622 lines
18 KiB
C
622 lines
18 KiB
C
/*---------------------------------------------------------------------------+
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| fpu_entry.c |
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| |
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| The entry function for wm-FPU-emu |
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| |
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| Copyright (C) 1992,1993,1994 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@vaxc.cc.monash.edu.au |
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| |
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| See the files "README" and "COPYING" for further copyright and warranty |
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| information. |
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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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/*---------------------------------------------------------------------------+
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| math_emulate() is the sole entry point for wm-FPU-emu |
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+---------------------------------------------------------------------------*/
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#include <linux/signal.h>
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#include <linux/segment.h>
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#include "fpu_system.h"
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#include "fpu_emu.h"
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#include "exception.h"
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#include "control_w.h"
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#include "status_w.h"
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#include <asm/segment.h>
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#define __BAD__ FPU_illegal /* Illegal on an 80486, causes SIGILL */
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#ifndef NO_UNDOC_CODE /* Un-documented FPU op-codes supported by default. */
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/* WARNING: These codes are not documented by Intel in their 80486 manual
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and may not work on FPU clones or later Intel FPUs. */
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/* Changes to support the un-doc codes provided by Linus Torvalds. */
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#define _d9_d8_ fstp_i /* unofficial code (19) */
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#define _dc_d0_ fcom_st /* unofficial code (14) */
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#define _dc_d8_ fcompst /* unofficial code (1c) */
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#define _dd_c8_ fxch_i /* unofficial code (0d) */
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#define _de_d0_ fcompst /* unofficial code (16) */
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#define _df_c0_ ffreep /* unofficial code (07) ffree + pop */
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#define _df_c8_ fxch_i /* unofficial code (0f) */
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#define _df_d0_ fstp_i /* unofficial code (17) */
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#define _df_d8_ fstp_i /* unofficial code (1f) */
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static FUNC const st_instr_table[64] = {
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fadd__, fld_i_, __BAD__, __BAD__, fadd_i, ffree_, faddp_, _df_c0_,
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fmul__, fxch_i, __BAD__, __BAD__, fmul_i, _dd_c8_, fmulp_, _df_c8_,
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fcom_st, fp_nop, __BAD__, __BAD__, _dc_d0_, fst_i_, _de_d0_, _df_d0_,
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fcompst, _d9_d8_, __BAD__, __BAD__, _dc_d8_, fstp_i, fcompp, _df_d8_,
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fsub__, fp_etc, __BAD__, finit_, fsubri, fucom_, fsubrp, fstsw_,
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fsubr_, fconst, fucompp, __BAD__, fsub_i, fucomp, fsubp_, __BAD__,
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fdiv__, trig_a, __BAD__, __BAD__, fdivri, __BAD__, fdivrp, __BAD__,
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fdivr_, trig_b, __BAD__, __BAD__, fdiv_i, __BAD__, fdivp_, __BAD__,
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};
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#else /* Support only documented FPU op-codes */
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static FUNC const st_instr_table[64] = {
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fadd__, fld_i_, __BAD__, __BAD__, fadd_i, ffree_, faddp_, __BAD__,
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fmul__, fxch_i, __BAD__, __BAD__, fmul_i, __BAD__, fmulp_, __BAD__,
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fcom_st, fp_nop, __BAD__, __BAD__, __BAD__, fst_i_, __BAD__, __BAD__,
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fcompst, __BAD__, __BAD__, __BAD__, __BAD__, fstp_i, fcompp, __BAD__,
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fsub__, fp_etc, __BAD__, finit_, fsubri, fucom_, fsubrp, fstsw_,
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fsubr_, fconst, fucompp, __BAD__, fsub_i, fucomp, fsubp_, __BAD__,
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fdiv__, trig_a, __BAD__, __BAD__, fdivri, __BAD__, fdivrp, __BAD__,
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fdivr_, trig_b, __BAD__, __BAD__, fdiv_i, __BAD__, fdivp_, __BAD__,
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};
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#endif NO_UNDOC_CODE
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#define _NONE_ 0 /* Take no special action */
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#define _REG0_ 1 /* Need to check for not empty st(0) */
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#define _REGI_ 2 /* Need to check for not empty st(0) and st(rm) */
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#define _REGi_ 0 /* Uses st(rm) */
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#define _PUSH_ 3 /* Need to check for space to push onto stack */
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#define _null_ 4 /* Function illegal or not implemented */
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#define _REGIi 5 /* Uses st(0) and st(rm), result to st(rm) */
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#define _REGIp 6 /* Uses st(0) and st(rm), result to st(rm) then pop */
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#define _REGIc 0 /* Compare st(0) and st(rm) */
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#define _REGIn 0 /* Uses st(0) and st(rm), but handle checks later */
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#ifndef NO_UNDOC_CODE
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/* Un-documented FPU op-codes supported by default. (see above) */
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static unsigned char const type_table[64] = {
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_REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _REGi_,
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_REGI_, _REGIn, _null_, _null_, _REGIi, _REGI_, _REGIp, _REGI_,
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_REGIc, _NONE_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
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_REGIc, _REG0_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
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_REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
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_REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
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_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
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_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
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};
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#else /* Support only documented FPU op-codes */
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static unsigned char const type_table[64] = {
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_REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _null_,
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_REGI_, _REGIn, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
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_REGIc, _NONE_, _null_, _null_, _null_, _REG0_, _null_, _null_,
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_REGIc, _null_, _null_, _null_, _null_, _REG0_, _REGIc, _null_,
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_REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
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_REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
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_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
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_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
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};
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#endif NO_UNDOC_CODE
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/* Be careful when using any of these global variables...
