From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 764A72931EE for ; Mon, 12 Oct 2026 13:42:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.71 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791812530; cv=none; b=eTOk5aeHuCTHogVIvwfZpKlY4Ax7aP/NkNDo6ni3xj85dTFORYM/5TsECNJVWoz5JzgsKGr2g3uOKvA4c3eQaj66nOn55yAch0t0etd19T/Obiq774rMYi6LI9cBMBWLt6XGZ6syN4s3rI7krhCH9cw5fjjM2i4mnGJU+wcvHcI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791812530; c=relaxed/simple; bh=834HCsT+yG6FoiMCNmsSF0KuEbbYNjXGWtFDC+r4/lU=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=hV2+Kl+Uj4oP04kObOWfhJ6frrl8GbDUcstxONqOKVq0+mAQJD6D1HfxhWuauRXxkmdIV9MiPmb082qm2kNxpE1xq+WbCG4Cc3wv1RznKFcyzao0d249kTKRL4e1Sk903efslWX0/Ihqr4GczN7AgUjO+lYEcXvktAK6wzpdMmI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--elver.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Fz/W7yGE; arc=none smtp.client-ip=209.85.128.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--elver.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Fz/W7yGE" Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4a01c621dc2so14244275e9.2 for ; Mon, 12 Oct 2026 06:42:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1791812526; x=1792417326; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=PWBgbU9wWHlrfBumGJ2ey37GLEs4mFig313aUL/JPgY=; b=Fz/W7yGEXsBlppDtivPiKEoGKO2CberpbbAp5P1DDjbGF8BshorxXGEeH9cQnYZhMF 3An3QgkMPX64zcP1Ak5OBvYmmHMipv92JsI9DvHu20MwG2z44gfb+TtsJS4xPNcwNUqt QrmAAkquVuTHZUjRizozcEmDjjb+qOswx2by413vyTncPlhuwFR/5OjttqJJmF09HYYk YPUIuzjpHtA4gn6hLIQUTQr+ajBrJeVZHIGZu5txS070+84WARo3ljEtoIDM456EpTZ7 fIMcx2pNuk1O1UMLSyVPdliHqMpEYBZ2KGQljg8hAYeS43Grf+WFICzbPxLY/SpDa3Ny hLAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791812526; x=1792417326; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=PWBgbU9wWHlrfBumGJ2ey37GLEs4mFig313aUL/JPgY=; b=UFqrGHaoZJ/XknB+t487HzjWkRUKuhIzTEvUt+BEIwGipOnv3dO57BPVKmqQV/MklC R2O+cDChU9qwBLL1cbAHx5XkbCwXJv+c8gquObv/57KP50rURxJFiPIrt3bSq5WHYR5k qrd2bgU2Tmgl9ZF+5wtMNxE75dEdX4CHKyiT22xjkoNHcp6tVzG2i3IdnbM/9GxF61KS qGgKxzautUSjcIXxM5dtoWVDezfvt2JAlYnGpIKpQPPeRlLu8CeIA6IHTA9BhDTOmGFL 7jjNJjhHPxUvhn8f4RG9E6vScSCNBzJcL0n31VZdoIgO4P5i9MpL0zUgL4yRE/2l/Y09 JhHw== X-Forwarded-Encrypted: i=1; AKwUvBxTCYfU2OFZBMAUnsrcxI726snytu6fBfvPuhGs14lmHQuCuw5He99b/j+kbT4YGs7vUUH4LIHN/qobt04=@vger.kernel.org X-Gm-Message-State: AFq9FYI1jUnyaE/nHrAH8WxwR04jD3VbPcDNT1WLdcgGookgRcEGi7TL rDtwFkgDO3U4cpUsc0sGooMkC95XQ58kJcJFx74dz6jrsJu8f7kx3bg5AfR5djUldDQ9qQpdl4Q mbA== X-Received: from wmrp18.prod.google.com ([2002:a05:600c:8a92:b0:4a1:9311:9d1d]) (user=elver job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:8518:b0:49f:cbf3:551c with SMTP id 5b1f17b1804b1-4a18e4a8ca6mr166715615e9.12.1791812524523; Mon, 12 Oct 2026 06:42:04 -0700 (PDT) Date: Mon, 12 Oct 2026 13:39:14 +0000 Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.56.0.385.gd3acb90ef8-goog Message-ID: <20261012134159.912183-1-elver@google.com> Subject: [PATCH 1/2] kbuild: rust: enable KCSAN support From: Marco Elver To: elver@google.com, Boqun Feng , Miguel Ojeda , Gary Guo Cc: Alexander Potapenko , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, Jonathan Corbet , Shuah Khan , Randy Dunlap , Andrew Morton , Boqun Feng , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , "=?UTF-8?q?Onur=20=C3=96zkan?=" , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Asahi Lina , Yury Norov , Eliot Courtney , Joel Fernandes , workflows@vger.kernel.org, linux-doc@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Rust supports ThreadSanitizer instrumentation via LLVM, which is what KCSAN relies on; however, Rust code is not currently instrumented. Pass -Zsanitizer=thread and the same TSan backend options used for C code to rustc. Wire up KCSAN_SANITIZE in scripts/Makefile.lib for parity with C (though rustc currently rejects linking crates with mismatched instrumentation). rustc only accepts -Zsanitizer=thread for targets that declare support for it. Of the targets used by the kernel, this is only possible for the generated x86_64 target specification, so restrict instrumentation of Rust code to x86_64 for now via HAVE_KCSAN_RUSTC. On other architectures