Date: Mon, 6 Dec 2021 14:04:55 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 3f9a6f6cf317 - stable/13 - elf.5: Document compressed section headers Message-ID: <202112061404.1B6E4tFx081746@gitrepo.freebsd.org>
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The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=3f9a6f6cf3179a4ea3652779f40d640b0dc6083a commit 3f9a6f6cf3179a4ea3652779f40d640b0dc6083a Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2021-11-29 18:51:50 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2021-12-06 14:03:50 +0000 elf.5: Document compressed section headers Reviewed by: emaste Sponsored by: The FreeBSD Foundation (cherry picked from commit e0189cf66a94e1149793caf4dea17288da22a0c3) --- share/man/man5/elf.5 | 49 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) diff --git a/share/man/man5/elf.5 b/share/man/man5/elf.5 index 3134e8614988..81376e7e6bb9 100644 --- a/share/man/man5/elf.5 +++ b/share/man/man5/elf.5 @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd March 11, 2020 +.Dd November 27, 2021 .Dt ELF 5 .Os .Sh NAME @@ -795,6 +795,8 @@ The section contains executable machine instructions. .It Dv SHF_MASKPROC All bits included in this mask are reserved for processor-specific semantics. +.It Dv SHF_COMPRESSED +The section data is compressed. .El .Pp .It Dv sh_addr @@ -1069,6 +1071,50 @@ be registered. This section holds information used for C++ exception-handling. .El .Pp +A section with the +.Dv SHF_COMPRESSED +flag set contains a compressed copy of the section data. +Compressed section data begins with an +.Vt Elf64_Chdr +or +.Vt Elf32_Chdr structure +which encodes the compression algorithm and some characteristics of the +uncompressed data. +.Bd -literal -offset indent +typedef struct { + Elf32_Word ch_type; + Elf32_Word ch_size; + Elf32_Word ch_addralign; +} Elf32_Chdr; +.Ed +.Bd -literal -offset indent +typedef struct { + Elf64_Word ch_type; + Elf64_Word ch_reserved; + Elf64_Xword ch_size; + Elf64_Xword ch_addralign; +} Elf64_Chdr; +.Ed +.Pp +.Bl -tag -width "ch_addralign" -compact +.It Dv ch_type +The compression algorithm used. +A value of +.Dv ELFCOMPRESS_ZLIB +indicates that the data is compressed using +.Xr zlib 3 . +.It Dv ch_size +The size, in bytes, of the uncompressed section data. +This corresponds to the +.Sy sh_size +field of a section header containing uncompressed data. +.It Dv ch_addralign +The address alignment of the uncompressed section data. +This corresponds to the +.Sy sh_addralign +field of a section header containing uncompressed data. +.El +.Pp String table sections hold null-terminated character sequences, commonly called strings. The object file uses these strings to represent symbol @@ -1342,6 +1388,7 @@ writeable and executable. .Xr objdump 1 , .Xr readelf 1 , .Xr execve 2 , +.Xr zlib 3 , .Xr ar 5 , .Xr core 5 .Rs
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