objtool: Detect infinite recursion
I don't _think_ dead_end_function() can get into a recursive loop, but
just in case, stop the loop and print a warning.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/ff489a63e6feb88abb192cfb361d81626dcf3e89.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 80d9ed9..51da270 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -121,8 +121,14 @@
*
* For local functions, we have to detect them manually by simply looking for
* the lack of a return instruction.
+ *
+ * Returns:
+ * -1: error
+ * 0: no dead end
+ * 1: dead end
*/
-static bool dead_end_function(struct objtool_file *file, struct symbol *func)
+static int __dead_end_function(struct objtool_file *file, struct symbol *func,
+ int recursion)
{
int i;
struct instruction *insn, *func_insn;
@@ -144,19 +150,19 @@
};
if (func->bind == STB_WEAK)
- return false;
+ return 0;
if (func->bind == STB_GLOBAL)
for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
if (!strcmp(func->name, global_noreturns[i]))
- return true;
+ return 1;
if (!func->sec)
- return false;
+ return 0;
func_insn = find_instruction(file, func->sec, func->offset);
if (!func_insn)
- return false;
+ return 0;
insn = func_insn;
list_for_each_entry_from(insn, &file->insns, list) {
@@ -167,11 +173,11 @@
empty = false;
if (insn->type == INSN_RETURN)
- return false;
+ return 0;
}
if (empty)
- return false;
+ return 0;
/*
* A function can have a sibling call instead of a return. In that
@@ -190,7 +196,7 @@
if (!dest)
/* sibling call to another file */
- return false;
+ return 0;
if (dest->sec != func->sec ||
dest->offset < func->offset ||
@@ -201,16 +207,28 @@
if (!dest_func)
continue;
- return dead_end_function(file, dest_func);
+ if (recursion == 5) {
+ WARN_FUNC("infinite recursion (objtool bug!)",
+ dest->sec, dest->offset);
+ return -1;
+ }
+
+ return __dead_end_function(file, dest_func,
+ recursion + 1);
}
}
if (insn->type == INSN_JUMP_DYNAMIC)
/* sibling call */
- return false;
+ return 0;
}
- return true;
+ return 1;
+}
+
+static int dead_end_function(struct objtool_file *file, struct symbol *func)
+{
+ return __dead_end_function(file, func, 0);
}
/*
@@ -809,8 +827,11 @@
break;
}
- if (dead_end_function(file, insn->call_dest))
+ ret = dead_end_function(file, insn->call_dest);
+ if (ret == 1)
return warnings;
+ if (ret == -1)
+ warnings++;
/* fallthrough */
case INSN_CALL_DYNAMIC: