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 --- tools/perf/util/setup.py | 107 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) create mode 100644 tools/perf/util/setup.py (limited to 'tools/perf/util/setup.py') diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py new file mode 100644 index 000000000..a0ce76624 --- /dev/null +++ b/tools/perf/util/setup.py @@ -0,0 +1,107 @@ +from os import getenv, path +from subprocess import Popen, PIPE +from re import sub +import shlex + +cc = getenv("CC") +assert cc, "Environment variable CC not set" + +# Check if CC has options, as is the case in yocto, where it uses CC="cc --sysroot..." +cc_tokens = cc.split() +if len(cc_tokens) > 1: + cc = cc_tokens[0] + cc_options = " ".join([str(e) for e in cc_tokens[1:]]) + " " +else: + cc_options = "" + +# ignore optional stderr could be None as it is set to PIPE to avoid that. +# mypy: disable-error-code="union-attr" +cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline() + +srctree = getenv('srctree') +assert srctree, "Environment variable srctree, for the Linux sources, not set" +src_feature_tests = f'{srctree}/tools/build/feature' + +def clang_has_option(option): + error_substrings = ( + b"unknown argument", + b"is not supported", + b"unknown warning option" + ) + cmd = shlex.split(f"{cc} {cc_options} {option}") + [ + "-o", "/dev/null", + path.join(src_feature_tests, "test-hello.c") + ] + cc_output = Popen(cmd, stderr=PIPE).stderr.readlines() + return not any(any(error in line for error in error_substrings) for line in cc_output) + +if cc_is_clang: + from sysconfig import get_config_vars + vars = get_config_vars() + for var in ('CFLAGS', 'OPT'): + vars[var] = sub("-specs=[^ ]+", "", vars[var]) + if not clang_has_option("-mcet"): + vars[var] = sub("-mcet", "", vars[var]) + if not clang_has_option("-fcf-protection"): + vars[var] = sub("-fcf-protection", "", vars[var]) + if not clang_has_option("-fstack-clash-protection"): + vars[var] = sub("-fstack-clash-protection", "", vars[var]) + if not clang_has_option("-fstack-protector-strong"): + vars[var] = sub("-fstack-protector-strong", "", vars[var]) + if not clang_has_option("-fno-semantic-interposition"): + vars[var] = sub("-fno-semantic-interposition", "", vars[var]) + if not clang_has_option("-ffat-lto-objects"): + vars[var] = sub("-ffat-lto-objects", "", vars[var]) + if not clang_has_option("-ftree-loop-distribute-patterns"): + vars[var] = sub("-ftree-loop-distribute-patterns", "", vars[var]) + if not clang_has_option("-gno-variable-location-views"): + vars[var] = sub("-gno-variable-location-views", "", vars[var]) + +from setuptools import setup, Extension + +from setuptools.command.build_ext import build_ext as _build_ext +from setuptools.command.install_lib import install_lib as _install_lib + +class build_ext(_build_ext): + def finalize_options(self): + _build_ext.finalize_options(self) + self.build_lib = build_lib + self.build_temp = build_tmp + +class install_lib(_install_lib): + def finalize_options(self): + _install_lib.finalize_options(self) + self.build_dir = build_lib + + +# switch off several checks (need to be at the end of cflags list) +extra_cflags = ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ] +if cc_is_clang: + extra_cflags += ["-Wno-unused-command-line-argument" ] + if clang_has_option("-Wno-cast-function-type-mismatch"): + extra_cflags += ["-Wno-cast-function-type-mismatch" ] +else: + extra_cflags += ['-Wno-cast-function-type' ] + +# The python headers have mixed code with declarations (decls after asserts, for instance) +extra_cflags += [ "-Wno-declaration-after-statement" ] + +src_perf = f'{srctree}/tools/perf' +build_lib = getenv('PYTHON_EXTBUILD_LIB') +build_tmp = getenv('PYTHON_EXTBUILD_TMP') + +perf = Extension('perf', + sources = [ src_perf + '/util/python.c' ], + include_dirs = ['util/include'], + extra_compile_args = extra_cflags, + ) + +setup(name='perf', + version='0.1', + description='Interface with the Linux profiling infrastructure', + author='Arnaldo Carvalho de Melo', + author_email='acme@redhat.com', + license='GPLv2', + url='http://perf.wiki.kernel.org', + ext_modules=[perf], + cmdclass={'build_ext': build_ext, 'install_lib': install_lib}) -- cgit v1.3.1