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they might change if swapping is triggered */
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unsigned char FPU_rm;
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char FPU_st0_tag;
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FPU_REG *FPU_st0_ptr;
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/* ######## To be shifted */
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unsigned long FPU_entry_op_cs;
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unsigned short FPU_data_selector;
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#ifdef PARANOID
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char emulating=0;
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#endif PARANOID
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static int valid_prefix(unsigned char *byte, overrides *override);
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asmlinkage void math_emulate(long arg)
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{
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unsigned char FPU_modrm, byte1;
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overrides override;
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int unmasked;
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#ifdef PARANOID
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if ( emulating )
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{
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printk("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
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}
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RE_ENTRANT_CHECK_ON;
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#endif PARANOID
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if (!current->used_math)
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{
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int i;
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for ( i = 0; i < 8; i++ )
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{
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/* Make sure that the registers are compatible
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with the assumptions of the emulator. */
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regs[i].exp = 0;
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regs[i].sigh = 0x80000000;
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}
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finit();
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current->used_math = 1;
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}
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SETUP_DATA_AREA(arg);
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FPU_ORIG_EIP = FPU_EIP;
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/* We cannot handle emulation in v86-mode */
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if (FPU_EFLAGS & 0x00020000)
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{
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math_abort(FPU_info,SIGILL);
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}
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/* user code space? */
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if (FPU_CS == KERNEL_CS)
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{
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printk("math_emulate: %04x:%08lx\n",FPU_CS,FPU_EIP);
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panic("Math emulation needed in kernel");
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}
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/* We cannot handle multiple segments yet */
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if (FPU_CS != USER_CS || FPU_DS != USER_DS)
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{
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math_abort(FPU_info,SIGILL);
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}
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FPU_lookahead = 1;
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if (current->flags & PF_PTRACED)
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FPU_lookahead = 0;
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if ( !valid_prefix(&byte1, &override) )
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{
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RE_ENTRANT_CHECK_OFF;
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printk("FPU emulator: Unknown prefix byte 0x%02x\n", byte1);
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RE_ENTRANT_CHECK_ON;
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EXCEPTION(EX_INTERNAL|0x126);
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math_abort(FPU_info,SIGILL);
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}
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do_another_FPU_instruction:
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FPU_EIP++; /* We have fetched the prefix and first code bytes. */
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#ifdef PECULIAR_486
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/* It would be more logical to do this only in get_address(),
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but although it is supposed to be undefined for many fpu
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instructions, an 80486 behaves as if this were done here: */
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FPU_data_selector = FPU_DS;
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#endif PECULIAR_486
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if ( (byte1 & 0xf8) != 0xd8 )
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{
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if ( byte1 == FWAIT_OPCODE )
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{
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if (partial_status & SW_Summary)
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goto do_the_FPU_interrupt;
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else
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goto FPU_fwait_done;
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}
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#ifdef PARANOID
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EXCEPTION(EX_INTERNAL|0x128);
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math_abort(FPU_info,SIGILL);
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#endif PARANOID
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}
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RE_ENTRANT_CHECK_OFF;
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FPU_code_verify_area(1);
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FPU_modrm = get_fs_byte((unsigned short *) FPU_EIP);
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RE_ENTRANT_CHECK_ON;
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FPU_EIP++;
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if (partial_status & SW_Summary)
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{
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/* Ignore the error for now if the current instruction is a no-wait
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control instruction */
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/* The 80486 manual contradicts itself on this topic,
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but a real 80486 uses the following instructions:
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fninit, fnstenv, fnsave, fnstsw, fnstenv, fnclex.
