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kernel/linux-rt-4.4.41/arch/mips/lib/strnlen_user.S 1.81 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) 1996, 1998, 1999, 2004 by Ralf Baechle
   * Copyright (c) 1999 Silicon Graphics, Inc.
   */
  #include <asm/asm.h>
  #include <asm/asm-offsets.h>
  #include <asm/regdef.h>
  
  #define EX(insn,reg,addr,handler)			\
  9:	insn	reg, addr;				\
  	.section __ex_table,"a";			\
  	PTR	9b, handler;				\
  	.previous
  
  /*
   * Return the size of a string including the ending NUL character up to a
   * maximum of a1 or 0 in case of error.
   *
   * Note: for performance reasons we deliberately accept that a user may
   *	 make strlen_user and strnlen_user access the first few KSEG0
   *	 bytes.	 There's nothing secret there.	On 64-bit accessing beyond
   *	 the maximum is a tad hairier ...
   */
  	.macro __BUILD_STRNLEN_ASM func
  LEAF(__strnlen_\func\()_asm)
  	LONG_L		v0, TI_ADDR_LIMIT($28)	# pointer ok?
  	and		v0, a0
  	bnez		v0, .Lfault\@
  
  FEXPORT(__strnlen_\func\()_nocheck_asm)
  	move		v0, a0
  	PTR_ADDU	a1, a0			# stop pointer
  1:
  #ifdef CONFIG_CPU_DADDI_WORKAROUNDS
  	.set		noat
  	li		AT, 1
  #endif
  	beq		v0, a1, 1f		# limit reached?
  .ifeqs "\func", "kernel"
  	EX(lb, t0, (v0), .Lfault\@)
  .else
  	EX(lbe, t0, (v0), .Lfault\@)
  .endif
  	.set		noreorder
  	bnez		t0, 1b
  1:
  #ifndef CONFIG_CPU_DADDI_WORKAROUNDS
  	 PTR_ADDIU	v0, 1
  #else
  	 PTR_ADDU	v0, AT
  	.set		at
  #endif
  	.set		reorder
  	PTR_SUBU	v0, a0
  	jr		ra
  	END(__strnlen_\func\()_asm)
  
  .Lfault\@:
  	move		v0, zero
  	jr		ra
  	.endm
  
  #ifndef CONFIG_EVA
  	/* Set aliases */
  	.global __strnlen_user_asm
  	.global __strnlen_user_nocheck_asm
  	.set __strnlen_user_asm, __strnlen_kernel_asm
  	.set __strnlen_user_nocheck_asm, __strnlen_kernel_nocheck_asm
  #endif
  
  __BUILD_STRNLEN_ASM kernel
  
  #ifdef CONFIG_EVA
  
  	.set push
  	.set eva
  __BUILD_STRNLEN_ASM user
  	.set pop
  #endif