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kernel/linux-rt-4.4.41/drivers/misc/sgi-xp/xp_nofault.S 1.3 KB
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  /*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
   */
  
  /*
   * The xp_nofault_PIOR function takes a pointer to a remote PIO register
   * and attempts to load and consume a value from it.  This function
   * will be registered as a nofault code block.  In the event that the
   * PIO read fails, the MCA handler will force the error to look
   * corrected and vector to the xp_error_PIOR which will return an error.
   *
   * The definition of "consumption" and the time it takes for an MCA
   * to surface is processor implementation specific.  This code
   * is sufficient on Itanium through the Montvale processor family.
   * It may need to be adjusted for future processor implementations.
   *
   *	extern int xp_nofault_PIOR(void *remote_register);
   */
  
  	.global xp_nofault_PIOR
  xp_nofault_PIOR:
  	mov	r8=r0			// Stage a success return value
  	ld8.acq	r9=[r32];;		// PIO Read the specified register
  	adds	r9=1,r9;;		// Add to force consumption
  	srlz.i;;			// Allow time for MCA to surface
  	br.ret.sptk.many b0;;		// Return success
  
  	.global xp_error_PIOR
  xp_error_PIOR:
  	mov	r8=1			// Return value of 1
  	br.ret.sptk.many b0;;		// Return failure