1 /* This file is part of the program psim.
2
3 Copyright (C) 1994-1996, Andrew Cagney <cagney@highland.com.au>
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <http://www.gnu.org/licenses/>.
17
18 */
19
20
21 #ifndef _HW_VM_C_
22 #define _HW_VM_C_
23
24 #include "device_table.h"
25 #include "cpu.h"
26
27 #include <signal.h>
28
29 /* DEVICE
30
31 vm - virtual memory device for user simulation modes
32
33 DESCRIPTION
34
35 In user mode, mapped text, data and stack addresses are managed by
36 the core. Unmapped addresses are passed onto this device (because
37 it establishes its self as the fallback device) for processing.
38
39 During initialization, children of this device will request the
40 mapping of the initial text and data segments. Those requests are
41 passed onto the core device so that that may establish the initial
42 memory regions.
43
44 Once the simulation has started (as noted above) any access to an
45 unmapped address range will be passed down to this device as an IO
46 access. This device will then either attach additional memory to
47 the core device or signal the access as being invalid.
48
49 The IOCTL function is used to notify this device of any changes to
50 the users `brk' point.
51
52 PROPERTIES
53
54 stack-base = <number>
55
56 Specifies the lower address of the stack segment in the users
57 virtual address space. The initial stack page is defined by
58 stack-base + nr-bytes.
59
60 nr-bytes = <number>
61
62 Specifies the maximum size of the stack segment in the users
63 address space.
64
65 */
66
67 typedef struct _hw_vm_device {
68 /* area of memory valid for stack addresses */
69 unsigned_word stack_base; /* min possible stack value */
70 unsigned_word stack_bound;
71 unsigned_word stack_lower_limit;
72 /* area of memory valid for heap addresses */
73 unsigned_word heap_base;
74 unsigned_word heap_bound;
75 unsigned_word heap_upper_limit;
76 } hw_vm_device;
77
78
79 static void
hw_vm_init_address_callback(device * me)80 hw_vm_init_address_callback(device *me)
81 {
82 hw_vm_device *vm = (hw_vm_device*)device_data(me);
83
84 /* revert the stack/heap variables to their defaults */
85 vm->stack_base = device_find_integer_property(me, "stack-base");
86 vm->stack_bound = (vm->stack_base
87 + device_find_integer_property(me, "nr-bytes"));
88 vm->stack_lower_limit = vm->stack_bound;
89 vm->heap_base = 0;
90 vm->heap_bound = 0;
91 vm->heap_upper_limit = 0;
92
93 /* establish this device as the default memory handler */
94 device_attach_address(device_parent(me),
95 attach_callback + 1,
96 0 /*address space - ignore*/,
97 0 /*addr - ignore*/,
98 (((unsigned)0)-1) /*nr_bytes - ignore*/,
99 access_read_write /*access*/,
100 me);
101 }
102
103
104 static void
hw_vm_attach_address(device * me,attach_type attach,int space,unsigned_word addr,unsigned nr_bytes,access_type access,device * client)105 hw_vm_attach_address(device *me,
106 attach_type attach,
107 int space,
108 unsigned_word addr,
109 unsigned nr_bytes,
110 access_type access,
111 device *client) /*callback/default*/
112 {
113 hw_vm_device *vm = (hw_vm_device*)device_data(me);
114 /* update end of bss if necessary */
115 if (vm->heap_base < addr + nr_bytes) {
116 vm->heap_base = addr + nr_bytes;
117 vm->heap_bound = addr + nr_bytes;
118 vm->heap_upper_limit = addr + nr_bytes;
119 }
120 device_attach_address(device_parent(me),
121 attach_raw_memory,
122 0 /*address space*/,
123 addr,
124 nr_bytes,
125 access,
126 me);
127 }
128
129
130 static unsigned
hw_vm_add_space(device * me,unsigned_word addr,unsigned nr_bytes,cpu * processor,unsigned_word cia)131 hw_vm_add_space(device *me,
132 unsigned_word addr,
133 unsigned nr_bytes,
134 cpu *processor,
135 unsigned_word cia)
136 {
137 hw_vm_device *vm = (hw_vm_device*)device_data(me);
138 unsigned_word block_addr;
139 unsigned block_nr_bytes;
140
141 /* an address in the stack area, allocate just down to the addressed
