On Tue, 13 Jun 2023 01:13:11 +0530 Aakash Sen Sharma <aakashsensharma@xxxxxxxxx> wrote: > * Rationale: > > Upgrades bindgen to code-generation for anonymous unions, structs, and enums [7] > for LLVM-16 based toolchains. > > The following upgrade also incorporates `noreturn` support from bindgen > allowing us to remove useless `loop` calls which was placed as a > workaround. > > * Truncated build logs on using bindgen `v0.56.0` prior to LLVM-16 toolchain: > > ``` > $ make rustdoc LLVM=1 CLIPPY=1 -j$(nproc) > RUSTC L rust/core.o > BINDGEN rust/bindings/bindings_generated.rs > BINDGEN rust/bindings/bindings_helpers_generated.rs > BINDGEN rust/uapi/uapi_generated.rs > thread 'main' panicked at '"ftrace_branch_data_union_(anonymous_at__/_/include/linux/compiler_types_h_146_2)" is not a valid Ident', .../proc-macro2-1.0.24/src/fallback.rs:693:9 > ... > thread 'main' panicked at '"ftrace_branch_data_union_(anonymous_at__/_/include/linux/compiler_types_h_146_2)" is not a valid Ident', .../proc-macro2-1.0.24/src/fallback.rs:693:9 > ... > ``` > > * LLVM-16 Changes: > > API changes [1] were introduced such that libclang would emit names like > "(unnamed union at compiler_types.h:146:2)" for unnamed unions, structs, and > enums whereas it previously returned an empty string. > > * Bindgen Changes: > > Bindgen `v0.56.0` on LLVM-16 based toolchains hence was unable to process the > anonymous union in `include/linux/compiler_types` `struct ftrace_branch_data` > and caused subsequent panics as the new `libclang` API emitted name was not > being handled. The following issue was fixed in Bindgen `v0.62.0` [2]. > > Bindgen `v0.58.0` changed the flags `--whitelist-*` and `--blacklist-*` > to `--allowlist-*` and `--blocklist-*` respectively [3]. > > Bindgen `v0.61.0` added support for `_Noreturn`, `[[noreturn]]`, `__attribute__((noreturn))` [4], > hence the empty `loop`s used to circumvent bindgen returning `!` in place of `()` > for noreturn attributes have been removed completely. > > Bindgen `v0.61.0` also changed default functionality to bind `size_t` to `usize` [5] and > added the `--no-size_t-is-usize` [5] flag to not bind `size_t` as `usize`. > > Bindgen `v0.65.0` removed `--size_t-is-usize` flag [6]. > > Link: https://github.com/llvm/llvm-project/commit/19e984ef8f49bc3ccced15621989fa9703b2cd5b [1] > Link: https://github.com/rust-lang/rust-bindgen/pull/2319 [2] > Link: https://github.com/rust-lang/rust-bindgen/pull/1990 [3] > Link: https://github.com/rust-lang/rust-bindgen/issues/2094 [4] > Link: https://github.com/rust-lang/rust-bindgen/commit/cc78b6fdb6e829e5fb8fa1639f2182cb49333569 [5] > Link: https://github.com/rust-lang/rust-bindgen/pull/2408 [6] > Closes: https://github.com/Rust-for-Linux/linux/issues/1013 [7] > Signed-off-by: Aakash Sen Sharma <aakashsensharma@xxxxxxxxx> Reviewed-by: Gary Guo <gary@xxxxxxxxxxx> > --- > Documentation/process/changes.rst | 2 +- > rust/Makefile | 6 +++--- > rust/helpers.c | 13 ++++++------- > rust/kernel/lib.rs | 3 --- > scripts/min-tool-version.sh | 2 +- > 5 files changed, 11 insertions(+), 15 deletions(-) > > diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst > index ef540865ad22..5f21c4c6cf5c 100644 > --- a/Documentation/process/changes.rst > +++ b/Documentation/process/changes.rst > @@ -32,7 +32,7 @@ you probably needn't concern yourself with pcmciautils. > GNU C 5.1 gcc --version > Clang/LLVM (optional) 11.0.0 clang --version > Rust (optional) 1.62.0 rustc --version > -bindgen (optional) 0.56.0 bindgen --version > +bindgen (optional) 0.65.1 bindgen --version > GNU make 3.82 make --version > bash 4.2 bash --version > binutils 2.25 ld -v > diff --git a/rust/Makefile b/rust/Makefile > index f88d108fbef0..c187c6f3a384 100644 > --- a/rust/Makefile > +++ b/rust/Makefile > @@ -279,7 +279,7 @@ quiet_cmd_bindgen = BINDGEN $@ > $(BINDGEN) $< $(bindgen_target_flags) \ > --use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \ > --no-debug '.