LXR linux/arch/alpha/boot/bootp.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * arch/alpha/boot/bootp.c
   4 *
   5 * Copyright (C) 1997 Jay Estabrook
   6 *
   7 * This file is used for creating a bootp file for the Linux/AXP kernel
   8 *
   9 * based significantly on the arch/alpha/boot/main.c of Linus Torvalds
  10 */
  11#include <linux/kernel.h>
  12#include <linux/slab.h>
  13#include <linux/string.h>
  14#include <generated/utsrelease.h>
  15#include <linux/mm.h>
  16
  17#include <asm/console.h>
  18#include <asm/hwrpb.h>
  19#include <asm/io.h>
  20
  21#include <stdarg.h>
  22
  23#include "ksize.h"
  24
  25extern unsigned long switch_to_osf_pal(unsigned long nr,
  26        struct pcb_struct *pcb_va, struct pcb_struct *pcb_pa,
  27        unsigned long *vptb);
  28
  29extern void move_stack(unsigned long new_stack);
  30
  31struct hwrpb_struct *hwrpb = INIT_HWRPB;
  32static struct pcb_struct pcb_va[1];
  33
  34/*
  35 * Find a physical address of a virtual object..
  36 *
  37 * This is easy using the virtual page table address.
  38 */
  39
  40static inline void *
  41find_pa(unsigned long *vptb, void *ptr)
  42{
  43        unsigned long address = (unsigned long) ptr;
  44        unsigned long result;
  45
  46        result = vptb[address >> 13];
  47        result >>= 32;
  48        result <<= 13;
  49        result |= address & 0x1fff;
  50        return (void *) result;
  51}       
  52
  53/*
  54 * This function moves into OSF/1 pal-code, and has a temporary
  55 * PCB for that. The kernel proper should replace this PCB with
  56 * the real one as soon as possible.
  57 *
  58 * The page table muckery in here depends on the fact that the boot
  59 * code has the L1 page table identity-map itself in the second PTE
  60 * in the L1 page table. Thus the L1-page is virtually addressable
  61 * itself (through three levels) at virtual address 0x200802000.
  62 */
  63
  64#define VPTB    ((unsigned long *) 0x200000000)
  65#define L1      ((unsigned long *) 0x200802000)
  66
  67void
  68pal_init(void)
  69{
  70        unsigned long i, rev;
  71        struct percpu_struct * percpu;
  72        struct pcb_struct * pcb_pa;
  73
  74        /* Create the dummy PCB.  */
  75        pcb_va->ksp = 0;
  76        pcb_va->usp = 0;
  77        pcb_va->ptbr = L1[1] >> 32;
  78        pcb_va->asn = 0;
  79        pcb_va->pcc = 0;
  80        pcb_va->unique = 0;
  81        pcb_va->flags = 1;
  82        pcb_va->res1 = 0;
  83        pcb_va->res2 = 0;
  84        pcb_pa = find_pa(VPTB, pcb_va);
  85
  86        /*
  87         * a0 = 2 (OSF)
  88         * a1 = return address, but we give the asm the vaddr of the PCB
  89         * a2 = physical addr of PCB
  90         * a3 = new virtual page table pointer
  91         * a4 = KSP (but the asm sets it)
  92         */
  93        srm_printk("Switching to OSF PAL-code .. ");
  94
  95        i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB);
  96        if (i) {
  97                srm_printk("failed, code %ld\n", i);
  98                __halt();
  99        }
 100
 101        percpu = (struct percpu_struct *)
 102                (INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB);
 103        rev = percpu->pal_revision = percpu->palcode_avail[2];
 104
 105        srm_printk("Ok (rev %lx)\n", rev);
 106
 107        tbia(); /* do it directly in case we are SMP */
 108}
 109
 110static inline void
 111load(unsigned long dst, unsigned long src, unsigned long count)
 112{
 113        memcpy((void *)dst, (void *)src, count);
 114}
 115
 116/*
 117 * Start the kernel.