Rust code remains uninstrumented as before. All TSan options used are supported by the LLVM versions of the minimum supported rustc, so no rustc-option checks are needed (they would also fail, because x86_64-unknown-none used for option checks does not support -Zsanitizer=thread). With this enabled we can detect data races in kernel Rust code and between Rust and C code. Signed-off-by: Marco Elver --- Documentation/dev-tools/kcsan.rst | 7 +++++++ lib/Kconfig.kcsan | 7 +++++++ scripts/Makefile.kcsan | 13 +++++++++++++ scripts/Makefile.lib | 3 +++ scripts/generate_rust_target.rs | 2 +- 5 files changed, 31 insertions(+), 1 deletion(-) diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst index 8575178aa87f..3bb8754f844b 100644 --- a/Documentation/dev-tools/kcsan.rst +++ b/Documentation/dev-tools/kcsan.rst @@ -14,6 +14,9 @@ Usage KCSAN is supported by both GCC and Clang. With GCC we require version 11 or later, and with Clang also require version 11 or later. +Rust code is instrumented as well on architectures whose Rust target supports +it (currently only x86_64; see ``CONFIG_HAVE_KCSAN_RUSTC``). + To enable KCSAN configure the kernel with:: CONFIG_KCSAN = y @@ -121,6 +124,10 @@ the below options are available: KCSAN_SANITIZE := n + Note that ``rustc`` rejects linking crates built with and without KCSAN + instrumentation, so ``KCSAN_SANITIZE`` and ``KCSAN_SANITIZE_.o`` + cannot currently be used for Rust code. + .. _"Marking Shared-Memory Accesses" in the LKMM: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/memory-model/Documentation/access-marking.txt Furthermore, it is possible to tell KCSAN to show or hide entire classes of diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan index 4ce4b0c0109c..f0096e1c8b61 100644 --- a/lib/Kconfig.kcsan +++ b/lib/Kconfig.kcsan @@ -10,6 +10,13 @@ config HAVE_KCSAN_COMPILER For the list of compilers that support KCSAN, please see . +config HAVE_KCSAN_RUSTC + def_bool RUST && X86_64 + help + rustc only accepts -Zsanitizer=thread for targets that declare + support for it; of the kernel's Rust targets, only x86_64 does. + Elsewhere, Rust code is not instrumented. + menuconfig KCSAN bool "KCSAN: dynamic data race detector" depends on HAVE_ARCH_KCSAN && HAVE_KCSAN_COMPILER diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan index 19f693b68a96..01af6fd71006 100644 --- a/scripts/Makefile.kcsan +++ b/scripts/Makefile.kcsan @@ -24,3 +24,16 @@ kcsan-cflags += $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit endif export CFLAGS_KCSAN := $(kcsan-cflags) + +ifdef CONFIG_HAVE_KCSAN_RUSTC +# The minimum supported rustc's LLVM supports all of these options. +rustc-param = -Cllvm-args=-$(1) +kcsan-rustflags := -Zsanitizer=thread \ + $(call rustc-param,tsan-compound-read-before-write=1) \ + $(call rustc-param,tsan-distinguish-volatile=1) +ifndef CONFIG_KCSAN_WEAK_MEMORY +kcsan-rustflags += $(call rustc-param,tsan-instrument-func-entry-exit=0) +endif +endif + +export RUSTFLAGS_KCSAN := $(kcsan-rustflags) diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 0a4fdd8bd975..78f1c23e54be 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -98,6 +98,9 @@ ifeq ($(CONFIG_KCSAN),y) _c_flags += $(if $(patsubst n%,, \ $(KCSAN_SANITIZE_$(target-stem).o)$(KCSAN_SANITIZE)$(is-kernel-object)), \ $(CFLAGS_KCSAN)) +_rust_flags += $(if $(patsubst n%,, \ + $(KCSAN_SANITIZE_$(target-stem).o)$(KCSAN_SANITIZE)$(is-kernel-object)), \ + $(RUSTFLAGS_KCSAN)) # Some uninstrumented files provide implied barriers required to avoid false # positives: set KCSAN_INSTRUMENT_BARRIERS for barrier instrumentation only. _c_flags += $(if $(patsubst n%,, \ diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs index 7687b0dd5474..4b02bffa6b46 100644 --- a/scripts/generate_rust_target.rs +++ b/scripts/generate_rust_target.rs @@ -231,7 +231,7 @@ fn main() { } ts.push("features", features); ts.push("llvm-target", "x86_64-linux-gnu"); - ts.push("supported-sanitizers", ["kcfi", "kernel-address"]); + ts.push("supported-sanitizers", ["kcfi", "kernel-address", "thread"]); if cfg.rustc_version_atleast(1, 91, 0) { ts.push("target-pointer-width", 64); } else { -- 2.56.0.385.gd3acb90ef8-goog