From patchwork Tue Nov 26 21:13:07 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Simon Marchi (Code Review)" X-Patchwork-Id: 36249 Received: (qmail 110731 invoked by alias); 26 Nov 2019 21:13:41 -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 110647 invoked by uid 89); 26 Nov 2019 21:13:41 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_SHORT autolearn=ham version=3.3.1 spammy=exhausted X-HELO: mx1.osci.io Received: from polly.osci.io (HELO mx1.osci.io) (8.43.85.229) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 26 Nov 2019 21:13:38 +0000 Received: by mx1.osci.io (Postfix, from userid 994) id 8A49F2227A; Tue, 26 Nov 2019 16:13:33 -0500 (EST) Received: from gnutoolchain-gerrit.osci.io (gnutoolchain-gerrit.osci.io [IPv6:2620:52:3:1:5054:ff:fe06:16ca]) by mx1.osci.io (Postfix) with ESMTP id AEB4620A7F; Tue, 26 Nov 2019 16:13:10 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by gnutoolchain-gerrit.osci.io (Postfix) with ESMTP id 8CAAE28173; Tue, 26 Nov 2019 16:13:10 -0500 (EST) X-Gerrit-PatchSet: 5 Date: Tue, 26 Nov 2019 16:13:07 -0500 From: "Sourceware to Gerrit sync (Code Review)" To: Tom Tromey , Pedro Alves , gdb-patches@sourceware.org Auto-Submitted: auto-generated X-Gerrit-MessageType: newpatchset Subject: [pushed] Introduce alternate_signal_stack RAII class X-Gerrit-Change-Id: I721c047ae9d51a35fd274a6dbc00a58c6440dae6 X-Gerrit-Change-Number: 169 X-Gerrit-ChangeURL: X-Gerrit-Commit: c3efb9654847822620010922cb7ea61e8901479c In-Reply-To: References: Reply-To: noreply@gnutoolchain-gerrit.osci.io, tromey@sourceware.org, palves@redhat.com, gdb-patches@sourceware.org MIME-Version: 1.0 Content-Disposition: inline User-Agent: Gerrit/3.0.3-79-g83ff7f88f1 Message-Id: <20191126211310.8CAAE28173@gnutoolchain-gerrit.osci.io> The original change was created by Tom Tromey. Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/169 ...................................................................... Introduce alternate_signal_stack RAII class This introduces a new RAII class that temporarily installs an alternate signal stack (on systems that have sigaltstack); then changes the one gdb use of sigaltstack to use this class instead. This will be used in a later patch, when creating new threads that may want to handle SIGSEGV. gdb/ChangeLog 2019-11-26 Tom Tromey * main.c (setup_alternate_signal_stack): Remove. (captured_main_1): Use gdb::alternate_signal_stack. * gdbsupport/alt-stack.h: New file. Change-Id: I721c047ae9d51a35fd274a6dbc00a58c6440dae6 --- M gdb/ChangeLog A gdb/gdbsupport/alt-stack.h M gdb/main.c 3 files changed, 78 insertions(+), 24 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9d4fe36..7535016 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,11 @@ 2019-11-26 Tom Tromey + * main.c (setup_alternate_signal_stack): Remove. + (captured_main_1): Use gdb::alternate_signal_stack. + * gdbsupport/alt-stack.h: New file. + +2019-11-26 Tom Tromey + * gdbsupport/signals-state-save-restore.c (original_signal_mask): Remove comment. (save_original_signals_state, restore_original_signals_state): Use diff --git a/gdb/gdbsupport/alt-stack.h b/gdb/gdbsupport/alt-stack.h new file mode 100644 index 0000000..1708fb4 --- /dev/null +++ b/gdb/gdbsupport/alt-stack.h @@ -0,0 +1,70 @@ +/* Temporarily install an alternate signal stack + + Copyright (C) 2019 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 . */ + +#ifndef GDBSUPPORT_ALT_STACK_H +#define GDBSUPPORT_ALT_STACK_H + +#include + +namespace gdb +{ + +/* Try to set up an alternate signal stack for SIGSEGV handlers. + This allows us to handle SIGSEGV signals generated when the + normal process stack is exhausted. If this stack is not set + up (sigaltstack is unavailable or fails) and a SIGSEGV is + generated when the normal stack is exhausted then the program + will behave as though no SIGSEGV handler was installed. */ +class alternate_signal_stack +{ +public: + alternate_signal_stack () + { +#ifdef HAVE_SIGALTSTACK + m_stack.reset ((char *) xmalloc (SIGSTKSZ)); + + stack_t stack; + stack.ss_sp = m_stack.get (); + stack.ss_size = SIGSTKSZ; + stack.ss_flags = 0; + + sigaltstack (&stack, &m_old_stack); +#endif + } + + ~alternate_signal_stack () + { +#ifdef HAVE_SIGALTSTACK + sigaltstack (&m_old_stack, nullptr); +#endif + } + + DISABLE_COPY_AND_ASSIGN (alternate_signal_stack); + +private: + +#ifdef HAVE_SIGALTSTACK + gdb::unique_xmalloc_ptr m_stack; + stack_t m_old_stack; +#endif +}; + +} + +#endif /* GDBSUPPORT_ALT_STACK_H */ diff --git a/gdb/main.c b/gdb/main.c index a051254..1acf53e 100644 --- a/gdb/main.c +++ b/gdb/main.c @@ -52,6 +52,7 @@ #ifdef GDBTK #include "gdbtk/generic/gdbtk.h" #endif +#include "gdbsupport/alt-stack.h" /* The selected interpreter. This will be used as a set command variable, so it should always be malloc'ed - since @@ -334,29 +335,6 @@ *local_gdbinit = localinit; } -/* Try to set up an alternate signal stack for SIGSEGV handlers. - This allows us to handle SIGSEGV signals generated when the - normal process stack is exhausted. If this stack is not set - up (sigaltstack is unavailable or fails) and a SIGSEGV is - generated when the normal stack is exhausted then the program - will behave as though no SIGSEGV handler was installed. */ - -static void -setup_alternate_signal_stack (void) -{ -#ifdef HAVE_SIGALTSTACK - stack_t ss; - - /* FreeBSD versions older than 11.0 use char * for ss_sp instead of - void *. This cast works with both types. */ - ss.ss_sp = (char *) xmalloc (SIGSTKSZ); - ss.ss_size = SIGSTKSZ; - ss.ss_flags = 0; - - sigaltstack(&ss, NULL); -#endif -} - /* Call command_loop. */ /* Prevent inlining this function for the benefit of GDB's selftests @@ -898,7 +876,7 @@ save_original_signals_state (quiet); /* Try to set up an alternate signal stack for SIGSEGV handlers. */ - setup_alternate_signal_stack (); + gdb::alternate_signal_stack signal_stack; /* Initialize all files. */ gdb_init (gdb_program_name);