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 #include <linux/string.h>
16 #include <linux/kallsyms.h>
17
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);
23 */
24 #define BRANCH_SET_LINK 0x1
25 #define BRANCH_ABSOLUTE 0x2
26
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);
34 int raw_patch_instruction(unsigned int *addr, unsigned int instr);
35 int patch_instruction_site(s32 *addr, unsigned int instr);
36 int patch_branch_site(s32 *site, unsigned long target, int flags);
37
38 int instr_is_relative_branch(unsigned int instr);
39 int instr_is_relative_link_branch(unsigned int instr);
40 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
41 unsigned long branch_target(const unsigned int *instr);
42 unsigned int translate_branch(const unsigned int *dest,
43 const unsigned int *src);
44 extern bool is_conditional_branch(unsigned int instr);
45 #ifdef CONFIG_PPC_BOOK3E_64
46 void __patch_exception(int exc, unsigned long addr);
47 #define patch_exception(exc, name) do { \
48 extern unsigned int name; \
49 __patch_exception((exc), (unsigned long)&name); \
50 } while (0)
51 #endif
52
53 #define OP_RT_RA_MASK 0xffff0000UL
54 #define LIS_R2 0x3c020000UL
55 #define ADDIS_R2_R12 0x3c4c0000UL
56 #define ADDI_R2_R2 0x38420000UL
57
ppc_function_entry(void * func)58 static inline unsigned long ppc_function_entry(void *func)
59 {
60 #ifdef PPC64_ELF_ABI_v2
61 u32 *insn = func;
62
63 /*
64 * A PPC64 ABIv2 function may have a local and a global entry
65 * point. We need to use the local entry point when patching
66 * functions, so identify and step over the global entry point
67 * sequence.
68 *
69 * The global entry point sequence is always of the form:
70 *
71 * addis r2,r12,XXXX
72 * addi r2,r2,XXXX
73 *
74 * A linker optimisation may convert the addis to lis:
75 *
76 * lis r2,XXXX
77 * addi r2,r2,XXXX
78 */
79 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
80 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
81 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
82 return (unsigned long)(insn + 2);
83 else
84 return (unsigned long)func;
85 #elif defined(PPC64_ELF_ABI_v1)
86 /*
87 * On PPC64 ABIv1 the function pointer actually points to the
88 * function's descriptor. The first entry in the descriptor is the
89 * address of the function text.
90 */
91 return ((func_descr_t *)func)->entry;
92 #else
93 return (unsigned long)func;
94 #endif
95 }
96
ppc_global_function_entry(void * func)97 static inline unsigned long ppc_global_function_entry(void *func)
98 {
99 #ifdef PPC64_ELF_ABI_v2
100 /* PPC64 ABIv2 the global entry point is at the address */
101 return (unsigned long)func;
102 #else
103 /* All other cases there is no change vs ppc_function_entry() */
104 return ppc_function_entry(func);
105 #endif
106 }
107
108 /*
109 * Wrapper around kallsyms_lookup() to return function entry address:
110 * - For ABIv1, we lookup the dot variant.
111 * - For ABIv2, we return the local entry point.
112 */
ppc_kallsyms_lookup_name(const char * name)113 static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
114 {
115 unsigned long addr;
116 #ifdef PPC64_ELF_ABI_v1
117 /* check for dot variant */
118 char dot_name[1 + KSYM_NAME_LEN];
119 bool dot_appended = false;
120
121 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
122 return 0;
123
124 if (name[0] != '.') {
125 dot_name[0] = '.';
126 dot_name[1] = '\0';
127 strlcat(dot_name, name, sizeof(dot_name));
128 dot_appended = true;
129 } else {
130 dot_name[0] = '\0';
131 strlcat(dot_name, name, sizeof(dot_name));
132 }
133 addr = kallsyms_lookup_name(dot_name);
134 if (!addr && dot_appended)
135 /* Let's try the original non-dot symbol lookup */
136 addr = kallsyms_lookup_name(name);
137 #elif defined(PPC64_ELF_ABI_v2)
138 addr = kallsyms_lookup_name(name);
139 if (addr)
140 addr = ppc_function_entry((void *)addr);
141 #else
142 addr = kallsyms_lookup_name(name);
143 #endif
144 return addr;
145 }
146
147 #ifdef CONFIG_PPC64
148 /*
149 * Some instruction encodings commonly used in dynamic ftracing
150 * and function live patching.
151 */
152
153 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
154 #ifdef PPC64_ELF_ABI_v2
155 #define R2_STACK_OFFSET 24
156 #else
157 #define R2_STACK_OFFSET 40
158 #endif
159
160 #define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
161 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
162
163 /* usually preceded by a mflr r0 */
164 #define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
165 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
166 #endif /* CONFIG_PPC64 */
167
168 #endif /* _ASM_POWERPC_CODE_PATCHING_H */
169