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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
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#ifdef PPC64_ELF_ABI_v2
53 u32 *insn = func;
54
55 /*
56 * A PPC64 ABIv2 function may have a local and a global entry
57 * point. We need to use the local entry point when patching
58 * functions, so identify and step over the global entry point
59 * sequence.
60 *
61 * The global entry point sequence is always of the form:
62 *
63 * addis r2,r12,XXXX
64 * addi r2,r2,XXXX
65 *
66 * A linker optimisation may convert the addis to lis:
67 *
68 * lis r2,XXXX
69 * addi r2,r2,XXXX
70 */
71 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
72 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
73 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
74 return (unsigned long)(insn + 2);
75 else
76 return (unsigned long)func;
77#elif defined(PPC64_ELF_ABI_v1)
78 /*
79 * On PPC64 ABIv1 the function pointer actually points to the
80 * function's descriptor. The first entry in the descriptor is the
81 * address of the function text.
82 */
83 return ((func_descr_t *)func)->entry;
84#else
85 return (unsigned long)func;
86#endif
87}
88
89static inline unsigned long ppc_global_function_entry(void *func)
90{
91#ifdef PPC64_ELF_ABI_v2
92 /* PPC64 ABIv2 the global entry point is at the address */
93 return (unsigned long)func;
94#else
95 /* All other cases there is no change vs ppc_function_entry() */
96 return ppc_function_entry(func);
97#endif
98}
99
100#ifdef CONFIG_PPC64
101/*
102 * Some instruction encodings commonly used in dynamic ftracing
103 * and function live patching.
104 */
105
106/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
107#ifdef PPC64_ELF_ABI_v2
108#define R2_STACK_OFFSET 24
109#else
110#define R2_STACK_OFFSET 40
111#endif
112
113#define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
114 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
115
116/* usually preceded by a mflr r0 */
117#define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
118 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
119#endif /* CONFIG_PPC64 */
120
121#endif /* _ASM_POWERPC_CODE_PATCHING_H */