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 <asm/uaccess.h>
24 #include "fpu_system.h"
25 #include "exception.h"
28 #define FPU_WRITE_BIT 0x10
30 static int reg_offset[] = {
31 offsetof(struct pt_regs, ax),
32 offsetof(struct pt_regs, cx),
33 offsetof(struct pt_regs, dx),
34 offsetof(struct pt_regs, bx),
35 offsetof(struct pt_regs, sp),
36 offsetof(struct pt_regs, bp),
37 offsetof(struct pt_regs, si),
38 offsetof(struct pt_regs, di)
41 #define REG_(x) (*(long *)(reg_offset[(x)] + (u_char *)FPU_info->regs))
43 static int reg_offset_vm86[] = {
44 offsetof(struct pt_regs, cs),
45 offsetof(struct kernel_vm86_regs, ds),
46 offsetof(struct kernel_vm86_regs, es),
47 offsetof(struct kernel_vm86_regs, fs),
48 offsetof(struct kernel_vm86_regs, gs),
49 offsetof(struct pt_regs, ss),
50 offsetof(struct kernel_vm86_regs, ds)
53 #define VM86_REG_(x) (*(unsigned short *) \
54 (reg_offset_vm86[((unsigned)x)] + (u_char *)FPU_info->regs))
56 static int reg_offset_pm[] = {
57 offsetof(struct pt_regs, cs),
58 offsetof(struct pt_regs, ds),
59 offsetof(struct pt_regs, es),
60 offsetof(struct pt_regs, fs),
61 offsetof(struct pt_regs, ds), /* dummy, not saved on stack */
62 offsetof(struct pt_regs, ss),
63 offsetof(struct pt_regs, ds)
66 #define PM_REG_(x) (*(unsigned short *) \
67 (reg_offset_pm[((unsigned)x)] + (u_char *)FPU_info->regs))
69 /* Decode the SIB byte. This function assumes mod != 0 */
70 static int sib(int mod, unsigned long *fpu_eip)
72 u_char ss, index, base;
76 FPU_code_access_ok(1);
77 FPU_get_user(base, (u_char __user *) (*fpu_eip)); /* The SIB byte */
81 index = (base >> 3) & 7;
84 if ((mod == 0) && (base == 5))
85 offset = 0; /* No base register */
90 /* No index register */
91 /* A non-zero ss is illegal */
93 EXCEPTION(EX_Invalid);
95 offset += (REG_(index)) << ss;
99 /* 8 bit signed displacement */
101 RE_ENTRANT_CHECK_OFF;
102 FPU_code_access_ok(1);
103 FPU_get_user(displacement, (signed char __user *)(*fpu_eip));
104 offset += displacement;
107 } else if (mod == 2 || base == 5) { /* The second condition also has mod==0 */
108 /* 32 bit displacement */
110 RE_ENTRANT_CHECK_OFF;
111 FPU_code_access_ok(4);
112 FPU_get_user(displacement, (long __user *)(*fpu_eip));
113 offset += displacement;
121 static unsigned long vm86_segment(u_char segment, struct address *addr)
125 if (segment > PREFIX_SS_) {
126 EXCEPTION(EX_INTERNAL | 0x130);
127 math_abort(FPU_info, SIGSEGV);
129 #endif /* PARANOID */
130 addr->selector = VM86_REG_(segment);
131 return (unsigned long)VM86_REG_(segment) << 4;
134 /* This should work for 16 and 32 bit protected mode. */
135 static long pm_address(u_char FPU_modrm, u_char segment,
136 struct address *addr, long offset)
138 struct desc_struct descriptor;
139 unsigned long base_address, limit, address, seg_top;
144 /* segment is unsigned, so this also detects if segment was 0: */
145 if (segment > PREFIX_SS_) {
146 EXCEPTION(EX_INTERNAL | 0x132);
147 math_abort(FPU_info, SIGSEGV);
149 #endif /* PARANOID */
153 /* user gs handling can be lazy, use special accessors */
154 addr->selector = get_user_gs(FPU_info->regs);
157 addr->selector = PM_REG_(segment);
160 descriptor = FPU_get_ldt_descriptor(addr->selector);
161 base_address = SEG_BASE_ADDR(descriptor);
162 address = base_address + offset;
164 + (SEG_LIMIT(descriptor) + 1) * SEG_GRANULARITY(descriptor) - 1;
165 if (limit < base_address)
168 if (SEG_EXPAND_DOWN(descriptor)) {
169 if (SEG_G_BIT(descriptor))
170 seg_top = 0xffffffff;
172 seg_top = base_address + (1 << 20);
173 if (seg_top < base_address)
174 seg_top = 0xffffffff;
177 (address <= limit) || (address >= seg_top) ? 0 :
178 ((seg_top - address) >= 255 ? 255 : seg_top - address);
181 (address > limit) || (address < base_address) ? 0 :
182 ((limit - address) >= 254 ? 255 : limit - address + 1);
184 if (SEG_EXECUTE_ONLY(descriptor) ||
185 (!SEG_WRITE_PERM(descriptor) && (FPU_modrm & FPU_WRITE_BIT))) {
192 MOD R/M byte: MOD == 3 has a special use for the FPU
193 SIB byte used iff R/M = 100b
196 ..... ......... .........
