bootp.c

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/*
 * arch/alpha/boot/bootp.c
 *
 * Copyright (C) 1997 Jay Estabrook
 *
 * This file is used for creating a bootp file for the Linux/AXP kernel
 *
 * based significantly on the arch/alpha/boot/main.c of Linus Torvalds
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <generated/utsrelease.h>
#include <linux/mm.h>

#include <asm/console.h>
#include <asm/hwrpb.h>
#include <asm/pgtable.h>
#include <asm/io.h>

#include <stdarg.h>

#include "ksize.h"

extern unsigned long switch_to_osf_pal(unsigned long nr,
    struct pcb_struct * pcb_va, struct pcb_struct * pcb_pa,
    unsigned long *vptb);

extern void move_stack(unsigned long new_stack);

struct hwrpb_struct *hwrpb = INIT_HWRPB;
static struct pcb_struct pcb_va[1];

/*
 * Find a physical address of a virtual object..
 *
 * This is easy using the virtual page table address.
 */

static inline void *
find_pa(unsigned long *vptb, void *ptr)
{
    unsigned long address = (unsigned long) ptr;
    unsigned long result;

    result = vptb[address >> 13];
    result >>= 32;
    result <<= 13;
    result |= address & 0x1fff;
    return (void *) result;
}   

/*
 * This function moves into OSF/1 pal-code, and has a temporary
 * PCB for that. The kernel proper should replace this PCB with
 * the real one as soon as possible.
 *
 * The page table muckery in here depends on the fact that the boot
 * code has the L1 page table identity-map itself in the second PTE
 * in the L1 page table. Thus the L1-page is virtually addressable
 * itself (through three levels) at virtual address 0x200802000.
 */

#define VPTB    ((unsigned long *) 0x200000000)
#define L1  ((unsigned long *) 0x200802000)

void
pal_init(void)
{
    unsigned long i, rev;
    struct percpu_struct * percpu;
    struct pcb_struct * pcb_pa;

    /* Create the dummy PCB.  */
    pcb_va->ksp = 0;
    pcb_va->usp = 0;
    pcb_va->ptbr = L1[1] >> 32;
    pcb_va->asn = 0;
    pcb_va->pcc = 0;
    pcb_va->unique = 0;
    pcb_va->flags = 1;
    pcb_va->res1 = 0;
    pcb_va->res2 = 0;
    pcb_pa = find_pa(VPTB, pcb_va);

    /*
     * a0 = 2 (OSF)
     * a1 = return address, but we give the asm the vaddr of the PCB
     * a2 = physical addr of PCB
     * a3 = new virtual page table pointer
     * a4 = KSP (but the asm sets it)
     */
    srm_printk("Switching to OSF PAL-code .. ");

    i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB);
    if (i) {
        srm_printk("failed, code %ld\n", i);
        __halt();
    }

    percpu = (struct percpu_struct *)
        (INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB);
    rev = percpu->pal_revision = percpu->palcode_avail[2];

    srm_printk("Ok (rev %lx)\n", rev);

    tbia(); /* do it directly in case we are SMP */
}

static inline void
load(unsigned long dst, unsigned long src, unsigned long count)
{
    memcpy((void *)dst, (void *)src, count);
}

/*
 * Start the kernel.
 */
static inline void
runkernel(void)
{
    __asm__ __volatile__(
        "bis %0,%0,$27\n\t"
        "jmp ($27)"
        : /* no outputs: it doesn't even return */
        : "r" (START_ADDR));
}

extern char _end;
#define KERNEL_ORIGIN \
    ((((unsigned long)&_end) + 511) & ~511)

void
start_kernel(void)
{
    /*
     * Note that this crufty stuff with static and envval
     * and envbuf is because:
     *
     * 1. Frequently, the stack is short, and we don't want to overrun;
     * 2. Frequently the stack is where we are going to copy the kernel to;
     * 3. A certain SRM console required the GET_ENV output to stack.
     *    ??? A comment in the aboot sources indicates that the GET_ENV
     *    destination must be quadword aligned.  Might this explain the
     *    behaviour, rather than requiring output to the stack, which
     *    seems rather far-fetched.
     */
    static long nbytes;
    static char envval[256] __attribute__((aligned(8)));
    static unsigned long initrd_start;

    srm_printk("Linux/AXP bootp loader for Linux " UTS_RELEASE "\n");
    if (INIT_HWRPB->pagesize != 8192) {
        srm_printk("Expected 8kB pages, got %ldkB\n",
                   INIT_HWRPB->pagesize >> 10);
        return;
    }
    if (INIT_HWRPB->vptb != (unsigned long) VPTB) {
        srm_printk("Expected vptb at %p, got %p\n",
               VPTB, (void *)INIT_HWRPB->vptb);
        return;
    }
    pal_init();

    /* The initrd must be page-aligned.  See below for the 
       cause of the magic number 5.  */
    initrd_start = ((START_ADDR + 5*KERNEL_SIZE + PAGE_SIZE) |
            (PAGE_SIZE-1)) + 1;
#ifdef INITRD_IMAGE_SIZE
    srm_printk("Initrd positioned at %#lx\n", initrd_start);
#endif

    /*
     * Move the stack to a safe place to ensure it won't be
     * overwritten by kernel image.
     */
    move_stack(initrd_start - PAGE_SIZE);

    nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval));
    if (nbytes < 0 || nbytes >= sizeof(envval)) {
        nbytes = 0;
    }
    envval[nbytes] = '\0';
    srm_printk("Loading the kernel...'%s'\n", envval);

    /* NOTE: *no* callbacks or printouts from here on out!!! */

    /* This is a hack, as some consoles seem to get virtual 20000000 (ie
     * where the SRM console puts the kernel bootp image) memory
     * overlapping physical memory where the kernel wants to be put,
     * which causes real problems when attempting to copy the former to
     * the latter... :-(
     *
     * So, we first move the kernel virtual-to-physical way above where
     * we physically want the kernel to end up, then copy it from there
     * to its final resting place... ;-}
     *
     * Sigh...  */

#ifdef INITRD_IMAGE_SIZE
    load(initrd_start, KERNEL_ORIGIN+KERNEL_SIZE, INITRD_IMAGE_SIZE);
#endif
        load(START_ADDR+(4*KERNEL_SIZE), KERNEL_ORIGIN, KERNEL_SIZE);
        load(START_ADDR, START_ADDR+(4*KERNEL_SIZE), KERNEL_SIZE);

    memset((char*)ZERO_PGE, 0, PAGE_SIZE);
    strcpy((char*)ZERO_PGE, envval);
#ifdef INITRD_IMAGE_SIZE
    ((long *)(ZERO_PGE+256))[0] = initrd_start;
    ((long *)(ZERO_PGE+256))[1] = INITRD_IMAGE_SIZE;
#endif

    runkernel();
}