main.c

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/*
 * Copyright (C) Paul Mackerras 1997.
 *
 * Updates for PPC64 by Todd Inglett, Dave Engebretsen & Peter Bergner.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <stdarg.h>
#include <stddef.h>
#include "elf.h"
#include "page.h"
#include "string.h"
#include "stdio.h"
#include "ops.h"
#include "gunzip_util.h"
#include "reg.h"

static struct gunzip_state gzstate;

struct addr_range {
    void *addr;
    unsigned long size;
};

#undef DEBUG

static struct addr_range prep_kernel(void)
{
    char elfheader[256];
    void *vmlinuz_addr = _vmlinux_start;
    unsigned long vmlinuz_size = _vmlinux_end - _vmlinux_start;
    void *addr = 0;
    struct elf_info ei;
    int len;

    /* gunzip the ELF header of the kernel */
    gunzip_start(&gzstate, vmlinuz_addr, vmlinuz_size);
    gunzip_exactly(&gzstate, elfheader, sizeof(elfheader));

    if (!parse_elf64(elfheader, &ei) && !parse_elf32(elfheader, &ei))
        fatal("Error: not a valid PPC32 or PPC64 ELF file!\n\r");

    if (platform_ops.image_hdr)
        platform_ops.image_hdr(elfheader);

    /* We need to alloc the memsize: gzip will expand the kernel
     * text/data, then possible rubbish we don't care about. But
     * the kernel bss must be claimed (it will be zero'd by the
     * kernel itself)
     */
    printf("Allocating 0x%lx bytes for kernel ...\n\r", ei.memsize);

    if (platform_ops.vmlinux_alloc) {
        addr = platform_ops.vmlinux_alloc(ei.memsize);
    } else {
        /*
         * Check if the kernel image (without bss) would overwrite the
         * bootwrapper. The device tree has been moved in fdt_init()
         * to an area allocated with malloc() (somewhere past _end).
         */
        if ((unsigned long)_start < ei.loadsize)
            fatal("Insufficient memory for kernel at address 0!"
                   " (_start=%p, uncompressed size=%08lx)\n\r",
                   _start, ei.loadsize);

        if ((unsigned long)_end < ei.memsize)
            fatal("The final kernel image would overwrite the "
                    "device tree\n\r");
    }

    /* Finally, gunzip the kernel */
    printf("gunzipping (0x%p <- 0x%p:0x%p)...", addr,
           vmlinuz_addr, vmlinuz_addr+vmlinuz_size);
    /* discard up to the actual load data */
    gunzip_discard(&gzstate, ei.elfoffset - sizeof(elfheader));
    len = gunzip_finish(&gzstate, addr, ei.loadsize);
    if (len != ei.loadsize)
        fatal("ran out of data!  only got 0x%x of 0x%lx bytes.\n\r",
                len, ei.loadsize);
    printf("done 0x%x bytes\n\r", len);

    flush_cache(addr, ei.loadsize);

    return (struct addr_range){addr, ei.memsize};
}

static struct addr_range prep_initrd(struct addr_range vmlinux, void *chosen,
                     unsigned long initrd_addr,
                     unsigned long initrd_size)
{
    /* If we have an image attached to us, it overrides anything
     * supplied by the loader. */
    if (_initrd_end > _initrd_start) {
        printf("Attached initrd image at 0x%p-0x%p\n\r",
               _initrd_start, _initrd_end);
        initrd_addr = (unsigned long)_initrd_start;
        initrd_size = _initrd_end - _initrd_start;
    } else if (initrd_size > 0) {
        printf("Using loader supplied ramdisk at 0x%lx-0x%lx\n\r",
               initrd_addr, initrd_addr + initrd_size);
    }

    /* If there's no initrd at all, we're done */
    if (! initrd_size)
        return (struct addr_range){0, 0};

