[PATCH] i386: Convert PDA into the percpu section
Currently x86 (similar to x84-64) has a special per-cpu structure
called "i386_pda" which can be easily and efficiently referenced via
the %fs register. An ELF section is more flexible than a structure,
allowing any piece of code to use this area. Indeed, such a section
already exists: the per-cpu area.
So this patch:
(1) Removes the PDA and uses per-cpu variables for each current member.
(2) Replaces the __KERNEL_PDA segment with __KERNEL_PERCPU.
(3) Creates a per-cpu mirror of __per_cpu_offset called this_cpu_off, which
can be used to calculate addresses for this CPU's variables.
(4) Simplifies startup, because %fs doesn't need to be loaded with a
special segment at early boot; it can be deferred until the first
percpu area is allocated (or never for UP).
The result is less code and one less x86-specific concept.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
diff --git a/include/asm-i386/irq_regs.h b/include/asm-i386/irq_regs.h
index a1b3f7f..3368b20 100644
--- a/include/asm-i386/irq_regs.h
+++ b/include/asm-i386/irq_regs.h
@@ -1,25 +1,27 @@
/*
* Per-cpu current frame pointer - the location of the last exception frame on
- * the stack, stored in the PDA.
+ * the stack, stored in the per-cpu area.
*
* Jeremy Fitzhardinge <jeremy@goop.org>
*/
#ifndef _ASM_I386_IRQ_REGS_H
#define _ASM_I386_IRQ_REGS_H
-#include <asm/pda.h>
+#include <asm/percpu.h>
+
+DECLARE_PER_CPU(struct pt_regs *, irq_regs);
static inline struct pt_regs *get_irq_regs(void)
{
- return read_pda(irq_regs);
+ return x86_read_percpu(irq_regs);
}
static inline struct pt_regs *set_irq_regs(struct pt_regs *new_regs)
{
struct pt_regs *old_regs;
- old_regs = read_pda(irq_regs);
- write_pda(irq_regs, new_regs);
+ old_regs = get_irq_regs();
+ x86_write_percpu(irq_regs, new_regs);
return old_regs;
}
