Remove the 'c_file' hack and fix function fallthrough detection for
vmlinux.
Josh Poimboeuf (4):
x86/uaccess: Don't jump between functions
objtool: Don't set 'jump_dest' for sibling calls
objtool: Fix sibling call detection in alternatives
objtool: Fix function fallthrough detection for vmlinux
arch/x86/lib/copy_user_64.S | 87 +++++++++++++++----------
tools/objtool/check.c | 73 +++++++++++----------
tools/objtool/include/objtool/objtool.h | 2 +-
tools/objtool/objtool.c | 1 -
4 files changed, 93 insertions(+), 70 deletions(-)
--
2.34.1
In add_jump_destinations(), sibling call detection requires 'insn->func'
to be valid. But alternative instructions get their 'func' set in
handle_group_alt(), which runs *after* add_jump_destinations(). So
sibling calls in alternatives code don't get properly detected.
Fix that by changing the initialization order: call
add_special_section_alts() *before* add_jump_destinations().
This also means the special case for a missing 'jump_dest' in
add_jump_destinations() can be removed, as it has already been dealt
with.
Signed-off-by: Josh Poimboeuf <[email protected]>
---
tools/objtool/check.c | 36 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6f492789c8c0..0f5d3de30e0d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1277,6 +1277,13 @@ static int add_jump_destinations(struct objtool_file *file)
unsigned long dest_off;
for_each_insn(file, insn) {
+ if (insn->jump_dest) {
+ /*
+ * handle_group_alt() may have previously set
+ * 'jump_dest' for some alternatives.
+ */
+ continue;
+ }
if (!is_static_jump(insn))
continue;
@@ -1308,15 +1315,6 @@ static int add_jump_destinations(struct objtool_file *file)
jump_dest = find_insn(file, dest_sec, dest_off);
if (!jump_dest) {
-
- /*
- * This is a special case where an alt instruction
- * jumps past the end of the section. These are
- * handled later in handle_group_alt().
- */
- if (!strcmp(insn->sec->name, ".altinstr_replacement"))
- continue;
-
WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
insn->sec, insn->offset, dest_sec->name,
dest_off);
@@ -1549,13 +1547,13 @@ static int handle_group_alt(struct objtool_file *file,
continue;
dest_off = arch_jump_destination(insn);
- if (dest_off == special_alt->new_off + special_alt->new_len)
+ if (dest_off == special_alt->new_off + special_alt->new_len) {
insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
-
- if (!insn->jump_dest) {
- WARN_FUNC("can't find alternative jump destination",
- insn->sec, insn->offset);
- return -1;
+ if (!insn->jump_dest) {
+ WARN_FUNC("can't find alternative jump destination",
+ insn->sec, insn->offset);
+ return -1;
+ }
}
}
@@ -2254,14 +2252,14 @@ static int decode_sections(struct objtool_file *file)
return ret;
/*
- * Must be before add_special_section_alts() as that depends on
- * jump_dest being set.
+ * Must be before add_jump_destinations(), which depends on 'func'
+ * being set for alternatives, to enable proper sibling call detection.
*/
- ret = add_jump_destinations(file);
+ ret = add_special_section_alts(file);
if (ret)
return ret;
- ret = add_special_section_alts(file);
+ ret = add_jump_destinations(file);
if (ret)
return ret;
--
2.34.1
The following commit has been merged into the objtool/urgent branch of tip:
Commit-ID: 34c861e806478ac2ea4032721defbf1d6967df08
Gitweb: https://git.kernel.org/tip/34c861e806478ac2ea4032721defbf1d6967df08
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Mon, 11 Apr 2022 16:10:31 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Tue, 19 Apr 2022 21:58:53 +02:00
objtool: Fix sibling call detection in alternatives
In add_jump_destinations(), sibling call detection requires 'insn->func'
to be valid. But alternative instructions get their 'func' set in
handle_group_alt(), which runs *after* add_jump_destinations(). So
sibling calls in alternatives code don't get properly detected.
Fix that by changing the initialization order: call
add_special_section_alts() *before* add_jump_destinations().
This also means the special case for a missing 'jump_dest' in
add_jump_destinations() can be removed, as it has already been dealt
with.
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/c02e0a0a2a4286b5f848d17c77fdcb7e0caf709c.1649718562.git.jpoimboe@redhat.com
---
tools/objtool/check.c | 36 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6f49278..0f5d3de 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1277,6 +1277,13 @@ static int add_jump_destinations(struct objtool_file *file)
unsigned long dest_off;
for_each_insn(file, insn) {
+ if (insn->jump_dest) {
+ /*
+ * handle_group_alt() may have previously set
+ * 'jump_dest' for some alternatives.
+ */
+ continue;
+ }
if (!is_static_jump(insn))
continue;
@@ -1308,15 +1315,6 @@ static int add_jump_destinations(struct objtool_file *file)
jump_dest = find_insn(file, dest_sec, dest_off);
if (!jump_dest) {
-
- /*
- * This is a special case where an alt instruction
- * jumps past the end of the section. These are
- * handled later in handle_group_alt().
- */
- if (!strcmp(insn->sec->name, ".altinstr_replacement"))
- continue;
-
WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
insn->sec, insn->offset, dest_sec->name,
dest_off);
@@ -1549,13 +1547,13 @@ static int handle_group_alt(struct objtool_file *file,
continue;
dest_off = arch_jump_destination(insn);
- if (dest_off == special_alt->new_off + special_alt->new_len)
+ if (dest_off == special_alt->new_off + special_alt->new_len) {
insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
-
- if (!insn->jump_dest) {
- WARN_FUNC("can't find alternative jump destination",
- insn->sec, insn->offset);
- return -1;
+ if (!insn->jump_dest) {
+ WARN_FUNC("can't find alternative jump destination",
+ insn->sec, insn->offset);
+ return -1;
+ }
}
}
@@ -2254,14 +2252,14 @@ static int decode_sections(struct objtool_file *file)
return ret;
/*
- * Must be before add_special_section_alts() as that depends on
- * jump_dest being set.
+ * Must be before add_jump_destinations(), which depends on 'func'
+ * being set for alternatives, to enable proper sibling call detection.
*/
- ret = add_jump_destinations(file);
+ ret = add_special_section_alts(file);
if (ret)
return ret;
- ret = add_special_section_alts(file);
+ ret = add_jump_destinations(file);
if (ret)
return ret;