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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#include <asm/inst.h>
15
16/* Flags for create_branch:
17 * "b" == create_branch(addr, target, 0);
18 * "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
19 * "bl" == create_branch(addr, target, BRANCH_SET_LINK);
20 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
21 */
22#define BRANCH_SET_LINK 0x1
23#define BRANCH_ABSOLUTE 0x2
24
25bool is_offset_in_branch_range(long offset);
26bool is_offset_in_cond_branch_range(long offset);
27int create_branch(ppc_inst_t *instr, const u32 *addr,
28 unsigned long target, int flags);
29int create_cond_branch(ppc_inst_t *instr, const u32 *addr,
30 unsigned long target, int flags);
31int patch_branch(u32 *addr, unsigned long target, int flags);
32int patch_instruction(u32 *addr, ppc_inst_t instr);
33int raw_patch_instruction(u32 *addr, ppc_inst_t instr);
34
35static inline unsigned long patch_site_addr(s32 *site)
36{
37 return (unsigned long)site + *site;
38}
39
40static inline int patch_instruction_site(s32 *site, ppc_inst_t instr)
41{
42 return patch_instruction((u32 *)patch_site_addr(site), instr);
43}
44
45static inline int patch_branch_site(s32 *site, unsigned long target, int flags)
46{
47 return patch_branch((u32 *)patch_site_addr(site), target, flags);
48}
49
50static inline int modify_instruction(unsigned int *addr, unsigned int clr,
51 unsigned int set)
52{
53 return patch_instruction(addr, ppc_inst((*addr & ~clr) | set));
54}
55
56static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set)
57{
58 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set);
59}
60
61static inline unsigned int branch_opcode(ppc_inst_t instr)
62{
63 return ppc_inst_primary_opcode(instr) & 0x3F;
64}
65
66static inline int instr_is_branch_iform(ppc_inst_t instr)
67{
68 return branch_opcode(instr) == 18;
69}
70
71static inline int instr_is_branch_bform(ppc_inst_t instr)
72{
73 return branch_opcode(instr) == 16;
74}
75
76int instr_is_relative_branch(ppc_inst_t instr);
77int instr_is_relative_link_branch(ppc_inst_t instr);
78unsigned long branch_target(const u32 *instr);
79int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src);
80bool is_conditional_branch(ppc_inst_t instr);
81
82#define OP_RT_RA_MASK 0xffff0000UL
83#define LIS_R2 (PPC_RAW_LIS(_R2, 0))
84#define ADDIS_R2_R12 (PPC_RAW_ADDIS(_R2, _R12, 0))
85#define ADDI_R2_R2 (PPC_RAW_ADDI(_R2, _R2, 0))
86
87
88static inline unsigned long ppc_function_entry(void *func)
89{
90#ifdef PPC64_ELF_ABI_v2
91 u32 *insn = func;
92
93 /*
94 * A PPC64 ABIv2 function may have a local and a global entry
95 * point. We need to use the local entry point when patching
96 * functions, so identify and step over the global entry point
97 * sequence.
98 *
99 * The global entry point sequence is always of the form:
100 *
101 * addis r2,r12,XXXX
102 * addi r2,r2,XXXX
103 *
104 * A linker optimisation may convert the addis to lis:
105 *
106 * lis r2,XXXX
107 * addi r2,r2,XXXX
108 */
109 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
110 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
111 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
112 return (unsigned long)(insn + 2);
113 else
114 return (unsigned long)func;
115#elif defined(PPC64_ELF_ABI_v1)
116 /*
117 * On PPC64 ABIv1 the function pointer actually points to the
118 * function's descriptor. The first entry in the descriptor is the
119 * address of the function text.
120 */
121 return ((struct func_desc *)func)->addr;
122#else
123 return (unsigned long)func;
124#endif
125}
126
127static inline unsigned long ppc_global_function_entry(void *func)
128{
129#ifdef PPC64_ELF_ABI_v2
130 /* PPC64 ABIv2 the global entry point is at the address */
131 return (unsigned long)func;
132#else
133 /* All other cases there is no change vs ppc_function_entry() */
134 return ppc_function_entry(func);
135#endif
136}
137
138/*
139 * Wrapper around kallsyms_lookup() to return function entry address:
140 * - For ABIv1, we lookup the dot variant.
141 * - For ABIv2, we return the local entry point.
142 */
143static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
144{
145 unsigned long addr;
146#ifdef PPC64_ELF_ABI_v1
147 /* check for dot variant */
148 char dot_name[1 + KSYM_NAME_LEN];
149 bool dot_appended = false;
150
151 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
152 return 0;
153
154 if (name[0] != '.') {
155 dot_name[0] = '.';
156 dot_name[1] = '\0';
157 strlcat(dot_name, name, sizeof(dot_name));
158 dot_appended = true;
159 } else {
160 dot_name[0] = '\0';
161 strlcat(dot_name, name, sizeof(dot_name));
162 }
163 addr = kallsyms_lookup_name(dot_name);
164 if (!addr && dot_appended)
165 /* Let's try the original non-dot symbol lookup */
166 addr = kallsyms_lookup_name(name);
167#elif defined(PPC64_ELF_ABI_v2)
168 addr = kallsyms_lookup_name(name);
169 if (addr)
170 addr = ppc_function_entry((void *)addr);
171#else
172 addr = kallsyms_lookup_name(name);
173#endif
174 return addr;
175}
176
177#ifdef CONFIG_PPC64
178/*
179 * Some instruction encodings commonly used in dynamic ftracing
180 * and function live patching.
181 */
182
183/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
184#ifdef PPC64_ELF_ABI_v2
185#define R2_STACK_OFFSET 24
186#else
187#define R2_STACK_OFFSET 40
188#endif
189
190#define PPC_INST_LD_TOC PPC_RAW_LD(_R2, _R1, R2_STACK_OFFSET)
191
192/* usually preceded by a mflr r0 */
193#define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF)
194#endif /* CONFIG_PPC64 */
195
196#endif /* _ASM_POWERPC_CODE_PATCHING_H */