kmodsrc/ksplice.h

   1 #include <linux/types.h>
   2
   3 /**
   4  * struct ksplice_symbol - Ksplice's analogue of an ELF symbol
   5  * @name:               The ELF name of the symbol
   6  * @label:              A unique Ksplice name for the symbol
   7  * @candidate_vals:     A linked list of possible values for the symbol, or NULL
   8  * @value:              The value of the symbol (valid when vals is NULL)
   9  **/
  10 struct ksplice_symbol {
  11         const char *name;
  12         const char *label;
  13 /* private: */
  14         struct list_head *candidate_vals;
  15         unsigned long value;
  16 };
  17
  18 /**
  19  * struct ksplice_reloc - Ksplice's analogue of an ELF relocation
  20  * @blank_addr:         The address of the relocation's storage unit
  21  * @symbol:             The ksplice_symbol associated with this relocation
  22  * @howto:              The information regarding the relocation type
  23  * @addend:             The ELF addend of the relocation
  24  **/
  25 struct ksplice_reloc {
  26         unsigned long blank_addr;
  27         struct ksplice_symbol *symbol;
  28         const struct ksplice_reloc_howto *howto;
  29         long insn_addend;
  30         long target_addend;
  31 };
  32
  33 enum ksplice_reloc_howto_type {
  34         KSPLICE_HOWTO_RELOC,
  35         KSPLICE_HOWTO_RELOC_PATCH,
  36         KSPLICE_HOWTO_DATE,
  37         KSPLICE_HOWTO_TIME,
  38         KSPLICE_HOWTO_BUG,
  39         KSPLICE_HOWTO_EXTABLE,
  40         KSPLICE_HOWTO_SYMBOL,
  41 };
  42
  43 /**
  44  * struct ksplice_reloc_howto - Ksplice's relocation type information
  45  * @type:               The type of the relocation
  46  * @pcrel:              Is the relocation PC relative?
  47  * @size:               The size, in bytes, of the item to be relocated
  48  * @dst_mask:           Bitmask for which parts of the instruction or data are
  49  *                      replaced with the relocated value
  50  *                      (based on dst_mask from GNU BFD's reloc_howto_struct)
  51  * @rightshift:         The value the final relocation is shifted right by;
  52  *                      used to drop unwanted data from the relocation
  53  *                      (based on rightshift from GNU BFD's reloc_howto_struct)
  54  * @signed_addend:      Should the addend be interpreted as a signed value?
  55  **/
  56 struct ksplice_reloc_howto {
  57         enum ksplice_reloc_howto_type type;
  58         int pcrel;
  59         int size;
  60         long dst_mask;
  61         unsigned int rightshift;
  62         int signed_addend;
  63 };
  64
  65 #if BITS_PER_LONG == 32
  66 #define KSPLICE_CANARY 0x77777777UL
  67 #elif BITS_PER_LONG == 64
  68 #define KSPLICE_CANARY 0x7777777777777777UL
  69 #endif /* BITS_PER_LONG */
  70
  71 /**
  72  * struct ksplice_section - Ksplice's analogue of an ELF section
  73  * @symbol:             The ksplice_symbol associated with this section
  74  * @size:               The length, in bytes, of this section
  75  * @address:            The address of the section
  76  * @flags:              Flags indicating the type of the section, whether or
  77  *                      not it has been matched, etc.
  78  **/
  79 struct ksplice_section {
  80         struct ksplice_symbol *symbol;
  81         unsigned long address;
  82         unsigned long size;
  83         unsigned int flags;
  84         const unsigned char **match_map;
  85 };
  86 #define KSPLICE_SECTION_TEXT 0x00000001
  87 #define KSPLICE_SECTION_RODATA 0x00000002
  88 #define KSPLICE_SECTION_DATA 0x00000004
  89 #define KSPLICE_SECTION_STRING 0x00000008
  90 #define KSPLICE_SECTION_MATCHED 0x10000000
  91
  92 #define MAX_TRAMPOLINE_SIZE 5
  93
  94 enum ksplice_patch_type {
  95         KSPLICE_PATCH_TEXT,
  96         KSPLICE_PATCH_DATA,
  97         KSPLICE_PATCH_EXPORT,
  98 };
  99
 100 /**
 101  * struct ksplice_patch - A replacement that Ksplice should perform
 102  * @oldaddr:            The address of the obsolete function or structure
 103  * @repladdr:           The address of the replacement function
 104  * @type:               The type of the ksplice patch
 105  * @size:               The size of the patch
 106  * @contents:           The bytes to be installed at oldaddr
 107  * @vaddr               The address of the page mapping used to write at oldaddr
 108  * @saved:              The bytes originally at oldaddr which were
 109  *                      overwritten by the patch
 110  **/
 111 struct ksplice_patch {
 112         unsigned long oldaddr;
 113         unsigned long repladdr;
 114         enum ksplice_patch_type type;
 115         unsigned int size;
 116         void *contents;
 117 /* private: */
 118         void *vaddr;
 119         void *saved;
 120 };
 121
 122 #ifdef KSPLICE_STANDALONE
 123 struct ksplice_system_map {
 124         const char *label;
 125         unsigned long nr_candidates;
 126         const unsigned long *candidates;
 127 };
 128 #endif /* KSPLICE_STANDALONE */
 129
 130 #ifdef __KERNEL__
 131 #include <linux/module.h>
 132 #include <linux/stringify.h>
 133 #include <linux/version.h>
 134
 135 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
 136 /* 6e21828743247270d09a86756a0c11702500dbfb was after 2.6.18 */
 137 #define bool _Bool
 138 #define false 0
 139 #define true 1
 140 #endif /* LINUX_VERSION_CODE */
 141
 142 #if defined(CONFIG_PARAVIRT) && defined(CONFIG_X86_64) &&       \
 143     LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,25) &&             \
 144     LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
 145 /* Linux 2.6.25 and 2.6.26 apply paravirt replacements to the core
 146  * kernel but not modules on x86-64.  If we are patching the core
 147  * kernel, we need to apply the same replacements to our update
 148  * modules in order for run-pre matching to succeed.
