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Sat, 12 Apr 2025 23:49:51 +0000 (UTC) Received: from f41-zbm-amd (unknown [10.22.80.11]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 576A619560AD; Sat, 12 Apr 2025 23:49:49 +0000 (UTC) Date: Sat, 12 Apr 2025 16:49:44 -0700 From: Kevin Buettner To: Guinevere Larsen Cc: gdb-patches@sourceware.org, Eli Zaretskii Subject: Re: [PATCH v2 1/3] gdb: add convenience variables around linker namespace debugging Message-ID: <20250412164826.508c8143@f41-zbm-amd> In-Reply-To: <20250409204427.1680979-2-guinevere@redhat.com> References: <20250409204427.1680979-1-guinevere@redhat.com> <20250409204427.1680979-2-guinevere@redhat.com> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: q8La76aAWGAuQViLbxSbD_D7h8mt2rdQov3Zu7_UnFY_1744501792 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org Hi Gwen, I found two nits - see below. Kevin On Wed, 9 Apr 2025 17:44:25 -0300 Guinevere Larsen wrote: > This commit adds 2 simple built-in convenience variables to help users > debug an inferior with multiple linker namespaces. The first is > $_active_linker_namespaces, which just counts how many namespaces have SOs > loaded onto them. The second is $_current_linker_namespace, and it tracks > which namespace does the current location in the inferior belongs to. s/does/that/ > > This commit also introduces a test ensuring that we track namespaces > correctly, and that a user can use the $_current_linker_namespace > variable to set a conditional breakpoint, while linespec changes aren't > finalized to make it more convenient. > > Reviewed-By: Eli Zaretskii > --- > gdb/NEWS | 6 +++ > gdb/doc/gdb.texinfo | 12 +++++ > gdb/solib-svr4.c | 6 +++ > gdb/solib.c | 43 +++++++++++++++ > gdb/testsuite/gdb.base/default.exp | 2 + > gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c | 6 +++ > gdb/testsuite/gdb.base/dlmopen-ns-ids.exp | 55 ++++++++++++++++++++ > 7 files changed, 130 insertions(+) > > diff --git a/gdb/NEWS b/gdb/NEWS > index 99ec392d4c4..053541683f1 100644 > --- a/gdb/NEWS > +++ b/gdb/NEWS > @@ -40,6 +40,12 @@ > namespace into which the library was loaded, if more than one namespace > is active. > > +* New built-in convenience variables $_active_linker_namespaces and > + $_current_linker_namespace. These show the number of active linkage > + namespaces, and the namespace to which the current location belongs to. > + In systems that don't support linkage namespaces, these always return 1 > + and [[0]] respectively. > + > * New commands > > maintenance check psymtabs > diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo > index b251c8e1228..2dda8abd407 100644 > --- a/gdb/doc/gdb.texinfo > +++ b/gdb/doc/gdb.texinfo > @@ -13046,6 +13046,18 @@ variable which may be @samp{truecolor} or @samp{24bit}. Other color spaces are > determined by the "Co" termcap which in turn depends on the @env{TERM} > environment variable. > > +@vindex $_active_linker_namespaces@r{, convenience variable} > +@item $_active_linker_namespaces > +Number of active linkage namespaces in the inferior. In systems with no > +support for linkage namespaces, this variable will always be set to @samp{1}. > + > +@vindex $_current_linker_namespace@r{, convenience variable} > +@item $_current_linker_namespace > +The namespace which contains the current location in the inferior. This > +returns GDB's internal identifier for namespaces, which is @samp{[[@var{n}]]} > +where @var{n} is a zero-based namespace number. In systems with no support > +for linkage namespaces, this variable will always be set to @samp{[[0]]}. > + > @end table > > @node Convenience Funs > diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c > index 83cb389dad5..148359a0227 100644 > --- a/gdb/solib-svr4.c > +++ b/gdb/solib-svr4.c > @@ -451,6 +451,12 @@ svr4_maybe_add_namespace (svr4_info *info, CORE_ADDR lmid) > info->namespace_id.push_back (lmid); > > info->active_namespaces.insert (i); > + > + /* Create or update the convenience variable "active_namespaces". > + It only needs to be updated here, as this only changes when a > + dlmopen or dlclose call happens. */ > + set_internalvar_integer (lookup_internalvar ("_active_linker_namespaces"), > + info->active_namespaces.size ()); > } > > /* Return whether DEBUG_BASE is the default namespace of INFO. */ > diff --git a/gdb/solib.c b/gdb/solib.c > index 4876f1a92ea..1ba98137f5e 100644 > --- a/gdb/solib.c > +++ b/gdb/solib.c > @@ -1715,6 +1715,42 @@ default_find_solib_addr (solib &so) > return {}; > } > > +/* Implementation of the current_linker_namespace convenience variable. > + This returns the GDB internal identifier of the linker namespace, > + for the current frame, in the form '[[]]'. If the inferior > + doesn't support linker namespaces, this always returns [[0]]. */ > + > +static value * > +current_linker_namespace_make_value (gdbarch *gdbarch, internalvar *var, > + void *ignore) > +{ > + const solib_ops *ops = gdbarch_so_ops (gdbarch); > + const language_defn *lang = language_def (get_frame_language > + (get_current_frame ())); > + std::string