From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id ELrAEDMKq1+VGAAAWB0awg (envelope-from ) for ; Tue, 10 Nov 2020 16:46:27 -0500 Received: by simark.ca (Postfix, from userid 112) id 3D5F21F08E; Tue, 10 Nov 2020 16:46:27 -0500 (EST) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,RDNS_NONE,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.2 Received: from sourceware.org (unknown [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 9E9D11E590 for ; Tue, 10 Nov 2020 16:46:24 -0500 (EST) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 55E58398702E; Tue, 10 Nov 2020 21:46:23 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 55E58398702E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1605044783; bh=Pm7UebKOhOpfniwJXdwmaqVKCV+yLHIiLE9eVlBzC5M=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=CmkDnpNmNwKsPbHXWurgfMpS1sbKd+PiTqxypULfPzhYw+tUQCUKTExF3g+zaySHf Wpkzh5tAVNYDUcARnOR9Qutoj3xgflkRRTOP/oIzvhHWJYYI+f7LFBayjR9dU7Dife 5dox9h5Tk7coJK999ivKBbIr3BX2lDSlKn63iB08= Received: from barracuda.ebox.ca (barracuda.ebox.ca [96.127.255.19]) by sourceware.org (Postfix) with ESMTPS id 0E8EA3986829 for ; Tue, 10 Nov 2020 21:46:18 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 0E8EA3986829 X-ASG-Debug-ID: 1605044776-0c856e6cd671690001-fS2M51 Received: from smtp.ebox.ca (smtp.ebox.ca [96.127.255.82]) by barracuda.ebox.ca with ESMTP id 6wj4QO5cbhZmb2E2 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 10 Nov 2020 16:46:17 -0500 (EST) X-Barracuda-Envelope-From: simon.marchi@efficios.com X-Barracuda-RBL-Trusted-Forwarder: 96.127.255.82 Received: from epycamd.internal.efficios.com (192-222-181-218.qc.cable.ebox.net [192.222.181.218]) by smtp.ebox.ca (Postfix) with ESMTP id B4F3B441D64; Tue, 10 Nov 2020 16:46:16 -0500 (EST) X-Barracuda-RBL-IP: 192.222.181.218 X-Barracuda-Effective-Source-IP: 192-222-181-218.qc.cable.ebox.net[192.222.181.218] X-Barracuda-Apparent-Source-IP: 192.222.181.218 To: gdb-patches@sourceware.org Subject: [PATCH 06/12] gdb: introduce status enum for displaced step prepare/finish Date: Tue, 10 Nov 2020 16:46:08 -0500 X-ASG-Orig-Subj: [PATCH 06/12] gdb: introduce status enum for displaced step prepare/finish Message-Id: <20201110214614.2842615-7-simon.marchi@efficios.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201110214614.2842615-1-simon.marchi@efficios.com> References: <20201110214614.2842615-1-simon.marchi@efficios.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Barracuda-Connect: smtp.ebox.ca[96.127.255.82] X-Barracuda-Start-Time: 1605044777 X-Barracuda-Encrypted: DHE-RSA-AES256-SHA X-Barracuda-URL: https://96.127.255.19:443/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at ebox.ca X-Barracuda-Scan-Msg-Size: 10980 X-Barracuda-BRTS-Status: 1 X-Barracuda-Spam-Score: 0.00 X-Barracuda-Spam-Status: No, SCORE=0.00 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=8.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.85785 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Simon Marchi via Gdb-patches Reply-To: Simon Marchi Cc: Simon Marchi Errors-To: gdb-patches-bounces@sourceware.org Sender: "Gdb-patches" This is a preparatory patch to reduce the size of the diff of the upcoming main patch. It introduces enum types for the return values of displaced step "prepare" and "finish" operations. I find that this expresses better the intention of the code, rather than returning arbitrary integer values (-1, 0 and 1) which are difficult to remember. That makes the code easier to read. I put the new enum types in a new displaced-stepping.h file, because I introduce that file in a later patch anyway. Putting it there avoids having to move it later. There is one change in behavior for displaced_step_finish: it currently returns 0 if the thread wasn't doing a displaced step and 1 if the thread was doing a displaced step which was executed successfully. It turns out that this distinction is not needed by any caller, so I've merged these two cases into "_OK", rather than adding an extra enumerator. gdb/ChangeLog: * infrun.c (displaced_step_prepare_throw): Change return type to displaced_step_prepare_status. (displaced_step_prepare): Likewise. (displaced_step_finish): Change