Re: [PING][PATCH v8] gdb: Print linker namespace when showing a frame
Guinevere Larsen <[email protected]>
| Newsgroups | gmane.comp.gdb.patches |
|---|---|
| Message-ID | <[email protected]> |
Ping :) On 6/22/26 5:34 PM, Guinevere Larsen wrote: > Ping :) > > On 5/7/26 10:48 AM, Guinevere Larsen wrote: >> When a user is stopped in a private linker namespace, the only way for >> them to realize that is using the _linker_namespace convenience >> variable. While serviceable, this is a sub-optimal solution, as most >> users are unaware of convenience variables. >> >> This commit introduces a new way for users to be informed of the linker >> namespace of a function, by printing it along with the function name. >> This is done by using the proposed syntax for symbols and locations, >> like so: >> >> #0 [[0]]::main () >> >> This is done by introducing a new function on solib.h, >> linker_namespace_prefix, that returns either an empty string (if only >> one namespace is active, or we can't determine the PC for the frame), or >> the correct identifier. This should be printed manually every time GDB >> will print a frame, so that we don't confuse other systems that look at >> function names. >> >> A previous revision would break GDB's ability to strip the parameters of >> C++ symbols, so this commit also adds a C++ SO to the test. However, >> libstdc++ never gets unloaded, so many changes were required to make the >> rest of the test still valid. >> >> Reviewed-By: Eli Zaretskii <[email protected]> >> --- >> gdb/NEWS | 4 + >> gdb/doc/gdb.texinfo | 9 +++ >> gdb/solib.c | 43 ++++++++--- >> gdb/solib.h | 13 ++++ >> gdb/stack.c | 2 + >> .../gdb.base/dlmopen-ns-ids-framefilter.py | 31 ++++++++ >> .../gdb.base/dlmopen-ns-ids-libc++.cc | 36 +++++++++ >> gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c | 19 ++++- >> gdb/testsuite/gdb.base/dlmopen-ns-ids.exp | 74 ++++++++++++++++--- >> gdb/testsuite/gdb.mi/mi-dlmopen.exp | 2 +- >> 10 files changed, 206 insertions(+), 27 deletions(-) >> create mode 100644 >> gdb/testsuite/gdb.base/dlmopen-ns-ids-framefilter.py >> create mode 100644 gdb/testsuite/gdb.base/dlmopen-ns-ids-libc++.cc >> >> diff --git a/gdb/NEWS b/gdb/NEWS >> index 480e1854002..941178c06a4 100644 >> --- a/gdb/NEWS >> +++ b/gdb/NEWS >> @@ -78,6 +78,10 @@ >> * The Windows native target now supports non-stop mode. This feature >> requires Windows 10 or later. >> +* When debugging an inferior with multiple linker namespaces, >> functions >> + will be printed like so [[N]]::foo, where N is the namespace that >> + contains foo. For example [[0]]::main. >> + >> * New targets >> GNU/Linux/MicroBlaze (gdbserver) microblazeel-*linux* >> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo >> index ab0216ff477..98a43f3a57e 100644 >> --- a/gdb/doc/gdb.texinfo >> +++ b/gdb/doc/gdb.texinfo >> @@ -22431,6 +22431,15 @@ possibility that those objects may >> cross-talk. Each set of isolated >> shared objects is said to belong to a ``namespace'', and linker >> related >> actions such as relocations do not cross namespace boundaries. >> +When multiple linker namespaces are active, @value{GDBN} will >> print the >> +identifier of the namespace that contains the function, when a function >> +is printed. It will look like this: >> + >> +@smallexample >> +#0 [[1]]::inc (n=0) at dlmopen-ns-ids-lib.c >> +#1 0x0000000000400591 in [[0]]::main () at dlmopen-ns-ids-main.c >> +@end smallexample >> + >> @kindex info dll >> @item info dll @var{regex} >> This is an alias of @code{info sharedlibrary}. >> diff --git a/gdb/solib.c b/gdb/solib.c >> index 782b844aa2f..add842b5771 