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lookup: skip discarded symbols in local symbol comparison 

A few symbols are discarded in the kernel linking phase, which means
they won't be in the lookup table.  Skip their comparison.

This fixes a bunch of warnings seen when building a patch which triggers
a tree-wide rebuild:

  create-diff-object: ERROR: aes_glue.o: find_local_syms: 112: find_local_syms for aes_glue.c: found_none
  create-diff-object: ERROR: aesni-intel_glue.o: find_local_syms: 112: find_local_syms for aesni-intel_glue.c: found_none
  create-diff-object: ERROR: init.o: find_local_syms: 112: find_local_syms for init.c: found_none
  create-diff-object: ERROR: iosf_mbi.o: find_local_syms: 112: find_local_syms for iosf_mbi.c: found_none
  create-diff-object: ERROR: setup.o: find_local_syms: 112: find_local_syms for setup.c: found_none
  ...

After this patch, there's still one warning remaining:

  create-diff-object: ERROR: dynamic_debug.o: find_local_syms: 133: find_local_syms for dynamic_debug.c: found_none

That one has a completely different cause, which I'll fix in another
pull request (coming soon).

Fixes: #676
This commit is contained in:
Josh Poimboeuf 2017-03-03 08:27:28 -06:00
parent 51f1f51f87
commit 85def82275
1 changed files with 23 additions and 0 deletions
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23
kpatch-build/lookup.c
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@ -56,6 +56,7 @@ struct lookup_table {
struct object_symbol *obj_syms;
struct export_symbol *exp_syms;
struct object_symbol *local_syms;
int vmlinux;
};
#define for_each_obj_symbol(ndx, iter, table) \
@ -64,6 +65,18 @@ struct lookup_table {
#define for_each_exp_symbol(ndx, iter, table) \
for (ndx = 0, iter = table->exp_syms; ndx < table->exp_nr; ndx++, iter++)
static int discarded_sym(struct lookup_table *table,
struct sym_compare_type *sym)
{
if (table->vmlinux && sym->name &&
(!strncmp(sym->name, "__exitcall_", 11) ||
!strncmp(sym->name, "__brk_reservation_fn_", 21) ||
!strncmp(sym->name, "__func_stack_frame_non_standard_", 32)))
return 1;
return 0;
}
static void find_local_syms(struct lookup_table *table, char *hint,
struct sym_compare_type *child_locals)
{
@ -95,6 +108,14 @@ static void find_local_syms(struct lookup_table *table, char *hint,
if (sym->bind != STB_LOCAL || (sym->type != STT_FUNC && sym->type != STT_OBJECT))
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++;
@ -262,6 +283,8 @@ struct lookup_table *lookup_open(char *obj_path, char *symvers_path,
ERROR("malloc table");
memset(table, 0, sizeof(*table));
table->vmlinux = !strcmp(basename(obj_path), "vmlinux");
obj_read(table, obj_path);
symvers_read(table, symvers_path);