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