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Mon, 7 Apr 2025 14:55:11 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.96.134.159]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5583C18009BC; Mon, 7 Apr 2025 14:55:09 +0000 (UTC) From: Guinevere Larsen To: gdb-patches@sourceware.org Cc: Guinevere Larsen Subject: [PATCH 1/3] gdb: add convenience variables around linker namespace debugging Date: Mon, 7 Apr 2025 11:54:41 -0300 Message-ID: <20250407145443.1895323-2-guinevere@redhat.com> In-Reply-To: <20250407145443.1895323-1-guinevere@redhat.com> References: <20250407145443.1895323-1-guinevere@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ctR7U154YlJCTrXf-1cqdW-ddNPAvwhk4bM1ZGhtTZg_1744037711 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true 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 This commit adds 2 simple built-in convenience variables to help users debug an inferior with multiple linker namespaces. The first is $_active_namespaces, which just counts how many namespaces have SOs loaded onto them. The second is $_current_namespace, and it tracks which namespace does the current location in the inferior belongs to. This commit also introduces a test ensuring that we track namespaces correctly, and that a user can use the $_current_namespace variable to set a conditional breakpoint, while linespec changes aren't finalized to make it more convenient. --- gdb/NEWS | 5 ++ gdb/doc/gdb.texinfo | 12 +++++ gdb/solib-svr4.c | 6 +++ gdb/solib.c | 42 +++++++++++++++ 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, 128 insertions(+) diff --git a/gdb/NEWS b/gdb/NEWS index 99ec392d4c4..4bf380cbadd 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -40,6 +40,11 @@ namespace into which the library was loaded, if more than one namespace is active. +* New built-in convenience variables $_active_namespaces and + $_current_namespace. These show the number of active linkage namespaces, + and which one 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 4e4509a4649..f0ebf4b7dcf 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. +@item $_active_namespaces +@vindex $_active_namespaces@r{, convenience variable} +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}. + +@item $_current_namespace +@vindex $_current_namespace@r{, convenience variable} +Which namespace contains the current location in the inferior. This returns +GDB's internal identifier for namespaces, which is @samp{[[]]} with an +integer in the middle. 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 2f839bd7b0b..60b61e7e07d 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_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 3ddd4f919c6..52fd6410429 100644 --- a/gdb/solib.c +++ b/gdb/solib.c @@ -1715,6 +1715,41 @@ default_find_solib_addr (solib &so) return {}; } +/* Implementation of the current_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_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 ()); +} + +static const struct internalvar_funcs current_namespace_funcs = +{ + current_namespace_make_value, + nullptr, +}; + void _initialize_solib (); void @@ -1727,6 +1762,13 @@ _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_namespace", + ¤t_namespace_funcs, nullptr); + set_internalvar_integer (lookup_internalvar ("_active_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 93a6733c9ad..8e42b23d038 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} \ + {$_active_namespaces = 1} \ + {$_current_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..51d461d05a3 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_namespaces" "1" \ + "1 namespace before starting inferior" + gdb_test "print \$_current_namespace" "No registers." \ + "No current namespace before starting inferior" + + if { ![runto_main] } { + return + } + + gdb_test "print \$_active_namespaces" "1" \ + "Before activating namespaces" + gdb_test "print \$_current_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_namespace" ".*\"\\\[\\\[$dl\\\]\\\]\"" \ + "Verify we're in namespace $dl" + } + + gdb_continue_to_breakpoint "first dlclose" + gdb_test "print \$_active_namespaces" "4" "all SOs loaded" + + gdb_test "next" ".*second dlclose.*" "close one SO" + gdb_test "print \$_active_namespaces" "3" "one SOs unloaded" + gdb_test "next" ".*third dlclose.*" "close another SO" + gdb_test "print \$_active_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_namespace, \"\[\[2\]\]\")" + gdb_continue_to_breakpoint "inc" + gdb_continue_to_end "" continue 1 +} + test_info_shared +test_conv_vars -- 2.49.0