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