Hans-Christian Noren Egtvedt 146fee59bc packages:mold: add version 2.33.0 ...

Add newly released mold version 2.33.0 from upstream
https://github.com/rui314/mold

New features
- mold gained a new linker flag --separate-debug-file to bundle debug
  info sections into a separate file instead of putting them into a main
  output file. You can optionally specify a filename in the form of
  --separate-debug-file=<filename>. By default, a debug info file is
  created in the same directory as the main output file with the .dbg
  extension. mold embeds the debug file's filename into the main output
  file so that gdb can automatically follow the link to find debug info
  when debugging the main output file.

- The main objective of this flag is to speed up the mold linker even
  more. By default, mold creates a separate debug file in the background
  after creating a main output file, so that you can start running the
  executable as soon as possible while mold is still working on linking
  its debug info sections. For example, linking clang with debug info
  normally takes ~1.70s on a Threadripper 7980X machine, while it takes
  only ~0.52s with --separate-debug-info. Shaving off a full second in
  quick edit-rebuild-run cycles should improve programmers'
  productivity. If you do not want mold to work in the background, pass
  the --no-detach option. (596ffa9)

- mold now supports the --no-allow-shlib-undefined flag. If the option
  is given, mold checks if all undefined symbols are resolved not only
  for input object files but also for shared libraries passed to the
  linker. To use the feature, you need to pass all shared libraries,
  including transitively dependent ones, to the linker so that the
  linker can resolve all symbols that are available at runtime.
  (3001f02)

- mold gained the --dynamic-list-data flag for the sake of compatibility
  with GNU ld. If the flag is given, all data symbols are exported as
  dynamic symbols. (dd8d971)

- [x86-64] -z x86-64-v2, -z x86-64-v3, -z x86-64-v4 flags are supported.
  (5606087)

Bug fixes and compatibility improvements
- [x86-64] Recent x86-64 processors support Intel CET to protect control
  flow integrity. When the feature is enabled, the instruction that is
  executed immediately after an indirect branch must be endbr64 or a CPU
  fault will raise. In other words, it restricts the locations where the
  control can transfer to with indirect branches. Doing that makes ROP
  attacks harder to conduct.

- A problem with that is the compiler needs to conservatively emit an
  endbr64 at the beginning of each global function because the compiler
  doesn't know whether or not the function's address is taken in other
  translation units. As a result, the resulting binary contains more
  endbr64s than necessary, weakening the protection.

- mold supports the -z rewrite-endbr option to conduct a whole program
  analysis and rewrite endbr64 with nop if a function's address is not
  actually taken within the program. Previously, mold didn't take
  section symbols into account when conducting the analysis, which
  resulted in culling some endbr64s that must not be removed. Now, the
  bug has been fixed. We confirmed that mold can build itself with -z
  rewrite-endbr, and the resulting mold executable works fine with Intel
  CET. (ed7eec5)

- mold now creates a .eh_frame section even if it's empty. (14a4b05)

- [LoongArch] The following relocations are now supported:
  R_LARCH_TLS_LE_HI20_R, R_LARCH_TLS_LE_ADD_R, R_LARCH_TLS_LE_LO12_R,
  R_LARCH_CALL36, R_LARCH_RELAX (36e5b4b, 98a7cff, 2c6f379)

- [LoongArch] Some relaxations that reduce the section size are now
  supported. (74b359f, 121f917)

- [LoongArch] Range extension thunk support has been removed in favor of
  R_LARCH_CALL36 relocations. (47c092a)

Signed-off-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>

2024-08-22 13:02:56 +12:00

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