2022-04-12 21:00:04

by Josh Poimboeuf

Subject: [PATCH 4/4] objtool: Fix function fallthrough detection for vmlinux

Objtool's function fallthrough detection only works on C objects.
The distinction between C and assembly objects no longer makes sense
with objtool running on vmlinux.o.

Now that copy_user_64.S has been fixed up, and an objtool sibling call
detection bug has been fixed, the asm code is in "compliance" and this
hack is no longer needed. Remove it.

Signed-off-by: Josh Poimboeuf <[email protected]>
---
tools/objtool/check.c | 2 +-
tools/objtool/include/objtool/objtool.h | 2 +-
tools/objtool/objtool.c | 1 -
3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0f5d3de30e0d..5f10653eb5c2 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3310,7 +3310,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
while (1) {
next_insn = next_insn_to_validate(file, insn);

- if (file->c_file && func && insn->func && func != insn->func->pfunc) {
+ if (func && insn->func && func != insn->func->pfunc) {
WARN("%s() falls through to next function %s()",
func->name, insn->func->name);
return 1;
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 7a5c13a78f87..a6e72d916807 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -27,7 +27,7 @@ struct objtool_file {
struct list_head static_call_list;
struct list_head mcount_loc_list;
struct list_head endbr_list;
- bool ignore_unreachables, c_file, hints, rodata;
+ bool ignore_unreachables, hints, rodata;

unsigned int nr_endbr;
unsigned int nr_endbr_int;
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index b09946f4e1d6..843ff3c2f28e 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -129,7 +129,6 @@ struct objtool_file *objtool_open_read(const char *_objname)
INIT_LIST_HEAD(&file.static_call_list);
INIT_LIST_HEAD(&file.mcount_loc_list);
INIT_LIST_HEAD(&file.endbr_list);
- file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;

--
2.34.1

2022-04-20 11:53:12

by tip-bot2 for Borislav Petkov (AMD)

Subject: [tip: objtool/urgent] objtool: Fix function fallthrough detection for vmlinux

The following commit has been merged into the objtool/urgent branch of tip:

Commit-ID: 08feafe8d1958febf3a9733a3d1564d8fc23340e
Gitweb: https://git.kernel.org/tip/08feafe8d1958febf3a9733a3d1564d8fc23340e
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Mon, 11 Apr 2022 16:10:32 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Tue, 19 Apr 2022 21:58:53 +02:00

objtool: Fix function fallthrough detection for vmlinux

Objtool's function fallthrough detection only works on C objects.
The distinction between C and assembly objects no longer makes sense
with objtool running on vmlinux.o.

Now that copy_user_64.S has been fixed up, and an objtool sibling call
detection bug has been fixed, the asm code is in "compliance" and this
hack is no longer needed. Remove it.

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/b434cff98eca3a60dcc64c620d7d5d405a0f441c.1649718562.git.jpoimboe@redhat.com
---
tools/objtool/check.c | 2 +-
tools/objtool/include/objtool/objtool.h | 2 +-
tools/objtool/objtool.c | 1 -
3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0f5d3de..5f10653 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3310,7 +3310,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
while (1) {
next_insn = next_insn_to_validate(file, insn);

- if (file->c_file && func && insn->func && func != insn->func->pfunc) {
+ if (func && insn->func && func != insn->func->pfunc) {
WARN("%s() falls through to next function %s()",
func->name, insn->func->name);
return 1;
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 7a5c13a..a6e72d9 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -27,7 +27,7 @@ struct objtool_file {
struct list_head static_call_list;
struct list_head mcount_loc_list;
struct list_head endbr_list;
- bool ignore_unreachables, c_file, hints, rodata;
+ bool ignore_unreachables, hints, rodata;

unsigned int nr_endbr;
unsigned int nr_endbr_int;
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index b09946f..843ff3c 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -129,7 +129,6 @@ struct objtool_file *objtool_open_read(const char *_objname)
INIT_LIST_HEAD(&file.static_call_list);
INIT_LIST_HEAD(&file.mcount_loc_list);
INIT_LIST_HEAD(&file.endbr_list);
- file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;

2022-04-21 12:27:02

by Josh Poimboeuf

Subject: Re: [PATCH 4/4] objtool: Fix function fallthrough detection for vmlinux

On Mon, Apr 11, 2022 at 04:10:32PM -0700, Josh Poimboeuf wrote:
> Objtool's function fallthrough detection only works on C objects.
> The distinction between C and assembly objects no longer makes sense
> with objtool running on vmlinux.o.
>
> Now that copy_user_64.S has been fixed up, and an objtool sibling call
> detection bug has been fixed, the asm code is in "compliance" and this
> hack is no longer needed. Remove it.
>
> Signed-off-by: Josh Poimboeuf <[email protected]>

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")

--
Josh