On Fri, Apr 14, 2023 at 09:04:36PM +0200, Miguel Ojeda wrote: > On Fri, Apr 14, 2023 at 7:12 PM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > > Not to mention how objtool will react to compiled rust code (has it > > already been tried?) > > Rust uses LLVM, so it should be generally fine -- at least some of the > checks appear to work. For instance, I can trigger: > > RUSTC L rust/kernel.o > rust/kernel.o: warning: objtool: .text+0x0: unreachable instruction > > RUSTC [M] samples/rust/rust_minimal.o > samples/rust/rust_minimal.o: warning: objtool: > _R..._6kernel6Module4init+0x172: unreachable instruction > > via a random instruction in the middle of nowhere in the former (with > `global_asm!`) and a jumped-over instruction in the latter (with > `asm!`). > > Moreover, we were already getting warnings when rethunk / x86 IBT is > enabled (since we got `objtool` called for `vmlinux.o`), e.g. > > vmlinux.o: warning: objtool: .rodata+0x18c58: data relocation to > !ENDBR: _R...IsWhitespaceEEB4_+0x0 > > vmlinux.o: warning: objtool: _R...into_foreign+0x5: 'naked' return > found in RETHUNK build > > I can send the patch to run it for all Rust object files via > `$(cmd_objtool)`, unless you think it is a bad idea. That's good to hear that it seems to just work. Feel free to send a patch to enable it for Rust objects, though I may need your help if we see any odd warnings ;-) -- Josh
