LXR linux/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
  25unsigned int create_branch(const unsigned int *addr,
  26                           unsigned long target, int flags);
  27unsigned int create_cond_branch(const unsigned int *addr,
  28                                unsigned long target, int flags);
  29int patch_branch(unsigned int *addr, unsigned long target, int flags);
  30int patch_instruction(unsigned int *addr, unsigned int instr);
  31
  32int instr_is_relative_branch(unsigned int instr);
  33int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
  34unsigned long branch_target(const unsigned int *instr);
  35unsigned int translate_branch(const unsigned int *dest,
  36                              const unsigned int *src);
  37#ifdef CONFIG_PPC_BOOK3E_64
  38void __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
  50static 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
  91static 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 */
 124