elf64_freebsd.c revision 346483 
1/*-
2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/11/stand/userboot/userboot/elf64_freebsd.c 346483 2019-04-21 04:35:49Z kevans $");
29
30#define __ELF_WORD_SIZE 64
31#include <sys/param.h>
32#include <sys/exec.h>
33#include <sys/linker.h>
34#ifdef DEBUG
35#include <machine/_inttypes.h>
36#endif
37#include <string.h>
38#include <i386/include/bootinfo.h>
39#include <machine/elf.h>
40#include <stand.h>
41
42#include "bootstrap.h"
43#include "libuserboot.h"
44
45static int	elf64_exec(struct preloaded_file *amp);
46static int	elf64_obj_exec(struct preloaded_file *amp);
47
48struct file_format amd64_elf = { elf64_loadfile, elf64_exec };
49struct file_format amd64_elf_obj = { elf64_obj_loadfile, elf64_obj_exec };
50
51#define MSR_EFER        0xc0000080
52#define EFER_LME        0x00000100
53#define	EFER_LMA 	0x00000400	/* Long mode active (R) */
54#define CR4_PAE         0x00000020
55#define	CR4_VMXE	(1UL << 13)
56#define CR4_PSE         0x00000010
57#define CR0_PG          0x80000000
58#define	CR0_PE		0x00000001	/* Protected mode Enable */
59#define	CR0_NE		0x00000020	/* Numeric Error enable (EX16 vs IRQ13) */
60
61#define PG_V	0x001
62#define PG_RW	0x002
63#define PG_U	0x004
64#define PG_PS	0x080
65
66typedef uint64_t p4_entry_t;
67typedef uint64_t p3_entry_t;
68typedef uint64_t p2_entry_t;
69
70#define	GUEST_NULL_SEL		0
71#define	GUEST_CODE_SEL		1
72#define	GUEST_DATA_SEL		2
73#define	GUEST_GDTR_LIMIT	(3 * 8 - 1)
74
75static void
76setup_freebsd_gdt(uint64_t *gdtr)
77{
78	gdtr[GUEST_NULL_SEL] = 0;
79	gdtr[GUEST_CODE_SEL] = 0x0020980000000000;
80	gdtr[GUEST_DATA_SEL] = 0x0000900000000000;
81}
82
83/*
84 * There is an ELF kernel and one or more ELF modules loaded.
85 * We wish to start executing the kernel image, so make such
86 * preparations as are required, and do so.
87 */
88static int
89elf64_exec(struct preloaded_file *fp)
90{
91	struct file_metadata	*md;
92	Elf_Ehdr 		*ehdr;
93	vm_offset_t		modulep, kernend;
94	int			err;
95	int			i;
96	uint32_t		stack[1024];
97	p4_entry_t		PT4[512];
98	p3_entry_t		PT3[512];
99	p2_entry_t		PT2[512];
100	uint64_t		gdtr[3];
101
102	if ((md = file_findmetadata(fp, MODINFOMD_ELFHDR)) == NULL)
103		return(EFTYPE);
104	ehdr = (Elf_Ehdr *)&(md->md_data);
105
106	err = bi_load64(fp->f_args, &modulep, &kernend);
107	if (err != 0)
108		return(err);
109
110	bzero(PT4, PAGE_SIZE);
111	bzero(PT3, PAGE_SIZE);
112	bzero(PT2, PAGE_SIZE);
113
114	/*
115	 * Build a scratch stack at physical 0x1000, page tables:
116	 *	PT4 at 0x2000,
117	 *	PT3 at 0x3000,
118	 *	PT2 at 0x4000,
119	 *      gdtr at 0x5000,
120	 */
121
122	/*
123	 * This is kinda brutal, but every single 1GB VM memory segment
124	 * points to the same first 1GB of physical memory.  But it is
125	 * more than adequate.
126	 */
127	for (i = 0; i < 512; i++) {
128		/* Each slot of the level 4 pages points to the same level 3 page */
129		PT4[i] = (p4_entry_t) 0x3000;
130		PT4[i] |= PG_V | PG_RW | PG_U;
131
132		/* Each slot of the level 3 pages points to the same level 2 page */
133		PT3[i] = (p3_entry_t) 0x4000;
134		PT3[i] |= PG_V | PG_RW | PG_U;
135
136		/* The level 2 page slots are mapped with 2MB pages for 1GB. */
137		PT2[i] = i * (2 * 1024 * 1024);
138		PT2[i] |= PG_V | PG_RW | PG_PS | PG_U;
139	}
140
141#ifdef DEBUG
142	printf("Start @ %#"PRIx64" ...\n", ehdr->e_entry);
143#endif
144
145	dev_cleanup();
146
147	stack[0] = 0;		/* return address */
148	stack[1] = modulep;
149	stack[2] = kernend;
150	CALLBACK(copyin, stack, 0x1000, sizeof(stack));
151	CALLBACK(copyin, PT4, 0x2000, sizeof(PT4));
152	CALLBACK(copyin, PT3, 0x3000, sizeof(PT3));
153	CALLBACK(copyin, PT2, 0x4000, sizeof(PT2));
154	CALLBACK(setreg, 4, 0x1000);
155
156	CALLBACK(setmsr, MSR_EFER, EFER_LMA | EFER_LME);
157	CALLBACK(setcr, 4, CR4_PAE | CR4_VMXE);
158	CALLBACK(setcr, 3, 0x2000);
159	CALLBACK(setcr, 0, CR0_PG | CR0_PE | CR0_NE);
160
161	setup_freebsd_gdt(gdtr);
162	CALLBACK(copyin, gdtr, 0x5000, sizeof(gdtr));
163        CALLBACK(setgdt, 0x5000, sizeof(gdtr));
164
165	CALLBACK(exec, ehdr->e_entry);
166
167	panic("exec returned");
168}
169
170static int
171elf64_obj_exec(struct preloaded_file *fp)
172{
173
174	return (EFTYPE);
175}
176