From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by sourceware.org (Postfix) with ESMTPS id AB40B3858D1E for ; Tue, 2 May 2023 14:45:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org AB40B3858D1E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=ispras.ru Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=ispras.ru Received: from localhost.intra.ispras.ru (unknown [10.10.3.121]) by mail.ispras.ru (Postfix) with ESMTP id E108140737D5; Tue, 2 May 2023 14:45:05 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru E108140737D5 From: Alexander Monakov To: gcc-patches@gcc.gnu.org Cc: Alexander Monakov Subject: [PATCH] do not tailcall __sanitizer_cov_trace_pc [PR90746] Date: Tue, 2 May 2023 17:45:04 +0300 Message-Id: <20230502144504.14654-1-amonakov@ispras.ru> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-9.2 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_STATUS,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: When instrumentation is requested via -fsanitize-coverage=trace-pc, GCC emits calls to __sanitizer_cov_trace_pc callback into each basic block. This callback is supposed to be implemented by the user, and should be able to identify the containing basic block by inspecting its return address. Tailcalling the callback prevents that, so disallow it. gcc/ChangeLog: PR sanitizer/90746 * calls.cc (can_implement_as_sibling_call_p): Reject calls to __sanitizer_cov_trace_pc. gcc/testsuite/ChangeLog: PR sanitizer/90746 * gcc.dg/sancov/basic0.c: Verify absence of tailcall. --- gcc/calls.cc | 10 ++++++++++ gcc/testsuite/gcc.dg/sancov/basic0.c | 4 +++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/gcc/calls.cc b/gcc/calls.cc index 4d7f6c3d2..c6ed2f189 100644 --- a/gcc/calls.cc +++ b/gcc/calls.cc @@ -2541,6 +2541,16 @@ can_implement_as_sibling_call_p (tree exp, return false; } + /* __sanitizer_cov_trace_pc is supposed to inspect its return address + to identify the caller, and therefore should not be tailcalled. */ + if (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL + && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_SANITIZER_COV_TRACE_PC) + { + /* No need for maybe_complain_about_tail_call here: the call + is synthesized by the compiler. */ + return false; + } + /* If the called function is nested in the current one, it might access some of the caller's arguments, but could clobber them beforehand if the argument areas are shared. */ diff --git a/gcc/testsuite/gcc.dg/sancov/basic0.c b/gcc/testsuite/gcc.dg/sancov/basic0.c index af69b2d12..dfdaea848 100644 --- a/gcc/testsuite/gcc.dg/sancov/basic0.c +++ b/gcc/testsuite/gcc.dg/sancov/basic0.c @@ -1,9 +1,11 @@ /* Basic test on number of inserted callbacks. */ /* { dg-do compile } */ -/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */ +/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized -fdump-rtl-expand" } */ void foo(void) { } /* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */ +/* The built-in should not be tail-called: */ +/* { dg-final { scan-rtl-dump-not "call_insn/j" "expand" } } */ -- 2.39.2