In preparation for porting the checksum code to other arches, make its
functionality independent from validate_branch().
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 71 +++++++++++++++++-------
tools/objtool/include/objtool/checksum.h | 6 +-
2 files changed, 53 insertions(+), 24 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a30379e4ff97..f73cf1382e5c 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2633,8 +2633,7 @@ static bool validate_branch_enabled(void)
{
return opts.stackval ||
opts.orc ||
- opts.uaccess ||
- opts.checksum;
+ opts.uaccess;
}
static int decode_sections(struct objtool_file *file)
@@ -3649,6 +3648,7 @@ static bool skip_alt_group(struct instruction *insn)
return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
}
+#ifdef BUILD_KLP
static int checksum_debug_init(struct objtool_file *file)
{
char *dup, *s;
@@ -3691,9 +3691,30 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
struct instruction *insn)
{
struct reloc *reloc = insn_reloc(file, insn);
+ struct alternative *alt;
unsigned long offset;
struct symbol *sym;
+ for (alt = insn->alts; alt; alt = alt->next) {
+ struct alt_group *alt_group = alt->insn->alt_group;
+
+ checksum_update(func, insn, &alt->type, sizeof(alt->type));
+
+ if (alt_group && alt_group->orig_group) {
+ struct instruction *alt_insn;
+
+ checksum_update(func, insn, &alt_group->feature, sizeof(alt_group->feature));
+
+ for (alt_insn = alt->insn; alt_insn; alt_insn = next_insn_same_sec(file, alt_insn)) {
+ checksum_update_insn(file, func, alt_insn);
+ if (alt_insn == alt_group->last_insn)
+ break;
+ }
+ } else {
+ checksum_update(func, insn, &alt->insn->offset, sizeof(alt->insn->offset));
+ }
+ }
+
if (insn->fake)
return;
@@ -3702,9 +3723,11 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
if (!reloc) {
struct symbol *call_dest = insn_call_dest(insn);
- if (call_dest)
+ if (call_dest) {
+ /* intra-TU call without reloc */
checksum_update(func, insn, call_dest->demangled_name,
strlen(call_dest->demangled_name));
+ }
return;
}
@@ -3731,6 +3754,29 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
checksum_update(func, insn, &offset, sizeof(offset));
}
+static int calculate_checksums(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct symbol *func;
+
+ if (checksum_debug_init(file))
+ return -1;
+
+ for_each_sym(file->elf, func) {
+ if (!is_func_sym(func))
+ continue;
+
+ checksum_init(func);
+
+ func_for_each_insn(file, func, insn)
+ checksum_update_insn(file, func, insn);
+
+ checksum_finish(func);
+ }
+ return 0;
+}
+#endif /* BUILD_KLP */
+
static int validate_branch(struct objtool_file *file, struct symbol *func,
struct instruction *insn, struct insn_state state);
static int do_validate_branch(struct objtool_file *file, struct symbol *func,
@@ -4012,9 +4058,6 @@ static int do_validate_branch(struct objtool_file *file, struct symbol *func,
insn->trace = 0;
next_insn = next_insn_to_validate(file, insn);
- if (opts.checksum && func && insn->sec)
- checksum_update_insn(file, func, insn);
-
if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
/* Ignore KCFI type preambles, which always fall through */
if (is_prefix_func(func))
@@ -4080,9 +4123,6 @@ static int validate_unwind_hint(struct objtool_file *file,
struct symbol *func = insn_func(insn);
int ret;
- if (opts.checksum)
- checksum_init(func);
-
ret = validate_branch(file, func, insn, *state);
if (ret)
BT_INSN(insn, "<=== (hint)");
@@ -4525,9 +4565,6 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
func = insn_func(insn);
- if (opts.checksum)
- checksum_init(func);
-
if (opts.trace && !fnmatch(opts.trace, sym->name, 0)) {
trace_enable();
TRACE("%s: validation begin\n", sym->name);
@@ -4540,9 +4577,6 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
TRACE("%s: validation %s\n\n", sym->name, ret ? "failed" : "end");
trace_disable();
- if (opts.checksum)
- checksum_finish(func);
-
return ret;
}
@@ -4997,10 +5031,6 @@ int check(struct objtool_file *file)
cfi_hash_add(&init_cfi);
cfi_hash_add(&func_cfi);
- ret = checksum_debug_init(file);
- if (ret)
- goto out;
-
ret = decode_sections(file);
if (ret)
goto out;
@@ -5091,6 +5121,9 @@ int check(struct objtool_file *file)
warnings += check_abs_references(file);
if (opts.checksum) {
+ ret = calculate_checksums(file);
+ if (ret)
+ goto out;
ret = create_sym_checksum_section(file);
if (ret)
goto out;
diff --git a/tools/objtool/include/objtool/checksum.h b/tools/objtool/include/objtool/checksum.h
index 7fe21608722a..36a17688c716 100644
--- a/tools/objtool/include/objtool/checksum.h
+++ b/tools/objtool/include/objtool/checksum.h
@@ -32,11 +32,7 @@ static inline void checksum_finish(struct symbol *func)
#else /* !BUILD_KLP */
-static inline void checksum_init(struct symbol *func) {}
-static inline void checksum_update(struct symbol *func,
- struct instruction *insn,
- const void *data, size_t size) {}
-static inline void checksum_finish(struct symbol *func) {}
+static inline int calculate_checksums(struct objtool_file *file) { return -ENOSYS; }
#endif /* !BUILD_KLP */
--
2.53.0Hi,
> @@ -3691,9 +3691,30 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
> struct instruction *insn)
> {
> struct reloc *reloc = insn_reloc(file, insn);
> + struct alternative *alt;
> unsigned long offset;
> struct symbol *sym;
>
> + for (alt = insn->alts; alt; alt = alt->next) {
> + struct alt_group *alt_group = alt->insn->alt_group;
> +
> + checksum_update(func, insn, &alt->type, sizeof(alt->type));
> +
> + if (alt_group && alt_group->orig_group) {
> + struct instruction *alt_insn;
> +
> + checksum_update(func, insn, &alt_group->feature, sizeof(alt_group->feature));
> +
> + for (alt_insn = alt->insn; alt_insn; alt_insn = next_insn_same_sec(file, alt_insn)) {
> + checksum_update_insn(file, func, alt_insn);
> + if (alt_insn == alt_group->last_insn)
> + break;
> + }
> + } else {
> + checksum_update(func, insn, &alt->insn->offset, sizeof(alt->insn->offset));
> + }
> + }
> +
does this hunk belong to the patch? Unless I am missing something, it
might be worth a separate one.
Miroslav
On Tue, Mar 10, 2026 at 11:47:41AM +0100, Miroslav Benes wrote:
> Hi,
>
> > @@ -3691,9 +3691,30 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
> > struct instruction *insn)
> > {
> > struct reloc *reloc = insn_reloc(file, insn);
> > + struct alternative *alt;
> > unsigned long offset;
> > struct symbol *sym;
> >
> > + for (alt = insn->alts; alt; alt = alt->next) {
> > + struct alt_group *alt_group = alt->insn->alt_group;
> > +
> > + checksum_update(func, insn, &alt->type, sizeof(alt->type));
> > +
> > + if (alt_group && alt_group->orig_group) {
> > + struct instruction *alt_insn;
> > +
> > + checksum_update(func, insn, &alt_group->feature, sizeof(alt_group->feature));
> > +
> > + for (alt_insn = alt->insn; alt_insn; alt_insn = next_insn_same_sec(file, alt_insn)) {
> > + checksum_update_insn(file, func, alt_insn);
> > + if (alt_insn == alt_group->last_insn)
> > + break;
> > + }
> > + } else {
> > + checksum_update(func, insn, &alt->insn->offset, sizeof(alt->insn->offset));
> > + }
> > + }
> > +
>
> does this hunk belong to the patch? Unless I am missing something, it
> might be worth a separate one.
It belongs, but I should have clarified that in the patch description.
This hunk wasn't needed before because validate_branch() already
iterates all the alternatives, so it was calling checksum_update_insn()
for every instruction in the function, including the alternatives.
Now that it's no longer called by validate_branch(),
checksum_update_insn() has to manually iterate the alternatives.
--
Josh
On Tue, 10 Mar 2026, Josh Poimboeuf wrote:
> On Tue, Mar 10, 2026 at 11:47:41AM +0100, Miroslav Benes wrote:
> > Hi,
> >
> > > @@ -3691,9 +3691,30 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
> > > struct instruction *insn)
> > > {
> > > struct reloc *reloc = insn_reloc(file, insn);
> > > + struct alternative *alt;
> > > unsigned long offset;
> > > struct symbol *sym;
> > >
> > > + for (alt = insn->alts; alt; alt = alt->next) {
> > > + struct alt_group *alt_group = alt->insn->alt_group;
> > > +
> > > + checksum_update(func, insn, &alt->type, sizeof(alt->type));
> > > +
> > > + if (alt_group && alt_group->orig_group) {
> > > + struct instruction *alt_insn;
> > > +
> > > + checksum_update(func, insn, &alt_group->feature, sizeof(alt_group->feature));
> > > +
> > > + for (alt_insn = alt->insn; alt_insn; alt_insn = next_insn_same_sec(file, alt_insn)) {
> > > + checksum_update_insn(file, func, alt_insn);
> > > + if (alt_insn == alt_group->last_insn)
> > > + break;
> > > + }
> > > + } else {
> > > + checksum_update(func, insn, &alt->insn->offset, sizeof(alt->insn->offset));
> > > + }
> > > + }
> > > +
> >
> > does this hunk belong to the patch? Unless I am missing something, it
> > might be worth a separate one.
