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_norm.S (3709B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*---------------------------------------------------------------------------+
      3 |  reg_norm.S                                                               |
      4 |                                                                           |
      5 | Copyright (C) 1992,1993,1994,1995,1997                                    |
      6 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
      7 |                       Australia.  E-mail billm@suburbia.net               |
      8 |                                                                           |
      9 | Normalize the value in a FPU_REG.                                         |
     10 |                                                                           |
     11 | Call from C as:                                                           |
     12 |    int FPU_normalize(FPU_REG *n)                                          |
     13 |                                                                           |
     14 |    int FPU_normalize_nuo(FPU_REG *n)                                      |
     15 |                                                                           |
     16 |    Return value is the tag of the answer, or-ed with FPU_Exception if     |
     17 |    one was raised, or -1 on internal error.                               |
     18 |                                                                           |
     19 +---------------------------------------------------------------------------*/
     20
     21#include "fpu_emu.h"
     22
     23
     24.text
     25SYM_FUNC_START(FPU_normalize)
     26	pushl	%ebp
     27	movl	%esp,%ebp
     28	pushl	%ebx
     29
     30	movl	PARAM1,%ebx
     31
     32	movl	SIGH(%ebx),%edx
     33	movl	SIGL(%ebx),%eax
     34
     35	orl	%edx,%edx	/* ms bits */
     36	js	L_done		/* Already normalized */
     37	jnz	L_shift_1	/* Shift left 1 - 31 bits */
     38
     39	orl	%eax,%eax
     40	jz	L_zero		/* The contents are zero */
     41
     42	movl	%eax,%edx
     43	xorl	%eax,%eax
     44	subw	$32,EXP(%ebx)	/* This can cause an underflow */
     45
     46/* We need to shift left by 1 - 31 bits */
     47L_shift_1:
     48	bsrl	%edx,%ecx	/* get the required shift in %ecx */
     49	subl	$31,%ecx
     50	negl	%ecx
     51	shld	%cl,%eax,%edx
     52	shl	%cl,%eax
     53	subw	%cx,EXP(%ebx)	/* This can cause an underflow */
     54
     55	movl	%edx,SIGH(%ebx)
     56	movl	%eax,SIGL(%ebx)
     57
     58L_done:
     59	cmpw	EXP_OVER,EXP(%ebx)
     60	jge	L_overflow
     61
     62	cmpw	EXP_UNDER,EXP(%ebx)
     63	jle	L_underflow
     64
     65L_exit_valid:
     66	movl	TAG_Valid,%eax
     67
     68	/* Convert the exponent to 80x87 form. */
     69	addw	EXTENDED_Ebias,EXP(%ebx)
     70	andw	$0x7fff,EXP(%ebx)
     71
     72L_exit:
     73	popl	%ebx
     74	leave
     75	RET
     76
     77
     78L_zero:
     79	movw	$0,EXP(%ebx)
     80	movl	TAG_Zero,%eax
     81	jmp	L_exit
     82
     83L_underflow:
     84	/* Convert the exponent to 80x87 form. */
     85	addw	EXTENDED_Ebias,EXP(%ebx)
     86	push	%ebx
     87	call	arith_underflow
     88	pop	%ebx
     89	jmp	L_exit
     90
     91L_overflow:
     92	/* Convert the exponent to 80x87 form. */
     93	addw	EXTENDED_Ebias,EXP(%ebx)
     94	push	%ebx
     95	call	arith_overflow
     96	pop	%ebx
     97	jmp	L_exit
     98SYM_FUNC_END(FPU_normalize)
     99
    100
    101
    102/* Normalise without reporting underflow or overflow */
    103SYM_FUNC_START(FPU_normalize_nuo)
    104	pushl	%ebp
    105	movl	%esp,%ebp
    106	pushl	%ebx
    107
    108	movl	PARAM1,%ebx
    109
    110	movl	SIGH(%ebx),%edx
    111	movl	SIGL(%ebx),%eax
    112
    113	orl	%edx,%edx	/* ms bits */
    114	js	L_exit_nuo_valid	/* Already normalized */
    115	jnz	L_nuo_shift_1	/* Shift left 1 - 31 bits */
    116
    117	orl	%eax,%eax
    118	jz	L_exit_nuo_zero		/* The contents are zero */
    119
    120	movl	%eax,%edx
    121	xorl	%eax,%eax
    122	subw	$32,EXP(%ebx)	/* This can cause an underflow */
    123
    124/* We need to shift left by 1 - 31 bits */
    125L_nuo_shift_1:
    126	bsrl	%edx,%ecx	/* get the required shift in %ecx */
    127	subl	$31,%ecx
    128	negl	%ecx
    129	shld	%cl,%eax,%edx
    130	shl	%cl,%eax
    131	subw	%cx,EXP(%ebx)	/* This can cause an underflow */
    132
    133	movl	%edx,SIGH(%ebx)
    134	movl	%eax,SIGL(%ebx)
    135
    136L_exit_nuo_valid:
    137	movl	TAG_Valid,%eax
    138
    139	popl	%ebx
    140	leave
    141	RET
    142
    143L_exit_nuo_zero:
    144	movl	TAG_Zero,%eax
    145	movw	EXP_UNDER,EXP(%ebx)
    146
    147	popl	%ebx
    148	leave
    149	RET
    150SYM_FUNC_END(FPU_normalize_nuo)