    /*
     * If the initrd is too low it will be clobbered when the
     * kernel relocates to its final location.  In this case,
     * allocate a safer place and move it.
     */
    if (initrd_addr < vmlinux.size) {
        void *old_addr = (void *)initrd_addr;

        printf("Allocating 0x%lx bytes for initrd ...\n\r",
               initrd_size);
        initrd_addr = (unsigned long)malloc(initrd_size);
        if (! initrd_addr)
            fatal("Can't allocate memory for initial "
                   "ramdisk !\n\r");
        printf("Relocating initrd 0x%lx <- 0x%p (0x%lx bytes)\n\r",
               initrd_addr, old_addr, initrd_size);
        memmove((void *)initrd_addr, old_addr, initrd_size);
    }

    printf("initrd head: 0x%lx\n\r", *((unsigned long *)initrd_addr));

    /* Tell the kernel initrd address via device tree */
    setprop_val(chosen, "linux,initrd-start", (u32)(initrd_addr));
    setprop_val(chosen, "linux,initrd-end", (u32)(initrd_addr+initrd_size));

    return (struct addr_range){(void *)initrd_addr, initrd_size};
}

/* A buffer that may be edited by tools operating on a zImage binary so as to
 * edit the command line passed to vmlinux (by setting /chosen/bootargs).
 * The buffer is put in it's own section so that tools may locate it easier.
 */
static char cmdline[COMMAND_LINE_SIZE]
    __attribute__((__section__("__builtin_cmdline")));

static void prep_cmdline(void *chosen)
{
    if (cmdline[0] == '\0')
        getprop(chosen, "bootargs", cmdline, COMMAND_LINE_SIZE-1);

    printf("\n\rLinux/PowerPC load: %s", cmdline);
    /* If possible, edit the command line */
    if (console_ops.edit_cmdline)
        console_ops.edit_cmdline(cmdline, COMMAND_LINE_SIZE);
    printf("\n\r");

    /* Put the command line back into the devtree for the kernel */
    setprop_str(chosen, "bootargs", cmdline);
}

struct platform_ops platform_ops;
struct dt_ops dt_ops;
struct console_ops console_ops;
struct loader_info loader_info;

void start(void)
{
    struct addr_range vmlinux, initrd;
    kernel_entry_t kentry;
    unsigned long ft_addr = 0;
    void *chosen;

    /* Do this first, because malloc() could clobber the loader's
     * command line.  Only use the loader command line if a
     * built-in command line wasn't set by an external tool */
    if ((loader_info.cmdline_len > 0) && (cmdline[0] == '\0'))
        memmove(cmdline, loader_info.cmdline,
            min(loader_info.cmdline_len, COMMAND_LINE_SIZE-1));

    if (console_ops.open && (console_ops.open() < 0))
        exit();
    if (platform_ops.fixups)
        platform_ops.fixups();

    printf("\n\rzImage starting: loaded at 0x%p (sp: 0x%p)\n\r",
           _start, get_sp());

    /* Ensure that the device tree has a /chosen node */
    chosen = finddevice("/chosen");
    if (!chosen)
        chosen = create_node(NULL, "chosen");

    vmlinux = prep_kernel();
    initrd = prep_initrd(vmlinux, chosen,
                 loader_info.initrd_addr, loader_info.initrd_size);
    prep_cmdline(chosen);

    printf("Finalizing device tree...");
    if (dt_ops.finalize)
        ft_addr = dt_ops.finalize();
    if (ft_addr)
        printf(" flat tree at 0x%lx\n\r", ft_addr);
    else
        printf(" using OF tree (promptr=%p)\n\r", loader_info.promptr);

    if (console_ops.close)
        console_ops.close();

    kentry = (kernel_entry_t) vmlinux.addr;
    if (ft_addr)
        kentry(ft_addr, 0, NULL);
    else
        kentry((unsigned long)initrd.addr, initrd.size,
               loader_info.promptr);

    /* console closed so printf in fatal below may not work */
    fatal("Error: Linux kernel returned to zImage boot wrapper!\n\r");
}