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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#include <linux/string.h>
16#include <linux/kallsyms.h>
17#include <asm/asm-compat.h>
18
19/* Flags for create_branch:
20 * "b" == create_branch(addr, target, 0);
21 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
22 * "bl" == create_branch(addr, target, BRANCH_SET_LINK);
23 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
24 */
25#define BRANCH_SET_LINK 0x1
26#define BRANCH_ABSOLUTE 0x2
27
28bool is_offset_in_branch_range(long offset);
29unsigned int create_branch(const unsigned int *addr,
30 unsigned long target, int flags);
31unsigned int create_cond_branch(const unsigned int *addr,
32 unsigned long target, int flags);
33int patch_branch(unsigned int *addr, unsigned long target, int flags);
34int patch_instruction(unsigned int *addr, unsigned int instr);
35int raw_patch_instruction(unsigned int *addr, unsigned int instr);
36
37static inline unsigned long patch_site_addr(s32 *site)
38{
39 return (unsigned long)site + *site;
40}
41
42static inline int patch_instruction_site(s32 *site, unsigned int instr)
43{
44 return patch_instruction((unsigned int *)patch_site_addr(site), instr);
45}
46
47static inline int patch_branch_site(s32 *site, unsigned long target, int flags)
48{
49 return patch_branch((unsigned int *)patch_site_addr(site), target, flags);
50}
51
52static inline int modify_instruction(unsigned int *addr, unsigned int clr,
53 unsigned int set)
54{
55 return patch_instruction(addr, (*addr & ~clr) | set);
56}
57
58static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set)
59{
60 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set);
61}
62
63int instr_is_relative_branch(unsigned int instr);
64int instr_is_relative_link_branch(unsigned int instr);
65int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
66unsigned long branch_target(const unsigned int *instr);
67unsigned int translate_branch(const unsigned int *dest,
68 const unsigned int *src);
69extern bool is_conditional_branch(unsigned int instr);
70#ifdef CONFIG_PPC_BOOK3E_64
71void __patch_exception(int exc, unsigned long addr);
72#define patch_exception(exc, name) do { \
73 extern unsigned int name; \
74 __patch_exception((exc), (unsigned long)&name); \
75} while (0)
76#endif
77
78#define OP_RT_RA_MASK 0xffff0000UL
79#define LIS_R2 0x3c020000UL
80#define ADDIS_R2_R12 0x3c4c0000UL
81#define ADDI_R2_R2 0x38420000UL
82
83static inline unsigned long ppc_function_entry(void *func)
84{
85#ifdef PPC64_ELF_ABI_v2
86 u32 *insn = func;
87
88 /*
89 * A PPC64 ABIv2 function may have a local and a global entry
90 * point. We need to use the local entry point when patching
91 * functions, so identify and step over the global entry point
92 * sequence.
93 *
94 * The global entry point sequence is always of the form:
95 *
96 * addis r2,r12,XXXX
97 * addi r2,r2,XXXX
98 *
99 * A linker optimisation may convert the addis to lis:
100 *
101 * lis r2,XXXX
102 * addi r2,r2,XXXX
103 */
104 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
105 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
106 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
107 return (unsigned long)(insn + 2);
108 else
109 return (unsigned long)func;
110#elif defined(PPC64_ELF_ABI_v1)
111 /*
112 * On PPC64 ABIv1 the function pointer actually points to the
113 * function's descriptor. The first entry in the descriptor is the
114 * address of the function text.
115 */
116 return ((func_descr_t *)func)->entry;
117#else
118 return (unsigned long)func;
119#endif
120}
121
122static inline unsigned long ppc_global_function_entry(void *func)
123{
124#ifdef PPC64_ELF_ABI_v2
125 /* PPC64 ABIv2 the global entry point is at the address */
126 return (unsigned long)func;
127#else
128 /* All other cases there is no change vs ppc_function_entry() */
129 return ppc_function_entry(func);
130#endif
131}
132
133/*
134 * Wrapper around kallsyms_lookup() to return function entry address:
135 * - For ABIv1, we lookup the dot variant.
136 * - For ABIv2, we return the local entry point.
137 */
138static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
139{
140 unsigned long addr;
141#ifdef PPC64_ELF_ABI_v1
142 /* check for dot variant */
143 char dot_name[1 + KSYM_NAME_LEN];
144 bool dot_appended = false;
145
146 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
147 return 0;
148
149 if (name[0] != '.') {
150 dot_name[0] = '.';
151 dot_name[1] = '\0';
152 strlcat(dot_name, name, sizeof(dot_name));
153 dot_appended = true;
154 } else {
155 dot_name[0] = '\0';
156 strlcat(dot_name, name, sizeof(dot_name));
157 }
158 addr = kallsyms_lookup_name(dot_name);
159 if (!addr && dot_appended)
160 /* Let's try the original non-dot symbol lookup */
161 addr = kallsyms_lookup_name(name);
162#elif defined(PPC64_ELF_ABI_v2)
163 addr = kallsyms_lookup_name(name);
164 if (addr)
165 addr = ppc_function_entry((void *)addr);
166#else
167 addr = kallsyms_lookup_name(name);
168#endif
169 return addr;
170}
171
172#ifdef CONFIG_PPC64
173/*
174 * Some instruction encodings commonly used in dynamic ftracing
175 * and function live patching.
176 */
177
178/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
179#ifdef PPC64_ELF_ABI_v2
180#define R2_STACK_OFFSET 24
181#else
182#define R2_STACK_OFFSET 40
183#endif
184
185#define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
186 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
187
188/* usually preceded by a mflr r0 */
189#define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
190 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
191#endif /* CONFIG_PPC64 */
192
193#endif /* _ASM_POWERPC_CODE_PATCHING_H */