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
  25 extern 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
  29 extern void move_stack(unsigned long new_stack);
  30
  31 struct hwrpb_struct *hwrpb = INIT_HWRPB;
  32 static 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
  40 static inline void *
  41 find_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
  67 void
  68 pal_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
 110 static inline void
 111 load(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  */
 119 static inline void
 120 runkernel(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
 129 extern char _end;
 130 #define KERNEL_ORIGIN \
 131         ((((unsigned long)&_end) + 511) & ~511)
 132
 133 void
 134 start_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 }