142 page */
143 if (addr >= vm->stack_base && addr < vm->stack_lower_limit) {
144 block_addr = FLOOR_PAGE(addr);
145 block_nr_bytes = vm->stack_lower_limit - block_addr;
146 vm->stack_lower_limit = block_addr;
147 }
148 /* an address in the heap area, allocate all of the required heap */
149 else if (addr >= vm->heap_upper_limit && addr < vm->heap_bound) {
150 block_addr = vm->heap_upper_limit;
151 block_nr_bytes = vm->heap_bound - vm->heap_upper_limit;
152 vm->heap_upper_limit = vm->heap_bound;
153 }
154 /* oops - an invalid address - abort the cpu */
155 else if (processor != NULL) {
156 cpu_halt(processor, cia, was_signalled, SIGSEGV);
157 return 0;
158 }
159 /* 2*oops - an invalid address and no processor */
160 else {
161 return 0;
162 }
163
164 /* got the parameters, allocate the space */
165 device_attach_address(device_parent(me),
166 attach_raw_memory,
167 0 /*address space*/,
168 block_addr,
169 block_nr_bytes,
170 access_read_write,
171 me);
172 return block_nr_bytes;
173 }
174
175
176 static unsigned
hw_vm_io_read_buffer_callback(device * me,void * dest,int space,unsigned_word addr,unsigned nr_bytes,cpu * processor,unsigned_word cia)177 hw_vm_io_read_buffer_callback(device *me,
178 void *dest,
179 int space,
180 unsigned_word addr,
181 unsigned nr_bytes,
182 cpu *processor,
183 unsigned_word cia)
184 {
185 if (hw_vm_add_space(me, addr, nr_bytes, processor, cia) >= nr_bytes) {
186 memset(dest, 0, nr_bytes); /* always initialized to zero */
187 return nr_bytes;
188 }
189 else
190 return 0;
191 }
192
193
194 static unsigned
hw_vm_io_write_buffer_callback(device * me,const void * source,int space,unsigned_word addr,unsigned nr_bytes,cpu * processor,unsigned_word cia)195 hw_vm_io_write_buffer_callback(device *me,
196 const void *source,
197 int space,
198 unsigned_word addr,
199 unsigned nr_bytes,
200 cpu *processor,
201 unsigned_word cia)
202 {
203 if (hw_vm_add_space(me, addr, nr_bytes, processor, cia) >= nr_bytes) {
204 return device_dma_write_buffer(device_parent(me), source,
205 space, addr,
206 nr_bytes,
207 0/*violate_read_only*/);
208 }
209 else
210 return 0;
211 }
212
213
214 static int
hw_vm_ioctl(device * me,cpu * processor,unsigned_word cia,device_ioctl_request request,va_list ap)215 hw_vm_ioctl(device *me,
216 cpu *processor,
217 unsigned_word cia,
218 device_ioctl_request request,
219 va_list ap)
220 {
221 /* While the caller is notified that the heap has grown by the
222 requested amount, the heap is actually extended out to a page
223 boundary. */
224 hw_vm_device *vm = (hw_vm_device*)device_data(me);
225 switch (request) {
226 case device_ioctl_break:
227 {
228 unsigned_word requested_break = va_arg(ap, unsigned_word);
229 unsigned_word new_break = ALIGN_8(requested_break);
230 unsigned_word old_break = vm->heap_bound;
231 signed_word delta = new_break - old_break;
232 if (delta > 0)
233 vm->heap_bound = ALIGN_PAGE(new_break);
234 break;
235 }
236 default:
237 device_error(me, "Unsupported ioctl request");
238 break;
239 }
240 return 0;
241
242 }
243
244
245 static device_callbacks const hw_vm_callbacks = {
246 { hw_vm_init_address_callback, },
247 { hw_vm_attach_address,
248 passthrough_device_address_detach, },
249 { hw_vm_io_read_buffer_callback,
250 hw_vm_io_write_buffer_callback, },
251 { NULL, passthrough_device_dma_write_buffer, },
252 { NULL, }, /* interrupt */
253 { generic_device_unit_decode,
254 generic_device_unit_encode, },
255 NULL, /* instance */
256 hw_vm_ioctl,
257 };
258
259
260 static void *
hw_vm_create(const char * name,const device_unit * address,const char * args)261 hw_vm_create(const char *name,
262 const device_unit *address,
263 const char *args)
264 {
265 hw_vm_device *vm = ZALLOC(hw_vm_device);
266 return vm;
267 }
268
269 const device_descriptor hw_vm_device_descriptor[] = {
270 { "vm", hw_vm_create, &hw_vm_callbacks },
271 { NULL },
272 };
273
274 #endif /* _HW_VM_C_ */
275