linux/arch/mips/cavium-octeon/smp.c
Alex Smith 4ace6139bf MIPS: SMP: Don't increment irq_count multiple times for call function IPIs
The majority of SMP platforms handle their IPIs through do_IRQ()
which calls irq_{enter/exit}(). When a call function IPI is received,
smp_call_function_interrupt() is called which also calls
irq_{enter,exit}(), meaning irq_count is raised twice.

When tick broadcasting is used (which is implemented via a call
function IPI), this incorrectly causes all CPU idle time on the core
receiving broadcast ticks to be accounted as time spent servicing
IRQs, as account_process_tick() will account as such if irq_count is
greater than 1. This results in 100% CPU usage being reported on a
core which receives its ticks via broadcast.

This patch removes the SMP smp_call_function_interrupt() wrapper which
calls irq_{enter,exit}(). Platforms which handle their IPIs through
do_IRQ() now call generic_smp_call_function_interrupt() directly to
avoid incrementing irq_count a second time. Platforms which don't
(loongson, sgi-ip27, sibyte) call generic_smp_call_function_interrupt()
wrapped in irq_{enter,exit}().

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10770/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-08-03 09:25:12 +02:00

391 lines
9.3 KiB
C

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2004-2008, 2009, 2010 Cavium Networks
*/
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <asm/mmu_context.h>
#include <asm/time.h>
#include <asm/setup.h>
#include <asm/octeon/octeon.h>
#include "octeon_boot.h"
volatile unsigned long octeon_processor_boot = 0xff;
volatile unsigned long octeon_processor_sp;
volatile unsigned long octeon_processor_gp;
#ifdef CONFIG_HOTPLUG_CPU
uint64_t octeon_bootloader_entry_addr;
EXPORT_SYMBOL(octeon_bootloader_entry_addr);
#endif
static irqreturn_t mailbox_interrupt(int irq, void *dev_id)
{
const int coreid = cvmx_get_core_num();
uint64_t action;
/* Load the mailbox register to figure out what we're supposed to do */
action = cvmx_read_csr(CVMX_CIU_MBOX_CLRX(coreid)) & 0xffff;
/* Clear the mailbox to clear the interrupt */
cvmx_write_csr(CVMX_CIU_MBOX_CLRX(coreid), action);
if (action & SMP_CALL_FUNCTION)
generic_smp_call_function_interrupt();
if (action & SMP_RESCHEDULE_YOURSELF)
scheduler_ipi();
/* Check if we've been told to flush the icache */
if (action & SMP_ICACHE_FLUSH)
asm volatile ("synci 0($0)\n");
return IRQ_HANDLED;
}
/**
* Cause the function described by call_data to be executed on the passed
* cpu. When the function has finished, increment the finished field of
* call_data.
*/
void octeon_send_ipi_single(int cpu, unsigned int action)
{
int coreid = cpu_logical_map(cpu);
/*
pr_info("SMP: Mailbox send cpu=%d, coreid=%d, action=%u\n", cpu,
coreid, action);
*/
cvmx_write_csr(CVMX_CIU_MBOX_SETX(coreid), action);
}
static inline void octeon_send_ipi_mask(const struct cpumask *mask,
unsigned int action)
{
unsigned int i;
for_each_cpu(i, mask)
octeon_send_ipi_single(i, action);
}
/**
* Detect available CPUs, populate cpu_possible_mask
*/
static void octeon_smp_hotplug_setup(void)
{
#ifdef CONFIG_HOTPLUG_CPU
struct linux_app_boot_info *labi;
if (!setup_max_cpus)
return;
labi = (struct linux_app_boot_info *)PHYS_TO_XKSEG_CACHED(LABI_ADDR_IN_BOOTLOADER);
if (labi->labi_signature != LABI_SIGNATURE) {
