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Diffstat (limited to '410kern/smp/mptable.c')
| -rw-r--r-- | 410kern/smp/mptable.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/410kern/smp/mptable.c b/410kern/smp/mptable.c new file mode 100644 index 0000000..cb0a5c9 --- /dev/null +++ b/410kern/smp/mptable.c @@ -0,0 +1,246 @@ +/** @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; +} |