airs-notes

Source

https://www.airs.com/blog/index.php?s=linkers+part

Authored and copyright by Ian Lance Taylor, collected here for easy lookup.

Index

Main series

• Linkers part 1: introduction
• Linkers part 2: technial introduction
• Linkers part 3: address spaces, object file formats
• Linkers part 4: shared libraries
• Linkers part 5: shared libraries redux, ELF symbols
• Linkers part 6: relocations, position-dependent libraries
• Linkers part 7: thread-local storage
• Linkers part 8: ELF segments and sections
• Linkers part 9: symbol versions, relaxation
• Linkers part 10: parallel linking
• Linkers part 11: archives
• Linkers part 12: symbol resolution
• Linkers part 13: symbol versions redux
• Linkers part 14: link-time optimization, initialization code
• Linkers part 15: COMDAT sections
• Linkers part 16: C++ template instantiation, exception frames
• Linkers part 17: warning symbols
• Linkers part 18: incremental linking
• Linkers part 19: __start and __stop symbols, byte swapping
• Linkers part 20: ending note

Other articles included as well

• GCC exception frames
• Linker combreloc
• Linker relro
• Combining versions
• Version scripts
• Protected symbols
• .eh_frame
• .eh_frame_hdr
• .gcc_except_table
• Executable stack
• Piece of PIE

Even more articles, from MaskRay’s blog

• Stack unwinding
• All about symbol versioning
• C++ exception handling ABI
• LLD and GNU linker incompatibilities
• Copy relocations, canonical PLT entries and protected visibility
• GNU indirect function
• Everything I know about GNU toolchain
• Metadata sections, COhtmlAT and SHF_LINK_ORDER

External links

Here’s a collection of links about the subject, I’m putting these here because people seem to find these useful.

• elf(5) manpage
• unofficial ELF docs (has more than the manpage, also has extra links)
• glibc internals
• stuff about .gnu.hash
• Linux Internals & Dynamic Linking Wizardy; Linux Internals: The Art of Symbol Resolution
• LWN article on the vDSO, the vDSO is a dynamic library automatically inserted into every process by the kernel, containing fast implementations of a few syscalls
• “The bits between the bits: how we get to main()”, a talk, mostly talks about process instantiation
• Everything You Always Wanted to Know About “Hello, World”, another talk
• “How programs get run” (LWN), part 1, part 2, also talks about eg. initial stack layout
• Glibc startup procedure, technically hurd but mostly the same on Linux
• The difference between all the crt*.o files
• Official x86-64 ELF ABI spec (PDF)
• Official ELF Auxiliary vector reference
  • Lots of useful stuff can be found on this website as well, see eg. here and here
• Glibc ld.so source code
• GNU ld source code
• Glibc How to debug ld.so
• Anatomy of a system call, LWN, part 1, part 2
• “Linkers and Loaders”, a book (PDF), more meant for general concepts than nitty ELF details. Also talks about Java for some reason.
• A Whirlwind Tutorial on Creating Really Teensy ELF Executables for Linux
• The Quest for minimal ELF binaries
• Linux sizecoding wiki
• Rough transcriptions of a thread on Mastodon, my posts had some useful info in them, so I saved these in this document.