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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
25bool is_offset_in_branch_range(long offset);
26unsigned int create_branch(const unsigned int *addr,
27 unsigned long target, int flags);
28unsigned int create_cond_branch(const unsigned int *addr,
29 unsigned long target, int flags);
30int patch_branch(unsigned int *addr, unsigned long target, int flags);
31int patch_instruction(unsigned int *addr, unsigned int instr);
32
33int instr_is_relative_branch(unsigned int instr);
34int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
35unsigned long branch_target(const unsigned int *instr);
36unsigned int translate_branch(const unsigned int *dest,
37 const unsigned int *src);
38extern bool is_conditional_branch(unsigned int instr);
39#ifdef CONFIG_PPC_BOOK3E_64
40void __patch_exception(int exc, unsigned long addr);
41#define patch_exception(exc, name) do { \
42 extern unsigned int name; \
43 __patch_exception((exc), (unsigned long)&name); \
44} while (0)
45#endif
46
47#define OP_RT_RA_MASK 0xffff0000UL
48#define LIS_R2 0x3c020000UL
49#define ADDIS_R2_R12 0x3c4c0000UL
50#define ADDI_R2_R2 0x38420000UL
51
52static inline unsigned long ppc_function_entry(void *func)
53{
54#ifdef PPC64_ELF_ABI_v2
55 u32 *insn = func;
56
57 /*
58 * A PPC64 ABIv2 function may have a local and a global entry
59 * point. We need to use the local entry point when patching
60 * functions, so identify and step over the global entry point
61 * sequence.
62 *
63 * The global entry point sequence is always of the form:
64 *
65 * addis r2,r12,XXXX
66 * addi r2,r2,XXXX
67 *
68 * A linker optimisation may convert the addis to lis:
69 *
70 * lis r2,XXXX
71 * addi r2,r2,XXXX
72 */
73 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
74 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
75 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
76 return (unsigned long)(insn + 2);
77 else
78 return (unsigned long)func;
79#elif defined(PPC64_ELF_ABI_v1)
80 /*
81 * On PPC64 ABIv1 the function pointer actually points to the
82 * function's descriptor. The first entry in the descriptor is the
83 * address of the function text.
84 */
85 return ((func_descr_t *)func)->entry;
86#else
87 return (unsigned long)func;
88#endif
89}
90
91static inline unsigned long ppc_global_function_entry(void *func)
92{
93#ifdef PPC64_ELF_ABI_v2
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#ifdef PPC64_ELF_ABI_v2
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 */