This adds an "override" keyword for use in *.symvers / *.symref files. When a symbol is overridden, the symbol's old definition will be used for computing checksums instead of the new one, preserving the previous checksum. (Genksyms will still warn about the change.) This is meant to allow distributions to hide minor actual as well as fake ABI changes. (For example, when extra type information becomes available because additional headers are included, this may change checksums even though none of the types used have actully changed.) This approach also allows to get rid of "#ifdef __GENKSYMS__" hacks in the code, which are currently used in some vendor kernels to work around checksum changes.
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| @@ -191,11 +191,26 @@ struct symbol *__add_symbol(const char *name, enum symbol_type type, · 190 unmodified lines | ||
| 191 | 191 | /* fall through */ ; |
| 192 | 192 | else if (sym->type == type && |
| 193 | 193 | equal_list(sym->defn, defn)) { |
| 194 | + if (!sym->is_declared && sym->is_override) { | |
| 195 | + print_location(); | |
| 196 | + print_type_name(type, name); | |
| 197 | + fprintf(stderr, " modversion is " | |
| 198 | + "unchanged\n"); | |
| 199 | + } | |
| 194 | 200 | sym->is_declared = 1; |
| 195 | 201 | return sym; |
| 196 | 202 | } else if (!sym->is_declared) { |
| 197 | − status = is_unknown_symbol(sym) ? | |
| 198 | − STATUS_DEFINED : STATUS_MODIFIED; | |
| 203 | + if (sym->is_override && flag_preserve) { | |
| 204 | + print_location(); | |
| 205 | + fprintf(stderr, "ignoring "); | |
| 206 | + print_type_name(type, name); | |
| 207 | + fprintf(stderr, " modversion change\n"); | |
| 208 | + sym->is_declared = 1; | |
| 209 | + return sym; | |
| 210 | + } else { | |
| 211 | + status = is_unknown_symbol(sym) ? | |
| 212 | + STATUS_DEFINED : STATUS_MODIFIED; | |
| 213 | + } | |
| 199 | 214 | } else { |
| 200 | 215 | error_with_pos("redefinition of %s", name); |
| 201 | 216 | return sym; |
| @@ -229,6 +244,7 @@ struct symbol *__add_symbol(const char *name, enum symbol_type type, · 27 unmodified lines | ||
| 229 | 244 | |
| 230 | 245 | sym->is_declared = !is_reference; |
| 231 | 246 | sym->status = status; |
| 247 | + sym->is_override = 0; | |
| 232 | 248 | |
| 233 | 249 | if (flag_debug) { |
| 234 | 250 | fprintf(debugfile, "Defn for %s %s == <", |
| @@ -348,9 +364,16 @@ static void read_reference(FILE *f) · 113 unmodified lines | ||
| 348 | 364 | while (!feof(f)) { |
| 349 | 365 | struct string_list *defn = NULL; |
| 350 | 366 | struct string_list *sym, *def; |
| 351 | − int is_extern = 0; | |
| 367 | + int is_extern = 0, is_override = 0; | |
| 368 | + struct symbol *subsym; | |
| 352 | 369 | |
| 353 | 370 | sym = read_node(f); |
| 371 | + if (sym && sym->tag == SYM_NORMAL && | |
| 372 | + !strcmp(sym->string, "override")) { | |
| 373 | + is_override = 1; | |
| 374 | + free_node(sym); | |
| 375 | + sym = read_node(f); | |
| 376 | + } | |
| 354 | 377 | if (!sym) |
| 355 | 378 | continue; |
| 356 | 379 | def = read_node(f); |
| @@ -365,8 +388,9 @@ static void read_reference(FILE *f) · 8 unmodified lines | ||
| 365 | 388 | defn = def; |
| 366 | 389 | def = read_node(f); |
| 367 | 390 | } |
| 368 | − add_reference_symbol(xstrdup(sym->string), sym->tag, | |
| 391 | + subsym = add_reference_symbol(xstrdup(sym->string), sym->tag, | |
| 369 | 392 | defn, is_extern); |
| 393 | + subsym->is_override = is_override; | |
| 370 | 394 | free_node(sym); |
| 371 | 395 | } |
| 372 | 396 | } |
| @@ -743,6 +767,8 @@ int main(int argc, char **argv) · 370 unmodified lines | ||
| 743 | 767 | while (visited_symbols != (struct symbol *)-1L) { |
| 744 | 768 | struct symbol *sym = visited_symbols; |
| 745 | 769 | |
| 770 | + if (sym->is_override) | |
| 771 | + fputs("override ", dumpfile); | |
| 746 | 772 | if (sym->type != SYM_NORMAL) { |
| 747 | 773 | putc(symbol_type_name[sym->type][0], dumpfile); |
| 748 | 774 | putc('#', dumpfile); |
| @@ -49,6 +49,7 @@ struct symbol { · 48 unmodified lines | ||
| 49 | 49 | int is_extern; |
| 50 | 50 | int is_declared; |
| 51 | 51 | enum symbol_status status; |
| 52 | + int is_override; | |
| 52 | 53 | }; |
| 53 | 54 | |
| 54 | 55 | typedef struct string_list **yystype; |