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401 lines
10 KiB
401 lines
10 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/*---------------------------------------------------------------------------+ |
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| get_address.c | |
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| | |
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| Get the effective address from an FPU instruction. | |
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| | |
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| Copyright (C) 1992,1993,1994,1997 | |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | |
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| Australia. E-mail [email protected] | |
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| | |
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| | |
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+---------------------------------------------------------------------------*/ |
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/*---------------------------------------------------------------------------+ |
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| Note: | |
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| The file contains code which accesses user memory. | |
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| Emulator static data may change when user memory is accessed, due to | |
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| other processes using the emulator while swapping is in progress. | |
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+---------------------------------------------------------------------------*/ |
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#include <linux/stddef.h> |
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#include <linux/uaccess.h> |
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#include <asm/vm86.h> |
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#include "fpu_system.h" |
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#include "exception.h" |
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#include "fpu_emu.h" |
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#define FPU_WRITE_BIT 0x10 |
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static int reg_offset[] = { |
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offsetof(struct pt_regs, ax), |
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offsetof(struct pt_regs, cx), |
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offsetof(struct pt_regs, dx), |
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offsetof(struct pt_regs, bx), |
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offsetof(struct pt_regs, sp), |
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offsetof(struct pt_regs, bp), |
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offsetof(struct pt_regs, si), |
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offsetof(struct pt_regs, di) |
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}; |
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#define REG_(x) (*(long *)(reg_offset[(x)] + (u_char *)FPU_info->regs)) |
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static int reg_offset_vm86[] = { |
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offsetof(struct pt_regs, cs), |
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offsetof(struct kernel_vm86_regs, ds), |
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offsetof(struct kernel_vm86_regs, es), |
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offsetof(struct kernel_vm86_regs, fs), |
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offsetof(struct kernel_vm86_regs, gs), |
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offsetof(struct pt_regs, ss), |
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offsetof(struct kernel_vm86_regs, ds) |
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}; |
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#define VM86_REG_(x) (*(unsigned short *) \ |
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(reg_offset_vm86[((unsigned)x)] + (u_char *)FPU_info->regs)) |
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static int reg_offset_pm[] = { |
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offsetof(struct pt_regs, cs), |
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offsetof(struct pt_regs, ds), |
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offsetof(struct pt_regs, es), |
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offsetof(struct pt_regs, fs), |
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offsetof(struct pt_regs, ds), /* dummy, not saved on stack */ |
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offsetof(struct pt_regs, ss), |
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offsetof(struct pt_regs, ds) |
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}; |
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#define PM_REG_(x) (*(unsigned short *) \ |
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(reg_offset_pm[((unsigned)x)] + (u_char *)FPU_info->regs)) |
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/* Decode the SIB byte. This function assumes mod != 0 */ |
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static int sib(int mod, unsigned long *fpu_eip) |
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{ |
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u_char ss, index, base; |
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long offset; |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(1); |
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FPU_get_user(base, (u_char __user *) (*fpu_eip)); /* The SIB byte */ |
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RE_ENTRANT_CHECK_ON; |
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(*fpu_eip)++; |
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ss = base >> 6; |
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index = (base >> 3) & 7; |
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base &= 7; |
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if ((mod == 0) && (base == 5)) |
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offset = 0; /* No base register */ |
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else |
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offset = REG_(base); |
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if (index == 4) { |
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/* No index register */ |
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/* A non-zero ss is illegal */ |
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if (ss) |
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EXCEPTION(EX_Invalid); |
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} else { |
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offset += (REG_(index)) << ss; |
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} |
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if (mod == 1) { |
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/* 8 bit signed displacement */ |
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long displacement; |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(1); |
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FPU_get_user(displacement, (signed char __user *)(*fpu_eip)); |
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offset += displacement; |
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RE_ENTRANT_CHECK_ON; |
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(*fpu_eip)++; |
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} else if (mod == 2 || base == 5) { /* The second condition also has mod==0 */ |
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/* 32 bit displacement */ |
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long displacement; |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(4); |
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FPU_get_user(displacement, (long __user *)(*fpu_eip)); |
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offset += displacement; |
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RE_ENTRANT_CHECK_ON; |
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(*fpu_eip) += 4; |
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} |
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return offset; |
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} |
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static unsigned long vm86_segment(u_char segment, struct address *addr) |
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{ |
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segment--; |
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#ifdef PARANOID |
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if (segment > PREFIX_SS_) { |
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EXCEPTION(EX_INTERNAL | 0x130); |
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math_abort(FPU_info, SIGSEGV); |
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} |
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#endif /* PARANOID */ |
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addr->selector = VM86_REG_(segment); |
