/*---------------------------------------------------------------------------+ | get_address.c | | | | Get the effective address from an FPU instruction. | | | | Copyright (C) 1992,1993,1994,1997 | | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | | Australia. E-mail billm@suburbia.net | | | | | +---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------+ | Note: | | The file contains code which accesses user memory. | | Emulator static data may change when user memory is accessed, due to | | other processes using the emulator while swapping is in progress. | +---------------------------------------------------------------------------*/ #include #include #include "fpu_system.h" #include "exception.h" #include "fpu_emu.h" #define FPU_WRITE_BIT 0x10 static int reg_offset[] = { offsetof(struct info,___eax), offsetof(struct info,___ecx), offsetof(struct info,___edx), offsetof(struct info,___ebx), offsetof(struct info,___esp), offsetof(struct info,___ebp), offsetof(struct info,___esi), offsetof(struct info,___edi) }; #define REG_(x) (*(long *)(reg_offset[(x)]+(u_char *) FPU_info)) static int reg_offset_vm86[] = { offsetof(struct info,___cs), offsetof(struct info,___vm86_ds), offsetof(struct info,___vm86_es), offsetof(struct info,___vm86_fs), offsetof(struct info,___vm86_gs), offsetof(struct info,___ss), offsetof(struct info,___vm86_ds) }; #define VM86_REG_(x) (*(unsigned short *) \ (reg_offset_vm86[((unsigned)x)]+(u_char *) FPU_info)) /* These are dummy, fs and gs are not saved on the stack. */ #define ___FS ___ds #define ___GS ___ds static int reg_offset_pm[] = { offsetof(struct info,___cs), offsetof(struct info,___ds), offsetof(struct info,___es), offsetof(struct info,___FS), offsetof(struct info,___GS), offsetof(struct info,___ss), offsetof(struct info,___ds) }; #define PM_REG_(x) (*(unsigned short *) \ (reg_offset_pm[((unsigned)x)]+(u_char *) FPU_info)) /* Decode the SIB byte. This function assumes mod != 0 */ static int sib(int mod, unsigned long *fpu_eip) { u_char ss,index,base; long offset; RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(1); FPU_get_user(base, (u_char *) (*fpu_eip)); /* The SIB byte */ RE_ENTRANT_CHECK_ON; (*fpu_eip)++; ss = base >> 6; index = (base >> 3) & 7; base &= 7; if ((mod == 0) && (base == 5)) offset = 0; /* No base register */ else offset = REG_(base); if (index == 4) { /* No index register */ /* A non-zero ss is illegal */ if ( ss ) EXCEPTION(EX_Invalid); } else { offset += (REG_(index)) << ss; } if (mod == 1) { /* 8 bit signed displacement */ long displacement; RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(1); FPU_get_user(displacement, (signed char *) (*fpu_eip)); offset += displacement; RE_ENTRANT_CHECK_ON; (*fpu_eip)++; } else if (mod == 2 || base == 5) /* The second condition also has mod==0 */ { /* 32 bit displacement */ long displacement; RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(4); FPU_get_user(displacement, (long *) (*fpu_eip)); offset += displacement; RE_ENTRANT_CHECK_ON; (*fpu_eip) += 4; } return offset; } static unsigned long vm86_segment(u_char segment, struct address *addr) { segment--; #ifdef PARANOID if ( segment > PREFIX_SS_ ) { EXCEPTION(EX_INTERNAL|0x130); math_abort(FPU_info,SIGSEGV); } #endif PARANOID addr->selector = VM86_REG_(segment); return (unsigned long)VM86_REG_(segment) << 4; } /* This should work for 16 and 32 bit protected mode. */ static long pm_address(u_char FPU_modrm, u_char segment, struct address *addr, long offset) { struct desc_struct descriptor; unsigned long base_address, limit, address, seg_top; segment--; #ifdef PARANOID /* segment is unsigned, so this also detects if segment was 0: */ if ( segment > PREFIX_SS_ ) { EXCEPTION(EX_INTERNAL|0x132); math_abort(FPU_info,SIGSEGV); } #endif PARANOID switch ( segment ) { /* fs and gs aren't used by the kernel, so they still have their user-space values. */ case PREFIX_FS_-1: /* The cast is needed here to get gcc 2.8.0 to use a 16 bit register in the assembler statement. */ __asm__("mov %%fs,%0":"=r" ((unsigned short)addr->selector)); break; case PREFIX_GS_-1: /* The cast is needed here to get gcc 2.8.0 to use a 16 bit register in the assembler statement. */ __asm__("mov %%gs,%0":"=r" ((unsigned short)addr->selector)); break; default: addr->selector = PM_REG_(segment); } descriptor = LDT_DESCRIPTOR(PM_REG_(segment)); base_address = SEG_BASE_ADDR(descriptor); address = base_address + offset; limit = base_address + (SEG_LIMIT(descriptor)+1) * SEG_GRANULARITY(descriptor) - 1; if ( limit < base_address ) limit = 0xffffffff; if ( SEG_EXPAND_DOWN(descriptor) ) { if ( SEG_G_BIT(descriptor) ) seg_top = 0xffffffff; else { seg_top = base_address + (1 << 20); if ( seg_top < base_address ) seg_top = 0xffffffff; } access_limit = (address <= limit) || (address >= seg_top) ? 