>
> It belongs, but I should have clarified that in the patch description.
>
> This hunk wasn't needed before because validate_branch() already
> iterates all the alternatives, so it was calling checksum_update_insn()
> for every instruction in the function, including the alternatives.
>
> Now that it's no longer called by validate_branch(),
> checksum_update_insn() has to manually iterate the alternatives.
After writing the email I had a suspicion it must have been something like
above but failed to find it. Now I see that next_insn_to_validate() called
in do_validate_branch() handles exactly that. Thanks for the pointer. The
patch looks good to me then (and the rest as well as far as I can judge).
I must admit that objtool has gotten so complex that I have a hard time to
track everything in the code :).
Regards
Miroslav
On Wed, Mar 11, 2026 at 09:24:22AM +0100, Miroslav Benes wrote:
> On Tue, 10 Mar 2026, Josh Poimboeuf wrote:
>
> > On Tue, Mar 10, 2026 at 11:47:41AM +0100, Miroslav Benes wrote:
> > > Hi,
> > >
> > > > @@ -3691,9 +3691,30 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
> > > > struct instruction *insn)
> > > > {
> > > > struct reloc *reloc = insn_reloc(file, insn);
> > > > + struct alternative *alt;
> > > > unsigned long offset;
> > > > struct symbol *sym;
> > > >
> > > > + for (alt = insn->alts; alt; alt = alt->next) {
> > > > + struct alt_group *alt_group = alt->insn->alt_group;
> > > > +
> > > > + checksum_update(func, insn, &alt->type, sizeof(alt->type));
> > > > +
> > > > + if (alt_group && alt_group->orig_group) {
> > > > + struct instruction *alt_insn;
> > > > +
> > > > + checksum_update(func, insn, &alt_group->feature, sizeof(alt_group->feature));
> > > > +
> > > > + for (alt_insn = alt->insn; alt_insn; alt_insn = next_insn_same_sec(file, alt_insn)) {
> > > > + checksum_update_insn(file, func, alt_insn);
> > > > + if (alt_insn == alt_group->last_insn)
> > > > + break;
> > > > + }
> > > > + } else {
> > > > + checksum_update(func, insn, &alt->insn->offset, sizeof(alt->insn->offset));
> > > > + }
> > > > + }
> > > > +
> > >
> > > does this hunk belong to the patch? Unless I am missing something, it
> > > might be worth a separate one.
> >
> > It belongs, but I should have clarified that in the patch description.
> >
> > This hunk wasn't needed before because validate_branch() already
> > iterates all the alternatives, so it was calling checksum_update_insn()
> > for every instruction in the function, including the alternatives.
> >
> > Now that it's no longer called by validate_branch(),
> > checksum_update_insn() has to manually iterate the alternatives.
>
> After writing the email I had a suspicion it must have been something like
> above but failed to find it. Now I see that next_insn_to_validate() called
> in do_validate_branch() handles exactly that. Thanks for the pointer. The
> patch looks good to me then (and the rest as well as far as I can judge).
Actually, next_insn_to_validate() helps with an edge case for directing
code flow from the end of an alternative back to the original code.
The code which traverses the alternatives is in validate_insn():
if (insn->alts) {
for (alt = insn->alts; alt; alt = alt->next) {
TRACE_ALT_BEGIN(insn, alt, alt_name);
ret = validate_branch(file, func, alt->insn, *statep);
TRACE_ALT_END(insn, alt, alt_name);
if (ret) {
BT_INSN(insn, "(alt)");
return ret;
}
}
TRACE_ALT_INFO_NOADDR(insn, "/ ", "DEFAULT");
}
> I must admit that objtool has gotten so complex that I have a hard time to
> track everything in the code :).
The code hasn't changed *too* much, it's just that validate_branch() got
split up more when the tracing code went in, so things are organized a
bit differently. Most of that code is now in validate_insn().
--
Josh
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