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return (unsigned long)VM86_REG_(segment) << 4; |
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} |
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/* This should work for 16 and 32 bit protected mode. */ |
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static long pm_address(u_char FPU_modrm, u_char segment, |
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struct address *addr, long offset) |
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{ |
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struct desc_struct descriptor; |
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unsigned long base_address, limit, address, seg_top; |
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segment--; |
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#ifdef PARANOID |
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/* segment is unsigned, so this also detects if segment was 0: */ |
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if (segment > PREFIX_SS_) { |
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EXCEPTION(EX_INTERNAL | 0x132); |
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math_abort(FPU_info, SIGSEGV); |
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} |
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#endif /* PARANOID */ |
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switch (segment) { |
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case PREFIX_GS_ - 1: |
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/* user gs handling can be lazy, use special accessors */ |
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addr->selector = get_user_gs(FPU_info->regs); |
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break; |
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default: |
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addr->selector = PM_REG_(segment); |
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} |
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descriptor = FPU_get_ldt_descriptor(addr->selector); |
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base_address = seg_get_base(&descriptor); |
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address = base_address + offset; |
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limit = seg_get_limit(&descriptor) + 1; |
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limit *= seg_get_granularity(&descriptor); |
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limit += base_address - 1; |
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if (limit < base_address) |
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limit = 0xffffffff; |
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if (seg_expands_down(&descriptor)) { |
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if (descriptor.g) { |
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seg_top = 0xffffffff; |
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} else { |
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seg_top = base_address + (1 << 20); |
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if (seg_top < base_address) |
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seg_top = 0xffffffff; |
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} |
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access_limit = |
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(address <= limit) || (address >= seg_top) ? 0 : |
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((seg_top - address) >= 255 ? 255 : seg_top - address); |
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} else { |
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access_limit = |
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(address > limit) || (address < base_address) ? 0 : |
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((limit - address) >= 254 ? 255 : limit - address + 1); |
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} |
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if (seg_execute_only(&descriptor) || |
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(!seg_writable(&descriptor) && (FPU_modrm & FPU_WRITE_BIT))) { |
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access_limit = 0; |
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} |
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return address; |
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} |
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/* |
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MOD R/M byte: MOD == 3 has a special use for the FPU |
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SIB byte used iff R/M = 100b |
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7 6 5 4 3 2 1 0 |
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..... ......... ......... |
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MOD OPCODE(2) R/M |
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SIB byte |
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7 6 5 4 3 2 1 0 |
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..... ......... ......... |
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SS INDEX BASE |
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*/ |
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void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip, |
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struct address *addr, fpu_addr_modes addr_modes) |
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{ |
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u_char mod; |
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unsigned rm = FPU_modrm & 7; |
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long *cpu_reg_ptr; |
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int address = 0; /* Initialized just to stop compiler warnings. */ |
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/* Memory accessed via the cs selector is write protected |
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in `non-segmented' 32 bit protected mode. */ |
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if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) |
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&& (addr_modes.override.segment == PREFIX_CS_)) { |
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math_abort(FPU_info, SIGSEGV); |
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} |
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addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ |
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mod = (FPU_modrm >> 6) & 3; |
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if (rm == 4 && mod != 3) { |
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address = sib(mod, fpu_eip); |
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} else { |
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cpu_reg_ptr = ®_(rm); |
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switch (mod) { |
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case 0: |
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if (rm == 5) { |
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/* Special case: disp32 */ |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(4); |
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FPU_get_user(address, |
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(unsigned long __user |
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*)(*fpu_eip)); |
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(*fpu_eip) += 4; |
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RE_ENTRANT_CHECK_ON; |
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addr->offset = address; |
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return (void __user *)address; |
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} else { |
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address = *cpu_reg_ptr; /* Just return the contents |
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of the cpu register */ |
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addr->offset = address; |
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return (void __user *)address; |
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} |
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case 1: |
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/* 8 bit signed displacement */ |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(1); |
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FPU_get_user(address, (signed char __user *)(*fpu_eip)); |
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RE_ENTRANT_CHECK_ON; |
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(*fpu_eip)++; |
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break; |
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case 2: |
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/* 32 bit displacement */ |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(4); |
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FPU_get_user(address, (long __user *)(*fpu_eip)); |
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(*fpu_eip) += 4; |
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RE_ENTRANT_CHECK_ON; |