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*/
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unsigned short code = (FPU_modrm << 8) | byte1;
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if ( ! ( (((code & 0xf803) == 0xe003) || /* fnclex, fninit, fnstsw */
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(((code & 0x3003) == 0x3001) && /* fnsave, fnstcw, fnstenv,
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fnstsw */
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((code & 0xc000) != 0xc000))) ) )
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{
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/*
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* We need to simulate the action of the kernel to FPU
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* interrupts here.
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* Currently, the "real FPU" part of the kernel (0.99.10)
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* clears the exception flags, sets the registers to empty,
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* and passes information back to the interrupted process
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* via the cs selector and operand selector, so we do the same.
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*/
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do_the_FPU_interrupt:
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cs_selector &= 0xffff0000;
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cs_selector |= status_word();
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operand_selector = tag_word();
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partial_status = 0;
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top = 0;
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{
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int r;
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for (r = 0; r < 8; r++)
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{
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regs[r].tag = TW_Empty;
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}
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}
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RE_ENTRANT_CHECK_OFF;
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current->tss.trap_no = 16;
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current->tss.error_code = 0;
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send_sig(SIGFPE, current, 1);
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return;
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}
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}
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FPU_entry_eip = FPU_ORIG_EIP;
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FPU_entry_op_cs = (byte1 << 24) | (FPU_modrm << 16) | (FPU_CS & 0xffff) ;
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FPU_rm = FPU_modrm & 7;
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if ( FPU_modrm < 0300 )
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{
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/* All of these instructions use the mod/rm byte to get a data address */
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get_address(FPU_modrm, override);
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if ( !(byte1 & 1) )
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{
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unsigned short status1 = partial_status;
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FPU_st0_ptr = &st(0);
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FPU_st0_tag = FPU_st0_ptr->tag;
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/* Stack underflow has priority */
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if ( NOT_EMPTY_0 )
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{
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unmasked = 0; /* Do this here to stop compiler warnings. */
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switch ( (byte1 >> 1) & 3 )
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{
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case 0:
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unmasked = reg_load_single(override);
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break;
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case 1:
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reg_load_int32(override);
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break;
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case 2:
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unmasked = reg_load_double(override);
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break;
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case 3:
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reg_load_int16(override);
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break;
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}
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/* No more access to user memory, it is safe
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to use static data now */
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FPU_st0_ptr = &st(0);
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FPU_st0_tag = FPU_st0_ptr->tag;
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/* NaN operands have the next priority. */
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/* We have to delay looking at st(0) until after
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loading the data, because that data might contain an SNaN */
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if ( (FPU_st0_tag == TW_NaN) ||
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(FPU_loaded_data.tag == TW_NaN) )
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{
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/* Restore the status word; we might have loaded a
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denormal. */
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partial_status = status1;
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if ( (FPU_modrm & 0x30) == 0x10 )
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{
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/* fcom or fcomp */
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EXCEPTION(EX_Invalid);
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setcc(SW_C3 | SW_C2 | SW_C0);
