There's an inconsistency in how sibling calls are detected in
non-function asm code, depending on the scope of the object. If the
target code is external to the object, objtool considers it a sibling
call. If the target code is internal but not a function, objtool
*doesn't* consider it a sibling call.
This can cause some inconsistencies between per-object and vmlinux.o
validation.
Instead, assume only ELF functions can do sibling calls. This generally
matches existing reality, and makes sibling call validation consistent
between vmlinux.o and per-object.
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
tools/objtool/check.c | 36 ++++++++++++++++++++++--------------
1 file changed, 22 insertions(+), 14 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b1327789d049..d833855f3aa8 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -111,15 +111,20 @@ static struct instruction *prev_insn_same_sym(struct
objtool_file *file,
static bool is_sibling_call(struct instruction *insn)
{
+ /*
+ * Assume only ELF functions can make sibling calls. This ensures
+ * sibling call detection consistency between vmlinux.o and individual
+ * objects.
+ */
+ if (!insn->func)
+ return false;
+
/* An indirect jump is either a sibling call or a jump to a table. */
if (insn->type == INSN_JUMP_DYNAMIC)
return list_empty(&insn->alts);
- if (!is_static_jump(insn))
- return false;
-
/* add_jump_destinations() sets insn->call_dest for sibling calls. */
- return !!insn->call_dest;
+ return (is_static_jump(insn) && insn->call_dest);
}
/*
@@ -778,7 +783,7 @@ static int add_jump_destinations(struct objtool_file *file)
continue;
reloc = find_reloc_by_dest_range(file->elf, insn->sec,
- insn->offset, insn->len);
+ insn->offset, insn->len);
if (!reloc) {
dest_sec = insn->sec;
dest_off = arch_jump_destination(insn);
@@ -798,18 +803,21 @@ static int add_jump_destinations(struct objtool_file
*file)
insn->retpoline_safe = true;
continue;
- } else if (reloc->sym->sec->idx) {
- dest_sec = reloc->sym->sec;
- dest_off = reloc->sym->sym.st_value +
- arch_dest_reloc_offset(reloc->addend);
- } else {
- /* external sibling call */
+ } else if (insn->func) {
+ /* internal or external sibling call (with reloc) */
insn->call_dest = reloc->sym;
if (insn->call_dest->static_call_tramp) {
list_add_tail(&insn->static_call_node,
&file->static_call_list);
}
continue;
+ } else if (reloc->sym->sec->idx) {
+ dest_sec = reloc->sym->sec;
+ dest_off = reloc->sym->sym.st_value +
+ arch_dest_reloc_offset(reloc->addend);
+ } else {
+ /* non-func asm code jumping to another file */
+ continue;
}
insn->jump_dest = find_insn(file, dest_sec, dest_off);
@@ -858,7 +866,7 @@ static int add_jump_destinations(struct objtool_file *file)
} else if (insn->jump_dest->func->pfunc !=
insn->func->pfunc &&
insn->jump_dest->offset ==
insn->jump_dest->func->offset) {
- /* internal sibling call */
+ /* internal sibling call (without reloc) */
insn->call_dest = insn->jump_dest->func;
if (insn->call_dest->static_call_tramp) {
list_add_tail(&insn->static_call_node,
@@ -2528,7 +2536,7 @@ static int validate_branch(struct objtool_file *file,
struct symbol *func,
case INSN_JUMP_CONDITIONAL:
case INSN_JUMP_UNCONDITIONAL:
- if (func && is_sibling_call(insn)) {
+ if (is_sibling_call(insn)) {
ret = validate_sibling_call(insn, &state);
if (ret)
return ret;
@@ -2550,7 +2558,7 @@ static int validate_branch(struct objtool_file *file,
struct symbol *func,
case INSN_JUMP_DYNAMIC:
case INSN_JUMP_DYNAMIC_CONDITIONAL:
- if (func && is_sibling_call(insn)) {
+ if (is_sibling_call(insn)) {
ret = validate_sibling_call(insn, &state);
if (ret)
return ret;
--
2.29.2
