include/linux/kallsyms.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* Rewritten and vastly simplified by Rusty Russell for in-kernel
   3  * module loader:
   4  *   Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
   5  */
   6 #ifndef _LINUX_KALLSYMS_H
   7 #define _LINUX_KALLSYMS_H
   8
   9 #include <linux/errno.h>
  10 #include <linux/buildid.h>
  11 #include <linux/kernel.h>
  12 #include <linux/stddef.h>
  13 #include <linux/mm.h>
  14 #include <linux/module.h>
  15
  16 #include <asm/sections.h>
  17
  18 #define KSYM_NAME_LEN 512
  19 #define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s %s]") + \
  20                         (KSYM_NAME_LEN - 1) + \
  21                         2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + \
  22                         (BUILD_ID_SIZE_MAX * 2) + 1)
  23
  24 struct cred;
  25 struct module;
  26
  27 static inline int is_kernel_text(unsigned long addr)
  28 {
  29         if (__is_kernel_text(addr))
  30                 return 1;
  31         return in_gate_area_no_mm(addr);
  32 }
  33
  34 static inline int is_kernel(unsigned long addr)
  35 {
  36         if (__is_kernel(addr))
  37                 return 1;
  38         return in_gate_area_no_mm(addr);
  39 }
  40
  41 static inline int is_ksym_addr(unsigned long addr)
  42 {
  43         if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
  44                 return is_kernel(addr);
  45
  46         return is_kernel_text(addr) || is_kernel_inittext(addr);
  47 }
  48
  49 static inline void *dereference_symbol_descriptor(void *ptr)
  50 {
  51 #ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
  52         struct module *mod;
  53
  54         ptr = dereference_kernel_function_descriptor(ptr);
  55         if (is_ksym_addr((unsigned long)ptr))
  56                 return ptr;
  57
  58         preempt_disable();
  59         mod = __module_address((unsigned long)ptr);
  60         preempt_enable();
  61
  62         if (mod)
  63                 ptr = dereference_module_function_descriptor(mod, ptr);
  64 #endif
  65         return ptr;
  66 }
  67
  68 #ifdef CONFIG_KALLSYMS
  69 unsigned long kallsyms_sym_address(int idx);
  70 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long),
  71                             void *data);
  72 int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long),
  73                                   const char *name, void *data);
  74
  75 /* Lookup the address for a symbol. Returns 0 if not found. */
  76 unsigned long kallsyms_lookup_name(const char *name);
  77
  78 extern int kallsyms_lookup_size_offset(unsigned long addr,
  79                                   unsigned long *symbolsize,
  80                                   unsigned long *offset);
  81
  82 /* Lookup an address.  modname is set to NULL if it's in the kernel. */
  83 const char *kallsyms_lookup(unsigned long addr,
  84                             unsigned long *symbolsize,
  85                             unsigned long *offset,
  86                             char **modname, char *namebuf);
  87
  88 /* Look up a kernel symbol and return it in a text buffer. */
  89 extern int sprint_symbol(char *buffer, unsigned long address);
  90 extern int sprint_symbol_build_id(char *buffer, unsigned long address);
  91 extern int sprint_symbol_no_offset(char *buffer, unsigned long address);
  92 extern int sprint_backtrace(char *buffer, unsigned long address);
  93 extern int sprint_backtrace_build_id(char *buffer, unsigned long address);
  94
  95 int lookup_symbol_name(unsigned long addr, char *symname);
  96 int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name);
  97
  98 /* How and when do we show kallsyms values? */
  99 extern bool kallsyms_show_value(const struct cred *cred);
 100
 101 #else /* !CONFIG_KALLSYMS */
 102
 103 static inline unsigned long kallsyms_lookup_name(const char *name)
 104 {
 105         return 0;
 106 }
 107
 108 static inline int kallsyms_lookup_size_offset(unsigned long addr,
 109                                               unsigned long *symbolsize,
 110                                               unsigned long *offset)
 111 {
 112         return 0;
 113 }
 114
 115 static inline const char *kallsyms_lookup(unsigned long addr,
 116                                           unsigned long *symbolsize,
 117                                           unsigned long *offset,
 118                                           char **modname, char *namebuf)
 119 {
 120         return NULL;
 121 }
 122
 123 static inline int sprint_symbol(char *buffer, unsigned long addr)
 124 {
 125         *buffer = '\0';
 126         return 0;
 127 }
 128
 129 static inline int sprint_symbol_build_id(char *buffer, unsigned long address)
 130 {
 131         *buffer = '\0';
 132         return 0;
 133 }
 134
 135 static inline int sprint_symbol_no_offset(char *buffer, unsigned long addr)
 136 {
 137         *buffer = '\0';
 138         return 0;
 139 }
 140
 141 static inline int sprint_backtrace(char *buffer, unsigned long addr)
 142 {
 143         *buffer = '\0';
 144         return 0;
 145 }
 146
 147 static inline int sprint_backtrace_build_id(char *buffer, unsigned long addr)
 148 {
 149         *buffer = '\0';
 150         return 0;
 151 }
 152
 153 static inline int lookup_symbol_name(unsigned long addr, char *symname)
 154 {
 155         return -ERANGE;
 156 }
 157
 158 static inline int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name)
 159 {
 160         return -ERANGE;
 161 }
 162
 163 static inline bool kallsyms_show_value(const struct cred *cred)
 164 {
 165         return false;
 166 }
 167
 168 static inline int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long),
 169                                           void *data)
 170 {
 171         return -EOPNOTSUPP;
 172 }
 173
 174 static inline int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long),
 175                                                 const char *name, void *data)
 176 {
 177         return -EOPNOTSUPP;
 178 }
 179 #endif /*CONFIG_KALLSYMS*/
 180
 181 static inline void print_ip_sym(const char *loglvl, unsigned long ip)
 182 {
 183         printk("%s[<%px>] %pS\n", loglvl, (void *) ip, (void *) ip);
 184 }
 185
 186 #endif /*_LINUX_KALLSYMS_H*/