From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (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 2B1D17A for ; Thu, 3 Mar 2022 09:06:53 +0000 (UTC) Received: by mail-pg1-f201.google.com with SMTP id z10-20020a634c0a000000b0036c5eb39076so2467338pga.18 for ; Thu, 03 Mar 2022 01:06:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=2bQdkuF0SOPnoGthP45kPV6bs5nvMHTPUBqrBi7KDmE=; b=CwcLSYEWIYkwRIiSSoxKp+6DeCkwVywNCvkORnPKqsNTneqEIEtKoa1z3mwpqSO5W4 C4EHKgRYdUXjCIOSBiph61mK8NoMu3VVGZdQoh1vzbAAj6PmbcMhAyb+4ErMMn/svnDL FP8rthWhTrzh2Va1j3Zfzp+FYQz4qCJD1gVJd7MbjNd/ghRt2JDE69B0eP4rYOZJWtNk iy8+/9w5gmFETfLE9rVgJeZuSKmAoHiJKgxbZtHPkGMaD2ChCzD6jJS3mXJoVYXdg2Zb Nn0/DhX7zv8c3bY7H6zzF0hk+Q/LD8THdUGTyGynCcth2eoJxJBm37j1FQ/tcNYb/tBi a+Kw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=2bQdkuF0SOPnoGthP45kPV6bs5nvMHTPUBqrBi7KDmE=; b=ZT/DQ9Gm2ktWmlbegDeRRvU9LaYAPqFV/nAShpeQ0YqSIeVar90u8eziLsdNTLkJ7/ nSjPNw+mFi5LtANqlG7ownWDxAm041r/welmY91AI9jqttSp5aHkDLlXsxR2lI821cec ItdN7V/R4ZFSNkYu2gon6i7zsPnNuJiq1lgKb8zGTGARCHgnWgIUF8sA9yYtU9ofDnlZ T8w7b+BhPea/0qIZ2oGmb+itVAs9RWZ7JDZTTUVZmU58oGRonGyq5ZqVMWyaj0exl7M7 R1iA9qZQt7+KjfeFNH2glCVpEWVOYJVVNBHBA1rlzjHXhbdBLgAx5Q1brgfHwlN4xjaS FVZQ== X-Gm-Message-State: AOAM530LMeIL5j/YF49gk+MMRe4BWLeYJhSSiwceMMIw3zLGW2ukhOgY iLskiED7Xx8P8lWWXKo7F7qad0tm+7ne7g== X-Google-Smtp-Source: ABdhPJxF438b/WEu22WxHZgv3A03n8SRdHWfJx5cX+REUymSJzQW01Ac5BTggzKnp1cW4D9MmVLPr1IGpLealw== X-Received: from slicestar.c.googlers.com ([fda3:e722:ac3:cc00:4f:4b78:c0a8:20a1]) (user=davidgow job=sendgmr) by 2002:a17:90b:4b52:b0:1bc:b208:dc5c with SMTP id mi18-20020a17090b4b5200b001bcb208dc5cmr1023750pjb.1.1646298411425; Thu, 03 Mar 2022 01:06:51 -0800 (PST) Date: Thu, 3 Mar 2022 17:06:42 +0800 Message-Id: <20220303090643.241747-1-davidgow@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.35.1.616.g0bdcbb4464-goog Subject: [PATCH] um: clang: Strip out -mno-global-merge from USER_CFLAGS From: David Gow To: Kees Cook Cc: David Gow , Jeff Dike , Richard Weinberger , Anton Ivanov , Masahiro Yamada , Nick Desaulniers , Nathan Chancellor , linux-um@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, llvm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Content-Type: text/plain; charset="UTF-8" The things built with USER_CFLAGS don't seem to recognise it as a compiler option, and print a warning: clang: warning: argument unused during compilation: '-mno-global-merge' [-Wunused-command-line-argument] Fixes: 744814d2fa ("um: Allow builds with Clang") Signed-off-by: David Gow --- This warning shows up after merging: https://lore.kernel.org/lkml/20220227184517.504931-6-keescook@chromium.org/ I'm not 100% sure why this is necessary, but it does seem to work. All the attempts to get rid of -mno-global-merge entirely have been met with skepticism, but I'm guessing that it's not a problem for just the UML "user" files, as they shouldn't(?) interact too much with modules. arch/um/Makefile | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/um/Makefile b/arch/um/Makefile index f2fe63bfd819..320b09cd513c 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -75,6 +75,10 @@ USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \ -D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \ -idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__ +ifdef CONFIG_CC_IS_CLANG +USER_CFLAGS := $(patsubst -mno-global-merge,,$(USER_CFLAGS)) +endif + #This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS) -- 2.35.1.616.g0bdcbb4464-goog