From nobody Thu Oct 2 16:59:01 2025 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 293332D73AE; Mon, 15 Sep 2025 07:22:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757920933; cv=none; b=Mrb2Sk2u8BsT0E8Z+1PTBohs84FhDnn53jX3Ink7TFCAUaYhRNFpi5b32g1cRqsZ3wrcVKT5KscAT9+B/No2ASCggNyy9LTW/Twv+AbosRKeHIyWEY7qRugWpO/AZ8BAbq4lWQrWMeefgnM+O6UgFHbYQ7n9ptJxA+zu4XlJ41c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757920933; c=relaxed/simple; bh=zzhgr2MSz+WwIyXeNFgpi85yheVgDVQre4NsMvzcufk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hK8UVP21jM077BsDuEXhaIwZmZm6ylIataJtCQRDIR9ABWUhrsN8lWwV7J6F7il053wSIJ6sDBStOfG1ZBp9nas0pg9u3TGZV1QiWN8PT4tN5CrOtqcvf4IC2SU/vJKEIIqjUg8UJyxjNfMoW1zVfM1TIvNiW6/m43IcgReSjgU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=TtBtOXaQ; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="TtBtOXaQ" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Content-Type:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=HVA8rahyRRzDT6UOZjkHUe+vnU2a954Je71AnOZJQWI=; t=1757920931; x=1759130531; b=TtBtOXaQ2Ak+W9e/Fc1CHThxCBUfVKzUO2+BLELQq19M8vs qJCm4FpDosv1DKICSahwsF2tcKcno0AtVoR0A16kQJk567QLAoh2A1xHB25Vzm3N73mcmJfVeH1sq JVoziv4jWVH/F2SRSUiOid4gCoO4Ei+jxsuw2l/+FBVVkNjd53yl7uJXehU8ztT9fUfWPU8cQj0JU +7rVZDnHHYCrR76AnlU0Py/rX6NROH7yFOimgdELya8yC+/wtqJWLUpYDtMMk2vwjXGyyw+Yt3LNv nxhd29qexlzf6noAo91AZWUX6+iFfaPjO3HNx1IMeBCm44QBCSjAAiIwZLIYTdnA==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.98.2) (envelope-from ) id 1uy3XL-00000005w6o-3k8S; Mon, 15 Sep 2025 09:22:08 +0200 From: Benjamin Berg To: linux-um@lists.infradead.org, Willy Tarreau , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , linux-kselftest@vger.kernel.org, Arnaldo Carvalho de Melo Cc: linux-kernel@vger.kernel.org, Tiwei Bie , Benjamin Berg Subject: [PATCH 7/9] um: add infrastructure to build files using nolibc Date: Mon, 15 Sep 2025 09:11:13 +0200 Message-ID: <20250915071115.1429196-8-benjamin@sipsolutions.net> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250915071115.1429196-1-benjamin@sipsolutions.net> References: <20250915071115.1429196-1-benjamin@sipsolutions.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Benjamin Berg Add NOLIBC_CFLAGS and NOLIBC_OBJS to build files against nolibc rather than libc. With this it is possible to move to nolibc in smaller steps. Set NOLIBC_IGNORE_ERRNO, as the nolibc errno implementation is overly simple and cannot handle threading. nolibc provides sys_* functions that do not emulate the libc errno behaviour and can be used instead. Guard the syscall definition as it is a macro in nolibc. Signed-off-by: Benjamin Berg --- arch/um/Makefile | 21 ++++++++++++++++++++- arch/um/include/shared/os.h | 2 ++ arch/um/scripts/Makefile.rules | 8 +++++++- 3 files changed, 29 insertions(+), 2 deletions(-) diff --git a/arch/um/Makefile b/arch/um/Makefile index a3f27d791cc0..54aa26fcc32b 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -78,6 +78,25 @@ USER_CFLAGS =3D $(patsubst $(KERNEL_DEFINES),,$(patsubst= -I%,,$(KBUILD_CFLAGS))) \ -include $(srctree)/include/linux/kern_levels.h \ -include $(srctree)/$(ARCH_DIR)/include/shared/user.h =20 +NOLIBC_CFLAGS =3D $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_C= FLAGS))) \ + $(ARCH_INCLUDE) $(MODE_INCLUDE) $(filter -I%,$(CFLAGS)) \ + -I $(srctree)/tools/include \ + -D__EXPORTED_HEADERS__ \ + -D__UM_HOST__ -D__UM_NOLIBC__ \ + -DNOLIBC_NO_STARTCODE \ + -DNOLIBC_IGNORE_ERRNO \ + -nostdlib -nostdinc -static \ + -I$(srctree)/include/uapi \ + -I$(srctree)/$(HOST_DIR)/include/uapi \ + -I$(objtree)/$(HOST_DIR)/include/generated/uapi \ + -I $(srctree)/tools/include/nolibc \ + -I $(srctree)/usr/include \ + -include $(srctree)/include/generated/autoconf.h \ + -include $(srctree)/tools/include/linux/kconfig.h \ + -include $(srctree)/include/linux/kern_levels.h \ + -include $(srctree)/tools/include/nolibc/nolibc.h \ + -include $(srctree)/$(ARCH_DIR)/include/shared/user.h + #This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux =20 @@ -157,4 +176,4 @@ archclean: -o -name '*.gcov' \) -type f -print | xargs rm -f $(Q)$(MAKE) -f $(srctree)/Makefile ARCH=3D$(HEADER_ARCH) clean =20 -export HEADER_ARCH SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING DEV_NULL_PATH +export HEADER_ARCH SUBARCH USER_CFLAGS NOLIBC_CFLAGS CFLAGS_NO_HARDENING D= EV_NULL_PATH diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index b35cc8ce333b..3e9f3ae61658 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -327,7 +327,9 @@ extern int __ignore_sigio_fd(int fd); /* tty.c */ extern int get_pty(void); =20 +#ifndef syscall long syscall(long number, ...); +#endif =20 /* irqflags tracing */ extern void block_signals_trace(void); diff --git a/arch/um/scripts/Makefile.rules b/arch/um/scripts/Makefile.rules index b4a2e0058503..5f07551935c3 100644 --- a/arch/um/scripts/Makefile.rules +++ b/arch/um/scripts/Makefile.rules @@ -11,6 +11,12 @@ USER_OBJS :=3D $(foreach file,$(USER_OBJS),$(obj)/$(file= )) $(USER_OBJS:.o=3D.%): \ c_flags =3D -Wp,-MD,$(depfile) $(USER_CFLAGS) $(CFLAGS_$(basetarget).o) =20 +# Similar USER_OBJS but compiled against nolibc (may include kernel header= s?) +NOLIBC_OBJS :=3D $(foreach file,$(NOLIBC_OBJS),$(obj)/$(file)) + +$(NOLIBC_OBJS:.o=3D.%): \ + c_flags =3D -Wp,-MD,$(depfile) $(NOLIBC_CFLAGS) $(CFLAGS_$(basetarget).o) + # These are like USER_OBJS but filter USER_CFLAGS through unprofile instea= d of # using it directly. UNPROFILE_OBJS :=3D $(foreach file,$(UNPROFILE_OBJS),$(obj)/$(file)) @@ -18,7 +24,7 @@ UNPROFILE_OBJS :=3D $(foreach file,$(UNPROFILE_OBJS),$(ob= j)/$(file)) $(UNPROFILE_OBJS:.o=3D.%): \ c_flags =3D -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS)) $(CFLAGS_= $(basetarget).o) =20 -$(USER_OBJS) $(UNPROFILE_OBJS): \ +$(USER_OBJS) $(NOLIBC_OBJS) $(UNPROFILE_OBJS): \ CHECKFLAGS :=3D $(patsubst $(NOSTDINC_FLAGS),,$(CHECKFLAGS)) =20 # The stubs can't try to call mcount or update basic block data --=20 2.51.0