1 /*---------------------------------------------------------------------------+
4 | Get the effective address from an FPU instruction. |
6 | Copyright (C) 1992,1993,1994,1997 |
7 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
8 | Australia. E-mail billm@suburbia.net |
11 +---------------------------------------------------------------------------*/
13 /*---------------------------------------------------------------------------+
15 | The file contains code which accesses user memory. |
16 | Emulator static data may change when user memory is accessed, due to |
17 | other processes using the emulator while swapping is in progress. |
18 +---------------------------------------------------------------------------*/
20 #include <linux/stddef.h>
22 #include <linux/uaccess.h>
25 #include "fpu_system.h"
26 #include "exception.h"
29 #define FPU_WRITE_BIT 0x10
31 static int reg_offset[] = {
32 offsetof(struct pt_regs, ax),
33 offsetof(struct pt_regs, cx),
34 offsetof(struct pt_regs, dx),
35 offsetof(struct pt_regs, bx),
36 offsetof(struct pt_regs, sp),
37 offsetof(struct pt_regs, bp),
38 offsetof(struct pt_regs, si),
39 offsetof(struct pt_regs, di)
42 #define REG_(x) (*(long *)(reg_offset[(x)] + (u_char *)FPU_info->regs))
44 static int reg_offset_vm86[] = {
45 offsetof(struct pt_regs, cs),
46 offsetof(struct kernel_vm86_regs, ds),
47 offsetof(struct kernel_vm86_regs, es),
48 offsetof(struct kernel_vm86_regs, fs),
49 offsetof(struct kernel_vm86_regs, gs),
50 offsetof(struct pt_regs, ss),
51 offsetof(struct kernel_vm86_regs, ds)
54 #define VM86_REG_(x) (*(unsigned short *) \
55 (reg_offset_vm86[((unsigned)x)] + (u_char *)FPU_info->regs))
57 static int reg_offset_pm[] = {
58 offsetof(struct pt_regs, cs),
59 offsetof(struct pt_regs, ds),
60 offsetof(struct pt_regs, es),
61 offsetof(struct pt_regs, fs),
62 offsetof(struct pt_regs, ds), /* dummy, not saved on stack */
63 offsetof(struct pt_regs, ss),
64 offsetof(struct pt_regs, ds)
67 #define PM_REG_(x) (*(unsigned short *) \
68 (reg_offset_pm[((unsigned)x)] + (u_char *)FPU_info->regs))
70 /* Decode the SIB byte. This function assumes mod != 0 */
71 static int sib(int mod, unsigned long *fpu_eip)
73 u_char ss, index, base;
77 FPU_code_access_ok(1);
78 FPU_get_user(base, (u_char __user *) (*fpu_eip)); /* The SIB byte */
82 index = (base >> 3) & 7;
85 if ((mod == 0) && (base == 5))
86 offset = 0; /* No base register */
91 /* No index register */
92 /* A non-zero ss is illegal */
94 EXCEPTION(EX_Invalid);
96 offset += (REG_(index)) << ss;
100 /* 8 bit signed displacement */
102 RE_ENTRANT_CHECK_OFF;
103 FPU_code_access_ok(1);
104 FPU_get_user(displacement, (signed char __user *)(*fpu_eip));
105 offset += displacement;
108 } else if (mod == 2 || base == 5) { /* The second condition also has mod==0 */
109 /* 32 bit displacement */
111 RE_ENTRANT_CHECK_OFF;
112 FPU_code_access_ok(4);
113 FPU_get_user(displacement, (long __user *)(*fpu_eip));
114 offset += displacement;
122 static unsigned long vm86_segment(u_char segment, struct address *addr)
126 if (segment > PREFIX_SS_) {
127 EXCEPTION(EX_INTERNAL | 0x130);
128 math_abort(FPU_info, SIGSEGV);
130 #endif /* PARANOID */
131 addr->selector = VM86_REG_(segment);
132 return (unsigned long)VM86_REG_(segment) << 4;
135 /* This should work for 16 and 32 bit protected mode. */
136 static long pm_address(u_char FPU_modrm, u_char segment,
137 struct address *addr, long offset)
139 struct desc_struct descriptor;
140 unsigned long base_address, limit, address, seg_top;
145 /* segment is unsigned, so this also detects if segment was 0: */
146 if (segment > PREFIX_SS_) {
147 EXCEPTION(EX_INTERNAL | 0x132);
148 math_abort(FPU_info, SIGSEGV);
150 #endif /* PARANOID */
154 /* user gs handling can be lazy, use special accessors */
155 addr->selector = get_user_gs(FPU_info->regs);
158 addr->selector = PM_REG_(segment);
161 descriptor = FPU_get_ldt_descriptor(addr->selector);
162 base_address = seg_get_base(&descriptor);
163 address = base_address + offset;
164 limit = seg_get_limit(&descriptor) + 1;
165 limit *= seg_get_granularity(&descriptor);
166 limit += base_address - 1;
167 if (limit < base_address)
170 if (seg_expands_down(&descriptor)) {
172 seg_top = 0xffffffff;
174 seg_top = base_address + (1 << 20);
175 if (seg_top < base_address)
176 seg_top = 0xffffffff;
179 (address <= limit) || (address >= seg_top) ? 0 :
180 ((seg_top - address) >= 255 ? 255 : seg_top - address);
183 (address > limit) || (address < base_address) ? 0 :
184 ((limit - address) >= 254 ? 255 : limit - address + 1);
186 if (seg_execute_only(&descriptor) ||
187 (!seg_writable(&descriptor) && (FPU_modrm & FPU_WRITE_BIT))) {
194 MOD R/M byte: MOD == 3 has a special use for the FPU
195 SIB byte used iff R/M = 100b
198 ..... ......... .........
