[PATCH] per-cpu areas for 2.5.3-pre6

From: Rusty Russell (rusty@rustcorp.com.au)
Date: Tue Jan 29 2002 - 04:01:17 EST

This patch introduces the __per_cpu_data tag for data, and the
per_cpu() & this_cpu() macros to go with it.

This allows us to get rid of all those special case structures
springing up all over the place for CPU-local data.

Thanks!
Rusty.

diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.3-pre6/include/linux/smp.h working-2.5.3-pre6-percpu/include/linux/smp.h
--- linux-2.5.3-pre6/include/linux/smp.h Thu Jan 17 16:35:24 2002
+++ working-2.5.3-pre6-percpu/include/linux/smp.h Wed Jan 30 04:17:59 2002
@@ -71,7 +71,17 @@
 #define MSG_RESCHEDULE 0x0003 /* Reschedule request from master CPU*/
 #define MSG_CALL_FUNCTION 0x0004 /* Call function on all other CPUs */
 
-#else
+#define __per_cpu_data __attribute__((section(".data.percpu")))
+
+#ifndef __HAVE_ARCH_CPU_OFFSET
+#define per_cpu_offset(cpu) (__per_cpu_offset[(cpu)])
+#endif
+
+#define per_cpu(var, cpu) \
+(*(__typeof__(&var)((void *)&var + per_cpu_offset(cpu))))
+
+extern unsigned long __per_cpu_offset[NR_CPUS];
+#else /* !SMP */
 
 /*
  * These macros fold the SMP functionality into a single CPU system
@@ -88,6 +98,10 @@
 #define cpu_online_map 1
 static inline void smp_send_reschedule(int cpu) { }
 static inline void smp_send_reschedule_all(void) { }
+#define __per_cpu_data
+#define per_cpu(var, cpu) var
 
 #endif
+
+#define this_cpu(var) per_cpu(var,smp_processor_id())
 #endif
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.3-pre6/arch/i386/vmlinux.lds working-2.5.3-pre6-percpu/arch/i386/vmlinux.lds
--- linux-2.5.3-pre6/arch/i386/vmlinux.lds Tue Jan 29 09:16:52 2002
+++ working-2.5.3-pre6-percpu/arch/i386/vmlinux.lds Wed Jan 30 04:00:34 2002
@@ -58,6 +58,10 @@
         *(.initcall7.init)
   }
   __initcall_end = .;
+ . = ALIGN(32);
+ __per_cpu_start = .;
+ .data.percpu : { *(.data.percpu) }
+ __per_cpu_end = .;
   . = ALIGN(4096);
   __init_end = .;
 
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.3-pre6/arch/ppc/vmlinux.lds working-2.5.3-pre6-percpu/arch/ppc/vmlinux.lds
--- linux-2.5.3-pre6/arch/ppc/vmlinux.lds Tue Jan 29 09:16:53 2002
+++ working-2.5.3-pre6-percpu/arch/ppc/vmlinux.lds Wed Jan 30 04:00:34 2002
@@ -104,6 +104,10 @@
         *(.initcall7.init)
   }
   __initcall_end = .;
+ . = ALIGN(32);
+ __per_cpu_start = .;
+ .data.percpu : { *(.data.percpu) }
+ __per_cpu_end = .;
   . = ALIGN(4096);
   __init_end = .;
 
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.3-pre6/init/main.c working-2.5.3-pre6-percpu/init/main.c
--- linux-2.5.3-pre6/init/main.c Tue Jan 29 09:17:09 2002
+++ working-2.5.3-pre6-percpu/init/main.c Wed Jan 30 06:43:10 2002
@@ -274,16 +274,42 @@
 
 #else
 
+unsigned long __per_cpu_offset[NR_CPUS];
+/* Created by linker magic */
+extern char __per_cpu_start, __per_cpu_end;
+
+static void setup_per_cpu_areas(void)
+{
+ unsigned int i;
+ size_t per_cpu_size;
+ char *region;
+
+ /* Set up per-CPU offset pointers. Page align to be safe. */
+ per_cpu_size = ((&__per_cpu_end - &__per_cpu_start) + PAGE_SIZE-1)
+ & ~(PAGE_SIZE-1);
+ region = kmalloc(per_cpu_size * smp_num_cpus, GFP_KERNEL);
+ if (!region)
+ panic("Could not allocate per-cpu regions: %u bytes\n",
+ per_cpu_size * smp_num_cpus);
+ for (i = 0; i < smp_num_cpus; i++) {
+ memcpy(region + per_cpu_size*i, &__per_cpu_start,
+ &__per_cpu_end - &__per_cpu_start);
+ __per_cpu_offset[i]
+ = (region + per_cpu_size*i) - &__per_cpu_start;
+ }
+ printk("Did %u cpu regions...\n", smp_num_cpus);
+}
+
 /* Called by boot processor to activate the rest. */
 static void __init smp_init(void)
 {
         /* Get other processors into their bootup holding patterns. */
         smp_boot_cpus();
 
+ setup_per_cpu_areas();
         smp_threads_ready=1;
         smp_commence();
 }
-
 #endif
 
 /* 

--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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