arch/powerpc/include/asm/code-patching.h

   1 #ifndef _ASM_POWERPC_CODE_PATCHING_H
   2 #define _ASM_POWERPC_CODE_PATCHING_H
   3
   4 /*
   5  * Copyright 2008, Michael Ellerman, IBM Corporation.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <asm/types.h>
  14 #include <asm/ppc-opcode.h>
  15
  16 /* Flags for create_branch:
  17  * "b"   == create_branch(addr, target, 0);
  18  * "ba"  == create_branch(addr, target, BRANCH_ABSOLUTE);
  19  * "bl"  == create_branch(addr, target, BRANCH_SET_LINK);
  20  * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
  21  */
  22 #define BRANCH_SET_LINK 0x1
  23 #define BRANCH_ABSOLUTE 0x2
  24
  25 unsigned int create_branch(const unsigned int *addr,
  26                            unsigned long target, int flags);
  27 unsigned int create_cond_branch(const unsigned int *addr,
  28                                 unsigned long target, int flags);
  29 int patch_branch(unsigned int *addr, unsigned long target, int flags);
  30 int patch_instruction(unsigned int *addr, unsigned int instr);
  31
  32 int instr_is_relative_branch(unsigned int instr);
  33 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
  34 unsigned long branch_target(const unsigned int *instr);
  35 unsigned int translate_branch(const unsigned int *dest,
  36                               const unsigned int *src);
  37 #ifdef CONFIG_PPC_BOOK3E_64
  38 void __patch_exception(int exc, unsigned long addr);
  39 #define patch_exception(exc, name) do { \
  40         extern unsigned int name; \
  41         __patch_exception((exc), (unsigned long)&name); \
  42 } while (0)
  43 #endif
  44
  45 #define OP_RT_RA_MASK   0xffff0000UL
  46 #define LIS_R2          0x3c020000UL
  47 #define ADDIS_R2_R12    0x3c4c0000UL
  48 #define ADDI_R2_R2      0x38420000UL
  49
  50 static inline unsigned long ppc_function_entry(void *func)
  51 {
  52 #if defined(CONFIG_PPC64)
  53 #if defined(_CALL_ELF) && _CALL_ELF == 2
  54         u32 *insn = func;
  55
  56         /*
  57          * A PPC64 ABIv2 function may have a local and a global entry
  58          * point. We need to use the local entry point when patching
  59          * functions, so identify and step over the global entry point
  60          * sequence.
  61          *
  62          * The global entry point sequence is always of the form:
  63          *
  64          * addis r2,r12,XXXX
  65          * addi  r2,r2,XXXX
  66          *
  67          * A linker optimisation may convert the addis to lis:
  68          *
  69          * lis   r2,XXXX
  70          * addi  r2,r2,XXXX
  71          */
  72         if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
  73              ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
  74             ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
  75                 return (unsigned long)(insn + 2);
  76         else
  77                 return (unsigned long)func;
  78 #else
  79         /*
  80          * On PPC64 ABIv1 the function pointer actually points to the
  81          * function's descriptor. The first entry in the descriptor is the
  82          * address of the function text.
  83          */
  84         return ((func_descr_t *)func)->entry;
  85 #endif
  86 #else
  87         return (unsigned long)func;
  88 #endif
  89 }
  90
  91 static inline unsigned long ppc_global_function_entry(void *func)
  92 {
  93 #if defined(CONFIG_PPC64) && defined(_CALL_ELF) && _CALL_ELF == 2
  94         /* PPC64 ABIv2 the global entry point is at the address */
  95         return (unsigned long)func;
  96 #else
  97         /* All other cases there is no change vs ppc_function_entry() */
  98         return ppc_function_entry(func);
  99 #endif
 100 }
 101
 102 #ifdef CONFIG_PPC64
 103 /*
 104  * Some instruction encodings commonly used in dynamic ftracing
 105  * and function live patching.
 106  */
 107
 108 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
 109 #if defined(_CALL_ELF) && _CALL_ELF == 2
 110 #define R2_STACK_OFFSET         24
 111 #else
 112 #define R2_STACK_OFFSET         40
 113 #endif
 114
 115 #define PPC_INST_LD_TOC         (PPC_INST_LD  | ___PPC_RT(__REG_R2) | \
 116                                  ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
 117
 118 /* usually preceded by a mflr r0 */
 119 #define PPC_INST_STD_LR         (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
 120                                  ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
 121 #endif /* CONFIG_PPC64 */
 122
 123 #endif /* _ASM_POWERPC_CODE_PATCHING_H */