 118 */
 119static inline void
 120runkernel(void)
 121{
 122        __asm__ __volatile__(
 123                "bis %0,%0,$27\n\t"
 124                "jmp ($27)"
 125                : /* no outputs: it doesn't even return */
 126                : "r" (START_ADDR));
 127}
 128
 129extern char _end;
 130#define KERNEL_ORIGIN \
 131        ((((unsigned long)&_end) + 511) & ~511)
 132
 133void
 134start_kernel(void)
 135{
 136        /*
 137         * Note that this crufty stuff with static and envval
 138         * and envbuf is because:
 139         *
 140         * 1. Frequently, the stack is short, and we don't want to overrun;
 141         * 2. Frequently the stack is where we are going to copy the kernel to;
 142         * 3. A certain SRM console required the GET_ENV output to stack.
 143         *    ??? A comment in the aboot sources indicates that the GET_ENV
 144         *    destination must be quadword aligned.  Might this explain the
 145         *    behaviour, rather than requiring output to the stack, which
 146         *    seems rather far-fetched.
 147         */
 148        static long nbytes;
 149        static char envval[256] __attribute__((aligned(8)));
 150        static unsigned long initrd_start;
 151
 152        srm_printk("Linux/AXP bootp loader for Linux " UTS_RELEASE "\n");
 153        if (INIT_HWRPB->pagesize != 8192) {
 154                srm_printk("Expected 8kB pages, got %ldkB\n",
 155                           INIT_HWRPB->pagesize >> 10);
 156                return;
 157        }
 158        if (INIT_HWRPB->vptb != (unsigned long) VPTB) {
 159                srm_printk("Expected vptb at %p, got %p\n",
 160                           VPTB, (void *)INIT_HWRPB->vptb);
 161                return;
 162        }
 163        pal_init();
 164
 165        /* The initrd must be page-aligned.  See below for the 
 166           cause of the magic number 5.  */
 167        initrd_start = ((START_ADDR + 5*KERNEL_SIZE + PAGE_SIZE) |
 168                        (PAGE_SIZE-1)) + 1;
 169#ifdef INITRD_IMAGE_SIZE
 170        srm_printk("Initrd positioned at %#lx\n", initrd_start);
 171#endif
 172
 173        /*
 174         * Move the stack to a safe place to ensure it won't be
 175         * overwritten by kernel image.
 176         */
 177        move_stack(initrd_start - PAGE_SIZE);
 178
 179        nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval));
 180        if (nbytes < 0 || nbytes >= sizeof(envval)) {
 181                nbytes = 0;
 182        }
 183        envval[nbytes] = '\0';
 184        srm_printk("Loading the kernel...'%s'\n", envval);
 185
 186        /* NOTE: *no* callbacks or printouts from here on out!!! */
 187
 188        /* This is a hack, as some consoles seem to get virtual 20000000 (ie
 189         * where the SRM console puts the kernel bootp image) memory
 190         * overlapping physical memory where the kernel wants to be put,
 191         * which causes real problems when attempting to copy the former to
 192         * the latter... :-(
 193         *
 194         * So, we first move the kernel virtual-to-physical way above where
 195         * we physically want the kernel to end up, then copy it from there
 196         * to its final resting place... ;-}
 197         *
 198         * Sigh...  */
 199
 200#ifdef INITRD_IMAGE_SIZE
 201        load(initrd_start, KERNEL_ORIGIN+KERNEL_SIZE, INITRD_IMAGE_SIZE);
 202#endif
 203        load(START_ADDR+(4*KERNEL_SIZE), KERNEL_ORIGIN, KERNEL_SIZE);
 204        load(START_ADDR, START_ADDR+(4*KERNEL_SIZE), KERNEL_SIZE);
 205
 206        memset((char*)ZERO_PGE, 0, PAGE_SIZE);
 207        strcpy((char*)ZERO_PGE, envval);
 208#ifdef INITRD_IMAGE_SIZE
 209        ((long *)(ZERO_PGE+256))[0] = initrd_start;
 210        ((long *)(ZERO_PGE+256))[1] = INITRD_IMAGE_SIZE;
 211#endif
 212
 213        runkernel();
 214}
 215