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/pgtable.h>
  20#include <asm/io.h>
  21
  22#include <stdarg.h>
  23
  24#include "ksize.h"
  25
  26extern unsigned long switch_to_osf_pal(unsigned long nr,
  27        struct pcb_struct * pcb_va, struct pcb_struct * pcb_pa,
  28        unsigned long *vptb);
  29
  30extern void move_stack(unsigned long new_stack);
  31
  32struct hwrpb_struct *hwrpb = INIT_HWRPB;
  33static struct pcb_struct pcb_va[1];
  34
  35/*
  36 * Find a physical address of a virtual object..
  37 *
  38 * This is easy using the virtual page table address.
  39 */
  40
  41static inline void *
  42find_pa(unsigned long *vptb, void *ptr)
  43{
  44        unsigned long address = (unsigned long) ptr;
  45        unsigned long result;
  46
  47        result = vptb[address >> 13];
  48        result >>= 32;
  49        result <<= 13;
  50        result |= address & 0x1fff;
  51        return (void *) result;
  52}       
  53
  54/*
  55 * This function moves into OSF/1 pal-code, and has a temporary
  56 * PCB for that. The kernel proper should replace this PCB with
  57 * the real one as soon as possible.
  58 *
  59 * The page table muckery in here depends on the fact that the boot
  60 * code has the L1 page table identity-map itself in the second PTE
  61 * in the L1 page table. Thus the L1-page is virtually addressable
  62 * itself (through three levels) at virtual address 0x200802000.
  63 */
  64
  65#define VPTB    ((unsigned long *) 0x200000000)
  66#define L1      ((unsigned long *) 0x200802000)
  67
  68void
  69pal_init(void)
  70{
  71        unsigned long i, rev;
  72        struct percpu_struct * percpu;
  73        struct pcb_struct * pcb_pa;
  74
  75        /* Create the dummy PCB.  */
  76        pcb_va->ksp = 0;
  77        pcb_va->usp = 0;
  78        pcb_va->ptbr = L1[1] >> 32;
  79        pcb_va->asn = 0;
  80        pcb_va->pcc = 0;
  81        pcb_va->unique = 0;
  82        pcb_va->flags = 1;
  83        pcb_va->res1 = 0;
  84        pcb_va->res2 = 0;
  85        pcb_pa = find_pa(VPTB, pcb_va);
  86
  87        /*
  88         * a0 = 2 (OSF)
  89         * a1 = return address, but we give the asm the vaddr of the PCB
  90         * a2 = physical addr of PCB
  91         * a3 = new virtual page table pointer
  92         * a4 = KSP (but the asm sets it)
  93         */
  94        srm_printk("Switching to OSF PAL-code .. ");
  95
  96        i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB);
  97        if (i) {
  98                srm_printk("failed, code %ld\n", i);
  99                __halt();
 100        }
 101
 102        percpu = (struct percpu_struct *)
 103                (INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB);
 104        rev = percpu->pal_revision = percpu->palcode_avail[2];
 105
 106        srm_printk("Ok (rev %lx)\n", rev);
 107
 108        tbia(); /* do it directly in case we are SMP */
 109}
 110
 111static inline void
 112load(unsigned long dst, unsigned long src, unsigned long count)
 113{
 114        memcpy((void *)dst, (void *)src, count);
 115}
 116
 117/*
 118 * Start the kernel.
 119 */
 120static inline void
 121runkernel(void)
 122{
 123        __asm__ __volatile__(
 124                "bis %0,%0,$27\n\t"
 125                "jmp ($27)"
 126                : /* no outputs: it doesn't even return */
 127                : "r" (START_ADDR));
 128}
 129
 130extern char _end;
 131#define KERNEL_ORIGIN \
 132        ((((unsigned long)&_end) + 511) & ~511)
 133
 134void
 135start_kernel(void)
 136{
 137        /*
 138         * Note that this crufty stuff with static and envval
 139         * and envbuf is because:
 140         *
 141         * 1. Frequently, the stack is short, and we don't want to overrun;
 142         * 2. Frequently the stack is where we are going to copy the kernel to;
 143         * 3. A certain SRM console required the GET_ENV output to stack.
 144         *    ??? A comment in the aboot sources indicates that the GET_ENV
 145         *    destination must be quadword aligned.  Might this explain the
 146         *    behaviour, rather than requiring output to the stack, which
 147         *    seems rather far-fetched.
 148         */
 149        static long nbytes;
 150        static char envval[256] __attribute__((aligned(8)));
 151        static unsigned long initrd_start;
 152
 153        srm_printk("Linux/AXP bootp loader for Linux " UTS_RELEASE "\n");
 154        if (INIT_HWRPB->pagesize != 8192) {
 155                srm_printk("Expected 8kB pages, got %ldkB\n",
 156                           INIT_HWRPB->pagesize >> 10);
 157                return;
 158        }
 159        if (INIT_HWRPB->vptb != (unsigned long) VPTB) {
 160                srm_printk("Expected vptb at %p, got %p\n",
 161                           VPTB, (void *)INIT_HWRPB->vptb);
 162                return;
 163        }
 164        pal_init();
 165
 166        /* The initrd must be page-aligned.  See below for the 
 167           cause of the magic number 5.  */
 168        initrd_start = ((START_ADDR + 5*KERNEL_SIZE + PAGE_SIZE) |
 169                        (PAGE_SIZE-1)) + 1;
 170#ifdef INITRD_IMAGE_SIZE
 171        srm_printk("Initrd positioned at %#lx\n", initrd_start);
 172#endif
 173
 174        /*
 175         * Move the stack to a safe place to ensure it won't be
 176         * overwritten by kernel image.
 177         */
 178        move_stack(initrd_start - PAGE_SIZE);
 179
 180        nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval));
 181        if (nbytes < 0 || nbytes >= sizeof(envval)) {
 182                nbytes = 0;
 183        }
 184        envval[nbytes] = '\0';
 185        srm_printk("Loading the kernel...'%s'\n", envval);
 186
 187        /* NOTE: *no* callbacks or printouts from here on out!!! */
 188
 189        /* This is a hack, as some consoles seem to get virtual 20000000 (ie
 190         * where the SRM console puts the kernel bootp image) memory
 191         * overlapping physical memory where the kernel wants to be put,
 192         * which causes real problems when attempting to copy the former to
 193         * the latter... :-(
 194         *
 195         * So, we first move the kernel virtual-to-physical way above where
 196         * we physically want the kernel to end up, then copy it from there
 197         * to its final resting place... ;-}
 198         *
 199         * Sigh...  */
 200
 201#ifdef INITRD_IMAGE_SIZE
 202        load(initrd_start, KERNEL_ORIGIN+KERNEL_SIZE, INITRD_IMAGE_SIZE);
 203#endif
 204        load(START_ADDR+(4*KERNEL_SIZE), KERNEL_ORIGIN, KERNEL_SIZE);
 205        load(START_ADDR, START_ADDR+(4*KERNEL_SIZE), KERNEL_SIZE);
 206
 207        memset((char*)ZERO_PGE, 0, PAGE_SIZE);
 208        strcpy((char*)ZERO_PGE, envval);
 209#ifdef INITRD_IMAGE_SIZE
 210        ((long *)(ZERO_PGE+256))[0] = initrd_start;
 211        ((long *)(ZERO_PGE+256))[1] = INITRD_IMAGE_SIZE;
 212#endif
 213
 214        runkernel();
 215}
 216