ b/contrib/elftoolchain/libelf/gelf_getchdr.3 @@ -0,0 +1,117 @@ +.\" SPDX-License-Identifier: BSD-2-Clause +.\" +.\" Copyright (c) 2020 The FreeBSD Foundation +.\" +.\" This document was written by Tiger Gao under sponsorship from +.\" the FreeBSD Foundation. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions are +.\" met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in +.\" the documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $Id: gelf_getchdr.3 3639 2020-10-20 16:07:02Z tig $ +.\" +.Dd October 23, 2020 +.Dt GELF_GETCHDR 3 +.Os +.Sh NAME +.Nm elf32_getchdr , +.Nm elf64_getchdr , +.Nm gelf_getchdr +.Nd retrieve the compression header of a section +.Sh LIBRARY +.Lb libelf +.Sh SYNOPSIS +.In libelf.h +.Ft "Elf32_Chdr *" +.Fn elf32_getchdr "Elf_Scn *s" +.Ft "Elf64_Chdr *" +.Fn elf64_getchdr "Elf_Scn *s" +.In gelf.h +.Ft "GElf_Chdr *" +.Fn gelf_getchdr "Elf_Scn *scn" "GElf_Chdr *chdr" +.Sh DESCRIPTION +These functions return a pointer to the ELF Compression Header data +structure associated with section descriptor +.Ar scn . +.Pp +Function +.Fn elf32_getchdr +retrieves a pointer to an +.Vt Elf32_Chdr +structure. +Section descriptor +.Ar scn +must be associated with an ELF descriptor of class +.Dv ELFCLASS32 . +.Pp +Function +.Fn elf64_getchdr +retrieves a pointer to an +.Vt Elf64_Chdr +structure. +Section descriptor +.Ar scn +must be associated with an ELF descriptor of class +.Dv ELFCLASS64 . +.Pp +Function +.Fn gelf_getchdr +copies the values in the compression header associated with argument +.Ar scn +to the structure pointed to be argument +.Ar dst . +The +.Vt GElf_Chdr +data structure is described in +.Xr gelf 3 . +.Sh RETURN VALUES +Functions +.Fn elf32_getchdr +and +.Fn elf64_getchdr +return a valid pointer to the appropriate compression header on success +or NULL if an error was encountered. +.Pp +Function +.Fn gelf_getchdr +returns argument +.Ar dst +if successful, or NULL if an error was encountered. +.Sh ERRORS +These functions may fail with the following errors: +.Bl -tag -width "[ELF_E_RESOURCE]" +.It Bq Er ELF_E_INVALID_SECTION_FLAGS +Arguments +.Ar scn +has invalid flags. +.It Bq Er ELF_E_INVALID_SECTION_TYPE +Argument +.Ar scn +has invalid type. +.It Bq Er ELF_E_NOT_COMPRESSED +Argument +.Ar scn +is not compressed. +.El +.Sh SEE ALSO +.Xr elf 3 , +.Xr elf_getscn 3 , +.Xr gelf 3 , diff --git a/contrib/elftoolchain/libelf/libelf.h b/contrib/elftoolchain/libelf/libelf.h index 151651d56473..9fa7035db30c 100644 --- a/contrib/elftoolchain/libelf/libelf.h +++ b/contrib/elftoolchain/libelf/libelf.h @@ -162,6 +162,9 @@ enum Elf_Error { ELF_E_SEQUENCE, /* API calls out of sequence */ ELF_E_UNIMPL, /* Feature is unimplemented */ ELF_E_VERSION, /* Unknown API version */ + ELF_E_INVALID_SECTION_FLAGS, /* Invalid ELF section header flags */ + ELF_E_INVALID_SECTION_TYPE, /* Invalid ELF section header type */ + ELF_E_NOT_COMPRESSED, /* Section is not compressed */ ELF_E_NUM /* Max error number */ }; @@ -227,6 +230,7 @@ unsigned