-
Notifications
You must be signed in to change notification settings - Fork 0
/
main.c
276 lines (224 loc) · 5.79 KB
/
main.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
#include "types.h"
#include "multiboot.h"
#include "elf.h"
#include "print.h"
#define VIRT_TO_PHYS (0xFFFFFF8000000000UL) /* PML4 511 */
#define TWO_MEGS (2*1024*1024)
extern u32 _bootloader_size;
extern u32 _stack_start;
void __attribute__((noreturn)) go_long(u32, u64, u32);
struct page_table_entry
{
union
{
struct
{
u64 present :1;
u64 rw :1;
u64 us :1;
u64 pwt :1;
u64 pcd :1;
u64 a :1;
u64 dirty :1;
u64 pat :1;
u64 global :1;
u64 ignore2 :3;
u64 addr :40;
u64 ignore3 :7;
u64 pke :4;
u64 nx :1;
};
u64 entry;
};
};
struct page_table
{
struct page_table_entry e[512];
};
struct mem_info
{
unsigned long free;
unsigned long e820_count;
char e820_buf[480];
} mem;
static unsigned long free_page;
static struct page_table *pml4;
static void clear_page(u32 page)
{
char *p;
for(p = (char *)page; p < (char *)page+4096; p++)
*p = 0;
}
static unsigned long new_page(void)
{
unsigned long t;
t = free_page;
free_page += 4096;
clear_page(t);
return t;
}
static void map_page(u64 vaddr, u32 paddr, u32 flags, u32 is_kernel)
{
int pml4e, pdpte, pde, pte;
struct page_table *p;
u32 new;
/* Calculate which entry in each table this address corresponds to */
pml4e = (vaddr>>39) & 0x1FF;
pdpte = (vaddr>>30) & 0x1FF;
pde = (vaddr>>21) & 0x1FF;
pte = (vaddr>>12) & 0x1FF;
/* If we haven't made set of page tables yet, make some */
if(!pml4)
pml4 = (struct page_table *)new_page(); /* New PML4 */
p = pml4;
if(!p->e[pml4e].present)
{
new = new_page(); /* New PDPT */
pml4->e[pml4e].entry = new;
pml4->e[pml4e].rw = 1;
pml4->e[pml4e].us = 1;
pml4->e[pml4e].present = 1;
p = (struct page_table *)new;
} else {
p = (struct page_table *)(u32)(p->e[pml4e].entry & 0xFFFFFFFFFE00ULL);
}
if(!p->e[pdpte].present)
{
new = new_page(); /* New PD */
p->e[pdpte].entry = new;
p->e[pdpte].rw = 1;
p->e[pdpte].us = 1;
p->e[pdpte].present = 1;
p = (struct page_table *)new;
} else {
p = (struct page_table *)(u32)(p->e[pdpte].entry & 0xFFFFFFFFFE00ULL);
}
if(!p->e[pde].present)
{
new = new_page(); /* New PT */
p->e[pde].entry = new;
p->e[pde].rw = 1;
p->e[pde].us = 1;
p->e[pde].present = 1;
p = (struct page_table *)new;
} else {
p = (struct page_table *)(u32)(p->e[pde].entry & 0xFFFFFFFFFE00ULL);
}
p->e[pte].entry = paddr;
p->e[pte].rw = !!(flags & PF_W);
p->e[pte].nx = !(flags & PF_X);
p->e[pte].us = !is_kernel;
p->e[pte].present = 1;
}
static void map_section(struct program_header *p, u64 elf_start, u32 is_kernel)
{
u64 paddr, vaddr;
paddr = p->p_offset + elf_start;
printf("Map section: %lx %lx\n", p->p_vaddr, paddr);
/* Map each page in the section */
for(vaddr = p->p_vaddr; vaddr < p->p_vaddr + p->p_memsz; vaddr += 4096)
{
if(p->p_filesz)
{
/* This page is backed by the file, subtract 4096 or
* filesz bytes, whichever is smaller. */
p->p_filesz -= p->p_filesz >= 4096 ? 4096 : p->p_filesz;
}
else
{
/* We ran out of file bytes, this must be bss,
* allocate memory and zero it instead. */
paddr = new_page();
}
printf("Mapping %lx to %lx (%x)\n", vaddr, paddr, p->p_flags);
map_page(vaddr, paddr, p->p_flags, is_kernel);
paddr += 4096;
}
}
static void map_bootloader(u32 size)
{
u32 addr, end;
/* Map the pages before .bss as executable */
end = (u32)&_stack_start - 0x1000;
for(addr = 0x100000; addr < end; addr += 0x1000)
map_page(addr, addr, PF_X, 1);
/* Map the pages in .bss as writeable */
printf("Addr: %x Size: %x\n", addr, size);
for(; addr < end + size; addr += 0x1000)
map_page(addr, addr, PF_W, 1);
}
static void map_range(unsigned long start, unsigned long len)
{
unsigned long page;
/* Displaced identity map each page */
for(page = start; page < start + len; page += 0x1000)
map_page(VIRT_TO_PHYS + page, page, PF_W, 0);
}
static void memcpy(void *d, void *s, unsigned long n)
{
unsigned char *dd = d, *ss = s;
while(n--)
*dd++ = *ss++;
}
static void init_mem(struct multiboot *mb, unsigned long kernel_end)
{
struct mem *m;
free_page = kernel_end;
for(m = mb->mmap_addr; (char *)m < (char *)mb->mmap_addr + mb->mmap_len; m++)
{
if(m->type != 1)
continue;
if(m->addr < 0x100000)
continue;
if(m->addr >= 0x100000000UL)
continue;
map_range(m->addr, m->addr + m->len);
}
if(mb->mmap_len > 480)
printf("E820 too big for buffer!\n");
/* Save a copy of the e820 for the kernel */
memcpy(mem.e820_buf, mb->mmap_addr, mb->mmap_len);
mem.e820_count = mb->mmap_len / 24;
}
void __attribute__((noreturn)) main(struct multiboot *mb)
{
int i;
u32 kernel_start, kernel_end;
struct elf_header *e, *ke;
struct program_header *p;
struct module *mod = mb->mods_addr, *last_mod;
printf("Bootloader started\n");
if(mb->mods_count < 1)
{
printf("Fatal: Kernel not supplied as grub module.\n");
while(1);
}
kernel_start = mod->mod_start;
last_mod = &mod[mb->mods_count-1];
kernel_end = ((last_mod->mod_end + 4095)/4096)*4096;
printf("Kernel: %x-%x\n", kernel_start, kernel_end);
/* Map RAM below 4G for the kernel to start with */
init_mem(mb, kernel_end);
printf("Memory initialized\n");
ke = (struct elf_header *)kernel_start;
p = (struct program_header *)(u32)(ke->e_phoff + kernel_start);
for(i = 0; i < ke->e_phnum; i++)
map_section(&p[i], kernel_start, 1);
printf("Kernel mapped\n");
map_bootloader((u32)&_bootloader_size);
printf("Bootloader mapped\n");
while(mb->mods_count-- > 1)
{
printf("Mapping module\n");
mod++;
e = (struct elf_header *)mod->mod_start;
printf("e->e_phoff: %x\n", e->e_phoff);
p = (struct program_header *)(u32)(e->e_phoff + (u32)e);
printf("e: %x, p: %x\n", e, p);
for(i = 0; i < e->e_phnum; i++)
map_section(&p[i], (u32)e, 0);
}
printf("Going to long mode...\n");
mem.free = free_page;
go_long((u32)pml4, ke->e_entry, (u32)&mem);
}