kernel_optimize_test/arch/x86_64/kernel/genapic_flat.c
Zwane Mwaikambo 329d400f47 [PATCH] x86_64/i386: Remove preempt disable calls in lowlevel IPI
I noticed that some lowlevel send_IPI_mask helpers had a hotplug/preempt
race whereupon the cpu_online_map was read before disabling preemption;

...
cpumask_t mask = cpu_online_map;
int cpu = get_cpu();
cpu_clear(cpu, mask);
...

But then i realised that there is no need for these lowlevel functions to
be going through all this trouble when all the callers are already made
hotplug/preempt safe.

Signed-off-by: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-11 19:01:57 -08:00

190 lines
4.4 KiB
C

/*
* Copyright 2004 James Cleverdon, IBM.
* Subject to the GNU Public License, v.2
*
* Flat APIC subarch code.
*
* Hacked for x86-64 by James Cleverdon from i386 architecture code by
* Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
* James Cleverdon.
*/
#include <linux/config.h>
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <asm/smp.h>
#include <asm/ipi.h>
static cpumask_t flat_target_cpus(void)
{
return cpu_online_map;
}
/*
* Set up the logical destination ID.
*
* Intel recommends to set DFR, LDR and TPR before enabling
* an APIC. See e.g. "AP-388 82489DX User's Manual" (Intel
* document number 292116). So here it goes...
*/
static void flat_init_apic_ldr(void)
{
unsigned long val;
unsigned long num, id;
num = smp_processor_id();
id = 1UL << num;
x86_cpu_to_log_apicid[num] = id;
apic_write(APIC_DFR, APIC_DFR_FLAT);
val = apic_read(APIC_LDR) & ~APIC_LDR_MASK;
val |= SET_APIC_LOGICAL_ID(id);
apic_write(APIC_LDR, val);
}
static void flat_send_IPI_mask(cpumask_t cpumask, int vector)
{
unsigned long mask = cpus_addr(cpumask)[0];
unsigned long cfg;
unsigned long flags;
local_save_flags(flags);
local_irq_disable();
/*
* Wait for idle.
*/
apic_wait_icr_idle();
/*
* prepare target chip field
*/
cfg = __prepare_ICR2(mask);
apic_write(APIC_ICR2, cfg);
/*
* program the ICR
*/
cfg = __prepare_ICR(0, vector, APIC_DEST_LOGICAL);
/*
* Send the IPI. The write to APIC_ICR fires this off.
*/
apic_write(APIC_ICR, cfg);
local_irq_restore(flags);
}
static void flat_send_IPI_allbutself(int vector)
{
#ifndef CONFIG_HOTPLUG_CPU
if (((num_online_cpus()) - 1) >= 1)
__send_IPI_shortcut(APIC_DEST_ALLBUT, vector,APIC_DEST_LOGICAL);
#else
cpumask_t allbutme = cpu_online_map;
cpu_clear(smp_processor_id(), allbutme);
if (!cpus_empty(allbutme))
flat_send_IPI_mask(allbutme, vector);
#endif
}
static void flat_send_IPI_all(int vector)
{
__send_IPI_shortcut(APIC_DEST_ALLINC, vector, APIC_DEST_LOGICAL);
}
static int flat_apic_id_registered(void)
{
return physid_isset(GET_APIC_ID(apic_read(APIC_ID)), phys_cpu_present_map);
}
static unsigned int flat_cpu_mask_to_apicid(cpumask_t cpumask)
{
return cpus_addr(cpumask)[0] & APIC_ALL_CPUS;
}
static unsigned int phys_pkg_id(int index_msb)
{
u32 ebx;
ebx = cpuid_ebx(1);
return ((ebx >> 24) & 0xFF) >> index_msb;
}
struct genapic apic_flat = {
.name = "flat",
.int_delivery_mode = dest_LowestPrio,
.int_dest_mode = (APIC_DEST_LOGICAL != 0),
.int_delivery_dest = APIC_DEST_LOGICAL | APIC_DM_LOWEST,
.target_cpus = flat_target_cpus,
.apic_id_registered = flat_apic_id_registered,
.init_apic_ldr = flat_init_apic_ldr,
.send_IPI_all = flat_send_IPI_all,
.send_IPI_allbutself = flat_send_IPI_allbutself,
.send_IPI_mask = flat_send_IPI_mask,
.cpu_mask_to_apicid = flat_cpu_mask_to_apicid,
.phys_pkg_id = phys_pkg_id,
};
/*
* Physflat mode is used when there are more than 8 CPUs on a AMD system.
* We cannot use logical delivery in this case because the mask
* overflows, so use physical mode.
*/
static cpumask_t physflat_target_cpus(void)
{
return cpumask_of_cpu(0);
}
static void physflat_send_IPI_mask(cpumask_t cpumask, int vector)
{
send_IPI_mask_sequence(cpumask, vector);
}
static void physflat_send_IPI_allbutself(int vector)
{
cpumask_t allbutme = cpu_online_map;
cpu_clear(smp_processor_id(), allbutme);
physflat_send_IPI_mask(allbutme, vector);
}
static void physflat_send_IPI_all(int vector)
{
physflat_send_IPI_mask(cpu_online_map, vector);
}
static unsigned int physflat_cpu_mask_to_apicid(cpumask_t cpumask)
{
int cpu;
/*
* We're using fixed IRQ delivery, can only return one phys APIC ID.
* May as well be the first.
*/
cpu = first_cpu(cpumask);
if ((unsigned)cpu < NR_CPUS)
return x86_cpu_to_apicid[cpu];
else
return BAD_APICID;
}
struct genapic apic_physflat = {
.name = "physical flat",
.int_delivery_mode = dest_Fixed,
.int_dest_mode = (APIC_DEST_PHYSICAL != 0),
.int_delivery_dest = APIC_DEST_PHYSICAL | APIC_DM_FIXED,
.target_cpus = physflat_target_cpus,
.apic_id_registered = flat_apic_id_registered,
.init_apic_ldr = flat_init_apic_ldr,/*not needed, but shouldn't hurt*/
.send_IPI_all = physflat_send_IPI_all,
.send_IPI_allbutself = physflat_send_IPI_allbutself,
.send_IPI_mask = physflat_send_IPI_mask,
.cpu_mask_to_apicid = physflat_cpu_mask_to_apicid,
.phys_pkg_id = phys_pkg_id,
};