Sometimes it is preferable to avoid changes of exported symbol checksums (to avoid breaking externally provided modules). When a checksum change occurs, it can be hard to figure out what caused this change: underlying types may have changed, or additional type information may simply have become available at the point where a symbol is exported. Add a new --reference option to genksyms which allows it to report why checksums change, based on the type information dumps it creates with the --dump-types flag. Genksyms will read in such a dump from a previous run, and report which symbols have changed (and why). The behavior can be controlled for an entire build as follows: If KBUILD_SYMTYPES is set, genksyms uses --dump-types to produce *.symtypes dump files. If any *.symref files exist, those will be used as the reference to check against. If KBUILD_PRESERVE is set, checksum changes will fail the build. Signed-off-by: Andreas Gruenbacher --- scripts/Makefile.build | 16 ++ scripts/genksyms/genksyms.c | 236 +++++++++++++++++++++++++++++++++++++++++--- scripts/genksyms/genksyms.h | 6 + 3 files changed, 239 insertions(+), 19 deletions(-) Index: b/scripts/genksyms/genksyms.c =================================================================== --- a/scripts/genksyms/genksyms.c +++ b/scripts/genksyms/genksyms.c @@ -42,7 +42,8 @@ static FILE *debugfile; int cur_line = 1; char *cur_filename; -static int flag_debug, flag_dump_defs, flag_dump_types, flag_warnings; +static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types, + flag_preserve, flag_warnings; static const char *arch = ""; static const char *mod_prefix = ""; @@ -58,6 +59,8 @@ static const char *const symbol_type_nam static int equal_list(struct string_list *a, struct string_list *b); static void print_list(FILE * f, struct string_list *list); +static void print_location(void); +static void print_type_name(enum symbol_type type, const char *name); /*----------------------------------------------------------------------*/ @@ -151,25 +154,66 @@ struct symbol *find_symbol(const char *n for (sym = symtab[h]; sym; sym = sym->hash_next) if (map_to_ns(sym->type) == map_to_ns(ns) && - strcmp(name, sym->name) == 0) + strcmp(name, sym->name) == 0 && + sym->is_declared) break; return sym; } -struct symbol *add_symbol(const char *name, enum symbol_type type, - struct string_list *defn, int is_extern) +static int is_unknown_symbol(struct symbol *sym) +{ + struct string_list *defn; + + return ((sym->type == SYM_STRUCT || + sym->type == SYM_UNION || + sym->type == SYM_ENUM) && + (defn = sym->defn) && defn->tag == SYM_NORMAL && + strcmp(defn->string, "}") == 0 && + (defn = defn->next) && defn->tag == SYM_NORMAL && + strcmp(defn->string, "UNKNOWN") == 0 && + (defn = defn->next) && defn->tag == SYM_NORMAL && + strcmp(defn->string, "{") == 0); +} + +struct symbol *__add_symbol(const char *name, enum symbol_type type, + struct string_list *defn, int is_extern, + int is_reference) { unsigned long h = crc32(name) % HASH_BUCKETS; struct symbol *sym; + enum symbol_status status = STATUS_UNCHANGED; for (sym = symtab[h]; sym; sym = sym->hash_next) { - if (map_to_ns(sym->type) == map_to_ns(type) - && strcmp(name, sym->name) == 0) { - if (!equal_list(sym->defn, defn)) + if (map_to_ns(sym->type) == map_to_ns(type) && + strcmp(name, sym->name) == 0) { + if (is_reference) + /* fall through */ ; + else if (sym->type == type && + equal_list(sym->defn, defn)) { + sym->is_declared = 1; + return sym; + } else if (!sym->is_declared) { + status = is_unknown_symbol(sym) ? + STATUS_DEFINED : STATUS_MODIFIED; + } else { error_with_pos("redefinition of %s", name); - return sym; + return sym; + } + break; + } + } + + if (sym) { + struct symbol **psym; + + for (psym = &symtab[h]; *psym; psym = &(*psym)->hash_next) { + if (*psym == sym) { + *psym = sym->hash_next; + break; + } } + --nsyms; } sym = xmalloc(sizeof(*sym)); @@ -183,6 +227,9 @@ struct symbol *add_symbol(const char *na sym->hash_next = symtab[h]; symtab[h] = sym; + sym->is_declared = !is_reference; + sym->status = status; + if (flag_debug) { fprintf(debugfile, "Defn for %s %s == <", symbol_type_name[type], name); @@ -196,6 +243,18 @@ struct symbol *add_symbol(const char *na return sym; } +struct symbol *add_symbol(const char *name, enum symbol_type type, + struct string_list *defn, int is_extern) +{ + return __add_symbol(name, type, defn, is_extern, 0); +} + +struct symbol *add_reference_symbol(const char *name, enum symbol_type type, + struct string_list *defn, int is_extern) +{ + return __add_symbol(name, type, defn, is_extern, 1); +} + /*----------------------------------------------------------------------*/ void free_node(struct string_list *node) @@ -236,6 +295,82 @@ static int equal_list(struct string_list return !a && !b; } +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) + +struct string_list *read_node(FILE *f) +{ + char buffer[256]; + struct string_list node = { + .string = buffer, + .tag = SYM_NORMAL }; + int c; + + while ((c = fgetc(f)) != EOF) { + if (c == ' ') { + if (node.string == buffer) + continue; + break; + } else if (c == '\n') { + if (node.string == buffer) + return NULL; + ungetc(c, f); + break; + } + if (node.string >= buffer + sizeof(buffer) - 1) { + fprintf(stderr, "Token too long\n"); + exit(1); + } + *node.string++ = c; + } + if (node.string == buffer) + return NULL; + *node.string = 0; + node.string = buffer; + + if (node.string[1] == '#') { + int n; + + for (n = 0; n < ARRAY_SIZE(symbol_type_name); n++) { + if (node.string[0] == symbol_type_name[n][0]) { + node.tag = n; + node.string += 2; + return copy_node(&node); + } + } + fprintf(stderr, "Unknown type %c\n", node.string[0]); + exit(1); + } + return copy_node(&node); +} + +static void read_reference(FILE *f) +{ + while (!feof(f)) { + struct string_list *defn = NULL; + struct string_list *sym, *def; + int is_extern = 0; + + sym = read_node(f); + if (!sym) + continue; + def = read_node(f); + if (def && def->tag == SYM_NORMAL && + !strcmp(def->string, "extern")) { + is_extern = 1; + free_node(def); + def = read_node(f); + } + while (def) { + def->next = defn; + defn = def; + def = read_node(f); + } + add_reference_symbol(xstrdup(sym->string), sym->tag, + defn, is_extern); + free_node(sym); + } +} + static void print_node(FILE * f, struct string_list *list) { if (list->tag != SYM_NORMAL) { @@ -311,6 +446,7 @@ static unsigned long expand_and_crc_sym( case SYM_TYPEDEF: subsym = find_symbol(cur->string, cur->tag); + /* FIXME: Bad reference files can segfault here. */ if (subsym->expansion_trail) { if (flag_dump_defs) fprintf(debugfile, "%s ", cur->string); @@ -347,9 +483,22 @@ static unsigned long expand_and_crc_sym( t = n; n = xmalloc(sizeof(*n)); - n->string = xstrdup("{ UNKNOWN }"); + n->string = xstrdup("{"); + n->tag = SYM_NORMAL; + n->next = t; + t = n; + + n = xmalloc(sizeof(*n)); + n->string = xstrdup("UNKNOWN"); + n->tag = SYM_NORMAL; + n->next = t; + t = n; + + n = xmalloc(sizeof(*n)); + n->string = xstrdup("}"); n->tag = SYM_NORMAL; n->next = t; + t = n; subsym = add_symbol(cur->string, cur->tag, n, 0); @@ -397,20 +546,42 @@ void export_symbol(const char *name) error_with_pos("export undefined symbol %s", name); else { unsigned long crc; + int has_changed = 0; if (flag_dump_defs) fprintf(debugfile, "Export %s == <", name); expansion_trail = (struct symbol *)-1L; + sym->expansion_trail = expansion_trail; + expansion_trail = sym; crc = expand_and_crc_sym(sym, 0xffffffff) ^ 0xffffffff; sym = expansion_trail; while (sym != (struct symbol *)-1L) { struct symbol *n = sym->expansion_trail; + + if (sym->status != STATUS_UNCHANGED) { + if (!has_changed) { + print_location(); + fprintf(stderr, "%s: %s: modversion " + "changed because of changes " + "in ", flag_preserve ? "error" : + "warning", name); + } else + fprintf(stderr, ", "); + print_type_name(sym->type, sym->name); + if (sym->status == STATUS_DEFINED) + fprintf(stderr, " (became defined)"); + has_changed = 1; + if (flag_preserve) + errors++; + } sym->expansion_trail = 0; sym = n; } + if (has_changed) + fprintf(stderr, "\n"); if (flag_dump_defs) fputs(">\n", debugfile); @@ -421,13 +592,26 @@ void export_symbol(const char *name) } /*----------------------------------------------------------------------*/ + +static void print_location(void) +{ + fprintf(stderr, "%s:%d: ", cur_filename ? : "", cur_line); +} + +static void print_type_name(enum symbol_type type, const char *name) +{ + if (type != SYM_NORMAL) + fprintf(stderr, "%s %s", symbol_type_name[type], name); + else + fprintf(stderr, "%s", name); +} + void error_with_pos(const char *fmt, ...) { va_list args; if (flag_warnings) { - fprintf(stderr, "%s:%d: ", cur_filename ? : "", - cur_line); + print_location(); va_start(args, fmt); vfprintf(stderr, fmt, args); @@ -445,7 +629,9 @@ static void genksyms_usage(void) " -a, --arch Select architecture\n" " -d, --debug Increment the debug level (repeatable)\n" " -D, --dump Dump expanded symbol defs (for debugging only)\n" - " -T, --dump-types file Dump expanded types into file (for debugging only)\n" + " -r, --reference file Read reference symbols from a file\n" + " -T, --dump-types file Dump expanded types into file\n" + " -p, --preserve Preserve reference modversions or fail\n" " -w, --warnings Enable warnings\n" " -q, --quiet Disable warnings (default)\n" " -h, --help Print this message\n" @@ -454,7 +640,9 @@ static void genksyms_usage(void) " -a Select architecture\n" " -d Increment the debug level (repeatable)\n" " -D Dump expanded symbol defs (for debugging only)\n" - " -T file Dump expanded types into file (for debugging only)\n" + " -r file Read reference symbols from a file\n" + " -T file Dump expanded types into file\n" + " -p Preserve reference modversions or fail\n" " -w Enable warnings\n" " -q Disable warnings (default)\n" " -h Print this message\n" @@ -465,7 +653,7 @@ static void genksyms_usage(void) int main(int argc, char **argv) { - FILE *dumpfile = NULL; + FILE *dumpfile = NULL, *ref_file = NULL; int o; #ifdef __GNU_LIBRARY__ @@ -475,16 +663,18 @@ int main(int argc, char **argv) {"warnings", 0, 0, 'w'}, {"quiet", 0, 0, 'q'}, {"dump", 0, 0, 'D'}, + {"reference", 1, 0, 'r'}, {"dump-types", 1, 0, 'T'}, + {"preserve", 0, 0, 'p'}, {"version", 0, 0, 'V'}, {"help", 0, 0, 'h'}, {0, 0, 0, 0} }; - while ((o = getopt_long(argc, argv, "a:dwqVDT:h", + while ((o = getopt_long(argc, argv, "a:dwqVDr:T:ph", &long_opts[0], NULL)) != EOF) #else /* __GNU_LIBRARY__ */ - while ((o = getopt(argc, argv, "a:dwqVDT:h")) != EOF) + while ((o = getopt(argc, argv, "a:dwqVDr:T:ph")) != EOF) #endif /* __GNU_LIBRARY__ */ switch (o) { case 'a': @@ -505,6 +695,14 @@ int main(int argc, char **argv) case 'D': flag_dump_defs = 1; break; + case 'r': + flag_reference = 1; + ref_file = fopen(optarg, "r"); + if (!ref_file) { + perror(optarg); + return 1; + } + break; case 'T': flag_dump_types = 1; dumpfile = fopen(optarg, "w"); @@ -513,6 +711,9 @@ int main(int argc, char **argv) return 1; } break; + case 'p': + flag_preserve = 1; + break; case 'h': genksyms_usage(); return 0; @@ -534,6 +735,9 @@ int main(int argc, char **argv) /* setlinebuf(debugfile); */ } + if (flag_reference) + read_reference(ref_file); + yyparse(); if (flag_dump_types && visited_symbols) { Index: b/scripts/genksyms/genksyms.h =================================================================== --- a/scripts/genksyms/genksyms.h +++ b/scripts/genksyms/genksyms.h @@ -29,6 +29,10 @@ enum symbol_type { SYM_NORMAL, SYM_TYPEDEF, SYM_ENUM, SYM_STRUCT, SYM_UNION }; +enum symbol_status { + STATUS_UNCHANGED, STATUS_DEFINED, STATUS_MODIFIED +}; + struct string_list { struct string_list *next; enum symbol_type tag; @@ -43,6 +47,8 @@ struct symbol { struct symbol *expansion_trail; struct symbol *visited; int is_extern; + int is_declared; + enum symbol_status status; }; typedef struct string_list **yystype; Index: b/scripts/Makefile.build =================================================================== --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -153,12 +153,18 @@ $(obj)/%.i: $(src)/%.c FORCE quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@ cmd_cc_symtypes_c = \ + set -e; \ $(CPP) -D__GENKSYMS__ $(c_flags) $< \ - | $(GENKSYMS) -T $@ >/dev/null; \ + | $(GENKSYMS) -T $@ \ + -r $(firstword $(wildcard \ + $(@:.symtypes=.symref) /dev/null)) \ + $(if $(KBUILD_PRESERVE),-p) \ + -a $(ARCH) \ + >/dev/null; \ test -s $@ || rm -f $@ $(obj)/%.symtypes : $(src)/%.c FORCE - $(call if_changed_dep,cc_symtypes_c) + $(call cmd,cc_symtypes_c) # C (.c) files # The C file is compiled and updated dependency information is generated. @@ -187,7 +193,11 @@ cmd_modversions = \ if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \ $(CPP) -D__GENKSYMS__ $(c_flags) $< \ | $(GENKSYMS) $(if $(KBUILD_SYMTYPES), \ - -T $(@D)/$(@F:.o=.symtypes)) -a $(ARCH) \ + -T $(@:.o=.symtypes)) \ + -r $(firstword $(wildcard \ + $(@:.o=.symref) /dev/null)) \ + $(if $(KBUILD_PRESERVE),-p) \ + -a $(ARCH) \ > $(@D)/.tmp_$(@F:.o=.ver); \ \ $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/