rust/tests/assembly/x86_64-function-return.rs
Miguel Ojeda 2d476222e8 Add -Zfunction-return={keep,thunk-extern} option
This is intended to be used for Linux kernel RETHUNK builds.

With this commit (optionally backported to Rust 1.73.0), plus a
patched Linux kernel to pass the flag, I get a RETHUNK build with
Rust enabled that is `objtool`-warning-free and is able to boot in
QEMU and load a sample Rust kernel module.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-11-30 20:21:31 +01:00

30 lines
1.1 KiB
Rust

// Test that the function return is (not) converted into a jump to the thunk
// when the `-Zfunction-return={keep,thunk-extern}` flag is (not) set.
// revisions: unset keep thunk-extern keep-thunk-extern thunk-extern-keep
// assembly-output: emit-asm
// compile-flags: -O
// [keep] compile-flags: -Zfunction-return=keep
// [thunk-extern] compile-flags: -Zfunction-return=thunk-extern
// [keep-thunk-extern] compile-flags: -Zfunction-return=keep -Zfunction-return=thunk-extern
// [thunk-extern-keep] compile-flags: -Zfunction-return=thunk-extern -Zfunction-return=keep
// only-x86_64
// ignore-x86_64-apple-darwin Symbol is called `___x86_return_thunk` (Darwin's extra underscore)
// ignore-sgx Tests incompatible with LVI mitigations
#![crate_type = "lib"]
// CHECK-LABEL: foo:
#[no_mangle]
pub unsafe fn foo() {
// unset: ret
// unset-NOT: jmp __x86_return_thunk
// keep: ret
// keep-NOT: jmp __x86_return_thunk
// thunk-extern: jmp __x86_return_thunk
// thunk-extern-NOT: ret
// keep-thunk-extern: jmp __x86_return_thunk
// keep-thunk-extern-NOT: ret
// thunk-extern-keep: ret
// thunk-extern-keep-NOT: jmp __x86_return_thunk
}