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