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Message-ID: <tip-0c1ddd33177530feb3685a800bba1ac4cc58cc4b@git.kernel.org>
Date: Thu, 18 Jul 2019 12:19:13 -0700
From: tip-bot for Josh Poimboeuf <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: tglx@...utronix.de, linux-kernel@...r.kernel.org,
ndesaulniers@...gle.com, mingo@...nel.org, jpoimboe@...hat.com,
hpa@...or.com, peterz@...radead.org
Subject: [tip:core/urgent] objtool: Refactor sibling call detection logic
Commit-ID: 0c1ddd33177530feb3685a800bba1ac4cc58cc4b
Gitweb: https://git.kernel.org/tip/0c1ddd33177530feb3685a800bba1ac4cc58cc4b
Author: Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Wed, 17 Jul 2019 20:36:52 -0500
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 18 Jul 2019 21:01:08 +0200
objtool: Refactor sibling call detection logic
Simplify the sibling call detection logic a bit.
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/8357dbef9e7f5512e76bf83a76c81722fc09eb5e.1563413318.git.jpoimboe@redhat.com
---
tools/objtool/check.c | 65 ++++++++++++++++++++++++++-------------------------
1 file changed, 33 insertions(+), 32 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0d2a8e54a82e..7fe31e0f8afe 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -97,6 +97,20 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
for (insn = next_insn_same_sec(file, insn); insn; \
insn = next_insn_same_sec(file, insn))
+static bool is_sibling_call(struct instruction *insn)
+{
+ /* 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 (insn->type != INSN_JUMP_CONDITIONAL &&
+ insn->type != INSN_JUMP_UNCONDITIONAL)
+ return false;
+
+ /* add_jump_destinations() sets insn->call_dest for sibling calls. */
+ return !!insn->call_dest;
+}
+
/*
* This checks to see if the given function is a "noreturn" function.
*
@@ -167,34 +181,25 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
* of the sibling call returns.
*/
func_for_each_insn_all(file, func, insn) {
- if (insn->type == INSN_JUMP_UNCONDITIONAL) {
+ if (is_sibling_call(insn)) {
struct instruction *dest = insn->jump_dest;
if (!dest)
/* sibling call to another file */
return false;
- if (dest->func && dest->func->pfunc != insn->func->pfunc) {
-
- /* local sibling call */
- if (recursion == 5) {
- /*
- * Infinite recursion: two functions
- * have sibling calls to each other.
- * This is a very rare case. It means
- * they aren't dead ends.
- */
- return false;
- }
-
- return __dead_end_function(file, dest->func,
- recursion + 1);
+ /* local sibling call */
+ if (recursion == 5) {
+ /*
+ * Infinite recursion: two functions have
+ * sibling calls to each other. This is a very
+ * rare case. It means they aren't dead ends.
+ */
+ return false;
}
- }
- if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
- /* sibling call */
- return false;
+ return __dead_end_function(file, dest->func, recursion+1);
+ }
}
return true;
@@ -581,9 +586,8 @@ static int add_jump_destinations(struct objtool_file *file)
insn->retpoline_safe = true;
continue;
} else {
- /* sibling call */
+ /* external sibling call */
insn->call_dest = rela->sym;
- insn->jump_dest = NULL;
continue;
}
@@ -633,9 +637,8 @@ 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) {
- /* sibling class */
+ /* internal sibling call */
insn->call_dest = insn->jump_dest->func;
- insn->jump_dest = NULL;
}
}
}
@@ -1889,7 +1892,7 @@ static inline bool func_uaccess_safe(struct symbol *func)
return false;
}
-static inline const char *insn_dest_name(struct instruction *insn)
+static inline const char *call_dest_name(struct instruction *insn)
{
if (insn->call_dest)
return insn->call_dest->name;
@@ -1901,13 +1904,13 @@ static int validate_call(struct instruction *insn, struct insn_state *state)
{
if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
WARN_FUNC("call to %s() with UACCESS enabled",
- insn->sec, insn->offset, insn_dest_name(insn));
+ insn->sec, insn->offset, call_dest_name(insn));
return 1;
}
if (state->df) {
WARN_FUNC("call to %s() with DF set",
- insn->sec, insn->offset, insn_dest_name(insn));
+ insn->sec, insn->offset, call_dest_name(insn));
return 1;
}
@@ -2088,14 +2091,12 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
case INSN_JUMP_CONDITIONAL:
case INSN_JUMP_UNCONDITIONAL:
- if (func && !insn->jump_dest) {
+ if (func && is_sibling_call(insn)) {
ret = validate_sibling_call(insn, &state);
if (ret)
return ret;
- } else if (insn->jump_dest &&
- (!func || !insn->jump_dest->func ||
- insn->jump_dest->func->pfunc == func)) {
+ } else if (insn->jump_dest) {
ret = validate_branch(file, func,
insn->jump_dest, state);
if (ret) {
@@ -2111,7 +2112,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
break;
case INSN_JUMP_DYNAMIC:
- if (func && list_empty(&insn->alts)) {
+ if (func && is_sibling_call(insn)) {
ret = validate_sibling_call(insn, &state);
if (ret)
return ret;
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