source: mainline/kernel/generic/src/main/main.c

/*
 * Copyright (c) 2025 Jiri Svoboda
 * Copyright (c) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author 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 ``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 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.
 */

/** @addtogroup kernel_generic
 * @{
 */

/**
 * @file
 * @brief Main initialization kernel function for all processors.
 *
 * During kernel boot, all processors, after architecture dependent
 * initialization, start executing code found in this file. After
 * bringing up all subsystems, control is passed to scheduler().
 *
 * The bootstrap processor starts executing main_bsp() while
 * the application processors start executing main_ap().
 *
 * @see scheduler()
 * @see main_bsp()
 * @see main_ap()
 */

#include <arch/asm.h>
#include <debug.h>
#include <context.h>
#include <stdio.h>
#include <panic.h>
#include <config.h>
#include <time/clock.h>
#include <time/timeout.h>
#include <proc/scheduler.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <main/kinit.h>
#include <main/version.h>
#include <console/kconsole.h>
#include <console/console.h>
#include <log.h>
#include <cpu.h>
#include <align.h>
#include <interrupt.h>
#include <str.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <genarch/mm/page_pt.h>
#include <mm/km.h>
#include <mm/tlb.h>
#include <mm/as.h>
#include <mm/slab.h>
#include <mm/reserve.h>
#include <synch/waitq.h>
#include <synch/syswaitq.h>
#include <arch/arch.h>
#include <arch.h>
#include <ipc/ipc.h>
#include <macros.h>
#include <smp/smp.h>
#include <ddi/ddi.h>
#include <main/main.h>
#include <ipc/event.h>
#include <sysinfo/sysinfo.h>
#include <sysinfo/stats.h>
#include <lib/ra.h>
#include <cap/cap.h>

/*
 * Ensure [u]int*_t types are of correct size.
 *
 * Probably, this is not the best place for such tests
 * but this file is compiled on all architectures.
 */
#define CHECK_INT_TYPE_(signness, size) \
        static_assert(sizeof(signness##size##_t) * 8 == size, \
            #signness #size "_t does not have " #size " bits");

#define CHECK_INT_TYPE(size) \
        CHECK_INT_TYPE_(int, size); \
        CHECK_INT_TYPE_(uint, size)

CHECK_INT_TYPE(8);
CHECK_INT_TYPE(16);
CHECK_INT_TYPE(32);
CHECK_INT_TYPE(64);

task_t *kernel_task;

/** Global configuration structure. */
config_t config = {
        .identity_configured = false,
        .non_identity_configured = false,
        .physmem_end = 0
};

/** Boot arguments. */
char bargs[CONFIG_BOOT_ARGUMENTS_BUFLEN] = { };

/** Initial user-space tasks */
init_t init = {
        .cnt = 0
};

/** Boot allocations. */
ballocs_t ballocs = {
        .base = (uintptr_t) NULL,
        .size = 0
};

static context_t ctx;

// NOTE: All kernel stacks must be aligned to STACK_SIZE, see CURRENT.
static const size_t bootstrap_stack_size = STACK_SIZE;
static _Alignas(STACK_SIZE) uint8_t bootstrap_stack[STACK_SIZE];

/* Just a convenient value for some assembly code. */
uint8_t *const bootstrap_stack_top = bootstrap_stack + STACK_SIZE;

/*
 * These two functions prevent stack from underflowing during the
 * kernel boot phase when SP is set to the very top of the reserved
 * space. The stack could get corrupted by a fooled compiler-generated
 * pop sequence otherwise.
 */
static void main_bsp_separated_stack(void);

#ifdef CONFIG_SMP
static void main_ap_separated_stack(void);
#endif

/** Main kernel routine for bootstrap CPU.
 *
 * The code here still runs on the boot stack, which knows nothing about
 * preemption counts.  Because of that, this function cannot directly call
 * functions that disable or enable preemption (e.g. spinlock_lock()). The
 * primary task of this function is to calculate address of a new stack and
 * switch to it.
 *
 * Assuming interrupts_disable().
 *
 */
_NO_TRACE void main_bsp(void)
{
        config.cpu_count = 1;
        config.cpu_active = 1;

        config.base = (uintptr_t) kernel_load_address;

        config.kernel_size =
            ALIGN_UP((uintptr_t) kdata_end - config.base, PAGE_SIZE);

        context_create(&ctx, main_bsp_separated_stack,
            bootstrap_stack, bootstrap_stack_size);
        context_restore(&ctx);
        /* not reached */
}

