Re: [Xen-devel] [PATCH 1/4] arm/percpu: Move {get, set}_processor_id() into smp.h

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrew,

Thank you for looking into this.

On 7/26/19 10:08 PM, Andrew Cooper wrote:
> For cleanup purposes, it is necessary for asm/percpu.h to not use
> DECLARE_PER_CPU() itself.  asm/smp.h is arguably a better place for it to
> live anyway.
I have noticed that a lot of arch helpers called by common code 
are defined in different headers. The most offenders are in mm.h
and page.h.

Looking at x86, the two helpers are defined in current.h. So I
think it would make sense to define them at the same places. I
don't have a particular preference between smp.h and current.h,
just want some consistency :).

FWIW, Xen build nicely when the helpers are moved in current.h:

diff --git a/xen/include/asm-arm/current.h b/xen/include/asm-arm/current.h
index c4af66fbb9..23fa6009d8 100644
--- a/xen/include/asm-arm/current.h
+++ b/xen/include/asm-arm/current.h
@@ -39,6 +39,13 @@ static inline struct cpu_info *get_cpu_info(void)
 
 #define reset_stack_and_jump(fn) switch_stack_and_jump(get_cpu_info(), fn)
 
+DECLARE_PER_CPU(unsigned int, cpu_id);
+#define get_processor_id()    (this_cpu(cpu_id))
+#define set_processor_id(id)  do {                      \
+    WRITE_SYSREG(__per_cpu_offset[id], TPIDR_EL2);      \
+    this_cpu(cpu_id) = (id);                            \
+} while(0)
+
 #endif
 
 #endif /* __ARM_CURRENT_H__ */
diff --git a/xen/include/asm-arm/percpu.h b/xen/include/asm-arm/percpu.h
index 9584b830d4..011016347b 100644
--- a/xen/include/asm-arm/percpu.h
+++ b/xen/include/asm-arm/percpu.h
@@ -27,12 +27,6 @@ void percpu_init_areas(void);
 
 #define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
 
-DECLARE_PER_CPU(unsigned int, cpu_id);
-#define get_processor_id()    (this_cpu(cpu_id))
-#define set_processor_id(id)  do {                      \
-    WRITE_SYSREG(__per_cpu_offset[id], TPIDR_EL2);      \
-    this_cpu(cpu_id) = (id);                            \
-} while(0)
 #endif
 
 #endif /* __ARM_PERCPU_H__ */


Cheers,

-- 
Julien Grall

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