2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-23 12:43:55 +08:00
linux-next/include/asm-i386/mmu_context.h
Jeremy Fitzhardinge 464d1a78fb [PATCH] i386: Convert i386 PDA code to use %fs
Convert the PDA code to use %fs rather than %gs as the segment for
per-processor data.  This is because some processors show a small but
measurable performance gain for reloading a NULL segment selector (as %fs
generally is in user-space) versus a non-NULL one (as %gs generally is).

On modern processors the difference is very small, perhaps undetectable.
Some old AMD "K6 3D+" processors are noticably slower when %fs is used
rather than %gs; I have no idea why this might be, but I think they're
sufficiently rare that it doesn't matter much.

This patch also fixes the math emulator, which had not been adjusted to
match the changed struct pt_regs.

[frederik.deweerdt@gmail.com: fixit with gdb]
[mingo@elte.hu: Fix KVM too]

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Ian Campbell <Ian.Campbell@XenSource.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Zachary Amsden <zach@vmware.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2007-02-13 13:26:20 +01:00

72 lines
1.7 KiB
C

#ifndef __I386_SCHED_H
#define __I386_SCHED_H
#include <asm/desc.h>
#include <asm/atomic.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
/*
* Used for LDT copy/destruction.
*/
int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
void destroy_context(struct mm_struct *mm);
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
#ifdef CONFIG_SMP
unsigned cpu = smp_processor_id();
if (per_cpu(cpu_tlbstate, cpu).state == TLBSTATE_OK)
per_cpu(cpu_tlbstate, cpu).state = TLBSTATE_LAZY;
#endif
}
static inline void switch_mm(struct mm_struct *prev,
struct mm_struct *next,
struct task_struct *tsk)
{
int cpu = smp_processor_id();
if (likely(prev != next)) {
/* stop flush ipis for the previous mm */
cpu_clear(cpu, prev->cpu_vm_mask);
#ifdef CONFIG_SMP
per_cpu(cpu_tlbstate, cpu).state = TLBSTATE_OK;
per_cpu(cpu_tlbstate, cpu).active_mm = next;
#endif
cpu_set(cpu, next->cpu_vm_mask);
/* Re-load page tables */
load_cr3(next->pgd);
/*
* load the LDT, if the LDT is different:
*/
if (unlikely(prev->context.ldt != next->context.ldt))
load_LDT_nolock(&next->context);
}
#ifdef CONFIG_SMP
else {
per_cpu(cpu_tlbstate, cpu).state = TLBSTATE_OK;
BUG_ON(per_cpu(cpu_tlbstate, cpu).active_mm != next);
if (!cpu_test_and_set(cpu, next->cpu_vm_mask)) {
/* We were in lazy tlb mode and leave_mm disabled
* tlb flush IPI delivery. We must reload %cr3.
*/
load_cr3(next->pgd);
load_LDT_nolock(&next->context);
}
}
#endif
}
#define deactivate_mm(tsk, mm) \
asm("movl %0,%%gs": :"r" (0));
#define activate_mm(prev, next) \
switch_mm((prev),(next),NULL)
#endif