From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- include/trace/define_trace.h | 174 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 include/trace/define_trace.h (limited to 'include/trace/define_trace.h') diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h new file mode 100644 index 000000000..b2ba5a805 --- /dev/null +++ b/include/trace/define_trace.h @@ -0,0 +1,174 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Trace files that want to automate creation of all tracepoints defined + * in their file should include this file. The following are macros that the + * trace file may define: + * + * TRACE_SYSTEM defines the system the tracepoint is for + * + * TRACE_INCLUDE_FILE if the file name is something other than TRACE_SYSTEM.h + * This macro may be defined to tell define_trace.h what file to include. + * Note, leave off the ".h". + * + * TRACE_INCLUDE_PATH if the path is something other than core kernel include/trace + * then this macro can define the path to use. Note, the path is relative to + * define_trace.h, not the file including it. Full path names for out of tree + * modules must be used. + */ + +#ifdef CREATE_TRACE_POINTS + +/* Prevent recursion */ +#undef CREATE_TRACE_POINTS + +#include + +#undef TRACE_EVENT +#define TRACE_EVENT(name, proto, args, tstruct, assign, print) \ + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) + +#undef TRACE_EVENT_CONDITION +#define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \ + TRACE_EVENT(name, \ + PARAMS(proto), \ + PARAMS(args), \ + PARAMS(tstruct), \ + PARAMS(assign), \ + PARAMS(print)) + +#undef TRACE_EVENT_FN +#define TRACE_EVENT_FN(name, proto, args, tstruct, \ + assign, print, reg, unreg) \ + DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args)) + +#undef TRACE_EVENT_FN_COND +#define TRACE_EVENT_FN_COND(name, proto, args, cond, tstruct, \ + assign, print, reg, unreg) \ + DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args)) + +#undef TRACE_EVENT_SYSCALL +#define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign, print, reg, unreg) \ + DEFINE_TRACE_SYSCALL(name, reg, unreg, PARAMS(proto), PARAMS(args)) + +#undef TRACE_EVENT_NOP +#define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) + +#undef DEFINE_EVENT_NOP +#define DEFINE_EVENT_NOP(template, name, proto, args) + +#undef DEFINE_EVENT +#define DEFINE_EVENT(template, name, proto, args) \ + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) + +#undef DEFINE_EVENT_FN +#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg) \ + DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args)) + +#undef DEFINE_EVENT_PRINT +#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) + +#undef DEFINE_EVENT_CONDITION +#define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \ + DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args)) + +#undef DECLARE_TRACE +#define DECLARE_TRACE(name, proto, args) \ + DEFINE_TRACE(name##_tp, PARAMS(proto), PARAMS(args)) + +#undef DECLARE_TRACE_CONDITION +#define DECLARE_TRACE_CONDITION(name, proto, args, cond) \ + DEFINE_TRACE(name##_tp, PARAMS(proto), PARAMS(args)) + +#undef DECLARE_TRACE_EVENT +#define DECLARE_TRACE_EVENT(name, proto, args) \ + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) + +#undef DECLARE_TRACE_EVENT_CONDITION +#define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond) \ + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) + +/* If requested, create helpers for calling these tracepoints from Rust. */ +#ifdef CREATE_RUST_TRACE_POINTS +#undef DEFINE_RUST_DO_TRACE +#define DEFINE_RUST_DO_TRACE(name, proto, args) \ + __DEFINE_RUST_DO_TRACE(name, PARAMS(proto), PARAMS(args)) +#endif + +#undef TRACE_INCLUDE +#undef __TRACE_INCLUDE + +#ifndef TRACE_INCLUDE_FILE +# define TRACE_INCLUDE_FILE TRACE_SYSTEM +# define UNDEF_TRACE_INCLUDE_FILE +#endif + +#ifndef TRACE_INCLUDE_PATH +# define __TRACE_INCLUDE(system) +# define UNDEF_TRACE_INCLUDE_PATH +#else +# define __TRACE_INCLUDE(system) __stringify(TRACE_INCLUDE_PATH/system.h) +#endif + +# define TRACE_INCLUDE(system) __TRACE_INCLUDE(system) + +/* Let the trace headers be reread */ +#define TRACE_HEADER_MULTI_READ + +#include TRACE_INCLUDE(TRACE_INCLUDE_FILE) + +/* Make all open coded DECLARE_TRACE nops */ +#undef DECLARE_TRACE +#define DECLARE_TRACE(name, proto, args) +#undef DECLARE_TRACE_CONDITION +#define DECLARE_TRACE_CONDITION(name, proto, args, cond) + +#undef DECLARE_TRACE_EVENT +#define DECLARE_TRACE_EVENT(name, proto, args) +#undef DECLARE_TRACE_EVENT_CONDITION +#define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond) + +#ifdef TRACEPOINTS_ENABLED +#include +#include +#include +#endif + +#undef TRACE_EVENT +#undef TRACE_EVENT_FN +#undef TRACE_EVENT_FN_COND +#undef TRACE_EVENT_SYSCALL +#undef TRACE_EVENT_CONDITION +#undef TRACE_EVENT_NOP +#undef DEFINE_EVENT_NOP +#undef DECLARE_EVENT_CLASS +#undef DEFINE_EVENT +#undef DEFINE_EVENT_FN +#undef DEFINE_EVENT_PRINT +#undef DEFINE_EVENT_CONDITION +#undef TRACE_HEADER_MULTI_READ +#undef DECLARE_TRACE +#undef DECLARE_TRACE_CONDITION +#undef DECLARE_TRACE_EVENT +#undef DECLARE_TRACE_EVENT_CONDITION + +/* Only undef what we defined in this file */ +#ifdef UNDEF_TRACE_INCLUDE_FILE +# undef TRACE_INCLUDE_FILE +# undef UNDEF_TRACE_INCLUDE_FILE +#endif + +#ifdef UNDEF_TRACE_INCLUDE_PATH +# undef TRACE_INCLUDE_PATH +# undef UNDEF_TRACE_INCLUDE_PATH +#endif + +#ifdef CREATE_RUST_TRACE_POINTS +# undef DEFINE_RUST_DO_TRACE +# define DEFINE_RUST_DO_TRACE(name, proto, args) +#endif + +/* We may be processing more files */ +#define CREATE_TRACE_POINTS + +#endif /* CREATE_TRACE_POINTS */ -- cgit v1.3.1