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/** @file mptable.c
*
* @brief Code to parse the MP table and determine information
* about the APIC.
*
* @author Ryan Pearl (rpearl)
*
* This code is directly based on FreeBSD's MP table parsing code. License and
* copyright information repeated below.
*/
/*-
* Copyright (c) 2003 John Baldwin <jhb@FreeBSD.org>
* Copyright (c) 1996, by Steve Passe
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. The name of the developer may NOT be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <stddef.h>
#include <multiboot.h>
#include <smp/smp.h>
#include <smp/mptable.h>
#include <smp/apic.h>
#include <compiler.h>
static int num_cpus = 1; /**< The number of CPUs */
static int bsp_id; /**< The cpu number for the BSP */
static int bsp_apic; /**< The APIC id for the BSP */
static void *lapic_base = NULL; /**< Location in physical memory of the Local
APIC base */
static void *ioapic_addr = NULL; /**< Location in physical memory of the I/O
APIC base */
extern int cpu2apic[MAX_CPUS];
extern int apic2cpu[MAX_CPUS];
/** @brief Reset state to uniprocessor
*
* @return unit
*/
static void mp_set_uniprocessor() {
num_cpus = 1;
ioapic_addr = NULL;
lapic_base = NULL;
}
/** @brief Fills in the book-keeping information for a CPU
*
* @param apic_id The local APIC ID for this CPU
* @param bsp Wether this CPU is the BSP
*
* @return unit
*/
static void mp_cpu_create(int apic_id, int bsp) {
if (num_cpus >= MAX_CPUS || apic_id >= MAX_CPUS)
return; // out of range; ignore it.
cpu2apic[num_cpus] = apic_id;
apic2cpu[apic_id] = num_cpus;
if (bsp) {
bsp_apic = apic_id;
bsp_id = num_cpus;
}
num_cpus++;
}
/** @brief Perform a checksum on an MP structure.
*
* @param addr The base of the structure
* @param len The length of the structure
* @return nonzero if sucessful, 0 otherwise.
*/
static int checksum(char *addr, int len) {
int i;
uint8_t sum = 0;
for (i = 0; i < len; i++) {
sum += addr[i];
}
return (sum == 0);
}
/**
* @brief Search for the MP floating pointer signature.
*
* @param addr The address to start searching at
* @param len The number of bytes to search.
*
* @return A pointer to the structure
*/
static struct mpfps *mp_scan_sig(uintptr_t addr, int len) {
char *ptr;
char *end = (char *)addr + len;
for (ptr = (char *)addr; ptr < end; ptr += sizeof(struct mpfps)) {
uint32_t sig = *(uint32_t *)ptr;
if (sig == MP_FPS_SIG && checksum(ptr, sizeof(struct mpfps)))
return (struct mpfps *)ptr;
}
return NULL;
}
/** @brief Walk the MP configuration table and gather data.
*
* @param cfg The configuration table to read.
* @return unit
*/
static void mptable_walk(struct mptable *cfg) {
num_cpus = 0; // mp_cpu_create() will count the BSP
STATIC_ASSERT(sizeof(struct mp_cpu) == 20);
STATIC_ASSERT(sizeof(struct mp_ioapic) == 8);
uint8_t *ptr = (uint8_t *)(cfg + 1);
int smp = 1;
uint16_t i;
for (i = 0; i < cfg->entries; i++) {
switch (*ptr) {
case MP_PROC: {
struct mp_cpu *cpu = (struct mp_cpu *)ptr;
if (cpu->flags & MP_PROC_EN) {
mp_cpu_create(cpu->apic_id, cpu->flags & MP_PROC_BSP);
}
ptr += sizeof(struct mp_cpu);
break;
}
case MP_IOAPIC: {
if (ioapic_addr != NULL) {
/* More complete code is needed to handle multiple I/O
* APICS. But, we don't even use the one we find. */
smp = 0;
} else {
struct mp_ioapic *ioapic = (struct mp_ioapic *)ptr;
ioapic_addr = ioapic->phys_addr;
}
ptr += sizeof(struct mp_ioapic);
break;
}
case MP_BUS:
case MP_IOINTR:
case MP_LINTR:
/* On a more complete system with actual devices, we need to
* care about these things.
*/
ptr += 8;
break;
default:
panic("Unknown MP configuration entry: %x", *ptr);
}
}
if (!smp) {
mp_set_uniprocessor();
}
}
/** @brief Find the EBDA from the BIOS.
*
* @return The EBDA base.
*/
static inline uint32_t get_ebda(void) {
uint32_t ebda_seg = (uint32_t)*(uint16_t *)MP_BIOS_EBDA;
return ebda_seg << 4;
}
/** @brief Reads MP Table Configuration and determines whether the system has
* multiple processors.
*
* @param info The multiboot info provided by the boatloader
* @return zero if multiprocessor, negative error code if not.
*/
int smp_init(mbinfo_t *info) {
struct mpfps *fp;
struct mptable *cfg;
uint32_t ebda = get_ebda();
if (ebda) {
if ((fp = mp_scan_sig(ebda, 1024)) != NULL)
goto found;
}
if ((fp = mp_scan_sig(info->mem_lower * 1024, 1024)) != NULL)
goto found;
if ((fp = mp_scan_sig(MP_BIOS_START, MP_BIOS_LEN)) != NULL)
goto found;
return -1;
found:
if (fp->type != 0) {
// These are default configurations.
if (fp->type != 5 && fp->type != 6)
return -1; // Unsupported configuration (old hardware)
lapic_base = (void *)LAPIC_DEFAULT_BASE;
ioapic_addr = (void *)IOAPIC_DEFAULT_BASE;
mp_cpu_create(0, 1);
mp_cpu_create(1, 0);
} else {
cfg = (struct mptable *)fp->phys_addr;
if (!checksum((char *)cfg, cfg->length) || cfg->sig != MP_CFG_SIG)
return -1;
lapic_base = (void *)cfg->lapic_addr;
mptable_walk(cfg);
}
return 0;
}
/** @brief Returns the number of CPUs in the system.
*/
int smp_num_cpus(void) {
return num_cpus;
}
/** @brief Return the base of the local APIC in physical memory.
*/
void *smp_lapic_base(void) {
return lapic_base;
}
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