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
|
/*
* Early initialization code for riscv virtual memory
*
* Copyright 2015 Google Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2 of
* the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
* GNU General Public License for more details.
*/
#include <arch/barrier.h>
#include <arch/encoding.h>
#include <arch/sbi.h>
#include <atomic.h>
#include <console/console.h>
#include <stdint.h>
#include <vm.h>
pte_t* root_page_table;
/* Indent the following text by 2*level spaces */
static void indent(int level)
{
int i;
for (i = 0; i < level; i++)
printk(BIOS_DEBUG, " ");
}
/*
* Convert a page table index at a given page table level to a virtual address
* offset
*/
static uintptr_t index_to_virt_addr(int index, int level)
{
/*
* Index is at most RISCV_PGLEVEL_BITS bits wide (not considering the
* leading zeroes. If level==0, the below expression thus shifts index
* into the highest bits of a 64-bit number, and then shifts it down
* with sign extension.
*
* If level>0, then the expression should work as expected, without any
* magic.
*/
return ((intptr_t)index)
<< (64 - RISCV_PGLEVEL_BITS - level * RISCV_PGLEVEL_BITS)
>> (64 - VA_BITS);
}
/* Dump the page table structures to the console -- helper function */
static void print_page_table_at(pte_t *pt, intptr_t virt_addr, int level)
{
int i;
indent(level);
printk(BIOS_DEBUG, "Level %d page table at 0x%p\n", level, pt);
for (i = 0; i < RISCV_PGSIZE / sizeof(pte_t); i++) {
char urwx[8];
uintptr_t pointer;
intptr_t next_virt_addr;
if (!(pt[i] & PTE_V))
continue;
urwx[0] = (pt[i] & PTE_U)? 'u' : '-';
urwx[1] = (pt[i] & PTE_R)? 'r' : '-';
urwx[2] = (pt[i] & PTE_W)? 'w' : '-';
urwx[3] = (pt[i] & PTE_X)? 'x' : '-';
urwx[4] = '\0';
next_virt_addr = virt_addr + index_to_virt_addr(i, level);
pointer = ((uintptr_t)pt[i] >> 10) << RISCV_PGSHIFT;
indent(level + 1);
printk(BIOS_DEBUG, "Valid PTE at index %d (0x%016zx -> 0x%zx), ",
i, (size_t) next_virt_addr, (size_t) pointer);
if (PTE_TABLE(pt[i]))
printk(BIOS_DEBUG, "page table\n");
else
printk(BIOS_DEBUG, "protections %s\n", urwx);
if (PTE_TABLE(pt[i])) {
print_page_table_at((pte_t *)pointer, next_virt_addr, level + 1);
}
}
}
/* Print the page table structures to the console */
void print_page_table(void) {
print_page_table_at(root_page_table, 0, 0);
}
void flush_tlb(void)
{
asm volatile("sfence.vm");
}
size_t pte_ppn(pte_t pte)
{
return pte >> PTE_PPN_SHIFT;
}
pte_t ptd_create(uintptr_t ppn)
{
return (ppn << PTE_PPN_SHIFT) | PTE_V;
}
pte_t pte_create(uintptr_t ppn, int prot, int user)
{
pte_t pte = (ppn << PTE_PPN_SHIFT) | PTE_R | PTE_V;
if (prot & PROT_WRITE)
pte |= PTE_W;
if (prot & PROT_EXEC)
pte |= PTE_X;
if (user)
pte |= PTE_U;
return pte;
}
void init_vm(uintptr_t virtMemStart, uintptr_t physMemStart, uintptr_t pageTableStart) {
pte_t* sbi_pt = (pte_t*) pageTableStart;
memset(sbi_pt, 0, RISCV_PGSIZE);
// need to leave room for sbi page
uintptr_t memorySize = 0x7F000000; // 0xFFF... - 0xFFFFFFFF81000000 - RISCV_PGSIZE
// middle page table
pte_t* middle_pt = (void*)sbi_pt + RISCV_PGSIZE;
