linux-kernel - [PATCH -tip v2 3/3] x86/percpu: Avoid sparse warning with cast to named address space

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Message-ID: <20231203232017.994963-3-ubizjak@gmail.com>
Date:   Mon,  4 Dec 2023 00:19:40 +0100
From:   Uros Bizjak <ubizjak@...il.com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     Uros Bizjak <ubizjak@...il.com>, kernel test robot <lkp@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH -tip v2 3/3] x86/percpu: Avoid sparse warning with cast to named address space

Currently sparse does not know about __seg_fs and __seg_fs named
address space qualifiers. Avoid thousands of warnings about unexpected
keyword at the end of cast operator by removing named address space
qualifier from __my_cpu_type() when __CHECKER__ is defined.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310080853.UhMe5iWa-lkp@intel.com/
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
---
 arch/x86/include/asm/percpu.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 3859abad19ec..cc4212d1491e 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -96,6 +96,15 @@
 
 #endif /* CONFIG_SMP */
 
+/*
+ * FIXME: Drop this hack once sparse learns how to ignore
+ * __seg_fs and __seg_gs named address space qualifiers.
+ */
+#ifdef __CHECKER__
+#undef __percpu_seg_override
+#define __percpu_seg_override
+#endif
+
 #define __my_cpu_type(var)	typeof(var) __percpu_seg_override
 #define __my_cpu_ptr(ptr)	(__my_cpu_type(*ptr) *)(uintptr_t)(ptr)
 #define __my_cpu_var(var)	(*__my_cpu_ptr(&var))
-- 
2.42.0