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if ( (FPU_modrm & 0x08) && (control_word & CW_Invalid) )
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pop(); /* fcomp, masked, so we pop. */
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}
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else
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{
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#ifdef PECULIAR_486
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/* This is not really needed, but gives behaviour
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identical to an 80486 */
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if ( (FPU_modrm & 0x28) == 0x20 )
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/* fdiv or fsub */
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real_2op_NaN(&FPU_loaded_data, FPU_st0_ptr,
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FPU_st0_ptr);
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else
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#endif PECULIAR_486
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/* fadd, fdivr, fmul, or fsubr */
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real_2op_NaN(FPU_st0_ptr, &FPU_loaded_data,
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FPU_st0_ptr);
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}
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goto reg_mem_instr_done;
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}
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if ( unmasked && !((FPU_modrm & 0x30) == 0x10) )
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{
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/* Is not a comparison instruction. */
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if ( (FPU_modrm & 0x38) == 0x38 )
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{
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/* fdivr */
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if ( (FPU_st0_tag == TW_Zero) &&
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(FPU_loaded_data.tag == TW_Valid) )
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{
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if ( divide_by_zero(FPU_loaded_data.sign,
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FPU_st0_ptr) )
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{
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/* We use the fact here that the unmasked
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exception in the loaded data was for a
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denormal operand */
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/* Restore the state of the denormal op bit */
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partial_status &= ~SW_Denorm_Op;
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partial_status |= status1 & SW_Denorm_Op;
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}
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}
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}
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goto reg_mem_instr_done;
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}
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switch ( (FPU_modrm >> 3) & 7 )
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{
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case 0: /* fadd */
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clear_C1();
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reg_add(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr,
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control_word);
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break;
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case 1: /* fmul */
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clear_C1();
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reg_mul(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr,
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control_word);
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break;
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case 2: /* fcom */
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compare_st_data();
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break;
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case 3: /* fcomp */
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if ( !compare_st_data() && !unmasked )
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pop();
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break;
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case 4: /* fsub */
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clear_C1();
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reg_sub(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr,
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control_word);
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break;
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case 5: /* fsubr */
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clear_C1();
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reg_sub(&FPU_loaded_data, FPU_st0_ptr, FPU_st0_ptr,
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control_word);
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break;
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case 6: /* fdiv */
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clear_C1();
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reg_div(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr,
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control_word);
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break;
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case 7: /* fdivr */
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clear_C1();
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if ( FPU_st0_tag == TW_Zero )
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partial_status = status1; /* Undo any denorm tag,
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zero-divide has priority. */
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reg_div(&FPU_loaded_data, FPU_st0_ptr, FPU_st0_ptr,
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control_word);
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break;
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}
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}
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else
