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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
25/*
26 * Powerpc branch instruction is :
27 *
28 * 0 6 30 31
29 * +---------+----------------+---+---+
30 * | opcode | LI |AA |LK |
31 * +---------+----------------+---+---+
32 * Where AA = 0 and LK = 0
33 *
34 * LI is a signed 24 bits integer. The real branch offset is computed
35 * by: imm32 = SignExtend(LI:'0b00', 32);
36 *
37 * So the maximum forward branch should be:
38 * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc
39 * The maximum backward branch should be:
40 * (0xff800000 << 2) = 0xfe000000 = -0x2000000
41 */
42static inline bool is_offset_in_branch_range(long offset)
43{
44 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
45}
46
47static inline bool is_offset_in_cond_branch_range(long offset)
48{
49 return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
50}
51
52static inline int create_branch(ppc_inst_t *instr, const u32 *addr,
53 unsigned long target, int flags)
54{
55 long offset;
56
57 *instr = ppc_inst(0);
58 offset = target;
59 if (! (flags & BRANCH_ABSOLUTE))
60 offset = offset - (unsigned long)addr;
61
62 /* Check we can represent the target in the instruction format */
63 if (!is_offset_in_branch_range(offset))
64 return 1;
65
66 /* Mask out the flags and target, so they don't step on each other. */
67 *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
68
69 return 0;
70}
71
72int create_cond_branch(ppc_inst_t *instr, const u32 *addr,
73 unsigned long target, int flags);
74int patch_branch(u32 *addr, unsigned long target, int flags);
75int patch_instruction(u32 *addr, ppc_inst_t instr);
76int raw_patch_instruction(u32 *addr, ppc_inst_t instr);
77int patch_instructions(u32 *addr, u32 *code, size_t len, bool repeat_instr);
78
79/*
80 * The data patching functions patch_uint() and patch_ulong(), etc., must be
81 * called on aligned addresses.
82 *
83 * The instruction patching functions patch_instruction() and similar must be
84 * called on addresses satisfying instruction alignment requirements.
85 */
86
87#ifdef CONFIG_PPC64
88
89int patch_uint(void *addr, unsigned int val);
90int patch_ulong(void *addr, unsigned long val);
91
92#define patch_u64 patch_ulong
93
94#else
95
96static inline int patch_uint(void *addr, unsigned int val)
97{
98 if (!IS_ALIGNED((unsigned long)addr, sizeof(unsigned int)))
99 return -EINVAL;
100
101 return patch_instruction(addr, ppc_inst(val));
102}
103
104static inline int patch_ulong(void *addr, unsigned long val)
105{
106 if (!IS_ALIGNED((unsigned long)addr, sizeof(unsigned long)))
107 return -EINVAL;
108
109 return patch_instruction(addr, ppc_inst(val));
110}
111
112#endif
113
114#define patch_u32 patch_uint
115
116static inline unsigned long patch_site_addr(s32 *site)
117{
118 return (unsigned long)site + *site;
119}
120
121static inline int patch_instruction_site(s32 *site, ppc_inst_t instr)
122{
123 return patch_instruction((u32 *)patch_site_addr(site), instr);
124}
125
126static inline int patch_branch_site(s32 *site, unsigned long target, int flags)
127{
128 return patch_branch((u32 *)patch_site_addr(site), target, flags);
129}
130
131static inline int modify_instruction(unsigned int *addr, unsigned int clr,
132 unsigned int set)
133{
134 return patch_instruction(addr, ppc_inst((*addr & ~clr) | set));
135}
136
137static inline int modify_instruction_site(s32 *site, unsigned int clr, unsigned int set)
138{
139 return modify_instruction((unsigned int *)patch_site_addr(site), clr, set);
140}
141
142static inline unsigned int branch_opcode(ppc_inst_t instr)
143{
144 return ppc_inst_primary_opcode(instr) & 0x3F;
145}
146
147static inline int instr_is_branch_iform(ppc_inst_t instr)
148{
149 return branch_opcode(instr) == 18;
150}
151
152static inline int instr_is_branch_bform(ppc_inst_t instr)
153{
154 return branch_opcode(instr) == 16;
155}
156
157int instr_is_relative_branch(ppc_inst_t instr);
158int instr_is_relative_link_branch(ppc_inst_t instr);
159unsigned long branch_target(const u32 *instr);
160int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src);
161bool is_conditional_branch(ppc_inst_t instr);
162
163#define OP_RT_RA_MASK 0xffff0000UL
164#define LIS_R2 (PPC_RAW_LIS(_R2, 0))
165#define ADDIS_R2_R12 (PPC_RAW_ADDIS(_R2, _R12, 0))
166#define ADDI_R2_R2 (PPC_RAW_ADDI(_R2, _R2, 0))
167
168
169static inline unsigned long ppc_function_entry(void *func)
170{
171#ifdef CONFIG_PPC64_ELF_ABI_V2
172 u32 *insn = func;
173
174 /*
175 * A PPC64 ABIv2 function may have a local and a global entry
176 * point. We need to use the local entry point when patching
177 * functions, so identify and step over the global entry point
178 * sequence.
