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
  26 extern 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
  30 extern void move_stack(unsigned long new_stack);
  31
  32 struct hwrpb_struct *hwrpb = INIT_HWRPB;
  33 static 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
  41 static inline void *
  42 find_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
  68 void
  69 pal_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
 111 static inline void
 112 load(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  */
 120 static inline void
 121 runkernel(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
 130 extern char _end;
 131 #define KERNEL_ORIGIN \
 132         ((((unsigned long)&_end) + 511) & ~511)
 133
 134 void
 135 start_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 }