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kernel/linux-rt-4.4.41/arch/powerpc/include/asm/code-patching.h 3.09 KB
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  #ifndef _ASM_POWERPC_CODE_PATCHING_H
  #define _ASM_POWERPC_CODE_PATCHING_H
  
  /*
   * Copyright 2008, Michael Ellerman, IBM Corporation.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <asm/types.h>
  #include <asm/ppc-opcode.h>
  
  /* Flags for create_branch:
   * "b"   == create_branch(addr, target, 0);
   * "ba"  == create_branch(addr, target, BRANCH_ABSOLUTE);
   * "bl"  == create_branch(addr, target, BRANCH_SET_LINK);
   * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
   */
  #define BRANCH_SET_LINK	0x1
  #define BRANCH_ABSOLUTE	0x2
  
  unsigned int create_branch(const unsigned int *addr,
  			   unsigned long target, int flags);
  unsigned int create_cond_branch(const unsigned int *addr,
  				unsigned long target, int flags);
  int patch_branch(unsigned int *addr, unsigned long target, int flags);
  int patch_instruction(unsigned int *addr, unsigned int instr);
  
  int instr_is_relative_branch(unsigned int instr);
  int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
  unsigned long branch_target(const unsigned int *instr);
  unsigned int translate_branch(const unsigned int *dest,
  			      const unsigned int *src);
  #ifdef CONFIG_PPC_BOOK3E_64
  void __patch_exception(int exc, unsigned long addr);
  #define patch_exception(exc, name) do { \
  	extern unsigned int name; \
  	__patch_exception((exc), (unsigned long)&name); \
  } while (0)
  #endif
  
  #define OP_RT_RA_MASK	0xffff0000UL
  #define LIS_R2		0x3c020000UL
  #define ADDIS_R2_R12	0x3c4c0000UL
  #define ADDI_R2_R2	0x38420000UL
  
  static inline unsigned long ppc_function_entry(void *func)
  {
  #if defined(CONFIG_PPC64)
  #if defined(_CALL_ELF) && _CALL_ELF == 2
  	u32 *insn = func;
  
  	/*
  	 * A PPC64 ABIv2 function may have a local and a global entry
  	 * point. We need to use the local entry point when patching
  	 * functions, so identify and step over the global entry point
  	 * sequence.
  	 *
  	 * The global entry point sequence is always of the form:
  	 *
  	 * addis r2,r12,XXXX
  	 * addi  r2,r2,XXXX
  	 *
  	 * A linker optimisation may convert the addis to lis:
  	 *
  	 * lis   r2,XXXX
  	 * addi  r2,r2,XXXX
  	 */
  	if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
  	     ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
  	    ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
  		return (unsigned long)(insn + 2);
  	else
  		return (unsigned long)func;
  #else
  	/*
  	 * On PPC64 ABIv1 the function pointer actually points to the
  	 * function's descriptor. The first entry in the descriptor is the
  	 * address of the function text.
  	 */
  	return ((func_descr_t *)func)->entry;
  #endif
  #else
  	return (unsigned long)func;
  #endif
  }
  
  static inline unsigned long ppc_global_function_entry(void *func)
  {
  #if defined(CONFIG_PPC64) && defined(_CALL_ELF) && _CALL_ELF == 2
  	/* PPC64 ABIv2 the global entry point is at the address */
  	return (unsigned long)func;
  #else
  	/* All other cases there is no change vs ppc_function_entry() */
  	return ppc_function_entry(func);
  #endif
  }
  
  #endif /* _ASM_POWERPC_CODE_PATCHING_H */