100644 >> --- a/gdb/solib.c >> +++ b/gdb/solib.c >> @@ -1796,6 +1796,36 @@ solib_linker_namespace_count (program_space >> *pspace) >> return 0; >> } >> +/* See solib.h. */ >> + >> +int >> +linker_namespace_for_addr (CORE_ADDR addr, program_space *pspace) >> +{ >> + for (const solib &so : pspace->solibs ()) >> + if (solib_contains_address_p (so, addr)) >> + { >> + if (so.ops ().supports_namespaces ()) >> + return so.ops ().find_solib_ns (so); >> + break; >> + } >> + >> + return 0; >> +} >> + >> +/* See solib.h. */ >> + >> +std::string >> +linker_namespace_prefix (const frame_info_ptr &frame) >> +{ >> + std::optional<CORE_ADDR> pc = get_frame_pc_if_available (frame); >> + program_space *pspace = get_frame_program_space (frame); >> + if (!pc.has_value () || solib_linker_namespace_count (pspace) <= 1) >> + return std::string (""); >> + >> + return string_printf ("[[%d]]::", linker_namespace_for_addr >> (pc.value (), >> + pspace)); >> +} >> + >> /* Implementation of the linker_namespace convenience variable. >> This returns the GDB internal identifier of the linker namespace, >> @@ -1804,19 +1834,10 @@ solib_linker_namespace_count (program_space >> *pspace) >> static value * >> linker_namespace_make_value (gdbarch *gdbarch, internalvar *var, >> - void *ignore) >> + void *ignore) >> { >> - int nsid = 0; >> CORE_ADDR curr_pc = get_frame_pc (get_selected_frame ()); >> - >> - for (const solib &so : current_program_space->solibs ()) >> - if (solib_contains_address_p (so, curr_pc)) >> - { >> - if (so.ops ().supports_namespaces ()) >> - nsid = so.ops ().find_solib_ns (so); >> - >> - break; >> - } >> + int nsid = linker_namespace_for_addr (curr_pc, >> current_program_space); >> /* If the PC is not in an SO, or the solib_ops doesn't support >> linker namespaces, the inferior is in the default namespace. */ >> diff --git a/gdb/solib.h b/gdb/solib.h >> index 564655c4a57..39931bb1b93 100644 >> --- a/gdb/solib.h >> +++ b/gdb/solib.h >> @@ -334,6 +334,19 @@ extern const char *solib_name_from_address >> (struct program_space *, CORE_ADDR); >> extern bool solib_contains_address_p (const solib &, CORE_ADDR); >> +/* Given the address ADDR, return which linker namespace contains >> + this address in PSPACE. If ADDR is present in multiple namespaces, >> + an arbitrary one is returned. If ADDR is not present in any >> + namespace, or if the target doesn't support linker namespaces, >> + returns 0. */ >> + >> +extern int linker_namespace_for_addr (CORE_ADDR addr, program_space >> *pspace); >> + >> +/* Calculate the linker namespace identifier, and turn it into a prefix >> + to be used to print a frame. */ >> + >> +extern std::string linker_namespace_prefix (const frame_info_ptr >> &frame); >> + >> /* Return whether the data starting at VADDR, size SIZE, must be kept >> in a core file for shared libraries loaded before "gcore" is used >> to be handled correctly when the core file is loaded. This only >> diff --git a/gdb/stack.c b/gdb/stack.c >> index 7329430adab..ac270718a91 100644 >> --- a/gdb/stack.c >> +++ b/gdb/stack.c >> @@ -1306,6 +1306,7 @@ print_frame (struct ui_out *uiout, >> annotate_frame_function_name (); >> string_file stb; >> + gdb_puts (linker_namespace_prefix (frame).c_str (), &stb); >> gdb_puts (funname ? funname.get () : "??", &stb); >> uiout->field_stream ("func", stb, function_name_style.style ()); >> uiout->wrap_hint (3); >> @@ -1466,6 +1467,7 @@ info_frame_command_core (const frame_info_ptr >> &fi, bool selected_frame_p) >> fputs_styled ("<unavailable>", metadata_style.style (), >> gdb_stdout); >> gdb_stdout->wrap_here (3); >> + gdb_puts (linker_namespace_prefix (fi).c_str ()); >> if (funname.get () != nullptr) >> { >> gdb_puts (" in "); >> diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids-framefilter.py >> b/gdb/testsuite/gdb.base/dlmopen-ns-ids-framefilter.py >> new file mode 100644 >> index 00000000000..11d96fcfbc4 >> --- /dev/null >> +++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids-framefilter.py >> @@ -0,0 +1,31 @@ >> +# Copyright (C) 2026 Free Software Foundation, Inc. >> + >> +# 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 <http://www.gnu.org/licenses/>. >> + >> + >> +# This file is part of the GDB testsuite. It tests if printing the >> +# linker namespace id is affected by a null frame filter >> + >> +import gdb >> + >> + >> +class NullFilter: >> + def __init__(self): >> + self.name = "null filter" >> + self.priority = 100 >> + self.enabled = True >> + gdb.frame_filters[self.name] = self >> + >> + def filter(self, iterator): >> + return iterator >> diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids-libc++.cc >> b/gdb/testsuite/gdb.base/dlmopen-ns-ids-libc++.cc >> new file mode 100644 >> index 00000000000..9abf3f25096 >> --- /dev/null >> +++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids-libc++.cc >> @@ -0,0 +1,36 @@ >> +/* This testcase is part of GDB, the GNU debugger. >> + >> + Copyright 2025-2026 Free Software Foundation, Inc. >> + >> + 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 >> <http://www.gnu.org/licenses/>. >> + >> +*/ >> + >> +int gdb_dlmopen_glob = 0; >> + >> +int >> +cpp_inc (int n) >> +{ >> + int amount = gdb_dlmopen_glob; >> + return n + amount; /* bp.inc. */ >> +} >> + >> +extern "C" { >> + __attribute__((visibility ("default"))) >> + int >> + inc (int n) >> + { >> + return cpp_inc (n); >> + } >> +} >> diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c >> b/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c >> index 4f08a5135b2..f13eb9168de 100644 >> --- a/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c >> +++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c >> @@ -27,7 +27,7 @@ >> int >> main (void) >> { >> - void *handle[4]; >> + void *handle[5]; >> int (*fun) (int); >> Lmid_t lmid; >> int dl; >> @@ -41,20 +41,31 @@ main (void) >> handle[2] = dlmopen (LM_ID_NEWLM, DSO_NAME, RTLD_LAZY | RTLD_LOCAL); >> assert (handle[2] != NULL); >> + /* We open the C++ SO on the main namespace because libstdc++ >> marks a >> + lot of objects as GNU_UNIQUE meaning that they effectively >> can't be >> + unloaded, so the final namespace would never be fully >> unloaded. */ >> + handle[3] = dlmopen (LM_ID_BASE, CPP_DSO_NAME, RTLD_LAZY | >> RTLD_LOCAL); >> + assert (handle[3] != NULL); >> + >> for (dl = 2; dl >= 0; dl--) >> { >> fun = dlsym (handle[dl], "inc"); >> fun (dl); >> } >> + /* C++ call, to make sure the linker namespace doesn't break anything >> + of the C++ handling of symbols. */ >> + fun = dlsym (handle[3], "inc"); >> + fun (-1); >> dlclose (handle[0]); /* TAG: first dlclose */ >> dlclose (handle[1]); /* TAG: second dlclose */ >> dlclose (handle[2]); /* TAG: third dlclose */ >> + dlclose (handle[3]); /* TAG: fourth dlclose */ >> - handle[3] = dlmopen (LM_ID_NEWLM, DSO_NAME, RTLD_LAZY | >> RTLD_LOCAL); >> - dlinfo (handle[3], RTLD_DI_LMID, &lmid); >> + handle[4] = dlmopen (LM_ID_NEWLM, DSO_NAME, RTLD_LAZY | RTLD_LOCAL); >> + dlinfo (handle[4], RTLD_DI_LMID, &lmid); >> - dlclose (handle[3]); /* TAG: fourth dlclose */ >> + dlclose (handle[4]); /* TAG: final dlclose */ >> return 0; >> } >> diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp >> b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp >> index e40bc213454..cc1696f4229 100644 >> --- a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp >> +++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp >> @@ -21,20 +21,29 @@ >> require allow_dlmopen_tests >> -standard_testfile -main.c -lib.c >> +standard_testfile -main.c -lib.c -framefilter.py -libc++.cc >> set srcfile_lib $srcfile2 >> +set srcfile_libcpp $srcfile4 >> set so_name dlmopen-lib.so >> +set cpp_so_name dlmopen-libc++.so >> set binfile_lib [standard_output_file $so_name] >> +set binfile_libcpp [standard_output_file $cpp_so_name] >> if { [build_executable "build shlib" $binfile_lib $srcfile_lib \ >> [list debug shlib]] == -1 } { >> return >> } >> +if { [build_executable "build shlib" $binfile_libcpp >> $srcfile_libcpp \ >> + [list debug shlib c++]] == -1 } { >> + return >> +} >> + >> if { [build_executable "failed to build" $testfile $srcfile \ >> [list additional_flags=-DDSO_NAME=\"$binfile_lib\" \ >> - shlib_load debug]] } { >> + additional_flags=-DCPP_DSO_NAME=\"$binfile_libcpp\" \ >> + shlib_load debug]] } { >> return >> } >> @@ -107,11 +116,13 @@ proc check_no_duplicates {} { >> proc get_first_so_ns {} { >> set ns -1 >> set lib_regexp [string_to_regexp ${::binfile_lib}] >> + set libcpp_regexp [string_to_regexp ${::binfile_libcpp}] >> + set both_regexp "($lib_regexp|$libcpp_regexp)" >> gdb_test_multiple "info sharedlibrary $::so_name" "get SO >> namespace" -lbl { >> -re "\r\nFrom\\s+To\\s+\(Linker NS\\s+\)?Syms\\s+Read\\s+Shared >> Object Library(?=\r\n)" { >> exp_continue >> } >> - -re >> "\r\n$::hex\\s+$::hex\\s+($::decimal)\\s+\[^\r\n]+${lib_regexp}(?=\r\n)" >> { >> + -re >> "\r\n$::hex\\s+$::hex\\s+($::decimal)\\s+\[^\r\n]+${both_regexp}(?=\r\n)" >> { >> if {$ns == -1} { >> set ns $expect_out(1,string) >> } >> @@ -155,8 +166,8 @@ proc test_info_shared {} { >> gdb_test "next" ".*third dlclose.*" "close second library" >> gdb_assert {[get_first_so_ns] == 3} "before closing two libraries" >> - gdb_breakpoint [gdb_get_line_number "TAG: fourth dlclose"] >> - gdb_continue_to_breakpoint "TAG: fourth dlclose" >> + gdb_breakpoint [gdb_get_line_number "TAG: final dlclose"] >> + gdb_continue_to_breakpoint "TAG: final dlclose" >> # As of writing this test, glibc's LMID is just an index on an >> array of >> # namespaces. After closing a namespace, requesting a new one >> will >> # return the index of the lowest-closed namespace, so this will >> likely >> @@ -192,6 +203,11 @@ proc_with_prefix test_conv_vars {} { >> gdb_test "print \$_linker_namespace" ".* = 0" \ >> "Still in the default namespace" >> + # There should be no namespace ID visible, since there's >> + # only one namespace loaded. >> + gdb_test "backtrace" "\#0\\s+main .*" \ >> + "No namespace ID in backtrace" >> + >> gdb_breakpoint "inc" allow-pending >> gdb_breakpoint [gdb_get_line_number "TAG: first dlclose"] >> @@ -200,14 +216,41 @@ proc_with_prefix test_conv_vars {} { >> gdb_test "print \$_linker_namespace" ".* = $dl" \ >> "Verify we're in namespace $dl" >> + >> + gdb_test "frame" "\#0\\s+\\\[\\\[$dl\\\]\\\]::inc.*" \ >> + "Namespace ID in the frame" >> } >> # Check that we display the namespace of the selected >> # frame, not the lowermost one. >> - gdb_test "up" "\#1.*in main.*" >> + gdb_test "up" "\#1.*in \\\[\\\[0\\\]\\\]::main.*" >> gdb_test "print \$_linker_namespace" ".