nsid = "[[0]]"; > + if (ops->find_solib_ns != nullptr) > + { > + CORE_ADDR curr_pc = get_frame_pc (get_current_frame ()); > + for (const solib &so : current_program_space->solibs ()) > + if (solib_contains_address_p (so, curr_pc)) > + { > + nsid = string_printf ("[[%d]]", ops->find_solib_ns (so)); > + break; > + } > + } > + > + > + /* If the PC is not in an SO, or the solib_ops doesn't support > + linker namespaces, the inferior is in the default namespace. */ > + return lang->value_string (gdbarch, nsid.c_str (), nsid.length ()); > +} > + Please add a comment here for current_linker_namespace_funcs, below. This should probably be: /* Implementation of `$_current_linker_namespace' variable. */ (I realize that the comment for the function above could probably apply here too, but this is how it's done in similar situations elsewhere in the GDB sources.) > +static const struct internalvar_funcs current_linker_namespace_funcs = > +{ > + current_linker_namespace_make_value, > + nullptr, > +}; > + > void _initialize_solib (); > > void > @@ -1727,6 +1763,13 @@ _initialize_solib () > }, > "solib"); > > + /* Convenience variables for debugging linker namespaces. These are > + set here, even if the solib_ops doesn't support them, > + for consistency. */ > + create_internalvar_type_lazy ("_current_linker_namespace", > + ¤t_linker_namespace_funcs, nullptr); > + set_internalvar_integer (lookup_internalvar ("_active_linker_namespaces"), 1); > + > add_com ( > "sharedlibrary", class_files, sharedlibrary_command, > _ ("Load shared object library symbols for files matching REGEXP.")); > diff --git a/gdb/testsuite/gdb.base/default.exp b/gdb/testsuite/gdb.base/default.exp > index d4d6b208057..3abd0495387 100644 > --- a/gdb/testsuite/gdb.base/default.exp > +++ b/gdb/testsuite/gdb.base/default.exp > @@ -699,6 +699,8 @@ set show_conv_list \ > {$_gdb_minor = 1} \ > {$_shell_exitsignal = void} \ > {$_shell_exitcode = 0} \ > + {$_active_linker_namespaces = 1} \ > + {$_current_linker_namespace = }\ > } > if [allow_python_tests] { > append show_conv_list \ > diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c b/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c > index 3bcd8196483..c7c038a08d1 100644 > --- a/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c > +++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c > @@ -41,6 +41,12 @@ main (void) > handle[2] = dlmopen (LM_ID_NEWLM, DSO_NAME, RTLD_LAZY | RTLD_LOCAL); > assert (handle[2] != NULL); > > + for (dl = 2; dl >= 0; dl--) > + { > + fun = dlsym (handle[dl], "inc"); > + fun (dl); > + } > + > dlclose (handle[0]); /* TAG: first dlclose */ > dlclose (handle[1]); /* TAG: second dlclose */ > dlclose (handle[2]); /* TAG: third dlclose */ > diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp > index 03b7a527af5..8f5376fa3de 100644 > --- a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp > +++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp > @@ -103,4 +103,59 @@ proc test_info_shared {} { > "after unloading everything" > } > > +# Run all tests related to the linkage namespaces convenience > +# variables, _active_namespaces and _current_namespaces. > +proc_with_prefix test_conv_vars {} { > + clean_restart $::binfile > + > + gdb_test "print \$_active_linker_namespaces" "1" \ > + "1 namespace before starting inferior" > + gdb_test "print \$_current_linker_namespace" "No registers." \ > + "No current namespace before starting inferior" > + > + if { ![runto_main] } { > + return > + } > + > + gdb_test "print \$_active_linker_namespaces" "1" \ > + "Before activating namespaces" > + gdb_test "print \$_current_linker_namespace" ".*\"\\\[\\\[0\\\]\\\]\"" \ > + "Still in the default namespace" > + > + gdb_breakpoint "inc" allow-pending > + gdb_breakpoint [gdb_get_line_number "TAG: first dlclose"] > + > + foreach_with_prefix dl {3 2 1} { > + gdb_continue_to_breakpoint "inc" > + > + gdb_test "print \$_current_linker_namespace" ".*\"\\\[\\\[$dl\\\]\\\]\"" \ > + "Verify we're in namespace $dl" > + } > + > + gdb_continue_to_breakpoint "first dlclose" > + gdb_test "print \$_active_linker_namespaces" "4" "all SOs loaded" > + > + gdb_test "next" ".*second dlclose.*" "close one SO" > + gdb_test "print \$_active_linker_namespaces" "3" "one SOs unloaded" > + gdb_test "next" ".*third dlclose.*" "close another SO" > + gdb_test "print \$_active_linker_namespaces" "2" "two SOs unloaded" > + > + # Restarting GDB so that we can test setting a breakpoint > + # using the convenience variable, while a proper bp syntax > + # isn't implemented for namespaces > + clean_restart $::binfile > + if {![runto_main]} { > + return > + } > + > + # We need to load one SO because you can't have confitional > + # breakpoints and pending breakpoints at the same time with > + # gdb_breakpoint. > + gdb_test "next" ".*assert.*" "load the first SO" > + gdb_breakpoint "inc if \$_streq(\$_current_linker_namespace, \"\[\[2\]\]\")" > + gdb_continue_to_breakpoint "inc" > + gdb_continue_to_end "" continue 1 > +} > + > test_info_shared > +test_conv_vars > -- > 2.49.0 >