linux/arch/x86/kernel/time.c
Andy Lutomirski 8c49d9a74b x86-64: Clean up vdso/kernel shared variables
Variables that are shared between the vdso and the kernel are
currently a bit of a mess.  They are each defined with their own
magic, they are accessed differently in the kernel, the vsyscall page,
and the vdso, and one of them (vsyscall_clock) doesn't even really
exist.

This changes them all to use a common mechanism.  All of them are
delcared in vvar.h with a fixed address (validated by the linker
script).  In the kernel (as before), they look like ordinary
read-write variables.  In the vsyscall page and the vdso, they are
accessed through a new macro VVAR, which gives read-only access.

The vdso is now loaded verbatim into memory without any fixups.  As a
side bonus, access from the vdso is faster because a level of
indirection is removed.

While we're at it, pack jiffies and vgetcpu_mode into the same
cacheline.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-24 14:51:28 +02:00

104 lines
2.2 KiB
C

/*
* Copyright (c) 1991,1992,1995 Linus Torvalds
* Copyright (c) 1994 Alan Modra
* Copyright (c) 1995 Markus Kuhn
* Copyright (c) 1996 Ingo Molnar
* Copyright (c) 1998 Andrea Arcangeli
* Copyright (c) 2002,2006 Vojtech Pavlik
* Copyright (c) 2003 Andi Kleen
*
*/
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/mca.h>
#include <asm/vsyscall.h>
#include <asm/x86_init.h>
#include <asm/i8259.h>
#include <asm/i8253.h>
#include <asm/timer.h>
#include <asm/hpet.h>
#include <asm/time.h>
#ifdef CONFIG_X86_64
DEFINE_VVAR(volatile unsigned long, jiffies) = INITIAL_JIFFIES;
#endif
unsigned long profile_pc(struct pt_regs *regs)
{
unsigned long pc = instruction_pointer(regs);
if (!user_mode_vm(regs) && in_lock_functions(pc)) {
#ifdef CONFIG_FRAME_POINTER
return *(unsigned long *)(regs->bp + sizeof(long));
#else
unsigned long *sp =
(unsigned long *)kernel_stack_pointer(regs);
/*
* Return address is either directly at stack pointer
* or above a saved flags. Eflags has bits 22-31 zero,
* kernel addresses don't.
*/
if (sp[0] >> 22)
return sp[0];
if (sp[1] >> 22)
return sp[1];
#endif
}
return pc;
}
EXPORT_SYMBOL(profile_pc);
/*
* Default timer interrupt handler for PIT/HPET
*/
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
/* Keep nmi watchdog up to date */
inc_irq_stat(irq0_irqs);
global_clock_event->event_handler(global_clock_event);
/* MCA bus quirk: Acknowledge irq0 by setting bit 7 in port 0x61 */
if (MCA_bus)
outb_p(inb_p(0x61)| 0x80, 0x61);
return IRQ_HANDLED;
}
static struct irqaction irq0 = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
.name = "timer"
};
void __init setup_default_timer_irq(void)
{
setup_irq(0, &irq0);
}
/* Default timer init function */
void __init hpet_time_init(void)
{
if (!hpet_enable())
setup_pit_timer();
setup_default_timer_irq();
}
static __init void x86_late_time_init(void)
{
x86_init.timers.timer_init();
tsc_init();
}
/*
* Initialize TSC and delay the periodic timer init to
* late x86_late_time_init() so ioremap works.
*/
void __init time_init(void)
{
late_time_init = x86_late_time_init;
}