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break; |
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case 3: |
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/* Not legal for the FPU */ |
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EXCEPTION(EX_Invalid); |
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} |
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address += *cpu_reg_ptr; |
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} |
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addr->offset = address; |
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switch (addr_modes.default_mode) { |
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case 0: |
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break; |
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case VM86: |
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address += vm86_segment(addr_modes.override.segment, addr); |
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break; |
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case PM16: |
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case SEG32: |
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address = pm_address(FPU_modrm, addr_modes.override.segment, |
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addr, address); |
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break; |
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default: |
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EXCEPTION(EX_INTERNAL | 0x133); |
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} |
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return (void __user *)address; |
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} |
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void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip, |
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struct address *addr, fpu_addr_modes addr_modes) |
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{ |
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u_char mod; |
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unsigned rm = FPU_modrm & 7; |
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int address = 0; /* Default used for mod == 0 */ |
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/* Memory accessed via the cs selector is write protected |
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in `non-segmented' 32 bit protected mode. */ |
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if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) |
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&& (addr_modes.override.segment == PREFIX_CS_)) { |
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math_abort(FPU_info, SIGSEGV); |
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} |
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addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ |
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mod = (FPU_modrm >> 6) & 3; |
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switch (mod) { |
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case 0: |
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if (rm == 6) { |
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/* Special case: disp16 */ |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(2); |
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FPU_get_user(address, |
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(unsigned short __user *)(*fpu_eip)); |
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(*fpu_eip) += 2; |
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RE_ENTRANT_CHECK_ON; |
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goto add_segment; |
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} |
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break; |
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case 1: |
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/* 8 bit signed displacement */ |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(1); |
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FPU_get_user(address, (signed char __user *)(*fpu_eip)); |
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RE_ENTRANT_CHECK_ON; |
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(*fpu_eip)++; |
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break; |
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case 2: |
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/* 16 bit displacement */ |
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RE_ENTRANT_CHECK_OFF; |
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FPU_code_access_ok(2); |
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FPU_get_user(address, (unsigned short __user *)(*fpu_eip)); |
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(*fpu_eip) += 2; |
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RE_ENTRANT_CHECK_ON; |
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break; |
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case 3: |
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/* Not legal for the FPU */ |
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EXCEPTION(EX_Invalid); |
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break; |
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} |
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switch (rm) { |
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case 0: |
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address += FPU_info->regs->bx + FPU_info->regs->si; |
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break; |
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case 1: |
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address += FPU_info->regs->bx + FPU_info->regs->di; |
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break; |
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case 2: |
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address += FPU_info->regs->bp + FPU_info->regs->si; |
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if (addr_modes.override.segment == PREFIX_DEFAULT) |
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addr_modes.override.segment = PREFIX_SS_; |
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break; |
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case 3: |
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address += FPU_info->regs->bp + FPU_info->regs->di; |
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if (addr_modes.override.segment == PREFIX_DEFAULT) |
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addr_modes.override.segment = PREFIX_SS_; |
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break; |
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case 4: |
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address += FPU_info->regs->si; |
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break; |
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case 5: |
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address += FPU_info->regs->di; |
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break; |
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case 6: |
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address += FPU_info->regs->bp; |
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if (addr_modes.override.segment == PREFIX_DEFAULT) |
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addr_modes.override.segment = PREFIX_SS_; |
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break; |
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case 7: |
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address += FPU_info->regs->bx; |
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break; |
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} |
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add_segment: |
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address &= 0xffff; |
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addr->offset = address; |
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switch (addr_modes.default_mode) { |
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case 0: |
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break; |
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case VM86: |
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address += vm86_segment(addr_modes.override.segment, addr); |
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break; |
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case PM16: |
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case SEG32: |
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address = pm_address(FPU_modrm, addr_modes.override.segment, |
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addr, address); |
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break; |
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default: |
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EXCEPTION(EX_INTERNAL | 0x131); |
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} |
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return (void __user *)address; |
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}
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