1 #ifndef _ASM_POWERPC_CODE_PATCHING_H
2 #define _ASM_POWERPC_CODE_PATCHING_H
5 * Copyright 2008, Michael Ellerman, IBM Corporation.
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.
13 #include <asm/types.h>
14 #include <asm/ppc-opcode.h>
15 #include <linux/string.h>
16 #include <linux/kallsyms.h>
18 /* Flags for create_branch:
19 * "b" == create_branch(addr, target, 0);
20 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
21 * "bl" == create_branch(addr, target, BRANCH_SET_LINK);
22 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
24 #define BRANCH_SET_LINK 0x1
25 #define BRANCH_ABSOLUTE 0x2
27 bool is_offset_in_branch_range(long offset);
28 unsigned int create_branch(const unsigned int *addr,
29 unsigned long target, int flags);
30 unsigned int create_cond_branch(const unsigned int *addr,
31 unsigned long target, int flags);
32 int patch_branch(unsigned int *addr, unsigned long target, int flags);
33 int patch_instruction(unsigned int *addr, unsigned int instr);
35 int instr_is_relative_branch(unsigned int instr);
36 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
37 unsigned long branch_target(const unsigned int *instr);
38 unsigned int translate_branch(const unsigned int *dest,
39 const unsigned int *src);
40 extern bool is_conditional_branch(unsigned int instr);
41 #ifdef CONFIG_PPC_BOOK3E_64
42 void __patch_exception(int exc, unsigned long addr);
43 #define patch_exception(exc, name) do { \
44 extern unsigned int name; \
45 __patch_exception((exc), (unsigned long)&name); \
49 #define OP_RT_RA_MASK 0xffff0000UL
50 #define LIS_R2 0x3c020000UL
51 #define ADDIS_R2_R12 0x3c4c0000UL
52 #define ADDI_R2_R2 0x38420000UL
54 static inline unsigned long ppc_function_entry(void *func)
56 #ifdef PPC64_ELF_ABI_v2
60 * A PPC64 ABIv2 function may have a local and a global entry
61 * point. We need to use the local entry point when patching
62 * functions, so identify and step over the global entry point
65 * The global entry point sequence is always of the form:
70 * A linker optimisation may convert the addis to lis:
75 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
76 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
77 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
78 return (unsigned long)(insn + 2);
80 return (unsigned long)func;
81 #elif defined(PPC64_ELF_ABI_v1)
83 * On PPC64 ABIv1 the function pointer actually points to the
84 * function's descriptor. The first entry in the descriptor is the
85 * address of the function text.
87 return ((func_descr_t *)func)->entry;
89 return (unsigned long)func;
93 static inline unsigned long ppc_global_function_entry(void *func)
95 #ifdef PPC64_ELF_ABI_v2
96 /* PPC64 ABIv2 the global entry point is at the address */
97 return (unsigned long)func;
99 /* All other cases there is no change vs ppc_function_entry() */
100 return ppc_function_entry(func);
105 * Wrapper around kallsyms_lookup() to return function entry address:
106 * - For ABIv1, we lookup the dot variant.
107 * - For ABIv2, we return the local entry point.
109 static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
112 #ifdef PPC64_ELF_ABI_v1
113 /* check for dot variant */
114 char dot_name[1 + KSYM_NAME_LEN];
115 bool dot_appended = false;
117 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
120 if (name[0] != '.') {
123 strlcat(dot_name, name, sizeof(dot_name));
127 strlcat(dot_name, name, sizeof(dot_name));
129 addr = kallsyms_lookup_name(dot_name);
130 if (!addr && dot_appended)
131 /* Let's try the original non-dot symbol lookup */
132 addr = kallsyms_lookup_name(name);
133 #elif defined(PPC64_ELF_ABI_v2)
134 addr = kallsyms_lookup_name(name);
136 addr = ppc_function_entry((void *)addr);
138 addr = kallsyms_lookup_name(name);
145 * Some instruction encodings commonly used in dynamic ftracing
146 * and function live patching.
149 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
150 #ifdef PPC64_ELF_ABI_v2
151 #define R2_STACK_OFFSET 24
153 #define R2_STACK_OFFSET 40
156 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
157 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
159 /* usually preceded by a mflr r0 */
160 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
161 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
162 #endif /* CONFIG_PPC64 */
164 #endif /* _ASM_POWERPC_CODE_PATCHING_H */