204 ..... ......... .........
209 void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip,
210 struct address *addr, fpu_addr_modes addr_modes)
213 unsigned rm = FPU_modrm & 7;
215 int address = 0; /* Initialized just to stop compiler warnings. */
217 /* Memory accessed via the cs selector is write protected
218 in `non-segmented' 32 bit protected mode. */
219 if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
220 && (addr_modes.override.segment == PREFIX_CS_)) {
221 math_abort(FPU_info, SIGSEGV);
224 addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
226 mod = (FPU_modrm >> 6) & 3;
228 if (rm == 4 && mod != 3) {
229 address = sib(mod, fpu_eip);
231 cpu_reg_ptr = ®_(rm);
235 /* Special case: disp32 */
236 RE_ENTRANT_CHECK_OFF;
237 FPU_code_access_ok(4);
238 FPU_get_user(address,
239 (unsigned long __user
243 addr->offset = address;
244 return (void __user *)address;
246 address = *cpu_reg_ptr; /* Just return the contents
247 of the cpu register */
248 addr->offset = address;
249 return (void __user *)address;
252 /* 8 bit signed displacement */
253 RE_ENTRANT_CHECK_OFF;
254 FPU_code_access_ok(1);
255 FPU_get_user(address, (signed char __user *)(*fpu_eip));
260 /* 32 bit displacement */
261 RE_ENTRANT_CHECK_OFF;
262 FPU_code_access_ok(4);
263 FPU_get_user(address, (long __user *)(*fpu_eip));
268 /* Not legal for the FPU */
269 EXCEPTION(EX_Invalid);
271 address += *cpu_reg_ptr;
274 addr->offset = address;
276 switch (addr_modes.default_mode) {
280 address += vm86_segment(addr_modes.override.segment, addr);
284 address = pm_address(FPU_modrm, addr_modes.override.segment,
288 EXCEPTION(EX_INTERNAL | 0x133);
291 return (void __user *)address;
294 void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip,
295 struct address *addr, fpu_addr_modes addr_modes)
298 unsigned rm = FPU_modrm & 7;
299 int address = 0; /* Default used for mod == 0 */
301 /* Memory accessed via the cs selector is write protected
302 in `non-segmented' 32 bit protected mode. */
303 if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
304 && (addr_modes.override.segment == PREFIX_CS_)) {
305 math_abort(FPU_info, SIGSEGV);
308 addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
310 mod = (FPU_modrm >> 6) & 3;
315 /* Special case: disp16 */
316 RE_ENTRANT_CHECK_OFF;
317 FPU_code_access_ok(2);
318 FPU_get_user(address,
319 (unsigned short __user *)(*fpu_eip));
326 /* 8 bit signed displacement */
327 RE_ENTRANT_CHECK_OFF;
328 FPU_code_access_ok(1);
329 FPU_get_user(address, (signed char __user *)(*fpu_eip));
334 /* 16 bit displacement */
335 RE_ENTRANT_CHECK_OFF;
336 FPU_code_access_ok(2);
337 FPU_get_user(address, (unsigned short __user *)(*fpu_eip));
342 /* Not legal for the FPU */
343 EXCEPTION(EX_Invalid);
348 address += FPU_info->regs->bx + FPU_info->regs->si;
351 address += FPU_info->regs->bx + FPU_info->regs->di;
354 address += FPU_info->regs->bp + FPU_info->regs->si;
355 if (addr_modes.override.segment == PREFIX_DEFAULT)
356 addr_modes.override.segment = PREFIX_SS_;
359 address += FPU_info->regs->bp + FPU_info->regs->di;
360 if (addr_modes.override.segment == PREFIX_DEFAULT)
361 addr_modes.override.segment = PREFIX_SS_;
364 address += FPU_info->regs->si;
367 address += FPU_info->regs->di;
370 address += FPU_info->regs->bp;
371 if (addr_modes.override.segment == PREFIX_DEFAULT)
372 addr_modes.override.segment = PREFIX_SS_;
375 address += FPU_info->regs->bx;
382 addr->offset = address;
384 switch (addr_modes.default_mode) {
388 address += vm86_segment(addr_modes.override.segment, addr);
392 address = pm_address(FPU_modrm, addr_modes.override.segment,
396 EXCEPTION(EX_INTERNAL | 0x131);
399 return (void __user *)address;