179 *
180 * The global entry point sequence is always of the form:
181 *
182 * addis r2,r12,XXXX
183 * addi r2,r2,XXXX
184 *
185 * A linker optimisation may convert the addis to lis:
186 *
187 * lis r2,XXXX
188 * addi r2,r2,XXXX
189 */
190 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
191 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
192 ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
193 return (unsigned long)(insn + 2);
194 else
195 return (unsigned long)func;
196#elif defined(CONFIG_PPC64_ELF_ABI_V1)
197 /*
198 * On PPC64 ABIv1 the function pointer actually points to the
199 * function's descriptor. The first entry in the descriptor is the
200 * address of the function text.
201 */
202 return ((struct func_desc *)func)->addr;
203#else
204 return (unsigned long)func;
205#endif
206}
207
208static inline unsigned long ppc_global_function_entry(void *func)
209{
210#ifdef CONFIG_PPC64_ELF_ABI_V2
211 /* PPC64 ABIv2 the global entry point is at the address */
212 return (unsigned long)func;
213#else
214 /* All other cases there is no change vs ppc_function_entry() */
215 return ppc_function_entry(func);
216#endif
217}
218
219/*
220 * Wrapper around kallsyms_lookup() to return function entry address:
221 * - For ABIv1, we lookup the dot variant.
222 * - For ABIv2, we return the local entry point.
223 */
224static inline unsigned long ppc_kallsyms_lookup_name(const char *name)
225{
226 unsigned long addr;
227#ifdef CONFIG_PPC64_ELF_ABI_V1
228 /* check for dot variant */
229 char dot_name[1 + KSYM_NAME_LEN];
230 bool dot_appended = false;
231
232 if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
233 return 0;
234
235 if (name[0] != '.') {
236 dot_name[0] = '.';
237 dot_name[1] = '\0';
238 strlcat(dot_name, name, sizeof(dot_name));
239 dot_appended = true;
240 } else {
241 dot_name[0] = '\0';
242 strlcat(dot_name, name, sizeof(dot_name));
243 }
244 addr = kallsyms_lookup_name(dot_name);
245 if (!addr && dot_appended)
246 /* Let's try the original non-dot symbol lookup */
247 addr = kallsyms_lookup_name(name);
248#elif defined(CONFIG_PPC64_ELF_ABI_V2)
249 addr = kallsyms_lookup_name(name);
250 if (addr)
251 addr = ppc_function_entry((void *)addr);
252#else
253 addr = kallsyms_lookup_name(name);
254#endif
255 return addr;
256}
257
258/*
259 * Some instruction encodings commonly used in dynamic ftracing
260 * and function live patching.
261 */
262
263/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
264#ifdef CONFIG_PPC64_ELF_ABI_V2
265#define R2_STACK_OFFSET 24
266#else
267#define R2_STACK_OFFSET 40
268#endif
269
270#define PPC_INST_LD_TOC PPC_RAW_LD(_R2, _R1, R2_STACK_OFFSET)
271
272/* usually preceded by a mflr r0 */
273#define PPC_INST_STD_LR PPC_RAW_STD(_R0, _R1, PPC_LR_STKOFF)
274
275#endif /* _ASM_POWERPC_CODE_PATCHING_H */