From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: AndrĂ© Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/x86/math-emu/get_address.c | 399 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 399 insertions(+) create mode 100644 arch/x86/math-emu/get_address.c (limited to 'arch/x86/math-emu/get_address.c') diff --git a/arch/x86/math-emu/get_address.c b/arch/x86/math-emu/get_address.c new file mode 100644 index 000000000..6ef5e9938 --- /dev/null +++ b/arch/x86/math-emu/get_address.c @@ -0,0 +1,399 @@ +/*---------------------------------------------------------------------------+ + | 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 + +#include "fpu_system.h" +#include "exception.h" +#include "fpu_emu.h" + +#define FPU_WRITE_BIT 0x10 + +static int reg_offset[] = { + offsetof(struct pt_regs, ax), + offsetof(struct pt_regs, cx), + offsetof(struct pt_regs, dx), + offsetof(struct pt_regs, bx), + offsetof(struct pt_regs, sp), + offsetof(struct pt_regs, bp), + offsetof(struct pt_regs, si), + offsetof(struct pt_regs, di) +}; + +#define REG_(x) (*(long *)(reg_offset[(x)] + (u_char *)FPU_info->regs)) + +static int reg_offset_vm86[] = { + offsetof(struct pt_regs, cs), + offsetof(struct kernel_vm86_regs, ds), + offsetof(struct kernel_vm86_regs, es), + offsetof(struct kernel_vm86_regs, fs), + offsetof(struct kernel_vm86_regs, gs), + offsetof(struct pt_regs, ss), + offsetof(struct kernel_vm86_regs, ds) +}; + +#define VM86_REG_(x) (*(unsigned short *) \ + (reg_offset_vm86[((unsigned)x)] + (u_char *)FPU_info->regs)) + +static int reg_offset_pm[] = { + offsetof(struct pt_regs, cs), + offsetof(struct pt_regs, ds), + offsetof(struct pt_regs, es), + offsetof(struct pt_regs, fs), + offsetof(struct pt_regs, ds), /* dummy, not saved on stack */ + offsetof(struct pt_regs, ss), + offsetof(struct pt_regs, ds) +}; + +#define PM_REG_(x) (*(unsigned short *) \ + (reg_offset_pm[((unsigned)x)] + (u_char *)FPU_info->regs)) + +/* 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_access_ok(1); + FPU_get_user(base, (u_char __user *) (*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_access_ok(1); + FPU_get_user(displacement, (signed char __user *)(*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_access_ok(4); + FPU_get_user(displacement, (long __user *)(*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) { + case PREFIX_GS_ - 1: + /* user gs handling can be lazy, use special accessors */ + addr->selector = get_user_gs(FPU_info->regs); + 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 __user *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 = ®_(rm); + switch (mod) { + case 0: + if (rm == 5) { + /* Special case: disp32 */ + RE_ENTRANT_CHECK_OFF; + FPU_code_access_ok(4); + FPU_get_user(address, + (unsigned long __user + *)(*fpu_eip)); + (*fpu_eip) += 4; + RE_ENTRANT_CHECK_ON; + addr->offset = address; + return (void __user *)address; + } else { + address = *cpu_reg_ptr; /* Just return the contents + of the cpu register */ + addr->offset = address; + return (void __user *)address; + } + case 1: + /* 8 bit signed displacement */ + RE_ENTRANT_CHECK_OFF; + FPU_code_access_ok(1); + FPU_get_user(address, (signed char __user *)(*fpu_eip)); + RE_ENTRANT_CHECK_ON; + (*fpu_eip)++; + break; + case 2: + /* 32 bit displacement */ + RE_ENTRANT_CHECK_OFF; + FPU_code_access_ok(4); + FPU_get_user(address, (long __user *)(*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 __user *)address; +} + +void __user *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_access_ok(2); + FPU_get_user(address, + (unsigned short __user *)(*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_access_ok(1); + FPU_get_user(address, (signed char __user *)(*fpu_eip)); + RE_ENTRANT_CHECK_ON; + (*fpu_eip)++; + break; + case 2: + /* 16 bit displacement */ + RE_ENTRANT_CHECK_OFF; + FPU_code_access_ok(2); + FPU_get_user(address, (unsigned short __user *)(*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->regs->bx + FPU_info->regs->si; + break; + case 1: + address += FPU_info->regs->bx + FPU_info->regs->di; + break; + case 2: + address += FPU_info->regs->bp + FPU_info->regs->si; + if (addr_modes.override.segment == PREFIX_DEFAULT) + addr_modes.override.segment = PREFIX_SS_; + break; + case 3: + address += FPU_info->regs->bp + FPU_info->regs->di; + if (addr_modes.override.segment == PREFIX_DEFAULT) + addr_modes.override.segment = PREFIX_SS_; + break; + case 4: + address += FPU_info->regs->si; + break; + case 5: + address += FPU_info->regs->di; + break; + case 6: + address += FPU_info->regs->bp; + if (addr_modes.override.segment == PREFIX_DEFAULT) + addr_modes.override.segment = PREFIX_SS_; + break; + case 7: + address += FPU_info->regs->bx; + 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 __user *)address; +} -- cgit v1.2.3-54-g00ecf