From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 19B413B6359 for ; Tue, 2 Jun 2026 09:09:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780391365; cv=none; b=P+jft+/PKzp0ayl+34ugCUiFTbIyIb1iHZ1ojd+Bd6fxo6kWjPkG9+ml2/UrdAPY7PNY1SfUJ818PsnWATeTHEUKoKINZQ1QV8sNItzZL6IIgXNm4h5XhY9G5W6DEbrTMV/0iytjZA9qis29TgKuRq5adXm5Y7saotjC4SwqHrQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780391365; c=relaxed/simple; bh=gX8k0ZyMxIYHMK58XA6RLns7N0QdDr8muAggRi5zRXw=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=kEVv16UwndiNXue2WEKAFBCvf6hM1CWF5xgrAhb+6f0+rEntPiOgrhmc6ooJctv6UqRXaAFojR0AyEJQIJpGf8/WIvjuXugkycq9Jp4H5XNHwUhW6Vesk0/8WfjP+Pilp+cjo114R9eYHBW2NeDiUzuYDh1qUjvj/cJOX+BT9Zs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=S9H6wen8; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="S9H6wen8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D54A1F00893; Tue, 2 Jun 2026 09:09:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780391363; bh=9z7WtBqXJK2da2fG5RFRrjonVyU9CvcGGKO0HeX9XGg=; h=Date:From:To:Cc:Subject:References; b=S9H6wen8Kwjc+ygQE2t1+TOC0EEUXnyFDI5y8RJbu3v88gHR8wYLOpiu8WuExDAFb dBHzx9uo9z2WfkKup02wmHbbNOT9pA/Gc7iBHs8HZY8HSS/opOViaoBSquu9ui25VQ hMmHjemEJZH/iRlxhansKhqV2hHa0g+g9WZpPN4RK8lZfvBtHG7v9UChNnhKA6y6DY KtO2vVvUSryxjE++B90cKbvJUJHcvFEFI8/x+xrzmD+KtsPxKjKbODUB/YhYt94n/1 rU8cGY3OCv8ZpnrlxuoJF90x4CkqgApA8BVBOXESc1YVQnNVTCJq5W7wNxB1jZZ4ms VbguMwhwiFYaA== Date: Tue, 02 Jun 2026 11:09:21 +0200 Message-ID: <20260602090535.254874125@kernel.org> User-Agent: quilt/0.69 From: Thomas Gleixner To: LKML Cc: Mathieu Desnoyers , =?UTF-8?q?Andr=C3=A9=20Almeida?= , Sebastian Andrzej Siewior , Carlos O'Donell , Peter Zijlstra , Florian Weimer , Rich Felker , Torvald Riegel , Darren Hart , Ingo Molnar , Davidlohr Bueso , Arnd Bergmann , "Liam R . Howlett" , Uros Bizjak , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Mark Brown , Richard Weinberger Subject: [patch V5 01/16] percpu: Sanitize __percpu_qual include hell References: <20260602084648.462672743@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Slapping __percpu_qual into the next available header is sloppy at best. It's required by __percpu which is defined in compiler_types.h and that is meant to be included without requiring a boatload of other headers so that a struct or function declaration can contain a __percpu qualifier w/o further prerequisites. This implicit dependency on linux/percpu.h makes that impossible and causes a major problem when trying to separate headers. Create asm/percpu_types.h and move it there. Include that from compiler_types.h and the whole recursion problem goes away. Fix up UM so it uses the generic header and includes it in the UM_HOST build, which pulls in compiler_types.h. The USER_CFLAGS fix was suggested by Richard. Signed-off-by: Thomas Gleixner Cc: Richard Weinberger --- V5: New. Address 0-day __percpu fallout --- arch/um/Makefile | 3 ++- arch/um/include/asm/Kbuild | 1 + arch/x86/include/asm/percpu.h | 5 ----- arch/x86/include/asm/percpu_types.h | 17 +++++++++++++++++ include/asm-generic/Kbuild | 1 + include/asm-generic/percpu_types.h | 19 +++++++++++++++++++ include/linux/compiler_types.h | 3 +++ include/linux/percpu.h | 9 +++++---- 8 files changed, 48 insertions(+), 10 deletions(-) --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -71,7 +71,8 @@ USER_CFLAGS = $(patsubst $(KERNEL_DEFINE -D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \ -idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__ \ -include $(srctree)/include/linux/compiler-version.h \ - -include $(srctree)/include/linux/kconfig.h + -include $(srctree)/include/linux/kconfig.h \ + -idirafter $(ARCH_DIR)/include/generated #This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux --- a/arch/um/include/asm/Kbuild +++ b/arch/um/include/asm/Kbuild @@ -16,6 +16,7 @@ generic-y += module.h generic-y += module.lds.h generic-y += parport.h generic-y += percpu.h +generic-y += percpu_types.h generic-y += preempt.h generic-y += runtime-const.h generic-y += softirq_stack.h --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -40,12 +40,10 @@ #endif #define __percpu_prefix -#define __percpu_seg_override CONCATENATE(__seg_, __percpu_seg) #else /* !CONFIG_CC_HAS_NAMED_AS: */ #define __percpu_prefix __force_percpu_prefix -#define __percpu_seg_override #endif /* CONFIG_CC_HAS_NAMED_AS */ @@ -82,7 +80,6 @@ #define __force_percpu_prefix #define __percpu_prefix -#define __percpu_seg_override #define PER_CPU_VAR(var) (var)__percpu_rel @@ -92,8 +89,6 @@ # define __my_cpu_type(var) typeof(var) # define __my_cpu_ptr(ptr) (ptr) # define __my_cpu_var(var) (var) - -# define __percpu_qual __percpu_seg_override #else # define __my_cpu_type(var) typeof(var) __percpu_seg_override # define __my_cpu_ptr(ptr) (__my_cpu_type(*(ptr))*)(__force uintptr_t)(ptr) --- /dev/null +++ b/arch/x86/include/asm/percpu_types.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_PERCPU_TYPES_H +#define _ASM_X86_PERCPU_TYPES_H + +#if defined(CONFIG_SMP) && defined(CONFIG_CC_HAS_NAMED_AS) +#define __percpu_seg_override CONCATENATE(__seg_, __percpu_seg) +#else /* !CONFIG_CC_HAS_NAMED_AS: */ +#define __percpu_seg_override +#endif + +#if defined(CONFIG_USE_X86_SEG_SUPPORT) && defined(USE_TYPEOF_UNQUAL) +#define __percpu_qual __percpu_seg_override +#endif + +#include + +#endif --- a/include/asm-generic/Kbuild +++ b/include/asm-generic/Kbuild @@ -44,6 +44,7 @@ mandatory-y += module.lds.h mandatory-y += msi.h mandatory-y += pci.h mandatory-y += percpu.h +mandatory-y += percpu_types.h mandatory-y += pgalloc.h mandatory-y += preempt.h mandatory-y += rqspinlock.h --- /dev/null +++ b/include/asm-generic/percpu_types.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_GENERIC_PERCPU_TYPES_H_ +#define _ASM_GENERIC_PERCPU_TYPES_H_ + +#ifndef __ASSEMBLER__ +/* + * __percpu_qual is the qualifier for the percpu named address space. + * + * Most architectures use generic named address space for percpu variables but + * some architectures define percpu variables in different named address space. + * E.g. on x86, percpu variable may be declared as being relative to the %fs or + * %gs segments using __seg_fs or __seg_gs named address space qualifier. + */ +#ifndef __percpu_qual +# define __percpu_qual +#endif + +#endif /* __ASSEMBLER__ */ +#endif /* _ASM_GENERIC_PERCPU_TYPES_H_ */ --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -634,6 +634,9 @@ struct ftrace_likely_data { #else #define __unqual_scalar_typeof(x) __typeof_unqual__(x) #endif + +#include + #endif /* !__ASSEMBLY__ */ /* --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -3,13 +3,14 @@ #define __LINUX_PERCPU_H #include +#include +#include +#include #include -#include -#include #include -#include -#include +#include #include +#include #include