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_relative_link_branch(unsigned int instr);
34 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
35 unsigned long branch_target(const unsigned int *instr);
36 unsigned int translate_branch(const unsigned int *dest,
37 const unsigned int *src);
38 #ifdef CONFIG_PPC_BOOK3E_64
39 void __patch_exception(int exc, unsigned long addr);
40 #define patch_exception(exc, name) do { \
41 extern unsigned int name; \
42 __patch_exception((exc), (unsigned long)&name); \
43 } while (0)
44 #endif
45
46 #define OP_RT_RA_MASK 0xffff0000UL
47 #define LIS_R2 0x3c020000UL
48 #define ADDIS_R2_R12 0x3c4c0000UL
49 #define ADDI_R2_R2 0x38420000UL
50
ppc_function_entry(void * func)51 static inline unsigned long ppc_function_entry(void *func)
52 {
53 #ifdef PPC64_ELF_ABI_v2
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 #elif defined(PPC64_ELF_ABI_v1)
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 #else
86 return (unsigned long)func;
87 #endif
88 }
89
ppc_global_function_entry(void * func)90 static inline unsigned long ppc_global_function_entry(void *func)
91 {
92 #ifdef PPC64_ELF_ABI_v2
93 /* PPC64 ABIv2 the global entry point is at the address */
94 return (unsigned long)func;
95 #else
96 /* All other cases there is no change vs ppc_function_entry() */
97 return ppc_function_entry(func);
98 #endif
99 }
100
101 #ifdef CONFIG_PPC64
102 /*
103 * Some instruction encodings commonly used in dynamic ftracing
104 * and function live patching.
105 */
106
107 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
108 #ifdef PPC64_ELF_ABI_v2
109 #define R2_STACK_OFFSET 24
110 #else
111 #define R2_STACK_OFFSET 40
112 #endif
113
114 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
115 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
116
117 /* usually preceded by a mflr r0 */
118 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
119 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
120 #endif /* CONFIG_PPC64 */
121
122 #endif /* _ASM_POWERPC_CODE_PATCHING_H */
123