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Subject[PATCH] __per_cpu_data
Date
This is the Richard Henderson-approved, cleaner, brighter per-cpu patch.  

Please apply,
Rusty.

diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.3/include/linux/compiler.h working-2.5.3-percpu/include/linux/compiler.h
--- linux-2.5.3/include/linux/compiler.h Wed Sep 19 07:12:45 2001
+++ working-2.5.3-percpu/include/linux/compiler.h Fri Feb 1 09:46:02 2002
@@ -13,4 +13,12 @@
#define likely(x) __builtin_expect((x),1)
#define unlikely(x) __builtin_expect((x),0)

+/* This macro obfuscates arithmetic on a variable address so that gcc
+ shouldn't recognize it. This prevents optimizations such as the
+ famous:
+ strcpy(s, "xxx"+X) => memcpy(s, "xxx"+X, 4-X) */
+#define reloc_hide(var, off) \
+ ({ __typeof__(&(var)) __ptr; \
+ __asm__ ("" : "=g"(__ptr) : "0"((void *)&(var) + (off))); \
+ *__ptr; })
#endif /* __LINUX_COMPILER_H */
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.3/include/linux/smp.h working-2.5.3-percpu/include/linux/smp.h
--- linux-2.5.3/include/linux/smp.h Fri Feb 1 19:21:37 2002
+++ working-2.5.3-percpu/include/linux/smp.h Fri Feb 1 19:17:09 2002
@@ -11,6 +11,7 @@
#ifdef CONFIG_SMP

#include <linux/kernel.h>
+#include <linux/compiler.h>
#include <asm/smp.h>

/*
@@ -71,7 +72,17 @@
#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_PER_CPU
+extern unsigned long __per_cpu_offset[NR_CPUS];
+
+/* var is in discarded region: offset to particular copy we want */
+#define per_cpu(var, cpu) reloc_hide(var, per_cpu_offset(cpu))
+
+#define this_cpu(var) per_cpu(var, smp_processor_id())
+#endif /* !__HAVE_ARCH_PER_CPU */
+#else /* !SMP */

/*
* These macros fold the SMP functionality into a single CPU system
@@ -88,6 +99,9 @@
#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
+#define this_cpu(var) var

#endif
#endif
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.3/init/main.c working-2.5.3-percpu/init/main.c
--- linux-2.5.3/init/main.c Thu Jan 31 08:59:17 2002
+++ working-2.5.3-percpu/init/main.c Fri Feb 1 19:13:52 2002
@@ -272,8 +272,32 @@
#define smp_init() do { } while (0)
#endif

+static inline void setup_per_cpu_areas(void)
+{
+}
#else

+#ifndef __HAVE_ARCH_PER_CPU
+unsigned long __per_cpu_offset[NR_CPUS];
+
+static void __init setup_per_cpu_areas(void)
+{
+ unsigned long size, i;
+ char *ptr;
+ /* Created by linker magic */
+ extern char __per_cpu_start[], __per_cpu_end[];
+
+ /* Copy section for each CPU (we discard the original) */
+ size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES);
+ ptr = alloc_bootmem(size * NR_CPUS);
+
+ for (i = 0; i < NR_CPUS; i++, ptr += size) {
+ __per_cpu_offset[i] = ptr - __per_cpu_start;
+ memcpy(ptr, __per_cpu_start, size);
+ }
+}
+#endif /* !__HAVE_ARCH_PER_CPU */
+
/* Called by boot processor to activate the rest. */
static void __init smp_init(void)
{
@@ -316,6 +340,7 @@
lock_kernel();
printk(linux_banner);
setup_arch(&command_line);
+ setup_per_cpu_areas();
printk("Kernel command line: %s\n", saved_command_line);
parse_options(command_line);
trap_init();
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.3/include/linux/cache.h working-2.5.3-percpu/include/linux/cache.h
--- linux-2.5.3/include/linux/cache.h Fri Feb 1 19:21:37 2002
+++ working-2.5.3-percpu/include/linux/cache.h Fri Feb 1 19:17:09 2002
@@ -4,8 +4,10 @@
#include <linux/config.h>
#include <asm/cache.h>

+#define ALIGN(x,a) (((x)+(a)-1)&~((a)-1))
+
#ifndef L1_CACHE_ALIGN
-#define L1_CACHE_ALIGN(x) (((x)+(L1_CACHE_BYTES-1))&~(L1_CACHE_BYTES-1))
+#define L1_CACHE_ALIGN(x) ALIGN(x, L1_CACHE_BYTES)
#endif

#ifndef SMP_CACHE_BYTES
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.3/arch/i386/vmlinux.lds working-2.5.3-percpu/arch/i386/vmlinux.lds
--- linux-2.5.3/arch/i386/vmlinux.lds Thu Jan 31 08:58:52 2002
+++ working-2.5.3-percpu/arch/i386/vmlinux.lds Fri Feb 1 09:11:18 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/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.3/arch/ppc/vmlinux.lds working-2.5.3-percpu/arch/ppc/vmlinux.lds
--- linux-2.5.3/arch/ppc/vmlinux.lds Thu Jan 31 08:58:55 2002
+++ working-2.5.3-percpu/arch/ppc/vmlinux.lds Fri Feb 1 09:11:18 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 = .;

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