elf64_freebsd.c revision 332154 
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 332154 2018-04-06 21:37:25Z kevans $");
29
30#define __ELF_WORD_SIZE 64
31#include <sys/param.h>
32#include <sys/exec.h>
33#include <sys/linker.h>
34#include <string.h>
35#include <i386/include/bootinfo.h>
36#include <machine/elf.h>
37#include <stand.h>
38
39#include "bootstrap.h"
40#include "libuserboot.h"
41
42static int	elf64_exec(struct preloaded_file *amp);
43static int	elf64_obj_exec(struct preloaded_file *amp);
44
45struct file_format amd64_elf = { elf64_loadfile, elf64_exec };
46struct file_format amd64_elf_obj = { elf64_obj_loadfile, elf64_obj_exec };
47
48#define MSR_EFER        0xc0000080
49#define EFER_LME        0x00000100
50#define	EFER_LMA 	0x00000400	/* Long mode active (R) */
51#define CR4_PAE         0x00000020
52#define	CR4_VMXE	(1UL << 13)
53#define CR4_PSE         0x00000010
54#define CR0_PG          0x80000000
55#define	CR0_PE		0x00000001	/* Protected mode Enable */
56#define	CR0_NE		0x00000020	/* Numeric Error enable (EX16 vs IRQ13) */
57
58#define PG_V	0x001
59#define PG_RW	0x002
60#define PG_U	0x004
61#define PG_PS	0x080
62
63typedef uint64_t p4_entry_t;
64typedef uint64_t p3_entry_t;
65typedef uint64_t p2_entry_t;
66
67#define	GUEST_NULL_SEL		0
68#define	GUEST_CODE_SEL		1
69#define	GUEST_DATA_SEL		2
70#define	GUEST_GDTR_LIMIT	(3 * 8 - 1)
71
72static void
73setup_freebsd_gdt(uint64_t *gdtr)
74{
75	gdtr[GUEST_NULL_SEL] = 0;
76	gdtr[GUEST_CODE_SEL] = 0x0020980000000000;
77	gdtr[GUEST_DATA_SEL] = 0x0000900000000000;
78}
79
80/*
81 * There is an ELF kernel and one or more ELF modules loaded.
82 * We wish to start executing the kernel image, so make such
83 * preparations as are required, and do so.
84 */
85static int
86elf64_exec(struct preloaded_file *fp)
87{
88	struct file_metadata	*md;
89	Elf_Ehdr 		*ehdr;
90	vm_offset_t		modulep, kernend;
91	int			err;
92	int			i;
93	uint32_t		stack[1024];
94	p4_entry_t		PT4[512];
95	p3_entry_t		PT3[512];
96	p2_entry_t		PT2[512];
97	uint64_t		gdtr[3];
98
99	if ((md = file_findmetadata(fp, MODINFOMD_ELFHDR)) == NULL)
100		return(EFTYPE);
101	ehdr = (Elf_Ehdr *)&(md->md_data);
102
103	err = bi_load64(fp->f_args, &modulep, &kernend);
104	if (err != 0)
105		return(err);
106
107	bzero(PT4, PAGE_SIZE);
108	bzero(PT3, PAGE_SIZE);
109	bzero(PT2, PAGE_SIZE);
110
111	/*
112	 * Build a scratch stack at physical 0x1000, page tables:
113	 *	PT4 at 0x2000,
114	 *	PT3 at 0x3000,
115	 *	PT2 at 0x4000,
116	 *      gdtr at 0x5000,
117	 */
118
119	/*
120	 * This is kinda brutal, but every single 1GB VM memory segment
121	 * points to the same first 1GB of physical memory.  But it is
122	 * more than adequate.
123	 */
124	for (i = 0; i < 512; i++) {
125		/* Each slot of the level 4 pages points to the same level 3 page */
126		PT4[i] = (p4_entry_t) 0x3000;
127		PT4[i] |= PG_V | PG_RW | PG_U;
128
129		/* Each slot of the level 3 pages points to the same level 2 page */
130		PT3[i] = (p3_entry_t) 0x4000;
131		PT3[i] |= PG_V | PG_RW | PG_U;
132
133		/* The level 2 page slots are mapped with 2MB pages for 1GB. */
134		PT2[i] = i * (2 * 1024 * 1024);
135		PT2[i] |= PG_V | PG_RW | PG_PS | PG_U;
136	}
137
138#ifdef DEBUG
139	printf("Start @ %#llx ...\n", ehdr->e_entry);
140#endif
141
142	dev_cleanup();
143
144	stack[0] = 0;		/* return address */
145	stack[1] = modulep;
146	stack[2] = kernend;
147	CALLBACK(copyin, stack, 0x1000, sizeof(stack));
148	CALLBACK(copyin, PT4, 0x2000, sizeof(PT4));
149	CALLBACK(copyin, PT3, 0x3000, sizeof(PT3));
150	CALLBACK(copyin, PT2, 0x4000, sizeof(PT2));
151	CALLBACK(setreg, 4, 0x1000);
152
153	CALLBACK(setmsr, MSR_EFER, EFER_LMA | EFER_LME);
154	CALLBACK(setcr, 4, CR4_PAE | CR4_VMXE);
155	CALLBACK(setcr, 3, 0x2000);
156	CALLBACK(setcr, 0, CR0_PG | CR0_PE | CR0_NE);
157
158	setup_freebsd_gdt(gdtr);
159	CALLBACK(copyin, gdtr, 0x5000, sizeof(gdtr));
160        CALLBACK(setgdt, 0x5000, sizeof(gdtr));
161
162	CALLBACK(exec, ehdr->e_entry);
163
164	panic("exec returned");
165}
166
167static int
168elf64_obj_exec(struct preloaded_file *fp)
169{
170
171	return (EFTYPE);
172}
173