 149  */
 150 #define KSPLICE_NEED_PARAINSTRUCTIONS 1
 151 #endif /* KSPLICE_NEED_PARAINSTRUCTIONS */
 152
 153 #define _PASTE(x, y) x##y
 154 #define PASTE(x, y) _PASTE(x, y)
 155 #define KSPLICE_UNIQ(s) PASTE(s##_, KSPLICE_MID)
 156 #define KSPLICE_KID_UNIQ(s) PASTE(s##_, KSPLICE_KID)
 157 #ifdef KSPLICE_STANDALONE
 158 #define init_ksplice_mod_change KSPLICE_KID_UNIQ(init_ksplice_mod_change)
 159 #define cleanup_ksplice_mod_change KSPLICE_KID_UNIQ(cleanup_ksplice_mod_change)
 160 #endif
 161
 162 /**
 163  * struct ksplice_module_list_entry - A record of a ksplice_mod_change's target
 164  * @target_mod_name:    The name of the ksplice_mod_change's target module
 165  * @new_code_mod_name:  The name of the ksplice_mod_change's new_code module
 166  * @applied:            Whether the ksplice_mod_change was applied or not (this
 167  *                      will be false for ksplice_mod_changes patching targets
 168  *                      that are not loaded when the partial flag is set)
 169  **/
 170 struct ksplice_module_list_entry {
 171         const char *target_mod_name;
 172         const char *new_code_mod_name;
 173         const char *kid;
 174         bool applied;
 175 /* private: */
 176         struct list_head update_list;   /* list head for this is per-update */
 177         struct list_head list;  /* list head for this is global */
 178 };
 179
 180 /* List of all ksplice modules and the module they patch */
 181 extern struct list_head ksplice_modules;
 182
 183 /* There are two actions, apply and reverse */
 184 #define KS_ACTIONS 2
 185 enum ksplice_action {
 186         KS_APPLY,
 187         KS_REVERSE,
 188 };
 189
 190 /**
 191  * struct ksplice_hooks - Hooks to be run during an action (apply or reverse)
 192  * @pre:                        Runs before the action;
 193  *                              may return nonzero to abort the action
 194  * @check:                      Runs inside stop_machine before the action;
 195  *                              may return nonzero to abort the action
 196  * @intra:                      Runs inside stop_machine during the action
 197  * @post:                       Runs after the action is successfully performed
 198  * @fail:                       Runs if the action is aborted for any reason
 199  */
 200 struct ksplice_hooks {
 201         const typeof(int (*)(void)) *pre, *pre_end, *check, *check_end;
 202         const typeof(void (*)(void)) *intra, *intra_end, *post, *post_end,
 203             *fail, *fail_end;
 204 };
 205
 206 /**
 207  * struct ksplice_code - Ksplice metadata for an object
 208  * @relocs:             The Ksplice relocations for the object
 209  * @symbols:            The Ksplice symbols for the object
 210  * @sections:           The Ksplice sections for the object
 211  **/
 212 struct ksplice_code {
 213         struct ksplice_reloc *relocs, *relocs_end;
 214         struct ksplice_section *sections, *sections_end;
 215         struct ksplice_symbol *symbols, *symbols_end;
 216 #ifdef KSPLICE_NEED_PARAINSTRUCTIONS
 217         struct paravirt_patch_site *parainstructions, *parainstructions_end;
 218 #endif /* KSPLICE_NEED_PARAINSTRUCTIONS */
 219 #ifdef KSPLICE_STANDALONE
 220         struct ksplice_system_map *system_map, *system_map_end;
 221 #endif /* KSPLICE_STANDALONE */
 222 };
 223
 224 /**
 225  * struct ksplice_mod_change - Data for one module modified by a Ksplice update
 226  * @name:                       The name of the new_code module for the change
 227  * @kid:                        The Ksplice unique identifier for the change
 228  * @target_name:                The name of the module modified by the change
 229  * @new_code_mod:               The new_code module for the change
 230  * @old_code:                   The old code for run-pre matching
 231  * @new_code:                   The new code to switch to
 232  * @patches:                    The function replacements in the change
 233  * @patches_end:                The end pointer for patches array
 234  * @hooks:                      Hooks to be run during apply and reverse
 235  * @update:                     The atomic update the change is part of
 236  * @target:                     The module modified by the change
 237  * @safety_records:             The ranges of addresses that must not be on a
 238  *                              kernel stack for the patch to apply safely
 239  **/
 240 struct ksplice_mod_change {
 241         const char *name;
 242         const char *kid;
 243         const char *target_name;
 244 #ifdef KSPLICE_STANDALONE
 245         unsigned long map_printk;
 246 #endif /* KSPLICE_STANDALONE */
 247         struct module *new_code_mod;
 248         struct ksplice_code old_code, new_code;
 249         struct ksplice_patch *patches, *patches_end;
 250         struct ksplice_hooks hooks[KS_ACTIONS];
 251 /* private: */
 252         struct update *update;
 253         struct module *target;
 254         struct list_head temp_labelvals;
 255         struct list_head safety_records;
 256         struct list_head list;
 257 };
 258
 259
 260 int init_ksplice_mod_change(struct ksplice_mod_change *change);
 261
 262 void cleanup_ksplice_mod_change(struct ksplice_mod_change *change);
 263
 264 #endif /* __KERNEL__ */