bjoernager/rust
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Add support for generating the EHCont section

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In the future Windows will enable Control-flow Enforcement Technology
(CET aka Shadow Stacks). To protect the path where the context is
updated during exception handling, the binary is required to enumerate
valid unwind entrypoints in a dedicated section which is validated when
the context is being set during exception handling.

The required support for EHCONT has already been merged into LLVM,
long ago. This change adds the Rust codegen option to enable it.

Reference:

* https://reviews.llvm.org/D40223

This also adds a new `ehcont-guard` option to the bootstrap config which
enables EHCont Guard when building std.
This commit is contained in:
Arlie Davis 2023-11-17 10:05:38 -08:00
parent 2f8d81f9db
commit e11d8d147b
10 changed files with 76 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

5
compiler/rustc_codegen_ssa/src/back/link.rs
View file

@ -2378,6 +2378,11 @@ fn add_order_independent_options(
cmd.control_flow_guard();
}
// OBJECT-FILES-NO, AUDIT-ORDER
if sess.opts.cg.ehcont_guard {
cmd.ehcont_guard();
}
add_rpath_args(cmd, sess, codegen_results, out_filename);
}

21
compiler/rustc_codegen_ssa/src/back/linker.rs
View file

@ -185,6 +185,7 @@ pub trait Linker {
fn optimize(&mut self);
fn pgo_gen(&mut self);
fn control_flow_guard(&mut self);
fn ehcont_guard(&mut self);
fn debuginfo(&mut self, strip: Strip, natvis_debugger_visualizers: &[PathBuf]);
fn no_crt_objects(&mut self);
fn no_default_libraries(&mut self);
@ -605,6 +606,8 @@ impl<'a> Linker for GccLinker<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn debuginfo(&mut self, strip: Strip, _: &[PathBuf]) {
// MacOS linker doesn't support stripping symbols directly anymore.
if self.sess.target.is_like_osx {
@ -914,6 +917,12 @@ impl<'a> Linker for MsvcLinker<'a> {
self.cmd.arg("/guard:cf");
}
fn ehcont_guard(&mut self) {
if self.sess.target.pointer_width == 64 {
self.cmd.arg("/guard:ehcont");
}
}
fn debuginfo(&mut self, strip: Strip, natvis_debugger_visualizers: &[PathBuf]) {
match strip {
Strip::None => {
@ -1127,6 +1136,8 @@ impl<'a> Linker for EmLinker<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
// Preserve names or generate source maps depending on debug info
// For more information see https://emscripten.org/docs/tools_reference/emcc.html#emcc-g
@ -1319,6 +1330,8 @@ impl<'a> Linker for WasmLd<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn no_crt_objects(&mut self) {}
fn no_default_libraries(&mut self) {}
@ -1472,6 +1485,8 @@ impl<'a> Linker for L4Bender<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn no_crt_objects(&mut self) {}
}
@ -1613,6 +1628,8 @@ impl<'a> Linker for AixLinker<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn debuginfo(&mut self, strip: Strip, _: &[PathBuf]) {
match strip {
Strip::None => {}
@ -1835,6 +1852,8 @@ impl<'a> Linker for PtxLinker<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType, _symbols: &[String]) {}
fn subsystem(&mut self, _subsystem: &str) {}
@ -1931,6 +1950,8 @@ impl<'a> Linker for BpfLinker<'a> {
fn control_flow_guard(&mut self) {}
fn ehcont_guard(&mut self) {}
fn export_symbols(&mut self, tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
let path = tmpdir.join("symbols");
let res: io::Result<()> = try {