0 : ((seg_top-address) >= 255 ? 255 : seg_top-address); } else { access_limit = (address > limit) || (address < base_address) ? 0 : ((limit-address) >= 254 ? 255 : limit-address+1); } if ( SEG_EXECUTE_ONLY(descriptor) || (!SEG_WRITE_PERM(descriptor) && (FPU_modrm & FPU_WRITE_BIT)) ) { access_limit = 0; } return address; } /* MOD R/M byte: MOD == 3 has a special use for the FPU SIB byte used iff R/M = 100b 7 6 5 4 3 2 1 0 ..... ......... ......... MOD OPCODE(2) R/M SIB byte 7 6 5 4 3 2 1 0 ..... ......... ......... SS INDEX BASE */ void *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip, struct address *addr, fpu_addr_modes addr_modes) { u_char mod; unsigned rm = FPU_modrm & 7; long *cpu_reg_ptr; int address = 0; /* Initialized just to stop compiler warnings. */ /* Memory accessed via the cs selector is write protected in `non-segmented' 32 bit protected mode. */ if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) && (addr_modes.override.segment == PREFIX_CS_) ) { math_abort(FPU_info,SIGSEGV); } addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ mod = (FPU_modrm >> 6) & 3; if (rm == 4 && mod != 3) { address = sib(mod, fpu_eip); } else { cpu_reg_ptr = & REG_(rm); switch (mod) { case 0: if (rm == 5) { /* Special case: disp32 */ RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(4); FPU_get_user(address, (unsigned long *) (*fpu_eip)); (*fpu_eip) += 4; RE_ENTRANT_CHECK_ON; addr->offset = address; return (void *) address; } else { address = *cpu_reg_ptr; /* Just return the contents of the cpu register */ addr->offset = address; return (void *) address; } case 1: /* 8 bit signed displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(1); FPU_get_user(address, (signed char *) (*fpu_eip)); RE_ENTRANT_CHECK_ON; (*fpu_eip)++; break; case 2: /* 32 bit displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(4); FPU_get_user(address, (long *) (*fpu_eip)); (*fpu_eip) += 4; RE_ENTRANT_CHECK_ON; break; case 3: /* Not legal for the FPU */ EXCEPTION(EX_Invalid); } address += *cpu_reg_ptr; } addr->offset = address; switch ( addr_modes.default_mode ) { case 0: break; case VM86: address += vm86_segment(addr_modes.override.segment, addr); break; case PM16: case SEG32: address = pm_address(FPU_modrm, addr_modes.override.segment, addr, address); break; default: EXCEPTION(EX_INTERNAL|0x133); } return (void *)address; } void *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip, struct address *addr, fpu_addr_modes addr_modes) { u_char mod; unsigned rm = FPU_modrm & 7; int address = 0; /* Default used for mod == 0 */ /* Memory accessed via the cs selector is write protected in `non-segmented' 32 bit protected mode. */ if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) && (addr_modes.override.segment == PREFIX_CS_) ) { math_abort(FPU_info,SIGSEGV); } addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ mod = (FPU_modrm >> 6) & 3; switch (mod) { case 0: if (rm == 6) { /* Special case: disp16 */ RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(2); FPU_get_user(address, (unsigned short *) (*fpu_eip)); (*fpu_eip) += 2; RE_ENTRANT_CHECK_ON; goto add_segment; } break; case 1: /* 8 bit signed displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(1); FPU_get_user(address, (signed char *) (*fpu_eip)); RE_ENTRANT_CHECK_ON; (*fpu_eip)++; break; case 2: /* 16 bit displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_verify_area(2); FPU_get_user(address, (unsigned short *) (*fpu_eip)); (*fpu_eip) += 2; RE_ENTRANT_CHECK_ON; break; case 3: /* Not legal for the FPU */ EXCEPTION(EX_Invalid); break; } switch ( rm ) { case 0: address += FPU_info->___ebx + FPU_info->___esi; break; case 1: address += FPU_info->___ebx + FPU_info->___edi; break; case 2: address += FPU_info->___ebp + FPU_info->___esi; if ( addr_modes.override.segment == PREFIX_DEFAULT ) addr_modes.override.segment = PREFIX_SS_; break; case 3: address += FPU_info->___ebp + FPU_info->___edi; if ( addr_modes.override.segment == PREFIX_DEFAULT ) addr_modes.override.segment = PREFIX_SS_; break; case 4: address += FPU_info->___esi; break; case 5: address += FPU_info->___edi; break; case 6: address += FPU_info->___ebp; if ( addr_modes.override.segment == PREFIX_DEFAULT ) addr_modes.override.segment = PREFIX_SS_; break; case 7: address += FPU_info->___ebx; break; } add_segment: address &= 0xffff; addr->offset = address; switch ( addr_modes.default_mode ) { case 0: break; case VM86: address += vm86_segment(addr_modes.override.segment, addr); break; case PM16: case SEG32: address = pm_address(FPU_modrm, addr_modes.override.segment, addr, address); break; default: EXCEPTION(EX_INTERNAL|0x131); } return (void *)address ; }