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 <linux/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