From patchwork Tue Aug 26 21:18:51 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergio Durigan Junior X-Patchwork-Id: 2542 Received: (qmail 9820 invoked by alias); 26 Aug 2014 21:18:56 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 9807 invoked by uid 89); 26 Aug 2014 21:18:55 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.2 required=5.0 tests=AWL, BAYES_00, RP_MATCHES_RCVD, SPF_HELO_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Tue, 26 Aug 2014 21:18:53 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s7QLIqHw005807 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 26 Aug 2014 17:18:52 -0400 Received: from localhost (dhcp-10-15-16-169.yyz.redhat.com [10.15.16.169]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s7QLIpnE015919 (version=TLSv1/SSLv3 cipher=AES128-GCM-SHA256 bits=128 verify=NO) for ; Tue, 26 Aug 2014 17:18:52 -0400 From: Sergio Durigan Junior To: GDB Patches Subject: [PATCH] Fix for PR gdb/17235: possible bug extracting systemtap probe operand X-URL: http://www.redhat.com Date: Tue, 26 Aug 2014 17:18:51 -0400 Message-ID: <87vbpf9cg4.fsf@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 X-IsSubscribed: yes Hi there, This patch is a fix to PR gdb/17235. The bug is about an unused variable that got declared and set during one of the parsing phases of an SDT probe's argument. I took the opportunity to rewrite some of the code to improve the parsing. The bug was actually a thinko, because what I wanted to do in the code was to discard the number on the string being parsed. During this portion, the code identifies that it is dealing with an expression that begins with a sign ('+', '-' or '~'). This means that the expression could be: - a numeric literal (e.g., '+5') - a register displacement (e.g., '-4(%rsp)') - a subexpression (e.g., '-(2*3)') So, after saving the sign and moving forward 1 char, now the code needs to know if there is a digit followed by a register displacement prefix operand (e.g., '(' on x86_64). If yes, then it is a register operation. If not, then it will be handled recursively, and the code will later apply the requested operation on the result (either a '+', a '-' or a '~'). With the bug, the code was correctly discarding the digit (though using strtol unnecessarily), but it wasn't properly dealing with subexpressions when the register indirection prefix was '(', like on x86_64. This patch also fixes this bug, and includes a testcase. It passes on x86_64 Fedora 20. OK to check it in? Thanks, diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c index 84714b5..23202d7 100644 --- a/gdb/stap-probe.c +++ b/gdb/stap-probe.c @@ -753,9 +753,9 @@ stap_parse_single_operand (struct stap_parse_info *p) if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+') { char c = *p->arg; - int number; /* We use this variable to do a lookahead. */ const char *tmp = p->arg; + int has_digit = 0; /* Skipping signal. */ ++tmp; @@ -772,26 +772,19 @@ stap_parse_single_operand (struct stap_parse_info *p) if (p->inside_paren_p) tmp = skip_spaces_const (tmp); - if (isdigit (*tmp)) + while (isdigit (*tmp)) { - char *endp; - - number = strtol (tmp, &endp, 10); - tmp = endp; + /* We skip the digit here because we are only interested in + knowing what kind of unary operation this is. The digit + will be handled by one of the functions that will be + called below ('stap_parse_argument_conditionally' or + 'stap_parse_register_operand'). */ + ++tmp; + has_digit = 1; } - if (!stap_is_register_indirection_prefix (gdbarch, tmp, NULL)) - { - /* This is not a displacement. We skip the operator, and deal - with it later. */ - ++p->arg; - stap_parse_argument_conditionally (p); - if (c == '-') - write_exp_elt_opcode (&p->pstate, UNOP_NEG); - else if (c == '~') - write_exp_elt_opcode (&p->pstate, UNOP_COMPLEMENT); - } - else + if (has_digit && stap_is_register_indirection_prefix (gdbarch, tmp, + NULL)) { /* If we are here, it means it is a displacement. The only operations allowed here are `-' and `+'. */ @@ -801,6 +794,17 @@ stap_parse_single_operand (struct stap_parse_info *p) stap_parse_register_operand (p); } + else + { + /* This is not a displacement. We skip the operator, and + deal with it when the recursion returns. */ + ++p->arg; + stap_parse_argument_conditionally (p); + if (c == '-') + write_exp_elt_opcode (&p->pstate, UNOP_NEG); + else if (c == '~') + write_exp_elt_opcode (&p->pstate, UNOP_COMPLEMENT); + } } else if (isdigit (*p->arg)) { diff --git a/gdb/testsuite/gdb.arch/amd64-stap-wrong-subexp.S b/gdb/testsuite/gdb.arch/amd64-stap-wrong-subexp.S new file mode 100644 index 0000000..2848462 --- /dev/null +++ b/gdb/testsuite/gdb.arch/amd64-stap-wrong-subexp.S @@ -0,0 +1,27 @@ +/* Copyright (C) 2014 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + + .file "amd64-stap-wrong-subexp.S" + .text + .globl main +main: + STAP_PROBE1(probe, foo, -4@$-3($4+$3)) + STAP_PROBE2(probe, bar, -4@-($4), -4@$-3+($22/$2)-$16) + xor %rax,%rax + ret diff --git a/gdb/testsuite/gdb.arch/amd64-stap-wrong-subexp.exp b/gdb/testsuite/gdb.arch/amd64-stap-wrong-subexp.exp new file mode 100644 index 0000000..5a1ad53 --- /dev/null +++ b/gdb/testsuite/gdb.arch/amd64-stap-wrong-subexp.exp @@ -0,0 +1,41 @@ +# Copyright 2014 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +if { ![istarget "x86_64-*-*"] || ![is_lp64_target] } { + verbose "Skipping amd64-stap-wrong-subexp.exp" + return +} + +standard_testfile amd64-stap-wrong-subexp.S + +if { [prepare_for_testing $testfile.exp $testfile $srcfile] } { + untested amd64-stap-wrong-subexp.exp + return -1 +} + +proc goto_probe { probe_name } { + if { ![runto "-pstap $probe_name"] } { + fail "run to probe $probe_name" + return + } +} + +goto_probe foo +gdb_test "print \$_probe_arg0" "Invalid operator `\\\(' on expression .*" \ + "print probe foo arg0" + +goto_probe bar +gdb_test "print \$_probe_arg0" " = -4" "print probe bar arg0" +gdb_test "print \$_probe_arg1" " = -8" "print probe bar arg1"