pr_info("The bootloader on this board does not support HOTPLUG_CPU.");
return;
}
octeon_bootloader_entry_addr = labi->InitTLBStart_addr;
#endif
}
static void octeon_smp_setup(void)
{
const int coreid = cvmx_get_core_num();
int cpus;
int id;
int core_mask = octeon_get_boot_coremask();
#ifdef CONFIG_HOTPLUG_CPU
unsigned int num_cores = cvmx_octeon_num_cores();
#endif
/* The present CPUs are initially just the boot cpu (CPU 0). */
for (id = 0; id < NR_CPUS; id++) {
set_cpu_possible(id, id == 0);
set_cpu_present(id, id == 0);
}
__cpu_number_map[coreid] = 0;
__cpu_logical_map[0] = coreid;
/* The present CPUs get the lowest CPU numbers. */
cpus = 1;
for (id = 0; id < NR_CPUS; id++) {
if ((id != coreid) && (core_mask & (1 << id))) {
set_cpu_possible(cpus, true);
set_cpu_present(cpus, true);
__cpu_number_map[id] = cpus;
__cpu_logical_map[cpus] = id;
cpus++;
}
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* The possible CPUs are all those present on the chip. We
* will assign CPU numbers for possible cores as well. Cores
* are always consecutively numberd from 0.
*/
for (id = 0; setup_max_cpus && octeon_bootloader_entry_addr &&
id < num_cores && id < NR_CPUS; id++) {
if (!(core_mask & (1 << id))) {
set_cpu_possible(cpus, true);
__cpu_number_map[id] = cpus;
__cpu_logical_map[cpus] = id;
cpus++;
}
}
#endif
octeon_smp_hotplug_setup();
}
/**
* Firmware CPU startup hook
*
*/
static void octeon_boot_secondary(int cpu, struct task_struct *idle)
{
int count;
pr_info("SMP: Booting CPU%02d (CoreId %2d)...\n", cpu,
cpu_logical_map(cpu));
octeon_processor_sp = __KSTK_TOS(idle);
octeon_processor_gp = (unsigned long)(task_thread_info(idle));
octeon_processor_boot = cpu_logical_map(cpu);
mb();
count = 10000;
while (octeon_processor_sp && count) {
/* Waiting for processor to get the SP and GP */
udelay(1);
count--;
}
if (count == 0)
pr_err("Secondary boot timeout\n");
}
/**
* After we've done initial boot, this function is called to allow the
* board code to clean up state, if needed
*/
static void octeon_init_secondary(void)
{
unsigned int sr;
sr = set_c0_status(ST0_BEV);
write_c0_ebase((u32)ebase);
write_c0_status(sr);
octeon_check_cpu_bist();
octeon_init_cvmcount();
octeon_irq_setup_secondary();
}
/**
* Callout to firmware before smp_init
*
*/
void octeon_prepare_cpus(unsigned int max_cpus)
{
/*
* Only the low order mailbox bits are used for IPIs, leave
* the other bits alone.
*/
cvmx_write_csr(CVMX_CIU_MBOX_CLRX(cvmx_get_core_num()), 0xffff);
if (request_irq(OCTEON_IRQ_MBOX0, mailbox_interrupt,
IRQF_PERCPU | IRQF_NO_THREAD, "SMP-IPI",
mailbox_interrupt)) {
panic("Cannot request_irq(OCTEON_IRQ_MBOX0)");
}
}
/**
* Last chance for the board code to finish SMP initialization before
* the CPU is "online".
*/
static void octeon_smp_finish(void)
{
octeon_user_io_init();
/* to generate the first CPU timer interrupt */
write_c0_compare(read_c0_count() + mips_hpt_frequency / HZ);
local_irq_enable();
}
#ifdef CONFIG_HOTPLUG_CPU
/* State of each CPU. */
DEFINE_PER_CPU(int, cpu_state);
static int octeon_cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
if (cpu == 0)
return -EBUSY;
if (!octeon_bootloader_entry_addr)
return -ENOTSUPP;
set_cpu_online(cpu, false);
cpumask_clear_cpu(cpu, &cpu_callin_map);
octeon_fixup_irqs();
flush_cache_all();
local_flush_tlb_all();
return 0;
}
static void octeon_cpu_die(unsigned int cpu)