/** Main kernel routine for bootstrap CPU using new stack.
 *
 * Second part of main_bsp().
 *
 */
void main_bsp_separated_stack(void)
{
        /* Keep this the first thing. */
        current_initialize(CURRENT);

        version_print();

        LOG("\nconfig.base=%p config.kernel_size=%zu",
            (void *) config.base, config.kernel_size);

#ifdef CONFIG_KCONSOLE
        /*
         * kconsole data structures must be initialized very early
         * because other subsystems will register their respective
         * commands.
         */
        kconsole_init();
#endif

        /*
         * Exception handler initialization, before architecture
         * starts adding its own handlers
         */
        exc_init();

        /*
         * Memory management subsystems initialization.
         */
        ARCH_OP(pre_mm_init);
        km_identity_init();
        frame_init();
        slab_cache_init();
        malloc_init();
        ra_init();
        sysinfo_init();
        as_init();
        page_init();
        tlb_init();
        km_non_identity_init();
        ddi_init();
        ARCH_OP(post_mm_init);
        reserve_init();
        ARCH_OP(pre_smp_init);
        smp_init();

        /* Slab must be initialized after we know the number of processors. */
        slab_enable_cpucache();

        uint64_t size;
        const char *size_suffix;
        bin_order_suffix(zones_total_size(), &size, &size_suffix, false);
        printf("Detected %u CPU(s), %" PRIu64 " %s free memory\n",
            config.cpu_count, size, size_suffix);

        cpu_init();
        calibrate_delay_loop();
        ARCH_OP(post_cpu_init);

        clock_counter_init();
        timeout_init();
        scheduler_init();
        caps_init();
        task_init();
        thread_init();
        sys_waitq_init();

        sysinfo_set_item_data("boot_args", NULL, bargs, str_size(bargs) + 1);

        if (init.cnt > 0) {
                size_t i;
                for (i = 0; i < init.cnt; i++)
                        LOG("init[%zu].addr=%p, init[%zu].size=%zu",
                            i, (void *) init.tasks[i].paddr, i, init.tasks[i].size);
        } else
                printf("No init binaries found.\n");

        ipc_init();
        event_init();
        kio_init();
        log_init();
        stats_init();

        /*
         * Create kernel task.
         */
        task_t *kernel = task_create(AS_KERNEL, "kernel");
        if (!kernel)
                panic("Cannot create kernel task.");

        kernel_task = kernel;

        /*
         * Create the first thread.
         */
        thread_t *kinit_thread = thread_create(kinit, NULL, kernel,
            THREAD_FLAG_UNCOUNTED, "kinit");
        if (!kinit_thread)
                panic("Cannot create kinit thread.");
        thread_start(kinit_thread);
        thread_detach(kinit_thread);

        /*
         * This call to scheduler_run() will return to kinit,
         * starting the thread of kernel threads.
         */
        current_copy(CURRENT, (current_t *) CPU_LOCAL->stack);
        context_replace(scheduler_run, CPU_LOCAL->stack, STACK_SIZE);
        /* not reached */
}

#ifdef CONFIG_SMP

/** Main kernel routine for application CPUs.
 *
 * Executed by application processors, temporary stack
 * is at ctx.sp which was set during BSP boot.
 * This function passes control directly to
 * main_ap_separated_stack().
 *
 * Assuming interrupts_disable()'d.
 *
 */
void main_ap(void)
{
        /*
         * Incrementing the active CPU counter will guarantee that the
         * *_init() functions can find out that they need to
         * do initialization for AP only.
         */
        config.cpu_active++;

        /*
         * The CURRENT structure is well defined because ctx.sp is used as stack.
         */
        current_initialize(CURRENT);

        ARCH_OP(pre_mm_init);
        frame_init();
        page_init();
        tlb_init();
        ARCH_OP(post_mm_init);

        cpu_init();
        calibrate_delay_loop();
        ARCH_OP(post_cpu_init);

        /*
         * If we woke kmp up before we left the kernel stack, we could
         * collide with another CPU coming up. To prevent this, we
         * switch to this cpu's private stack prior to waking kmp up.
         */
        current_copy(CURRENT, (current_t *) CPU_LOCAL->stack);
        context_replace(main_ap_separated_stack, CPU_LOCAL->stack, STACK_SIZE);
        /* not reached */
}

/** Main kernel routine for application CPUs using new stack.
 *
 * Second part of main_ap().
 *
 */
void main_ap_separated_stack(void)
{
        /*
         * Configure timeouts for this cpu.
         */
        timeout_init();

        semaphore_up(&ap_completion_semaphore);
        scheduler_run();
        /* not reached */
}

#endif /* CONFIG_SMP */

/** @}
 */