From: Alice Ryhl Date: Tue, 16 Jun 2026 12:30:38 +0000 (+0000) Subject: rust: Kbuild: set frame-pointer llvm module flag for CONFIG_FRAME_POINTER X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=191f49f1e38b1c10eb44b0f967c6175c884ef7db;p=thirdparty%2Flinux.git rust: Kbuild: set frame-pointer llvm module flag for CONFIG_FRAME_POINTER Due to a rustc bug, the -Cforce-frame-pointers=y flag only emits the frame-pointer annotation for functions, but not for the module. This means that functions generated by the LLVM backend such as 'asan.module_ctor' do not receive the frame-pointer annotation. This is likely to lead to broken backtraces and may also cause issues with ftrace if these features are used with functions generated by the LLVM backend. Thus, use -Zllvm_module_flag to work around this rustc bug if using a rustc without the fix. [ The fix [1] has landed for Rust 1.98.0 (expected release on 2026-08-20). - Miguel ] Cc: stable@vger.kernel.org # 6.12.y and later (flag not available in pinned Rust in older LTSs). Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support") Link: https://github.com/rust-lang/rust/pull/156980 [1] Signed-off-by: Alice Ryhl Link: https://patch.msgid.link/20260616-frame-ptr-fix-v1-1-dc6b29a631d9@google.com [ - Adjusted Cc: stable@ as discussed. - Added comment with link to the PR, similar to what we did in commit ac35b5580ace ("rust: arm64: set uwtable llvm module flag for CONFIG_UNWIND_TABLES"). - Miguel ] Signed-off-by: Miguel Ojeda --- diff --git a/Makefile b/Makefile index d33a7cadd237..82b2d8cd6804 100644 --- a/Makefile +++ b/Makefile @@ -966,6 +966,9 @@ KBUILD_CFLAGS += $(stackp-flags-y) ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y +# Work around rustc bug on compilers without +# https://github.com/rust-lang/rust/pull/156980. +KBUILD_RUSTFLAGS += $(if $(call rustc-min-version,109800),,-Zllvm_module_flag=frame-pointer:u32:2:max) else # Some targets (ARM with Thumb2, for example), can't be built with frame # pointers. For those, we don't have FUNCTION_TRACER automatically