From 6cea5ae714ba47ea4807d15903baca9857a450e6 Mon Sep 17 00:00:00 2001
From: Uros Bizjak <ubizjak@gmail.com>
Date: Mon, 27 Jan 2025 17:05:09 +0100
Subject: [PATCH] percpu: repurpose __percpu tag as a named address space
 qualifier

The patch introduces __percpu_qual define and repurposes __percpu tag as a
named address space qualifier using the new define.

Arches can now conditionally define __percpu_qual as their named address
space qualifier for percpu variables.

Link: https://lkml.kernel.org/r/20250127160709.80604-6-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Nadav Amit <nadav.amit@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/asm-generic/percpu.h   | 13 +++++++++++++
 include/linux/compiler_types.h |  2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 50597b975a499..02aeca21479a7 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -6,6 +6,19 @@
 #include <linux/threads.h>
 #include <linux/percpu-defs.h>
 
+/*
+ * __percpu_qual is the qualifier for the percpu named address space.
+ *
+ * Most arches use generic named address space for percpu variables but
+ * some arches define percpu variables in different named address space
+ * (on the x86 arch, 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
+
 #ifdef CONFIG_SMP
 
 /*
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 981cc3d7e3aa5..5d65445456589 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -57,7 +57,7 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
 #  define __user	BTF_TYPE_TAG(user)
 # endif
 # define __iomem
-# define __percpu	BTF_TYPE_TAG(percpu)
+# define __percpu	__percpu_qual BTF_TYPE_TAG(percpu)
 # define __rcu		BTF_TYPE_TAG(rcu)
 
 # define __chk_user_ptr(x)	(void)0
-- 
2.39.5