diff options
| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2007-05-02 17:27:16 (GMT) |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2007-05-02 17:27:16 (GMT) |
| commit | 7c3576d261ce046789a7db14f43303f8120910c7 (patch) | |
| tree | ad27a8459bbcdb183fe2411aec3b840942992ad5 /arch/i386/kernel/process.c | |
| parent | 7a61d35d4b4056e7711031202da7605e052f4137 (diff) | |
| download | linux-7c3576d261ce046789a7db14f43303f8120910c7.tar.xz | |
[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>
Diffstat (limited to 'arch/i386/kernel/process.c')
| -rw-r--r-- | arch/i386/kernel/process.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index 5fb9524..6199947 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -39,6 +39,7 @@ #include <linux/random.h> #include <linux/personality.h> #include <linux/tick.h> +#include <linux/percpu.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -57,7 +58,6 @@ #include <asm/tlbflush.h> #include <asm/cpu.h> -#include <asm/pda.h> asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); @@ -66,6 +66,12 @@ static int hlt_counter; unsigned long boot_option_idle_override = 0; EXPORT_SYMBOL(boot_option_idle_override); +DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; +EXPORT_PER_CPU_SYMBOL(current_task); + +DEFINE_PER_CPU(int, cpu_number); +EXPORT_PER_CPU_SYMBOL(cpu_number); + /* * Return saved PC of a blocked thread. */ @@ -342,7 +348,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) regs.xds = __USER_DS; regs.xes = __USER_DS; - regs.xfs = __KERNEL_PDA; + regs.xfs = __KERNEL_PERCPU; regs.orig_eax = -1; regs.eip = (unsigned long) kernel_thread_helper; regs.xcs = __KERNEL_CS | get_kernel_rpl(); @@ -711,7 +717,7 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas if (prev->gs | next->gs) loadsegment(gs, next->gs); - write_pda(pcurrent, next_p); + x86_write_percpu(current_task, next_p); return prev_p; } |