{
int coreid = cpu_logical_map(cpu);
uint32_t mask, new_mask;
const struct cvmx_bootmem_named_block_desc *block_desc;
while (per_cpu(cpu_state, cpu) != CPU_DEAD)
cpu_relax();
/*
* This is a bit complicated strategics of getting/settig available
* cores mask, copied from bootloader
*/
mask = 1 << coreid;
/* LINUX_APP_BOOT_BLOCK is initialized in bootoct binary */
block_desc = cvmx_bootmem_find_named_block(LINUX_APP_BOOT_BLOCK_NAME);
if (!block_desc) {
struct linux_app_boot_info *labi;
labi = (struct linux_app_boot_info *)PHYS_TO_XKSEG_CACHED(LABI_ADDR_IN_BOOTLOADER);
labi->avail_coremask |= mask;
new_mask = labi->avail_coremask;
} else { /* alternative, already initialized */
uint32_t *p = (uint32_t *)PHYS_TO_XKSEG_CACHED(block_desc->base_addr +
AVAIL_COREMASK_OFFSET_IN_LINUX_APP_BOOT_BLOCK);
*p |= mask;
new_mask = *p;
}
pr_info("Reset core %d. Available Coremask = 0x%x \n", coreid, new_mask);
mb();
cvmx_write_csr(CVMX_CIU_PP_RST, 1 << coreid);
cvmx_write_csr(CVMX_CIU_PP_RST, 0);
}
void play_dead(void)
{
int cpu = cpu_number_map(cvmx_get_core_num());
idle_task_exit();
octeon_processor_boot = 0xff;
per_cpu(cpu_state, cpu) = CPU_DEAD;
mb();
while (1) /* core will be reset here */
;
}
extern void kernel_entry(unsigned long arg1, ...);
static void start_after_reset(void)
{
kernel_entry(0, 0, 0); /* set a2 = 0 for secondary core */
}
static int octeon_update_boot_vector(unsigned int cpu)
{
int coreid = cpu_logical_map(cpu);
uint32_t avail_coremask;
const struct cvmx_bootmem_named_block_desc *block_desc;
struct boot_init_vector *boot_vect =
(struct boot_init_vector *)PHYS_TO_XKSEG_CACHED(BOOTLOADER_BOOT_VECTOR);
block_desc = cvmx_bootmem_find_named_block(LINUX_APP_BOOT_BLOCK_NAME);
if (!block_desc) {
struct linux_app_boot_info *labi;
labi = (struct linux_app_boot_info *)PHYS_TO_XKSEG_CACHED(LABI_ADDR_IN_BOOTLOADER);
avail_coremask = labi->avail_coremask;
labi->avail_coremask &= ~(1 << coreid);
} else { /* alternative, already initialized */
avail_coremask = *(uint32_t *)PHYS_TO_XKSEG_CACHED(
block_desc->base_addr + AVAIL_COREMASK_OFFSET_IN_LINUX_APP_BOOT_BLOCK);
}
if (!(avail_coremask & (1 << coreid))) {
/* core not available, assume, that catched by simple-executive */
cvmx_write_csr(CVMX_CIU_PP_RST, 1 << coreid);
cvmx_write_csr(CVMX_CIU_PP_RST, 0);
}
boot_vect[coreid].app_start_func_addr =
(uint32_t) (unsigned long) start_after_reset;
boot_vect[coreid].code_addr = octeon_bootloader_entry_addr;
mb();
cvmx_write_csr(CVMX_CIU_NMI, (1 << coreid) & avail_coremask);
return 0;
}
static int octeon_cpu_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
switch (action) {
case CPU_UP_PREPARE:
octeon_update_boot_vector(cpu);
break;
case CPU_ONLINE:
pr_info("Cpu %d online\n", cpu);
break;
case CPU_DEAD:
break;
}
return NOTIFY_OK;
}
static int register_cavium_notifier(void)
{
hotcpu_notifier(octeon_cpu_callback, 0);
return 0;
}
late_initcall(register_cavium_notifier);
#endif /* CONFIG_HOTPLUG_CPU */
struct plat_smp_ops octeon_smp_ops = {
.send_ipi_single = octeon_send_ipi_single,
.send_ipi_mask = octeon_send_ipi_mask,
.init_secondary = octeon_init_secondary,
.smp_finish = octeon_smp_finish,
.boot_secondary = octeon_boot_secondary,
.smp_setup = octeon_smp_setup,
.prepare_cpus = octeon_prepare_cpus,
#ifdef CONFIG_HOTPLUG_CPU
.cpu_disable = octeon_cpu_disable,
.cpu_die = octeon_cpu_die,
#endif
};