int elf_version(unsigned int _version); long elf32_checksum(Elf *_elf); size_t elf32_fsize(Elf_Type _type, size_t _count, unsigned int _version); +Elf32_Chdr *elf32_getchdr(Elf_Scn *_scn); Elf32_Ehdr *elf32_getehdr(Elf *_elf); Elf32_Phdr *elf32_getphdr(Elf *_elf); Elf32_Shdr *elf32_getshdr(Elf_Scn *_scn); @@ -240,6 +244,7 @@ Elf_Data *elf32_xlatetom(Elf_Data *_dst, const Elf_Data *_src, long elf64_checksum(Elf *_elf); size_t elf64_fsize(Elf_Type _type, size_t _count, unsigned int _version); +Elf64_Chdr *elf64_getchdr(Elf_Scn *_scn); Elf64_Ehdr *elf64_getehdr(Elf *_elf); Elf64_Phdr *elf64_getphdr(Elf *_elf); Elf64_Shdr *elf64_getshdr(Elf_Scn *_scn); diff --git a/contrib/elftoolchain/libelf/libelf_chdr.c b/contrib/elftoolchain/libelf/libelf_chdr.c new file mode 100644 index 000000000000..6a63d4086fc9 --- /dev/null +++ b/contrib/elftoolchain/libelf/libelf_chdr.c @@ -0,0 +1,104 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2020 The FreeBSD Foundation + * + * This software was developed by Tiger Gao under sponsorship from + * the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include +#include + +#include "_libelf.h" + +void * +_libelf_getchdr(Elf_Scn *s, int ec) +{ + Elf *e; + void *sh; + Elf32_Shdr *sh32; + Elf64_Shdr *sh64; + + sh32 = NULL; + sh64 = NULL; + + if (s == NULL || (e = s->s_elf) == NULL || e->e_kind != ELF_K_ELF) { + LIBELF_SET_ERROR(ARGUMENT, 0); + return (NULL); + } + + if (ec == ELFCLASSNONE) { + ec = e->e_class; + } else if (ec != e->e_class) { + LIBELF_SET_ERROR(CLASS, 0); + return (NULL); + } + + if ((sh = _libelf_getshdr(s, ec)) == NULL) { + LIBELF_SET_ERROR(HEADER, 0); + return (NULL); + } + + if (ec == ELFCLASS32) { + sh32 = (Elf32_Shdr *)sh; + if ((sh32->sh_flags & SHF_ALLOC) != 0) { + LIBELF_SET_ERROR(INVALID_SECTION_FLAGS, 0); + return (NULL); + } + + if (sh32->sh_type == SHT_NULL || sh32->sh_type == SHT_NOBITS) { + LIBELF_SET_ERROR(INVALID_SECTION_TYPE, 0); + return (NULL); + } + + if ((sh32->sh_flags & SHF_COMPRESSED) == 0) { + LIBELF_SET_ERROR(NOT_COMPRESSED, 0); + return (NULL); + } + } else { + sh64 = (Elf64_Shdr *)sh; + if ((sh64->sh_flags & SHF_ALLOC) != 0) { + LIBELF_SET_ERROR(INVALID_SECTION_FLAGS, 0); + return (NULL); + } + + if (sh64->sh_type == SHT_NULL || sh64->sh_type == SHT_NOBITS) { + LIBELF_SET_ERROR(INVALID_SECTION_TYPE, 0); + return (NULL); + } + + if ((sh64->sh_flags & SHF_COMPRESSED) == 0) { + LIBELF_SET_ERROR(NOT_COMPRESSED, 0); + return (NULL); + } + } + + Elf_Data *d = elf_getdata(s, NULL); + + if (!d) + return (NULL); + + return ((void *)d->d_buf); +} diff --git a/lib/libelf/Makefile b/lib/libelf/Makefile index f3fd14d1e2b4..8174f4e06bba 100644 --- a/lib/libelf/Makefile +++ b/lib/libelf/Makefile @@ -38,6 +38,7 @@ SRCS= elf.c \ elf_update.c \ elf_version.c \ gelf_cap.c \ + gelf_chdr.c \ gelf_checksum.c \ gelf_dyn.c \ gelf_ehdr.c \ @@ -57,6 +58,7 @@ SRCS= elf.c \ libelf_allocate.c \ libelf_ar.c \ libelf_ar_util.c \ + libelf_chdr.c \ libelf_checksum.c \ libelf_data.c \ libelf_ehdr.c \