From nobody Thu Oct 2 02:12:33 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 326D7306B06; Wed, 24 Sep 2025 14:22:00 +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=1758723725; cv=none; b=bg6HfTTDVhfxa2yFJuaq2DoUwjGsv20aeIx0Ys7ggJgDeCxF4WkGekSwtXoA7uvFEX9Ffh18qdz8BT7phXLnwPaDczMsIJPhGpVks1SKkknvm3q32zozEE2nTN1GA1mEq1r9GUozwZ/hf7Ve1q7mscRJ7Lawx55X8AQXGZqb4M4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758723725; c=relaxed/simple; bh=8bMnRYFdkzIrNPDO3xYUQlZ8A7wFLDXUvacn4AXaKi0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cyXNhbnjUqs7UlM6WBgOm6Vp3QjcSzY4UKwXsmnLmC64ds4Xa+jjV7rBMW+9Uoa4bHw52sYaqhTut1T9eTxd52c6OThNWHTQABZCOo6XFc6s+9dc3GmmEz4cs7FxN688EiTCiHeh8bM0GW27gRJlGZpeUp02vER4dRLZ+psJOgk= 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=BphDSxbn; 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="BphDSxbn" 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=t7nIw84Rl79y66+K3kgQqOWSKjjzBQe7De/659OAugM=; t=1758723723; x=1759933323; b=BphDSxbn2tbjenKvtDLL9Gf0agC12CssRXMWIJkfOlRH9pc oSG1e3VP+Gg+qoTPL67sFI5K4WTWHecAjVpTsWHz/NgNP7VBb/gs+18Wpg9voY2Jmv5K8zf0Tur6x IUCMwwMUBZ4yoqw/+nngHIDDHioue6TcpzGyWgysPgRJA9xDjY1bY78lj97B6eIoY+ert1A69BJZb FF3BesT9o/D8evXoqhFDLIerie2Xx5nIciazKgMzdGimNtO8mIXWrbSxG2tXkP/mQawyLYie5vMG7 1TCN4K+pI1eI/xEtRAPAnIs8H6ea0+oz82ovah8YpVMzecU9JrgdMZEl6ooSVeqw==; 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 1v1QNZ-000000090Bz-1P4q; Wed, 24 Sep 2025 16:21:58 +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, Benjamin Berg Subject: [PATCH v3 08/12] um: add infrastructure to build files using nolibc Date: Wed, 24 Sep 2025 16:20:55 +0200 Message-ID: <20250924142059.527768-9-benjamin@sipsolutions.net> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250924142059.527768-1-benjamin@sipsolutions.net> References: <20250924142059.527768-1-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. Leave the syscall definition for kernel code for now, but guard it as it is a macro in nolibc. Signed-off-by: Benjamin Berg --- v3: - Change the syscall guard to use __KERNEL__ v2: - Do not include nolibc.h via CFLAGS - Make syscall guard more explicit - Remove __UM_NOLIBC__ define, it is not needed - Fix out-of-tree building --- arch/um/Makefile | 20 +++++++++++++++++++- arch/um/include/shared/os.h | 2 ++ arch/um/include/shared/user.h | 1 - arch/um/scripts/Makefile.rules | 8 +++++++- 4 files changed, 28 insertions(+), 3 deletions(-) diff --git a/arch/um/Makefile b/arch/um/Makefile index f7c509262568..c3a81df50911 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -78,6 +78,24 @@ 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 $(srctree)/tools/include \ + -D__EXPORTED_HEADERS__ \ + -D__UM_HOST__ \ + -DNOLIBC_NO_RUNTIME \ + -DNOLIBC_IGNORE_ERRNO \ + -nostdlib -nostdinc -static \ + -I$(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 $(objtree)/include/generated/autoconf.h \ + -include $(srctree)/tools/include/linux/kconfig.h \ + -include $(srctree)/include/linux/kern_levels.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 @@ -160,4 +178,4 @@ 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..5dae5635b1f8 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 +#ifdef __KERNEL__ long syscall(long number, ...); +#endif =20 /* irqflags tracing */ extern void block_signals_trace(void); diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h index c9b853e1282f..e32bdd032029 100644 --- a/arch/um/include/shared/user.h +++ b/arch/um/include/shared/user.h @@ -16,7 +16,6 @@ */ #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) =20 -#include #include =20 extern void panic(const char *fmt, ...) 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