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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2#ifndef _ASM_POWERPC_CODE_PATCHING_H
3#define _ASM_POWERPC_CODE_PATCHING_H
4
5/*
6 * Copyright 2008, Michael Ellerman, IBM Corporation.
7 */
8
9#include <asm/types.h>
10#include <asm/ppc-opcode.h>
11#include <linux/string.h>
12#include <linux/kallsyms.h>
13#include <asm/asm-compat.h>
14
15/* Flags for create_branch:
16 * "b" == create_branch(addr, target, 0);
17 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
18 * "bl" == create_branch(addr, target, BRANCH_SET_LINK);
19 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
20 */
21#define BRANCH_SET_LINK 0x1
22#define BRANCH_ABSOLUTE 0x2
23
24bool is_offset_in_branch_range(long offset);
25unsigned int create_branch(const unsigned int *addr,
26 unsigned long target, int flags);
27unsigned int create_cond_branch(const unsigned int *addr,
28 unsigned long target, int flags);
29int patch_branch(unsigned int *addr, unsigned long target, int flags);
30int patch_instruction(unsigned int *addr, unsigned int instr);
31int raw_patch_instruction(unsigned int *addr, unsigned int instr);
32
33static inline unsigned long patch_site_addr(s32 *site)
34{
35 return (unsigned long)site + *site;
36}
37
38static inline int patch_instruction_site(s32 *site, unsigned int instr)
39{
40 return patch_instruction((unsigned int *)patch_site_addr(site), instr);
41}
42
43static inline int patch_branch_site(s32 *site, unsigned long target, int flags)
44{
45 return patch_branch((unsigned int *)patch_site_addr(site), target, flags);
46}
47
48static inline int modify_instruction(unsigned int *addr, unsigned int clr,
49 unsigned int set)
50{
51 return patch_instruction(addr, (*addr & ~clr) | set);
52}
53
54static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set)
55{
56 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set);
57}
58
59int instr_is_relative_branch(unsigned int instr);
60int instr_is_relative_link_branch(unsigned int instr);
61int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
62unsigned long branch_target(const unsigned int *instr);
63unsigned int translate_branch(const unsigned int *dest,
64 const unsigned int *src);
65extern bool is_conditional_branch(unsigned int instr);
66#ifdef CONFIG_PPC_BOOK3E_64
67void __patch_exception(int exc, unsigned long addr);
68#define patch_exception(exc, name) do { \
69 extern unsigned int name; \
70 __patch_exception((exc), (unsigned long)&name); \
71} while (0)
72#endif
73
74#define OP_RT_RA_MASK 0xffff0000UL
75#define LIS_R2 0x3c020000UL
76#define ADDIS_R2_R12 0x3c4c0000UL
77#define ADDI_R2_R2 0x38420000UL
78
79static inline unsigned long ppc_function_entry(void *func)
80{
81#ifdef PPC64_ELF_ABI_v2
82 u32 *insn = func;
83
84 /*
85 * A PPC64 ABIv2 function may have a local and a global entry
86 * point. We need to use the local entry point when patching
87 * functions, so identify and step over the global entry point
88 * sequence.
89 *
90 * The global entry point sequence is always of the form:
91 *
92 * addis r2,r12,XXXX
93 * addi r2,r2,XXXX
94 *
95 * A linker optimisation may convert the addis to lis:
96 *
97 * lis r2,XXXX
98 * addi r2,r2,XXXX
99 */
100 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
101 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
102 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
103 return (unsigned long)(insn + 2);
104 else
105 return (unsigned long)func;
106#elif defined(PPC64_ELF_ABI_v1)
107 /*
108 * On PPC64 ABIv1 the function pointer actually points to the
109 * function's descriptor. The first entry in the descriptor is the
110 * address of the function text.
111 */
112 return ((func_descr_t *)func)->entry;
113#else
114 return (unsigned long)func;
115#endif
116}
117
118static inline unsigned long ppc_global_function_entry(void *func)
119{
120#ifdef PPC64_ELF_ABI_v2
121 /* PPC64 ABIv2 the global entry point is at the address */
122 return (unsigned long)func;
123#else
124 /* All other cases there is no change vs ppc_function_entry() */
125 return ppc_function_entry(func);
126#endif
127}
128
129/*
130 * Wrapper around kallsyms_lookup() to return function entry address:
131 * - For ABIv1, we lookup the dot variant.
132 * - For ABIv2, we return the local entry point.
133 */
134static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
135{
136 unsigned long addr;
137#ifdef PPC64_ELF_ABI_v1
138 /* check for dot variant */
139 char dot_name[1 + KSYM_NAME_LEN];
140 bool dot_appended = false;
141
142 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
143 return 0;
144
145 if (name[0] != '.') {
146 dot_name[0] = '.';
147 dot_name[1] = '\0';
148 strlcat(dot_name, name, sizeof(dot_name));
149 dot_appended = true;
150 } else {
151 dot_name[0] = '\0';
152 strlcat(dot_name, name, sizeof(dot_name));
153 }
154 addr = kallsyms_lookup_name(dot_name);
155 if (!addr && dot_appended)
156 /* Let's try the original non-dot symbol lookup */
157 addr = kallsyms_lookup_name(name);
158#elif defined(PPC64_ELF_ABI_v2)
159 addr = kallsyms_lookup_name(name);
160 if (addr)
161 addr = ppc_function_entry((void *)addr);
162#else
163 addr = kallsyms_lookup_name(name);
164#endif
165 return addr;
166}
167
168#ifdef CONFIG_PPC64
169/*
170 * Some instruction encodings commonly used in dynamic ftracing
171 * and function live patching.
172 */
173
174/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
175#ifdef PPC64_ELF_ABI_v2
176#define R2_STACK_OFFSET 24
177#else
178#define R2_STACK_OFFSET 40
179#endif
180
181#define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
182 ___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
183
184/* usually preceded by a mflr r0 */
185#define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
186 ___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
187#endif /* CONFIG_PPC64 */
188
189#endif /* _ASM_POWERPC_CODE_PATCHING_H */