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Rollup merge of #130824 - Darksonn:fix-function-return, r=wesleywiser

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Add missing module flags for `-Zfunction-return=thunk-extern`

This fixes a bug in the `-Zfunction-return=thunk-extern` flag. The flag needs to be passed onto LLVM to ensure that functions such as `asan.module_ctor` and `asan.module_dtor` that are created internally in LLVM have the mitigation applied to them.

This was originally discovered [in the Linux kernel](https://lore.kernel.org/all/CANiq72myZL4_poCMuNFevtpYYc0V0embjSuKb7y=C+m3vVA_8g@mail.gmail.com/).

Original flag PR: #116892
PR for similar issue: #129373
Tracking issue: #116853

cc ``@ojeda``
r? ``@wesleywiser``
This commit is contained in:
Stuart Cook 2024-10-08 13:19:43 +11:00 committed by GitHub
commit 4d63896018
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2 changed files with 19 additions and 1 deletions
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14
compiler/rustc_codegen_llvm/src/context.rs
View File

@ -19,7 +19,7 @@ use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_session::Session;
use rustc_session::config::{
BranchProtection, CFGuard, CFProtection, CrateType, DebugInfo, PAuthKey, PacRet,
BranchProtection, CFGuard, CFProtection, CrateType, DebugInfo, FunctionReturn, PAuthKey, PacRet,
};
use rustc_span::source_map::Spanned;
use rustc_span::{DUMMY_SP, Span};
@ -378,6 +378,18 @@ pub(crate) unsafe fn create_module<'ll>(
}
}
match sess.opts.unstable_opts.function_return {
FunctionReturn::Keep => {}
FunctionReturn::ThunkExtern => unsafe {
llvm::LLVMRustAddModuleFlagU32(
llmod,
llvm::LLVMModFlagBehavior::Override,
c"function_return_thunk_extern".as_ptr(),
1,
)
},
}
match (sess.opts.unstable_opts.small_data_threshold, sess.target.small_data_threshold_support())
{
// Set up the small-data optimization limit for architectures that use

6
tests/codegen/function-return.rs
View File

@ -26,3 +26,9 @@ pub fn foo() {
// keep-thunk-extern: attributes #0 = { {{.*}}fn_ret_thunk_extern{{.*}} }
// thunk-extern-keep-NOT: fn_ret_thunk_extern
}
// unset-NOT: !{{[0-9]+}} = !{i32 4, !"function_return_thunk_extern", i32 1}
// keep-NOT: !{{[0-9]+}} = !{i32 4, !"function_return_thunk_extern", i32 1}
// thunk-extern: !{{[0-9]+}} = !{i32 4, !"function_return_thunk_extern", i32 1}
// keep-thunk-extern: !{{[0-9]+}} = !{i32 4, !"function_return_thunk_extern", i32 1}
// thunk-extern-keep-NOT: !{{[0-9]+}} = !{i32 4, !"function_return_thunk_extern", i32 1}