cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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reg_constant.c (3848B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*---------------------------------------------------------------------------+
      3 |  reg_constant.c                                                           |
      4 |                                                                           |
      5 | All of the constant FPU_REGs                                              |
      6 |                                                                           |
      7 | Copyright (C) 1992,1993,1994,1997                                         |
      8 |                     W. Metzenthen, 22 Parker St, Ormond, Vic 3163,        |
      9 |                     Australia.  E-mail   billm@suburbia.net               |
     10 |                                                                           |
     11 |                                                                           |
     12 +---------------------------------------------------------------------------*/
     13
     14#include "fpu_system.h"
     15#include "fpu_emu.h"
     16#include "status_w.h"
     17#include "reg_constant.h"
     18#include "control_w.h"
     19
     20#define MAKE_REG(s, e, l, h) { l, h, \
     21		(u16)((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) }
     22
     23FPU_REG const CONST_1 = MAKE_REG(POS, 0, 0x00000000, 0x80000000);
     24#if 0
     25FPU_REG const CONST_2 = MAKE_REG(POS, 1, 0x00000000, 0x80000000);
     26FPU_REG const CONST_HALF = MAKE_REG(POS, -1, 0x00000000, 0x80000000);
     27#endif /*  0  */
     28static FPU_REG const CONST_L2T = MAKE_REG(POS, 1, 0xcd1b8afe, 0xd49a784b);
     29static FPU_REG const CONST_L2E = MAKE_REG(POS, 0, 0x5c17f0bc, 0xb8aa3b29);
     30FPU_REG const CONST_PI = MAKE_REG(POS, 1, 0x2168c235, 0xc90fdaa2);
     31FPU_REG const CONST_PI2 = MAKE_REG(POS, 0, 0x2168c235, 0xc90fdaa2);
     32FPU_REG const CONST_PI4 = MAKE_REG(POS, -1, 0x2168c235, 0xc90fdaa2);
     33static FPU_REG const CONST_LG2 = MAKE_REG(POS, -2, 0xfbcff799, 0x9a209a84);
     34static FPU_REG const CONST_LN2 = MAKE_REG(POS, -1, 0xd1cf79ac, 0xb17217f7);
     35
     36/* Extra bits to take pi/2 to more than 128 bits precision. */
     37FPU_REG const CONST_PI2extra = MAKE_REG(NEG, -66,
     38					0xfc8f8cbb, 0xece675d1);
     39
     40/* Only the sign (and tag) is used in internal zeroes */
     41FPU_REG const CONST_Z = MAKE_REG(POS, EXP_UNDER, 0x0, 0x0);
     42
     43/* Only the sign and significand (and tag) are used in internal NaNs */
     44/* The 80486 never generates one of these
     45FPU_REG const CONST_SNAN = MAKE_REG(POS, EXP_OVER, 0x00000001, 0x80000000);
     46 */
     47/* This is the real indefinite QNaN */
     48FPU_REG const CONST_QNaN = MAKE_REG(NEG, EXP_OVER, 0x00000000, 0xC0000000);
     49
     50/* Only the sign (and tag) is used in internal infinities */
     51FPU_REG const CONST_INF = MAKE_REG(POS, EXP_OVER, 0x00000000, 0x80000000);
     52
     53static void fld_const(FPU_REG const * c, int adj, u_char tag)
     54{
     55	FPU_REG *st_new_ptr;
     56
     57	if (STACK_OVERFLOW) {
     58		FPU_stack_overflow();
     59		return;
     60	}
     61	push();
     62	reg_copy(c, st_new_ptr);
     63	st_new_ptr->sigl += adj;	/* For all our fldxxx constants, we don't need to
     64					   borrow or carry. */
     65	FPU_settag0(tag);
     66	clear_C1();
     67}
     68
     69/* A fast way to find out whether x is one of RC_DOWN or RC_CHOP
     70   (and not one of RC_RND or RC_UP).
     71   */
     72#define DOWN_OR_CHOP(x)  (x & RC_DOWN)
     73
     74static void fld1(int rc)
     75{
     76	fld_const(&CONST_1, 0, TAG_Valid);
     77}
     78
     79static void fldl2t(int rc)
     80{
     81	fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0, TAG_Valid);
     82}
     83
     84static void fldl2e(int rc)
     85{
     86	fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
     87}
     88
     89static void fldpi(int rc)
     90{
     91	fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
     92}
     93
     94static void fldlg2(int rc)
     95{
     96	fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
     97}
     98
     99static void fldln2(int rc)
    100{
    101	fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
    102}
    103
    104static void fldz(int rc)
    105{
    106	fld_const(&CONST_Z, 0, TAG_Zero);
    107}
    108
    109typedef void (*FUNC_RC) (int);
    110
    111static FUNC_RC constants_table[] = {
    112	fld1, fldl2t, fldl2e, fldpi, fldlg2, fldln2, fldz, (FUNC_RC) FPU_illegal
    113};
    114
    115void fconst(void)
    116{
    117	(constants_table[FPU_rm]) (control_word & CW_RC);
    118}