*' \ > - --size_t-is-usize -o $@ -- $(bindgen_c_flags_final) -DMODULE \ > + -o $@ -- $(bindgen_c_flags_final) -DMODULE \ > $(bindgen_target_cflags) $(bindgen_target_extra) > > $(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \ > @@ -293,8 +293,8 @@ $(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_helper.h \ > # given it is `libclang`; but for consistency, future Clang changes and/or > # a potential future GCC backend for `bindgen`, we disable it too. > $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_flags = \ > - --blacklist-type '.*' --whitelist-var '' \ > - --whitelist-function 'rust_helper_.*' > + --blocklist-type '.*' --allowlist-var '' \ > + --allowlist-function 'rust_helper_.*' > $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_cflags = \ > -I$(objtree)/$(obj) -Wno-missing-prototypes -Wno-missing-declarations > $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ; \ > diff --git a/rust/helpers.c b/rust/helpers.c > index 121583282976..98d9ef47225b 100644 > --- a/rust/helpers.c > +++ b/rust/helpers.c > @@ -122,19 +122,18 @@ void rust_helper_put_task_struct(struct task_struct *t) > EXPORT_SYMBOL_GPL(rust_helper_put_task_struct); > > /* > - * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type > - * as the Rust `usize` type, so we can use it in contexts where Rust > - * expects a `usize` like slice (array) indices. `usize` is defined to be > - * the same as C's `uintptr_t` type (can hold any pointer) but not > - * necessarily the same as `size_t` (can hold the size of any single > + * `bindgen` binds the C `size_t` type the Rust `usize` type, so we can > + * use it in contexts where Rust expects a `usize` like slice (array) indices. > + * `usize` is defined to be the same as C's `uintptr_t` type (can hold any pointer) > + * but not necessarily the same as `size_t` (can hold the size of any single > * object). Most modern platforms use the same concrete integer type for > * both of them, but in case we find ourselves on a platform where > * that's not true, fail early instead of risking ABI or > * integer-overflow issues. > * > * If your platform fails this assertion, it means that you are in > - * danger of integer-overflow bugs (even if you attempt to remove > - * `--size_t-is-usize`). It may be easiest to change the kernel ABI on > + * danger of integer-overflow bugs (even if you attempt to add > + * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on > * your platform such that `size_t` matches `uintptr_t` (i.e., to increase > * `size_t`, because `uintptr_t` has to be at least as big as `size_t`). > */ > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs > index ee27e10da479..1b0dcf03b9c2 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -95,7 +95,4 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { > pr_emerg!("{}\n", info); > // SAFETY: FFI call. > unsafe { bindings::BUG() }; > - // Bindgen currently does not recognize `__noreturn` so `BUG` returns `()` > - // instead of `!`. See <https://github.com/rust-lang/rust-bindgen/issues/2094>. > - loop {} > } > diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh > index 20d483ec6f5f..5b80c5d3a9f8 100755 > --- a/scripts/min-tool-version.sh > +++ b/scripts/min-tool-version.sh > @@ -30,7 +30,7 @@ rustc) > echo 1.62.0 > ;; > bindgen) > - echo 0.56.0 > + echo 0.65.1 > ;; > *) > echo "$1: unknown tool" >&2 > -- > 2.40.1 >