* = 0" \ >> "print namespace of selected frame" >> + gdb_test "backtrace" [multi_line \ >> + "\#0\\s+\\\[\\\[1\\\]\\\]::inc \[^\r\n\]*" \ >> + "\#1\\s+$::hex in \\\[\\\[0\\\]\\\]::main \[^\r\n\]*" ] \ >> + "raw backtrace" >> + >> + set remote_python_file [gdb_remote_download host \ >> + $::srcdir/$::subdir/$::srcfile3] >> + gdb_test_no_output "source $remote_python_file" "load frame filter" >> + gdb_test "backtrace" [multi_line \ >> + "\#0\\s+\\\[\\\[1\\\]\\\]::inc \[^\r\n\]*" \ >> + "\#1\\s+$::hex in \\\[\\\[0\\\]\\\]::main \[^\r\n\]*" ] \ >> + "With null frame filter" >> + >> + # Ensure that the code for identifying and removing parameters for >> + # C++ symbols still works with linker namespace IDs. >> + gdb_continue_to_breakpoint "inc on c++ SO" >> + gdb_test "step" "\\\[\\\[0\\\]\\\]::cpp_inc \\\(n=-1\\\).*" >> "step into c++ symbol" >> + gdb_test "backtrace" [multi_line \ >> + "\#0\\s+\\\[\\\[0\\\]\\\]::cpp_inc \\\(n=-1\\\)\[^\r\n\]*" \ >> + "\#1\\s+$::hex in \\\[\\\[0\\\]\\\]::inc >> \\\(n=-1\\\)\[^\r\n\]*" \ >> + "\#2\\s+$::hex in \\\[\\\[0\\\]\\\]::main \[^\r\n\]*" ] \ >> + "bt through c++ symbols" >> + >> + # Check that everything still works as we close namespaces. >> gdb_continue_to_breakpoint "first dlclose" >> gdb_test "print \$_linker_namespace_count" "4" "all SOs loaded" >> @@ -264,15 +307,23 @@ proc test_info_linker_namespaces {} { >> # Some systems may add libc and libm to every loaded namespace, >> # others may load only one or neither, because the SO doesn't >> - # actually use either library. The best we can do is check if >> - # we found the dynamic linker, and up to 2 more libraries. >> - gdb_assert {$n_libraries <= 3} "the correct number of libraries >> was reported" >> + # actually use either library. Similarly, because of the c++ >> + # SO, libstdc++ and libgcc_s may be included. The best we can >> + # do is check if we found the dynamic linker, the SO, and up to >> + # 4 more libraries. Ensuring that only the right one shows up is >> + # in the foreach block. >> + gdb_assert {$n_libraries <= 6} "the correct number of libraries >> was reported" >> set binfile_lib_re [string_to_regexp $::binfile_lib] >> - foreach_with_prefix ns {1 2 3} { >> + foreach_with_prefix ns {1 2 3 0} { >> set found_test_so false >> set n_libraries 999 >> + set expected_libs 4 >> + if {$ns == 0} { >> + set expected_libs 6 >> + set binfile_lib_re [string_to_regexp $::binfile_libcpp] >> + } >> gdb_test_multiple "info linker-namespaces $ns" "print >> namespace $ns" { >> -re ".*($::decimal) librar(?:y|ies) loaded in linker >> namespace $ns:\r\n" { >> @@ -290,7 +341,8 @@ proc test_info_linker_namespaces {} { >> # actually use either library. The best we can do is check if >> # we found the dynamic linker, the test SO, and maybe up to 2 >> # more libraries. >> - gdb_assert {$n_libraries <= 4} "the correct number of libraries >> was reported" >> + gdb_assert {$n_libraries <= $expected_libs} \ >> + "the correct number of libraries was reported" >> gdb_assert {$found_test_so} "this testfile's SO was reported" >> } >> diff --git a/gdb/testsuite/gdb.mi/mi-dlmopen.exp >> b/gdb/testsuite/gdb.mi/mi-dlmopen.exp >> index ff854ac7dd4..832c6ea6fe6 100644 >> --- a/gdb/testsuite/gdb.mi/mi-dlmopen.exp >> +++ b/gdb/testsuite/gdb.mi/mi-dlmopen.exp >> @@ -156,7 +156,7 @@ proc check_solib_unload_events {} { >> -disp keep -func main -file ".*$::srcfile" -line $::bp_main >> # Run past all the dlopen and dlmopen calls. >> - mi_execute_to "exec-continue" "breakpoint-hit" main "" ".*" >> $::bp_loaded \ >> + mi_execute_to "exec-continue" "breakpoint-hit" {\[\[0\]\]::main} >> "" ".*" $::bp_loaded \ >> {"" "disp=\"keep\""} "continue until all libraries are loaded" >> # Check that the dynamic linker has now been loaded multiple >> times. >> >> base-commit: 9e6e0c3cd9e6d5ee4953f72a805cff5f150aa2fd > > -- Cheers, Guinevere Larsen it/its she/her (deprecated)