202 ..... ......... .........
207 void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip,
208 struct address *addr, fpu_addr_modes addr_modes)
211 unsigned rm = FPU_modrm & 7;
213 int address = 0; /* Initialized just to stop compiler warnings. */
215 /* Memory accessed via the cs selector is write protected
216 in `non-segmented' 32 bit protected mode. */
217 if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
218 && (addr_modes.override.segment == PREFIX_CS_)) {
219 math_abort(FPU_info, SIGSEGV);
222 addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
224 mod = (FPU_modrm >> 6) & 3;
226 if (rm == 4 && mod != 3) {
227 address = sib(mod, fpu_eip);
229 cpu_reg_ptr = ®_(rm);
233 /* Special case: disp32 */
234 RE_ENTRANT_CHECK_OFF;
235 FPU_code_access_ok(4);
236 FPU_get_user(address,
237 (unsigned long __user
241 addr->offset = address;
242 return (void __user *)address;
244 address = *cpu_reg_ptr; /* Just return the contents
245 of the cpu register */
246 addr->offset = address;
247 return (void __user *)address;
250 /* 8 bit signed displacement */
251 RE_ENTRANT_CHECK_OFF;
252 FPU_code_access_ok(1);
253 FPU_get_user(address, (signed char __user *)(*fpu_eip));
258 /* 32 bit displacement */
259 RE_ENTRANT_CHECK_OFF;
260 FPU_code_access_ok(4);
261 FPU_get_user(address, (long __user *)(*fpu_eip));
266 /* Not legal for the FPU */
267 EXCEPTION(EX_Invalid);
269 address += *cpu_reg_ptr;
272 addr->offset = address;
274 switch (addr_modes.default_mode) {
278 address += vm86_segment(addr_modes.override.segment, addr);
282 address = pm_address(FPU_modrm, addr_modes.override.segment,
286 EXCEPTION(EX_INTERNAL | 0x133);
289 return (void __user *)address;
292 void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip,
293 struct address *addr, fpu_addr_modes addr_modes)
296 unsigned rm = FPU_modrm & 7;
297 int address = 0; /* Default used for mod == 0 */
299 /* Memory accessed via the cs selector is write protected
300 in `non-segmented' 32 bit protected mode. */
301 if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
302 && (addr_modes.override.segment == PREFIX_CS_)) {
303 math_abort(FPU_info, SIGSEGV);
306 addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
308 mod = (FPU_modrm >> 6) & 3;
313 /* Special case: disp16 */
314 RE_ENTRANT_CHECK_OFF;
315 FPU_code_access_ok(2);
316 FPU_get_user(address,
317 (unsigned short __user *)(*fpu_eip));
324 /* 8 bit signed displacement */
325 RE_ENTRANT_CHECK_OFF;
326 FPU_code_access_ok(1);
327 FPU_get_user(address, (signed char __user *)(*fpu_eip));
332 /* 16 bit displacement */
333 RE_ENTRANT_CHECK_OFF;
334 FPU_code_access_ok(2);
335 FPU_get_user(address, (unsigned short __user *)(*fpu_eip));
340 /* Not legal for the FPU */
341 EXCEPTION(EX_Invalid);
346 address += FPU_info->regs->bx + FPU_info->regs->si;
349 address += FPU_info->regs->bx + FPU_info->regs->di;
352 address += FPU_info->regs->bp + FPU_info->regs->si;
353 if (addr_modes.override.segment == PREFIX_DEFAULT)
354 addr_modes.override.segment = PREFIX_SS_;
357 address += FPU_info->regs->bp + FPU_info->regs->di;
358 if (addr_modes.override.segment == PREFIX_DEFAULT)
359 addr_modes.override.segment = PREFIX_SS_;
362 address += FPU_info->regs->si;
365 address += FPU_info->regs->di;
368 address += FPU_info->regs->bp;
369 if (addr_modes.override.segment == PREFIX_DEFAULT)
370 addr_modes.override.segment = PREFIX_SS_;
373 address += FPU_info->regs->bx;
380 addr->offset = address;
382 switch (addr_modes.default_mode) {
386 address += vm86_segment(addr_modes.override.segment, addr);
390 address = pm_address(FPU_modrm, addr_modes.override.segment,
394 EXCEPTION(EX_INTERNAL | 0x131);
397 return (void __user *)address;