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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uncached.c (2112B)

      1/*
      2 * This file is subject to the terms and conditions of the GNU General Public
      3 * License.  See the file "COPYING" in the main directory of this archive
      4 * for more details.
      5 *
      6 * Copyright (C) 2005 Thiemo Seufer
      7 * Copyright (C) 2005  MIPS Technologies, Inc.	All rights reserved.
      8 *	Author: Maciej W. Rozycki <macro@mips.com>
      9 */
     10
     11
     12#include <asm/addrspace.h>
     13#include <asm/bug.h>
     14#include <asm/cacheflush.h>
     15
     16#ifndef CKSEG2
     17#define CKSEG2 CKSSEG
     18#endif
     19#ifndef TO_PHYS_MASK
     20#define TO_PHYS_MASK -1
     21#endif
     22
     23/*
     24 * FUNC is executed in one of the uncached segments, depending on its
     25 * original address as follows:
     26 *
     27 * 1. If the original address is in CKSEG0 or CKSEG1, then the uncached
     28 *    segment used is CKSEG1.
     29 * 2. If the original address is in XKPHYS, then the uncached segment
     30 *    used is XKPHYS(2).
     31 * 3. Otherwise it's a bug.
     32 *
     33 * The same remapping is done with the stack pointer.  Stack handling
     34 * works because we don't handle stack arguments or more complex return
     35 * values, so we can avoid sharing the same stack area between a cached
     36 * and the uncached mode.
     37 */
     38unsigned long run_uncached(void *func)
     39{
     40	register long ret __asm__("$2");
     41	long lfunc = (long)func, ufunc;
     42	long usp;
     43	long sp;
     44
     45	__asm__("move %0, $sp" : "=r" (sp));
     46
     47	if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
     48		usp = CKSEG1ADDR(sp);
     49#ifdef CONFIG_64BIT
     50	else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0, 0) &&
     51		 (long long)sp < (long long)PHYS_TO_XKPHYS(8, 0))
     52		usp = PHYS_TO_XKPHYS(K_CALG_UNCACHED,
     53				     XKPHYS_TO_PHYS((long long)sp));
     54#endif
     55	else {
     56		BUG();
     57		usp = sp;
     58	}
     59	if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2)
     60		ufunc = CKSEG1ADDR(lfunc);
     61#ifdef CONFIG_64BIT
     62	else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0, 0) &&
     63		 (long long)lfunc < (long long)PHYS_TO_XKPHYS(8, 0))
     64		ufunc = PHYS_TO_XKPHYS(K_CALG_UNCACHED,
     65				       XKPHYS_TO_PHYS((long long)lfunc));
     66#endif
     67	else {
     68		BUG();
     69		ufunc = lfunc;
     70	}
     71
     72	__asm__ __volatile__ (
     73		"	move	$16, $sp\n"
     74		"	move	$sp, %1\n"
     75		"	jalr	%2\n"
     76		"	move	$sp, $16"
     77		: "=r" (ret)
     78		: "r" (usp), "r" (ufunc)
     79		: "$16", "$31");
     80
     81	return ret;
     82}