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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idiv32.S (2205B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 * Copyright (C) 2000 Hewlett-Packard Co
      4 * Copyright (C) 2000 David Mosberger-Tang <davidm@hpl.hp.com>
      5 *
      6 * 32-bit integer division.
      7 *
      8 * This code is based on the application note entitled "Divide, Square Root
      9 * and Remainder Algorithms for the IA-64 Architecture".  This document
     10 * is available as Intel document number 248725-002 or via the web at
     11 * http://developer.intel.com/software/opensource/numerics/
     12 *
     13 * For more details on the theory behind these algorithms, see "IA-64
     14 * and Elementary Functions" by Peter Markstein; HP Professional Books
     15 * (http://www.goodreads.com/book/show/2019887.Ia_64_and_Elementary_Functions)
     16 */
     17
     18#include <asm/asmmacro.h>
     19#include <asm/export.h>
     20
     21#ifdef MODULO
     22# define OP	mod
     23#else
     24# define OP	div
     25#endif
     26
     27#ifdef UNSIGNED
     28# define SGN	u
     29# define EXTEND	zxt4
     30# define INT_TO_FP(a,b)	fcvt.xuf.s1 a=b
     31# define FP_TO_INT(a,b)	fcvt.fxu.trunc.s1 a=b
     32#else
     33# define SGN
     34# define EXTEND	sxt4
     35# define INT_TO_FP(a,b)	fcvt.xf a=b
     36# define FP_TO_INT(a,b)	fcvt.fx.trunc.s1 a=b
     37#endif
     38
     39#define PASTE1(a,b)	a##b
     40#define PASTE(a,b)	PASTE1(a,b)
     41#define NAME		PASTE(PASTE(__,SGN),PASTE(OP,si3))
     42
     43GLOBAL_ENTRY(NAME)
     44	.regstk 2,0,0,0
     45	// Transfer inputs to FP registers.
     46	mov r2 = 0xffdd			// r2 = -34 + 65535 (fp reg format bias)
     47	EXTEND in0 = in0		// in0 = a
     48	EXTEND in1 = in1		// in1 = b
     49	;;
     50	setf.sig f8 = in0
     51	setf.sig f9 = in1
     52#ifdef MODULO
     53	sub in1 = r0, in1		// in1 = -b
     54#endif
     55	;;
     56	// Convert the inputs to FP, to avoid FP software-assist faults.
     57	INT_TO_FP(f8, f8)
     58	INT_TO_FP(f9, f9)
     59	;;
     60	setf.exp f7 = r2		// f7 = 2^-34
     61	frcpa.s1 f6, p6 = f8, f9	// y0 = frcpa(b)
     62	;;
     63(p6)	fmpy.s1 f8 = f8, f6		// q0 = a*y0
     64(p6)	fnma.s1 f6 = f9, f6, f1		// e0 = -b*y0 + 1 
     65	;;
     66#ifdef MODULO
     67	setf.sig f9 = in1		// f9 = -b
     68#endif
     69(p6)	fma.s1 f8 = f6, f8, f8		// q1 = e0*q0 + q0
     70(p6)	fma.s1 f6 = f6, f6, f7		// e1 = e0*e0 + 2^-34
     71	;;
     72#ifdef MODULO
     73	setf.sig f7 = in0
     74#endif
     75(p6)	fma.s1 f6 = f6, f8, f8		// q2 = e1*q1 + q1
     76	;;
     77	FP_TO_INT(f6, f6)		// q = trunc(q2)
     78	;;
     79#ifdef MODULO
     80	xma.l f6 = f6, f9, f7		// r = q*(-b) + a
     81	;;
     82#endif
     83	getf.sig r8 = f6		// transfer result to result register
     84	br.ret.sptk.many rp
     85END(NAME)
     86EXPORT_SYMBOL(NAME)