size_t num_middle_pts = 2; // 3 level page table, 39 bit virtual address space for now
// root page table
pte_t* root_pt = (void*)middle_pt + num_middle_pts * RISCV_PGSIZE;
memset(middle_pt, 0, (num_middle_pts + 1) * RISCV_PGSIZE); // 0's out middle_pt and root_pt
for (size_t i = 0; i < num_middle_pts; i++)
root_pt[(1<<RISCV_PGLEVEL_BITS)-num_middle_pts+i] = ptd_create(((uintptr_t)middle_pt >> RISCV_PGSHIFT) + i);
// fill the middle page table
for (uintptr_t vaddr = virtMemStart, paddr = physMemStart;
paddr < physMemStart + memorySize;
vaddr += SUPERPAGE_SIZE, paddr += SUPERPAGE_SIZE) {
int l2_shift = RISCV_PGLEVEL_BITS + RISCV_PGSHIFT;
size_t l2_idx = (virtMemStart >> l2_shift) & ((1 << RISCV_PGLEVEL_BITS)-1);
l2_idx += ((vaddr - virtMemStart) >> l2_shift);
middle_pt[l2_idx] = pte_create(paddr >> RISCV_PGSHIFT, PROT_READ|PROT_WRITE|PROT_EXEC, 0);
}
// map SBI at top of vaddr space
uintptr_t num_sbi_pages = 1; // only need to map a single page for sbi interface
uintptr_t sbiStartAddress = (uintptr_t) &sbi_page;
uintptr_t sbiAddr = sbiStartAddress;
for (uintptr_t i = 0; i < num_sbi_pages; i++) {
uintptr_t idx = (1 << RISCV_PGLEVEL_BITS) - num_sbi_pages + i;
sbi_pt[idx] = pte_create(sbiAddr >> RISCV_PGSHIFT, PROT_READ|PROT_EXEC, 0);
sbiAddr += RISCV_PGSIZE;
}
pte_t* sbi_pte = middle_pt + ((num_middle_pts << RISCV_PGLEVEL_BITS)-1);
*sbi_pte = ptd_create((uintptr_t)sbi_pt >> RISCV_PGSHIFT);
mb();
root_page_table = root_pt;
uintptr_t ptbr = ((uintptr_t) root_pt) >> RISCV_PGSHIFT;
write_csr(sptbr, ptbr);
}
void initVirtualMemory(void) {
uintptr_t ms;
ms = read_csr(mstatus);
ms = INSERT_FIELD(ms, MSTATUS_VM, VM_CHOICE);
write_csr(mstatus, ms);
ms = read_csr(mstatus);
if (EXTRACT_FIELD(ms, MSTATUS_VM) != VM_CHOICE) {
printk(BIOS_DEBUG, "We don't have virtual memory...\n");
return;
} else {
printk(BIOS_DEBUG, "-----------------------------\n");
printk(BIOS_DEBUG, "Virtual memory status enabled\n");
printk(BIOS_DEBUG, "-----------------------------\n");
}
printk(BIOS_DEBUG, "Initializing virtual memory...\n");
uintptr_t physicalStart = 0x90000000; // TODO: Figure out how to grab this from cbfs
uintptr_t virtualStart = 0xffffffff80000000;
uintptr_t pageTableStart = 0x91400000;
init_vm(virtualStart, physicalStart, pageTableStart);
mb();
#if IS_ENABLED(CONFIG_DEBUG_PRINT_PAGE_TABLES)
printk(BIOS_DEBUG, "Finished initializing virtual memory, starting walk...\n");
print_page_table();
#else
printk(BIOS_DEBUG, "Finished initializing virtual memory\n");
#endif
}
void mstatus_init(void)
{
uintptr_t ms = 0;
ms = INSERT_FIELD(ms, MSTATUS_FS, 3);
ms = INSERT_FIELD(ms, MSTATUS_XS, 3);
write_csr(mstatus, ms);
clear_csr(mip, MIP_MSIP);
set_csr(mie, MIP_MSIP);
/* Configure which exception causes are delegated to supervisor mode */
set_csr(medeleg, (1 << CAUSE_MISALIGNED_FETCH)
| (1 << CAUSE_FAULT_FETCH)
| (1 << CAUSE_ILLEGAL_INSTRUCTION)
| (1 << CAUSE_BREAKPOINT)
| (1 << CAUSE_FAULT_LOAD)
| (1 << CAUSE_FAULT_STORE)
| (1 << CAUSE_USER_ECALL)
);
/* Enable all user/supervisor-mode counters */
write_csr(mscounteren, 0b111);
write_csr(mucounteren, 0b111);
}
|
