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

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

Signed-off-by: Uros Bizjak <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Luc Van Oostenryck <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Peter Zijlstra <[email protected]>
---
 include/asm-generic/percpu.h   | 15 +++++++++++++++
 include/linux/compiler_types.h |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 50597b975a49..3b93b168faa1 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -6,6 +6,21 @@
 #include <linux/threads.h>
 #include <linux/percpu-defs.h>
 
+/*
+ * per_cpu_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).
+ */
+#ifdef __per_cpu_qual
+# define per_cpu_qual __per_cpu_qual
+#else
+# define per_cpu_qual
+#endif
+
 #ifdef CONFIG_SMP
 
 /*
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 981cc3d7e3aa..877fe0c43c5d 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      per_cpu_qual BTF_TYPE_TAG(percpu)
 # define __rcu         BTF_TYPE_TAG(rcu)
 
 # define __chk_user_ptr(x)     (void)0
-- 
2.42.0


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