Messages in this thread | | | From | Nick Desaulniers <> | Date | Mon, 5 Dec 2022 13:38:08 -0800 | Subject | Re: [PATCH v2] rust: make compiler-builtin stubs non-global |
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On Sun, Dec 4, 2022 at 3:17 PM Gary Guo <gary@garyguo.net> wrote: > > Currently we define a number of stubs for compiler-builtin intrinsics > that compiled libcore generates. The defined stubs are weak so they will > not conflict with genuine implementation of these intrinsics, but their > effect is global and will cause non-libcore code that accidently > generate these intrinsics calls compile and bug on runtime. > > Instead of defining a stub that can affect all code, this patch uses > objcopy's `--redefine-sym` flag to redirect these calls (from libcore > only) to a prefixed version (e.g. redirect `__multi3` to `__rust_multi3`), > so we can define panciking stubs that are only visible to libcore. > > This patch was previous discussed on GitHub. > Link: https://github.com/Rust-for-Linux/linux/pull/779 > > Signed-off-by: Gary Guo <gary@garyguo.net>
Thank you for addressing my feedback!
Link: https://lore.kernel.org/lkml/CAKwvOdkc0Qhwu=gfe1+H23TnAa6jnO6A3ZCO687dH6mSrATmDA@mail.gmail.com/ Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> > diff --git a/rust/Makefile b/rust/Makefile > index ff70c4c916f8..aed6f7eca36f 100644 > --- a/rust/Makefile > +++ b/rust/Makefile > @@ -359,8 +359,22 @@ rust-analyzer: > $(Q)$(srctree)/scripts/generate_rust_analyzer.py $(srctree) $(objtree) \ > $(RUST_LIB_SRC) > $(objtree)/rust-project.json > > +redirect-intrinsics = \ > + __eqsf2 __gesf2 __lesf2 __nesf2 __unordsf2 \ > + __unorddf2 \ > + __muloti4 __multi3 \ > + __udivmodti4 __udivti3 __umodti3 > + > +ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),) > + # These intrinsics are defined for ARM64 and RISCV64 > + redirect-intrinsics += \ > + __ashrti3 \ > + __ashlti3 __lshrti3 > +endif > + > $(obj)/core.o: private skip_clippy = 1 > $(obj)/core.o: private skip_flags = -Dunreachable_pub > +$(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym)) > $(obj)/core.o: private rustc_target_flags = $(core-cfgs) > $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs $(obj)/target.json FORCE > $(call if_changed_dep,rustc_library) > diff --git a/rust/compiler_builtins.rs b/rust/compiler_builtins.rs > index f8f39a3e6855..5f833dcca131 100644 > --- a/rust/compiler_builtins.rs > +++ b/rust/compiler_builtins.rs > @@ -28,7 +28,7 @@ macro_rules! define_panicking_intrinsics( > ($reason: tt, { $($ident: ident, )* }) => { > $( > #[doc(hidden)] > - #[no_mangle] > + #[export_name = concat!("__rust", stringify!($ident))] > pub extern "C" fn $ident() { > panic!($reason); > } > @@ -61,3 +61,6 @@ define_panicking_intrinsics!("`u128` should not be used", { > __udivti3, > __umodti3, > }); > + > +// NOTE: if you are adding a new intrinsic is added here, you should also add it to > +// `redirect-intrinsics` in `rust/Makefile`. > -- > 2.34.1 >
-- Thanks, ~Nick Desaulniers
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