return type to displaced_step_finish_status. (resume_1): Adjust. (stop_all_threads): Adjust. * displaced-stepping.h: New file. Change-Id: I5c8fe07212cd398d5b486b5936d9d0807acd3788 --- gdb/displaced-stepping.h | 46 +++++++++++++++++++++++++ gdb/infrun.c | 72 +++++++++++++++++++++++----------------- 2 files changed, 88 insertions(+), 30 deletions(-) create mode 100644 gdb/displaced-stepping.h diff --git a/gdb/displaced-stepping.h b/gdb/displaced-stepping.h new file mode 100644 index 00000000000..9c7e85c3769 --- /dev/null +++ b/gdb/displaced-stepping.h @@ -0,0 +1,46 @@ +/* Displaced stepping related things. + + Copyright (C) 2020 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 DISPLACED_STEPPING_H +#define DISPLACED_STEPPING_H + +enum displaced_step_prepare_status +{ + /* A displaced stepping buffer was successfully allocated and prepared. */ + DISPLACED_STEP_PREPARE_STATUS_OK, + + /* Something bad happened. */ + DISPLACED_STEP_PREPARE_STATUS_ERROR, + + /* Not enough resources are available at this time, try again later. */ + DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE, +}; + +enum displaced_step_finish_status +{ + /* Either the instruction was stepped and fixed up, or the specified thread + wasn't executing a displaced step (in which case there's nothing to + finish). */ + DISPLACED_STEP_FINISH_STATUS_OK, + + /* The thread was executing a displaced step, but didn't complete it. */ + DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED, +}; + +#endif /* DISPLACED_STEPPING_H */ diff --git a/gdb/infrun.c b/gdb/infrun.c index cdf198bb307..ed54c4331d7 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -19,6 +19,7 @@ along with this program. If not, see . */ #include "defs.h" +#include "displaced-stepping.h" #include "infrun.h" #include #include "symtab.h" @@ -1652,11 +1653,13 @@ displaced_step_dump_bytes (const gdb_byte *buf, size_t len) Comments in the code for 'random signals' in handle_inferior_event explain how we handle this case instead. - Returns 1 if preparing was successful -- this thread is going to be - stepped now; 0 if displaced stepping this thread got queued; or -1 - if this instruction can't be displaced stepped. */ + Returns DISPLACED_STEP_PREPARE_STATUS_OK if preparing was successful -- this + thread is going to be stepped now; DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE + if displaced stepping this thread got queued; or + DISPLACED_STEP_PREPARE_STATUS_ERROR if this instruction can't be displaced + stepped. */ -static int +static displaced_step_prepare_status displaced_step_prepare_throw (thread_info *tp) { regcache *regcache = get_thread_regcache (tp); @@ -1694,7 +1697,7 @@ displaced_step_prepare_throw (thread_info *tp) target_pid_to_str (tp->ptid).c_str ()); global_thread_step_over_chain_enqueue (tp); - return 0; + return DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE; } else displaced_debug_printf ("stepping %s now", @@ -1725,7 +1728,7 @@ displaced_step_prepare_throw (thread_info *tp) displaced_debug_printf ("breakpoint set in scratch pad. " "Stepping over breakpoint in-line instead."); - return -1; + return DISPLACED_STEP_PREPARE_STATUS_ERROR; } /* Save the original contents of the copy area. */ @@ -1749,7 +1752,7 @@ displaced_step_prepare_throw (thread_info *tp) /* The architecture doesn't know how or want to displaced step this instruction or instruction sequence. Fallback to stepping over the breakpoint in-line. */ - return -1; + return DISPLACED_STEP_PREPARE_STATUS_ERROR; } /* Save the information we need to fix things up if the step @@ -1770,20 +1773,21 @@ displaced_step_prepare_throw (thread_info *tp) displaced_debug_printf ("displaced pc to %s", paddress (gdbarch, copy)); - return 1; + return DISPLACED_STEP_PREPARE_STATUS_OK; } /* Wrapper for displaced_step_prepare_throw that disabled further attempts at displaced stepping if we get a memory error. */ -static int +static displaced_step_prepare_status displaced_step_prepare (thread_info *thread) { - int prepared = -1; + displaced_step_prepare_status status + = DISPLACED_STEP_PREPARE_STATUS_ERROR; try { - prepared = displaced_step_prepare_throw (thread); + status = displaced_step_prepare_throw (thread); } catch (const gdb_exception_error &ex) { @@ -1810,7 +1814,7 @@ displaced_step_prepare (thread_info *thread) displaced_state->failed_before = 1; } - return prepared; + return status; } static void @@ -1840,22 +1844,24 @@ displaced_step_restore (struct displaced_step_inferior_state *displaced, displaced->step_copy)); } -/* If we displaced stepped an instruction successfully, adjust - registers and memory to yield the same effect the instruction would - have had if we had executed it at its original address, and return - 1. If the instruction didn't complete, relocate the PC and return - -1. If the thread wasn't displaced stepping, return 0. */ +/* If we displaced stepped an instruction successfully, adjust registers and + memory to yield the same effect the instruction would have had if we had + executed it at its original address, and return + DISPLACED_STEP_PREPARE_STATUS_OK. If the instruction didn't complete, + relocate the PC and return DISPLACED_STEP_PREPARE_STATUS_NOT_EXECUTED. -static int + If the thread wasn't displaced stepping, return + DISPLACED_STEP_PREPARE_STATUS_OK as well.. */ + +static displaced_step_finish_status displaced_step_finish (thread_info *event_thread, enum gdb_signal signal) { struct displaced_step_inferior_state *displaced = get_displaced_stepping_state (event_thread->inf); - int ret; /* Was this event for the thread we displaced? */ if (displaced->step_thread != event_thread) - return 0; + return DISPLACED_STEP_FINISH_STATUS_OK; /* Fixup may need to read memory/registers. Switch to the thread that we're fixing up. Also, target_stopped_by_watchpoint checks @@ -1879,7 +1885,8 @@ displaced_step_finish (thread_info *event_thread, enum gdb_signal signal) displaced->step_original, displaced->step_copy, get_thread_regcache (displaced->step_thread)); - ret = 1; + + return DISPLACED_STEP_FINISH_STATUS_OK; } else { @@ -1890,10 +1897,9 @@ displaced_step_finish (thread_info *event_thread, enum gdb_signal signal) pc = displaced->step_original + (pc - displaced->step_copy); regcache_write_pc (regcache, pc); - ret = -1; - } - return ret; + return DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED; + } } /* Data to be passed around while handling an event. This data is @@ -2417,16 +2423,17 @@ resume_1 (enum gdb_signal sig) && sig == GDB_SIGNAL_0 && !current_inferior ()->waiting_for_vfork_done) { - int prepared = displaced_step_prepare (tp); + displaced_step_prepare_status prepare_status + = displaced_step_prepare (tp); - if (prepared == 0) + if (prepare_status == DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE) { infrun_debug_printf ("Got placed in step-over queue"); tp->control.trap_expected = 0; return; } - else if (prepared < 0) + else if (prepare_status == DISPLACED_STEP_PREPARE_STATUS_ERROR) { /* Fallback to stepping over the breakpoint in-line. */ @@ -2440,7 +2447,7 @@ resume_1 (enum gdb_signal sig) insert_breakpoints (); } - else if (prepared > 0) + else if (prepare_status == DISPLACED_STEP_PREPARE_STATUS_OK) { /* Update pc to reflect the new address from which we will execute instructions due to displaced stepping. */ @@ -2448,6 +2455,9 @@ resume_1 (enum gdb_signal sig) step = gdbarch_displaced_step_hw_singlestep (gdbarch); } + else + gdb_assert_not_reached (_("Invalid displaced_step_prepare_status " + "value.")); } /* Do we need to do it the hard way, w/temp breakpoints? */ @@ -4822,7 +4832,8 @@ stop_all_threads (void) t->suspend.waitstatus.kind = TARGET_WAITKIND_IGNORE; t->suspend.waitstatus_pending_p = 0; - if (displaced_step_finish (t, GDB_SIGNAL_0) < 0) + if (displaced_step_finish (t, GDB_SIGNAL_0) + == DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED) { /* Add it back to the step-over queue. */ infrun_debug_printf @@ -4850,7 +4861,8 @@ stop_all_threads (void) sig = (event.ws.kind == TARGET_WAITKIND_STOPPED ? event.ws.value.sig : GDB_SIGNAL_0); - if (displaced_step_finish (t, sig) < 0) + if (displaced_step_finish (t, sig) + == DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED) { /* Add it back to the step-over queue. */ t->control.trap_expected = 0; -- 2.28.0