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rustc_codegen_llvm: Add a new 'pc' option to branch-protection

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Add a new 'pc' option to -Z branch-protection for aarch64 that
enables the use of PC as a diversifier in PAC branch protection code.

When the pauth-lr target feature is enabled in combination
with -Z branch-protection=pac-ret,pc, the new 9.5-a instructions
(pacibsppc, retaasppc, etc) will be generated.
This commit is contained in:
Kajetan Puchalski 2024-10-16 15:39:58 +01:00
parent 4d296eabe4
commit 10edeea4b4
12 changed files with 97 additions and 17 deletions
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5
compiler/rustc_codegen_llvm/src/attributes.rs
View file

@ -424,7 +424,10 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
if bti {
to_add.push(llvm::CreateAttrString(cx.llcx, "branch-target-enforcement"));
}
if let Some(PacRet { leaf, key }) = pac_ret {
if let Some(PacRet { leaf, pc, key }) = pac_ret {
if pc {
to_add.push(llvm::CreateAttrString(cx.llcx, "branch-protection-pauth-lr"));
}
to_add.push(llvm::CreateAttrStringValue(
cx.llcx,
"sign-return-address",

8
compiler/rustc_codegen_llvm/src/context.rs
View file

@ -302,7 +302,13 @@ pub(crate) unsafe fn create_module<'ll>(
"sign-return-address",
pac_ret.is_some().into(),
);
let pac_opts = pac_ret.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
let pac_opts = pac_ret.unwrap_or(PacRet { leaf: false, pc: false, key: PAuthKey::A });
llvm::add_module_flag_u32(
llmod,
llvm::ModuleFlagMergeBehavior::Min,
"branch-protection-pauth-lr",
pac_opts.pc.into(),
);
llvm::add_module_flag_u32(
llmod,
llvm::ModuleFlagMergeBehavior::Min,