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{
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if ( (FPU_modrm & 0x30) == 0x10 )
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{
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/* The instruction is fcom or fcomp */
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EXCEPTION(EX_StackUnder);
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setcc(SW_C3 | SW_C2 | SW_C0);
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if ( (FPU_modrm & 0x08) && (control_word & CW_Invalid) )
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pop(); /* fcomp */
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}
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else
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stack_underflow();
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}
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}
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else
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{
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load_store_instr(((FPU_modrm & 0x38) | (byte1 & 6)) >> 1, override);
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}
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reg_mem_instr_done:
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#ifndef PECULIAR_486
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*(unsigned short *)&operand_selector = FPU_data_selector;
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#endif PECULIAR_486
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;
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}
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else
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{
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/* None of these instructions access user memory */
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unsigned char instr_index = (FPU_modrm & 0x38) | (byte1 & 7);
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#ifdef PECULIAR_486
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/* This is supposed to be undefined, but a real 80486 seems
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to do this: */
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FPU_data_address = 0;
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#endif PECULIAR_486
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FPU_st0_ptr = &st(0);
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FPU_st0_tag = FPU_st0_ptr->tag;
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switch ( type_table[(int) instr_index] )
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{
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case _NONE_: /* also _REGIc: _REGIn */
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break;
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case _REG0_:
|
|
if ( !NOT_EMPTY_0 )
|
|
{
|
|
stack_underflow();
|
|
goto FPU_instruction_done;
|
|
}
|
|
break;
|
|
case _REGIi:
|
|
if ( !NOT_EMPTY_0 || !NOT_EMPTY(FPU_rm) )
|
|
{
|
|
stack_underflow_i(FPU_rm);
|
|
goto FPU_instruction_done;
|
|
}
|
|
break;
|
|
case _REGIp:
|
|
if ( !NOT_EMPTY_0 || !NOT_EMPTY(FPU_rm) )
|
|
{
|
|
stack_underflow_pop(FPU_rm);
|
|
goto FPU_instruction_done;
|
|
}
|
|
break;
|
|
case _REGI_:
|
|
if ( !NOT_EMPTY_0 || !NOT_EMPTY(FPU_rm) )
|
|
{
|
|
stack_underflow();
|
|
goto FPU_instruction_done;
|
|
}
|
|
break;
|
|
case _PUSH_: /* Only used by the fld st(i) instruction */
|
|
break;
|
|
case _null_:
|
|
FPU_illegal();
|
|
goto FPU_instruction_done;
|
|
default:
|
|
EXCEPTION(EX_INTERNAL|0x111);
|
|
goto FPU_instruction_done;
|
|
}
|
|
(*st_instr_table[(int) instr_index])();
|
|
}
|
|
|
|
FPU_instruction_done:
|
|
|
|
ip_offset = FPU_entry_eip;
|
|
cs_selector = FPU_entry_op_cs;
|
|
data_operand_offset = (unsigned long)FPU_data_address;
|
|
#ifdef PECULIAR_486
|
|
*(unsigned short *)&operand_selector = FPU_data_selector;
|
|
#endif PECULIAR_486
|
|
|
|
FPU_fwait_done:
|
|
|
|
#ifdef DEBUG
|
|
RE_ENTRANT_CHECK_OFF;
|
|
emu_printall();
|
|
RE_ENTRANT_CHECK_ON;
|
|
#endif DEBUG
|
|
|
|
if (FPU_lookahead && !need_resched)
|
|
{
|
|
FPU_ORIG_EIP = FPU_EIP;
|
|
if ( valid_prefix(&byte1, &override) )
|
|
goto do_another_FPU_instruction;
|
|
}
|
|
|
|
RE_ENTRANT_CHECK_OFF;
|
|
}
|
|
|
|
|
|
/* Support for prefix bytes is not yet complete. To properly handle
|
|
all prefix bytes, further changes are needed in the emulator code
|
|
which accesses user address space. Access to separate segments is
|
|
important for msdos emulation. */
|
|
static int valid_prefix(unsigned char *Byte, overrides *override)
|
|
{
|
|
unsigned char byte;
|
|
unsigned long ip = FPU_EIP;
|
|
|
|
*override = (overrides) { 0, PREFIX_DS }; /* defaults */
|
|
|
|
RE_ENTRANT_CHECK_OFF;
|
|
FPU_code_verify_area(1);
|
|
byte = get_fs_byte((unsigned char *) FPU_EIP);
|
|
RE_ENTRANT_CHECK_ON;
|
|
|
|
while ( 1 )
|
|
{
|
|
switch ( byte )
|
|
{
|
|
case ADDR_SIZE_PREFIX:
|
|
override->address_size = ADDR_SIZE_PREFIX;
|
|
goto do_next_byte;
|
|
case PREFIX_CS:
|
|
override->segment = PREFIX_CS;
|
|
goto do_next_byte;
|
|
case PREFIX_ES:
|
|
override->segment = PREFIX_ES;
|
|
goto do_next_byte;
|
|
case PREFIX_SS:
|
|
override->segment = PREFIX_SS;
|
|
goto do_next_byte;
|
|
case PREFIX_FS:
|
|
override->segment = PREFIX_FS;
|
|
goto do_next_byte;
|
|
case PREFIX_GS:
|
|
override->segment = PREFIX_GS;
|
|
goto do_next_byte;
|
|
|
|
case PREFIX_DS: /* Redundant unless preceded by another override. */
|
|
override->segment = PREFIX_DS;
|
|
|
|
/* rep.. prefixes have no meaning for FPU instructions */
|
|
case PREFIX_LOCK:
|
|
case PREFIX_REPE:
|
|
case PREFIX_REPNE:
|
|
case OP_SIZE_PREFIX: /* Used often by gcc, but has no effect. */
|
|
do_next_byte:
|
|
FPU_EIP++;
|
|
RE_ENTRANT_CHECK_OFF;
|
|
FPU_code_verify_area(1);
|
|
byte = get_fs_byte((unsigned char *) (FPU_EIP));
|
|
RE_ENTRANT_CHECK_ON;
|
|
break;
|
|
case FWAIT_OPCODE:
|
|
*Byte = byte;
|
|
return 1;
|
|
default:
|
|
if ( (byte & 0xf8) == 0xd8 )
|
|
{
|
|
*Byte = byte;
|
|
return 1;
|
|
}
|
|
else
|
|
{
|
|
FPU_EIP = ip;
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void __math_abort(struct info * info, unsigned int signal)
|
|
{
|
|
FPU_EIP = FPU_ORIG_EIP;
|
|
current->tss.trap_no = 16;
|
|
current->tss.error_code = 0;
|
|
send_sig(signal,current,1);
|
|
RE_ENTRANT_CHECK_OFF;
|
|
__asm__("movl %0,%%esp ; ret": :"g" (((long) info)-4));
|
|
#ifdef PARANOID
|
|
printk("ERROR: wm-FPU-emu math_abort failed!\n");
|
|
#endif PARANOID
|
|
}
|