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genksyms: allow to ignore symbol checksum changes

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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.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
This commit is contained in:
Andreas Gruenbacher 2008-12-01 14:21:03 -08:00 committed by Sam Ravnborg
parent 64e6c1e123
commit 5dae9a550a
2 changed files with 31 additions and 4 deletions
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30
scripts/genksyms/genksyms.c
View file

@ -191,11 +191,26 @@ struct symbol *__add_symbol(const char *name, enum symbol_type type,
/* fall through */ ; /* fall through */ ;
else if (sym->type == type && else if (sym->type == type &&
equal_list(sym->defn, defn)) { equal_list(sym->defn, defn)) {
if (!sym->is_declared && sym->is_override) {
print_location();
print_type_name(type, name);
fprintf(stderr, " modversion is "
"unchanged\n");
}
sym->is_declared = 1; sym->is_declared = 1;
return sym; return sym;
} else if (!sym->is_declared) { } else if (!sym->is_declared) {
if (sym->is_override && flag_preserve) {
print_location();
fprintf(stderr, "ignoring ");
print_type_name(type, name);
fprintf(stderr, " modversion change\n");
sym->is_declared = 1;
return sym;
} else {
status = is_unknown_symbol(sym) ? status = is_unknown_symbol(sym) ?
STATUS_DEFINED : STATUS_MODIFIED; STATUS_DEFINED : STATUS_MODIFIED;
}
} else { } else {
error_with_pos("redefinition of %s", name); error_with_pos("redefinition of %s", name);
return sym; return sym;
@ -229,6 +244,7 @@ struct symbol *__add_symbol(const char *name, enum symbol_type type,
sym->is_declared = !is_reference; sym->is_declared = !is_reference;
sym->status = status; sym->status = status;
sym->is_override = 0;
if (flag_debug) { if (flag_debug) {
fprintf(debugfile, "Defn for %s %s == <", fprintf(debugfile, "Defn for %s %s == <",
@ -348,9 +364,16 @@ static void read_reference(FILE *f)
while (!feof(f)) { while (!feof(f)) {
struct string_list *defn = NULL; struct string_list *defn = NULL;
struct string_list *sym, *def; struct string_list *sym, *def;
int is_extern = 0; int is_extern = 0, is_override = 0;
struct symbol *subsym;
sym = read_node(f); sym = read_node(f);
if (sym && sym->tag == SYM_NORMAL &&
!strcmp(sym->string, "override")) {
is_override = 1;
free_node(sym);
sym = read_node(f);
}
if (!sym) if (!sym)
continue; continue;
def = read_node(f); def = read_node(f);
@ -365,8 +388,9 @@ static void read_reference(FILE *f)
defn = def; defn = def;
def = read_node(f); def = read_node(f);
} }
add_reference_symbol(xstrdup(sym->string), sym->tag, subsym = add_reference_symbol(xstrdup(sym->string), sym->tag,
defn, is_extern); defn, is_extern);
subsym->is_override = is_override;
free_node(sym); free_node(sym);
} }
} }
@ -743,6 +767,8 @@ int main(int argc, char **argv)
while (visited_symbols != (struct symbol *)-1L) { while (visited_symbols != (struct symbol *)-1L) {
struct symbol *sym = visited_symbols; struct symbol *sym = visited_symbols;
if (sym->is_override)
fputs("override ", dumpfile);
if (sym->type != SYM_NORMAL) { if (sym->type != SYM_NORMAL) {
putc(symbol_type_name[sym->type][0], dumpfile); putc(symbol_type_name[sym->type][0], dumpfile);
putc('#', dumpfile); putc('#', dumpfile);

1
scripts/genksyms/genksyms.h
View file

@ -49,6 +49,7 @@ struct symbol {
int is_extern; int is_extern;
int is_declared; int is_declared;
enum symbol_status status; enum symbol_status status;
int is_override;
}; };
typedef struct string_list **yystype; typedef struct string_list **yystype;