sched/topology: Split out SD_* flags declaration to its own file

To associate the SD flags with some metadata, we need some more structure
in the way they are declared.

Rather than shove that in a free-standing macro list, move the declaration
in a separate file that can be re-imported with different SD_FLAG
definitions. This is inspired by what is done with the syscall
table (see uapi/asm/unistd.h and sys_call_table).

The value assigned to a given SD flag now depends on the order it appears
in sd_flags.h. No change in functionality.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-4-valentin.schneider@arm.com

include/linux/sched/sd_flags.h

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * sched-domains (multiprocessor balancing) flag declarations.
+ */
+
+#ifndef SD_FLAG
+# error "Incorrect import of SD flags definitions"
+#endif
+
+/* Balance when about to become idle */
+SD_FLAG(SD_BALANCE_NEWIDLE)
+/* Balance on exec */
+SD_FLAG(SD_BALANCE_EXEC)
+/* Balance on fork, clone */
+SD_FLAG(SD_BALANCE_FORK)
+/* Balance on wakeup */
+SD_FLAG(SD_BALANCE_WAKE)
+/* Wake task to waking CPU */
+SD_FLAG(SD_WAKE_AFFINE)
+/* Domain members have different CPU capacities */
+SD_FLAG(SD_ASYM_CPUCAPACITY)
+/* Domain members share CPU capacity */
+SD_FLAG(SD_SHARE_CPUCAPACITY)
+/* Domain members share CPU pkg resources */
+SD_FLAG(SD_SHARE_PKG_RESOURCES)
+/* Only a single load balancing instance */
+SD_FLAG(SD_SERIALIZE)
+/* Place busy groups earlier in the domain */
+SD_FLAG(SD_ASYM_PACKING)
+/* Prefer to place tasks in a sibling domain */
+SD_FLAG(SD_PREFER_SIBLING)
+/* sched_domains of this level overlap */
+SD_FLAG(SD_OVERLAP)
+/* cross-node balancing */
+SD_FLAG(SD_NUMA)

include/linux/sched/topology.h

@@ -11,19 +11,19 @@
  */
 #ifdef CONFIG_SMP
 
-#define SD_BALANCE_NEWIDLE	0x0001	/* Balance when about to become idle */
-#define SD_BALANCE_EXEC		0x0002	/* Balance on exec */
-#define SD_BALANCE_FORK		0x0004	/* Balance on fork, clone */
-#define SD_BALANCE_WAKE		0x0008  /* Balance on wakeup */
-#define SD_WAKE_AFFINE		0x0010	/* Wake task to waking CPU */
-#define SD_ASYM_CPUCAPACITY	0x0020  /* Domain members have different CPU capacities */
-#define SD_SHARE_CPUCAPACITY	0x0040	/* Domain members share CPU capacity */
-#define SD_SHARE_PKG_RESOURCES	0x0080	/* Domain members share CPU pkg resources */
-#define SD_SERIALIZE		0x0100	/* Only a single load balancing instance */
-#define SD_ASYM_PACKING		0x0200  /* Place busy groups earlier in the domain */
-#define SD_PREFER_SIBLING	0x0400	/* Prefer to place tasks in a sibling domain */
-#define SD_OVERLAP		0x0800	/* sched_domains of this level overlap */
-#define SD_NUMA			0x1000	/* cross-node balancing */
+/* Generate SD flag indexes */
+#define SD_FLAG(name) __##name,
+enum {
+	#include <linux/sched/sd_flags.h>
+	__SD_FLAG_CNT,
+};
+#undef SD_FLAG
+/* Generate SD flag bits */
+#define SD_FLAG(name) name = 1 << __##name,
+enum {
+	#include <linux/sched/sd_flags.h>
+};
+#undef SD_FLAG
 
 #ifdef CONFIG_SCHED_SMT
 static inline int cpu_smt_flags(void)