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lookup: allow local symbols to be in any order 

With #650, we found that using -ffunction-sections and -fdata-sections
sometimes causes GCC to output the local symbols in a different order in
the symbol table.  So don't assume they're in the same order, and
instead search all the locals.

This requires two passes: once going through the lookup table symbols
and once going through the .o symbols.  This is needed to make sure
there aren't any extra symbols in one of the files.

I also reorganized the code a bit to simplify it.
This commit is contained in:
Josh Poimboeuf 2017-07-06 12:44:50 -05:00
parent 2ef755bbb9
commit c8c474ca0e
1 changed files with 70 additions and 40 deletions
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110
kpatch-build/lookup.c
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@ -62,6 +62,9 @@ struct lookup_table {
#define for_each_obj_symbol(ndx, iter, table) \
for (ndx = 0, iter = table->obj_syms; ndx < table->obj_nr; ndx++, iter++)
#define for_each_obj_symbol_continue(ndx, iter, table) \
for (iter = table->obj_syms + ndx; ndx < table->obj_nr; ndx++, iter++)
#define for_each_exp_symbol(ndx, iter, table) \
for (ndx = 0, iter = table->exp_syms; ndx < table->exp_nr; ndx++, iter++)
@ -77,59 +80,86 @@ static int discarded_sym(struct lookup_table *table,
return 0;
}
static int locals_match(struct lookup_table *table, int idx,
struct sym_compare_type *child_locals)
{
struct sym_compare_type *child;
struct object_symbol *sym;
int i, found;
i = idx + 1;
for_each_obj_symbol_continue(i, sym, table) {
if (sym->type == STT_FILE)
break;
if (sym->bind != STB_LOCAL)
continue;
if (sym->type != STT_FUNC && sym->type != STT_OBJECT)
continue;
found = 0;
for (child = child_locals; child->name; child++) {
if (child->type == sym->type &&
!strcmp(child->name, sym->name)) {
found = 1;
break;
}
}
if (!found)
return 0;
}
for (child = child_locals; child->name; child++) {
/*
* Symbols which get discarded at link time are missing from
* the lookup table, so skip them.
*/
if (discarded_sym(table, child))
continue;
found = 0;
i = idx + 1;
for_each_obj_symbol_continue(i, sym, table) {
if (sym->type == STT_FILE)
break;
if (sym->bind != STB_LOCAL)
continue;
if (sym->type != STT_FUNC && sym->type != STT_OBJECT)
continue;
if (!strcmp(child->name, sym->name)) {
found = 1;
break;
}
}
if (!found)
return 0;
}
return 1;
}
static void find_local_syms(struct lookup_table *table, char *hint,
struct sym_compare_type *child_locals)
{
struct object_symbol *sym, *file_sym = NULL;
int i, in_file = 0;
struct sym_compare_type *child_sym = NULL;
struct object_symbol *sym;
int i;
if (!child_locals)
return;
for_each_obj_symbol(i, sym, table) {
if (sym->type == STT_FILE) {
if (in_file && !child_sym->name) {
if (table->local_syms)
ERROR("find_local_syms for %s: found_dup", hint);
table->local_syms = file_sym;
}
if (!strcmp(hint, sym->name)) {
in_file = 1;
file_sym = sym;
child_sym = child_locals;
}
else
in_file = 0;
if (sym->type != STT_FILE)
continue;
}
if (!in_file)
if (strcmp(hint, sym->name))
continue;
if (sym->bind != STB_LOCAL || (sym->type != STT_FUNC && sym->type != STT_OBJECT))
if (!locals_match(table, i, child_locals))
continue;
/*
* Symbols which get discarded at link time are missing from
* the lookup table, so skip them.
*/
while (discarded_sym(table, child_sym))
child_sym++;
/* make sure the child symbol and parent symbol match */
if (child_sym->name && child_sym->type == sym->type &&
!strcmp(child_sym->name, sym->name))
child_sym++;
else
in_file = 0;
}
if (in_file && !child_sym->name) {
if (table->local_syms)
ERROR("find_local_syms for %s: found_dup", hint);
table->local_syms = file_sym;
table->local_syms = sym;
}
if (!table->local_syms)