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[LLD][MinGW] Add --[no-]guard-cf and --[no-]guard-longjmp 

These will be LLD-specific options to support Control Flow Guard for the
MinGW target. They are disabled by default, but enabling `--guard-cf`
will also enable `--guard-longjmp` unless `--no-guard-longjmp` is also
specified. These options maps to `-guard:cf,[no]longjmp`.

Note that these features require the `_load_config_used` symbol to
contain the load config directory and be filled with the required
symbols. While current versions of mingw-w64 do not supply this symbol,
the user can provide their own version of it.

Reviewed By: MaskRay, rnk

Differential Revision: https://reviews.llvm.org/D132808
This commit is contained in:
Alvin Wong 2022-09-09 09:17:33 +03:00 committed by Martin Storsjö
parent 06413618ea
commit bf7c5f1fae
4 changed files with 40 additions and 1 deletions
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11
lld/MinGW/Driver.cpp
View File

@ -379,6 +379,17 @@ bool mingw::link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
error("unknown parameter: -m" + s);
}
if (args.hasFlag(OPT_guard_cf, OPT_no_guard_cf, false)) {
if (args.hasFlag(OPT_guard_longjmp, OPT_no_guard_longjmp, true))
add("-guard:cf,longjmp");
else
add("-guard:cf,nolongjmp");
} else if (args.hasFlag(OPT_guard_longjmp, OPT_no_guard_longjmp, false)) {
auto *a = args.getLastArg(OPT_guard_longjmp);
warn("parameter " + a->getSpelling() +
" only takes effect when used with --guard-cf");
}
for (auto *a : args.filtered(OPT_mllvm))
add("-mllvm:" + StringRef(a->getValue()));

5
lld/MinGW/Options.td
View File

@ -141,6 +141,11 @@ defm pdb: Eq<"pdb", "Output PDB debug info file, chosen implicitly if the argume
defm thinlto_cache_dir: EqLong<"thinlto-cache-dir",
"Path to ThinLTO cached object file directory">;
defm Xlink : Eq<"Xlink", "Pass <arg> to the COFF linker">, MetaVarName<"<arg>">;
defm guard_cf : B<"guard-cf", "Enable Control Flow Guard" ,
"Do not enable Control Flow Guard (default)">;
defm guard_longjmp : B<"guard-longjmp",
"Enable Control Flow Guard long jump hardening (default for --guard-cf)" ,
"Do not enable Control Flow Guard long jump hardening">;
// Alias
def alias_Bdynamic_call_shared: Flag<["-"], "call_shared">, Alias<Bdynamic>;

10
lld/docs/ReleaseNotes.rst
View File

@ -37,7 +37,15 @@ COFF Improvements
MinGW Improvements
------------------
* ...
* The lld-specific options ``--guard-cf``, ``--no-guard-cf``,
``--guard-longjmp`` and ``--no-guard-longjmp`` has been added to allow
enabling Control Flow Guard and long jump hardening. These options are
disabled by default, but enabling ``--guard-cf`` will also enable
``--guard-longjmp`` unless ``--no-guard-longjmp`` is also specified.
``--guard-longjmp`` depends on ``--guard-cf`` and cannot be used by itself.
Note that these features require the ``_load_config_used`` symbol to contain
the load config directory and be filled with the required symbols.
(`D132808 <https://reviews.llvm.org/D132808>`_)
MachO Improvements
------------------

15
lld/test/MinGW/driver.test
View File

@ -356,3 +356,18 @@ RUN: ld.lld -### foo.o -m i386pep -heap 8388608,16384 2>&1 | FileCheck -check-pr
RUN: ld.lld -### foo.o -m i386pep --heap 8388608,16384 2>&1 | FileCheck -check-prefix=HEAP %s
RUN: ld.lld -### foo.o -m i386pep --heap=8388608,16384 2>&1 | FileCheck -check-prefix=HEAP %s
HEAP: -heap:8388608,16384
RUN: ld.lld -### foo.o -m i386pep --no-guard-cf 2>&1 | FileCheck -check-prefix=NO_GUARD_CF %s
RUN: ld.lld -### foo.o -m i386pep --no-guard-cf --no-guard-longjmp 2>&1 | FileCheck -check-prefix=NO_GUARD_CF %s
NO_GUARD_CF-NOT: -guard:
RUN: ld.lld -### foo.o -m i386pep --guard-cf 2>&1 | FileCheck -check-prefix=GUARD_CF %s
RUN: ld.lld -### foo.o -m i386pep --guard-cf --guard-longjmp 2>&1 | FileCheck -check-prefix=GUARD_CF %s
GUARD_CF: -guard:cf,longjmp
RUN: ld.lld -### foo.o -m i386pep --guard-cf --no-guard-longjmp 2>&1 | FileCheck -check-prefix=GUARD_CF_NOLONGJMP %s
GUARD_CF_NOLONGJMP: -guard:cf,nolongjmp
RUN: ld.lld -### foo.o -m i386pep --guard-longjmp 2>&1 | FileCheck -check-prefix=GUARD_LONGJMP_NO_CF %s
RUN: ld.lld -### foo.o -m i386pep --no-guard-cf --guard-longjmp 2>&1 | FileCheck -check-prefix=GUARD_LONGJMP_NO_CF %s
GUARD_LONGJMP_NO_CF: warning: parameter --guard-longjmp only takes effect when used with --guard-cf