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 bool is_offset_in_cond_branch_range(long offset);
29 unsigned int create_branch(const unsigned int *addr,
30 unsigned long target, int flags);
31 unsigned int create_cond_branch(const unsigned int *addr,
32 unsigned long target, int flags);
33 int patch_branch(unsigned int *addr, unsigned long target, int flags);
34 int patch_instruction(unsigned int *addr, unsigned int instr);
35 int raw_patch_instruction(unsigned int *addr, unsigned int instr);
36 int patch_instruction_site(s32 *addr, unsigned int instr);
37 int patch_branch_site(s32 *site, unsigned long target, int flags);
39 int instr_is_relative_branch(unsigned int instr);
40 int instr_is_relative_link_branch(unsigned int instr);
41 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
42 unsigned long branch_target(const unsigned int *instr);
43 unsigned int translate_branch(const unsigned int *dest,
44 const unsigned int *src);
45 extern bool is_conditional_branch(unsigned int instr);
46 #ifdef CONFIG_PPC_BOOK3E_64
47 void __patch_exception(int exc, unsigned long addr);
48 #define patch_exception(exc, name) do { \
49 extern unsigned int name; \
50 __patch_exception((exc), (unsigned long)&name); \
54 #define OP_RT_RA_MASK 0xffff0000UL
55 #define LIS_R2 0x3c400000UL
56 #define ADDIS_R2_R12 0x3c4c0000UL
57 #define ADDI_R2_R2 0x38420000UL
59 static inline unsigned long ppc_function_entry(void *func)
61 #ifdef PPC64_ELF_ABI_v2
65 * A PPC64 ABIv2 function may have a local and a global entry
66 * point. We need to use the local entry point when patching
67 * functions, so identify and step over the global entry point
70 * The global entry point sequence is always of the form:
75 * A linker optimisation may convert the addis to lis:
80 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
81 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
82 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
83 return (unsigned long)(insn + 2);
85 return (unsigned long)func;
86 #elif defined(PPC64_ELF_ABI_v1)
88 * On PPC64 ABIv1 the function pointer actually points to the
89 * function's descriptor. The first entry in the descriptor is the
90 * address of the function text.
92 return ((func_descr_t *)func)->entry;
94 return (unsigned long)func;
98 static inline unsigned long ppc_global_function_entry(void *func)
100 #ifdef PPC64_ELF_ABI_v2
101 /* PPC64 ABIv2 the global entry point is at the address */
102 return (unsigned long)func;
104 /* All other cases there is no change vs ppc_function_entry() */
105 return ppc_function_entry(func);
110 * Wrapper around kallsyms_lookup() to return function entry address:
111 * - For ABIv1, we lookup the dot variant.
112 * - For ABIv2, we return the local entry point.
114 static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
117 #ifdef PPC64_ELF_ABI_v1
118 /* check for dot variant */
119 char dot_name[1 + KSYM_NAME_LEN];
120 bool dot_appended = false;
122 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
125 if (name[0] != '.') {
128 strlcat(dot_name, name, sizeof(dot_name));
132 strlcat(dot_name, name, sizeof(dot_name));
134 addr = kallsyms_lookup_name(dot_name);
135 if (!addr && dot_appended)
136 /* Let's try the original non-dot symbol lookup */
137 addr = kallsyms_lookup_name(name);
138 #elif defined(PPC64_ELF_ABI_v2)
139 addr = kallsyms_lookup_name(name);
141 addr = ppc_function_entry((void *)addr);
143 addr = kallsyms_lookup_name(name);
150 * Some instruction encodings commonly used in dynamic ftracing
151 * and function live patching.
154 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
155 #ifdef PPC64_ELF_ABI_v2
156 #define R2_STACK_OFFSET 24
158 #define R2_STACK_OFFSET 40
161 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
162 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
164 /* usually preceded by a mflr r0 */
165 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
166 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
167 #endif /* CONFIG_PPC64 */
169 #endif /* _ASM_POWERPC_CODE_PATCHING_H */