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Use error-on-mismatch policy for PAuth module flags.

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This agrees with Clang, and avoids an error when using LTO with mixed
C/Rust. LLVM considers different behaviour flags to be a mismatch,
even when the flag value itself is the same.

This also makes the flag setting explicit for all uses of
LLVMRustAddModuleFlag.
This commit is contained in:
Jacob Bramley
2022-01-19 14:51:59 +00:00
parent 7bc7be860f
commit e02e9582d2
4 changed files with 73 additions and 13 deletions
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31
compiler/rustc_codegen_llvm/src/context.rs
View File

@@ -215,16 +215,19 @@ pub unsafe fn create_module<'ll>(
// to ensure intrinsic calls don't use it.
if !sess.needs_plt() {
let avoid_plt = "RtLibUseGOT\0".as_ptr().cast();
llvm::LLVMRustAddModuleFlag(llmod, avoid_plt, 1);
llvm::LLVMRustAddModuleFlag(llmod, llvm::LLVMModFlagBehavior::Warning, avoid_plt, 1);
}
if sess.is_sanitizer_cfi_enabled() {
// FIXME(rcvalle): Add support for non canonical jump tables.
let canonical_jump_tables = "CFI Canonical Jump Tables\0".as_ptr().cast();
// FIXME(rcvalle): Add it with Override behavior flag--LLVMRustAddModuleFlag adds it with
// Warning behavior flag. Add support for specifying the behavior flag to
// LLVMRustAddModuleFlag.
llvm::LLVMRustAddModuleFlag(llmod, canonical_jump_tables, 1);
// FIXME(rcvalle): Add it with Override behavior flag.
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Warning,
canonical_jump_tables,
1,
);
}
// Control Flow Guard is currently only supported by the MSVC linker on Windows.
@@ -233,11 +236,21 @@ pub unsafe fn create_module<'ll>(
CFGuard::Disabled => {}
CFGuard::NoChecks => {
// Set `cfguard=1` module flag to emit metadata only.
llvm::LLVMRustAddModuleFlag(llmod, "cfguard\0".as_ptr() as *const _, 1)
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Warning,
"cfguard\0".as_ptr() as *const _,
1,
)
}
CFGuard::Checks => {
// Set `cfguard=2` module flag to emit metadata and checks.
llvm::LLVMRustAddModuleFlag(llmod, "cfguard\0".as_ptr() as *const _, 2)
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Warning,
"cfguard\0".as_ptr() as *const _,
2,
)
}
}
}
@@ -247,24 +260,28 @@ pub unsafe fn create_module<'ll>(
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Error,
"branch-target-enforcement\0".as_ptr().cast(),
bti.into(),
);
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Error,
"sign-return-address\0".as_ptr().cast(),
pac.is_some().into(),
);
let pac_opts = pac.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Error,
"sign-return-address-all\0".as_ptr().cast(),
pac_opts.leaf.into(),
);
let is_bkey = if pac_opts.key == PAuthKey::A { false } else { true };
llvm::LLVMRustAddModuleFlag(
llmod,
llvm::LLVMModFlagBehavior::Error,
"sign-return-address-with-bkey\0".as_ptr().cast(),
is_bkey.into(),
);