From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19457 invoked by alias); 23 Feb 2012 21:51:52 -0000 Received: (qmail 19449 invoked by uid 22791); 23 Feb 2012 21:51:50 -0000 X-SWARE-Spam-Status: No, hits=-6.8 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 23 Feb 2012 21:51:35 +0000 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q1NLpWqV020349 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 23 Feb 2012 16:51:32 -0500 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q1NLpU5n012832; Thu, 23 Feb 2012 16:51:31 -0500 Message-ID: <4F46B4E2.6020504@redhat.com> Date: Thu, 23 Feb 2012 22:06:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0) Gecko/20120131 Thunderbird/10.0 MIME-Version: 1.0 To: Yao Qi CC: gdb-patches@sourceware.org Subject: Re: [PATCH 6/9] agent capability of static tracepoint References: <1329447300-18841-1-git-send-email-yao@codesourcery.com> <1329447300-18841-7-git-send-email-yao@codesourcery.com> In-Reply-To: <1329447300-18841-7-git-send-email-yao@codesourcery.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2012-02/txt/msg00521.txt.bz2 On 02/17/2012 02:54 AM, Yao Qi wrote: > This patch is to teach both GDB and GDBserver to check agent's capability on > static tracepoint, before performing any operations. > > gdb: > 2012-02-15 Yao Qi > > * tracepoint.c (info_static_tracepoint_markers_command): Call > agent_capability_check. > > gdb/gdbserver: > 2012-02-15 Yao Qi > > * tracepoint.c (gdb_agent_capability): New global. > (in_process_agent_loaded_ust): Renamed to > `in_process_agent_supports_ust'. > Update callers. > (in_process_agent_supports_ust): Call agent_capability_check. > (clear_installed_tracepoints): Assert that agent supports > agent. > (install_tracepoint): Call in_process_agent_supports_ust. > --- > gdb/gdbserver/tracepoint.c | 25 ++++++++++++++++++------- > gdb/tracepoint.c | 5 +++++ > 2 files changed, 23 insertions(+), 7 deletions(-) > > diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c > index 091af5a..0e1f9ed 100644 > --- a/gdb/gdbserver/tracepoint.c > +++ b/gdb/gdbserver/tracepoint.c > @@ -239,10 +239,11 @@ in_process_agent_loaded (void) > static int read_inferior_integer (CORE_ADDR symaddr, int *val); > > /* Returns true if both the in-process agent library and the static > - tracepoints libraries are loaded in the inferior. */ > + tracepoints libraries are loaded in the inferior, and agent has > + capability on static tracepoints. */ > > static int > -in_process_agent_loaded_ust (void) > +in_process_agent_supports_ust (void) > { > int loaded = 0; > > @@ -258,7 +259,10 @@ in_process_agent_loaded_ust (void) > return 0; > } > > - return loaded; > + if (loaded) > + return agent_capability_check (AGENT_CAPA_STATIC_TRACE); Hmm, this looks backwards. We're reading the existence of a global in the agent called "ust_loaded", indicating whether it has loaded ust, and after, we check for the static trace capability. If "ust_loaded" exists in the agent, then it sure understands static tracepoints. The right check is: 1. does the agent understand static tracepoints? 2. yes? good. and, is ust loaded perchance? If the agent doesn't understand AGENT_CAPA_STATIC_TRACE, then you'd fail right on the ust_loaded read, or some other mechanism to check whether ust is in fact loaded in the inferior. > + else > + return 0; > } > > static void > @@ -310,7 +314,7 @@ maybe_write_ipa_ust_not_loaded (char *buffer) > write_e_ipa_not_loaded (buffer); > return 1; > } > - else if (!in_process_agent_loaded_ust ()) > + else if (!in_process_agent_supports_ust ()) > { > write_e_ust_not_loaded (buffer); > return 1; > @@ -2315,6 +2319,10 @@ clear_installed_tracepoints (void) > ; > else > { > + /* Static tracepoints have been inserted, so agent should have > + been loaded and working. */ > + gdb_assert (in_process_agent_supports_ust ()); This triggers an extra read off the inferior at each installed tracepoints. Is it worth it? > + > unprobe_marker_at (tpoint->address); > prev_stpoint = tpoint; > } > @@ -2965,7 +2973,8 @@ install_tracepoint (struct tracepoint *tpoint, char *own_buf) > write_e_ipa_not_loaded (own_buf); > return; > } > - if (tpoint->type == static_tracepoint && !in_process_agent_loaded_ust ()) > + if (tpoint->type == static_tracepoint > + && !in_process_agent_supports_ust ()) > { > trace_debug ("Requested a static tracepoint, but static " > "tracepoints are not supported."); > @@ -2990,8 +2999,8 @@ install_tracepoint (struct tracepoint *tpoint, char *own_buf) > } > else > { > - if (tp) > - tpoint->handle = (void *) -1; Why do we lose this? This was just cloning another static tracepoint, but in the static tracepoint case, an installed static tracepoint has a handle == -1 (vs NULL). > + if (!in_process_agent_supports_ust ()) > + warning ("Agent does not have capability for static tracepoint."); How did we get so far then? There's that "Requested a static tracepoint, but static..." check quoted above, above. > else This if/else connection appears confused. > { > if (probe_marker_at (tpoint->address, own_buf) == 0) > @@ -7994,6 +8003,8 @@ gdb_agent_helper_thread (void *arg) > #include > #include > > +IP_AGENT_EXPORT int gdb_agent_capability = AGENT_CAPA_STATIC_TRACE; > + > static void > gdb_agent_init (void) > { > diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c > index c56a02c..c2801f9 100644 > --- a/gdb/tracepoint.c > +++ b/gdb/tracepoint.c > @@ -4893,6 +4893,11 @@ info_static_tracepoint_markers_command (char *arg, int from_tty) > warning (_("Agent is off. Run `set agent on'.")); > return; > } > + if (!agent_capability_check (AGENT_CAPA_STATIC_TRACE)) > + { > + warning (_("Agent is not capable of operating static tracepoints")); > + return; > + } Same comment as in the other patch. I don't think this is right. Also, does this work for remote debugging? Who is calling agent_look_up_symbols? gdb knowing about IPA's internals when remote debugging feels a bit dirty. > > old_chain > = make_cleanup_ui_out_table_begin_end (uiout, 5, -1, -- Pedro Alves