172 lines
7.3 KiB
Diff
172 lines
7.3 KiB
Diff
From f2ee6fa6c841ddc37ba665909dafbc7294c34d64 Mon Sep 17 00:00:00 2001
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From: Tao Liu <ltao@redhat.com>
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Date: Fri, 17 Nov 2023 15:52:19 +0800
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Subject: [PATCH 04/14] symbols: expand all kernel module symtable if not all
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expanded previously
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There is an issue that, for kernel modules, "dis -rl" fails to display
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modules code line number data after execute "bt" command in crash.
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Without the patch:
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crsah> mod -S
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crash> bt
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PID: 1500 TASK: ff2bd8b093524000 CPU: 16 COMMAND: "lpfc_worker_0"
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#0 [ff2c9f725c39f9e0] machine_kexec at ffffffff8e0686d3
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...snip...
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#8 [ff2c9f725c39fcc0] __lpfc_sli_release_iocbq_s4 at ffffffffc0f2f425 [lpfc]
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...snip...
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crash> dis -rl ffffffffc0f60f82
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0xffffffffc0f60eb0 <lpfc_nlp_get>: nopl 0x0(%rax,%rax,1) [FTRACE NOP]
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0xffffffffc0f60eb5 <lpfc_nlp_get+5>: push %rbp
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0xffffffffc0f60eb6 <lpfc_nlp_get+6>: push %rbx
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0xffffffffc0f60eb7 <lpfc_nlp_get+7>: test %rdi,%rdi
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With the patch:
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crash> mod -S
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crash> bt
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PID: 1500 TASK: ff2bd8b093524000 CPU: 16 COMMAND: "lpfc_worker_0"
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#0 [ff2c9f725c39f9e0] machine_kexec at ffffffff8e0686d3
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...snip...
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#8 [ff2c9f725c39fcc0] __lpfc_sli_release_iocbq_s4 at ffffffffc0f2f425 [lpfc]
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...snip...
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crash> dis -rl ffffffffc0f60f82
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/usr/src/debug/kernel-4.18.0-425.13.1.el8_7/linux-4.18.0-425.13.1.el8_7.x86_64/drivers/scsi/lpfc/lpfc_hbadisc.c: 6756
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0xffffffffc0f60eb0 <lpfc_nlp_get>: nopl 0x0(%rax,%rax,1) [FTRACE NOP]
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/usr/src/debug/kernel-4.18.0-425.13.1.el8_7/linux-4.18.0-425.13.1.el8_7.x86_64/drivers/scsi/lpfc/lpfc_hbadisc.c: 6759
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0xffffffffc0f60eb5 <lpfc_nlp_get+5>: push %rbp
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The root cause is, after kernel module been loaded by mod command, the symtable
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is not expanded in gdb side. crash bt or dis command will trigger such an
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expansion. However the symtable expansion is different for the 2 commands:
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The stack trace of "dis -rl" for symtable expanding:
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#0 0x00000000008d8d9f in add_compunit_symtab_to_objfile ...
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#1 0x00000000006d3293 in buildsym_compunit::end_symtab_with_blockvector ...
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#2 0x00000000006d336a in buildsym_compunit::end_symtab_from_static_block ...
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#3 0x000000000077e8e9 in process_full_comp_unit ...
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#4 process_queue ...
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#5 dw2_do_instantiate_symtab ...
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#6 0x000000000077ed67 in dw2_instantiate_symtab ...
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#7 0x000000000077f75e in dw2_expand_all_symtabs ...
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#8 0x00000000008f254d in gdb_get_line_number ...
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#9 0x00000000008f22af in gdb_command_funnel_1 ...
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#10 0x00000000008f2003 in gdb_command_funnel ...
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#11 0x00000000005b7f02 in gdb_interface ...
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#12 0x00000000005f5bd8 in get_line_number ...
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#13 0x000000000059e574 in cmd_dis ...
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The stack trace of "bt" for symtable expanding:
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#0 0x00000000008d8d9f in add_compunit_symtab_to_objfile ...
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#1 0x00000000006d3293 in buildsym_compunit::end_symtab_with_blockvector ...
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#2 0x00000000006d336a in buildsym_compunit::end_symtab_from_static_block ...
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#3 0x000000000077e8e9 in process_full_comp_unit ...
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#4 process_queue ...
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#5 dw2_do_instantiate_symtab ...
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#6 0x000000000077ed67 in dw2_instantiate_symtab ...
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#7 0x000000000077f8ed in dw2_lookup_symbol ...
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#8 0x00000000008e6d03 in lookup_symbol_via_quick_fns ...
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#9 0x00000000008e7153 in lookup_symbol_in_objfile ...
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#10 0x00000000008e73c6 in lookup_symbol_global_or_static_iterator_cb ...
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#11 0x00000000008b99c4 in svr4_iterate_over_objfiles_in_search_order ...
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#12 0x00000000008e754e in lookup_global_or_static_symbol ...
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#13 0x00000000008e75da in lookup_static_symbol ...
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#14 0x00000000008e632c in lookup_symbol_aux ...
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#15 0x00000000008e5a7a in lookup_symbol_in_language ...
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#16 0x00000000008e5b30 in lookup_symbol ...
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#17 0x00000000008f2a4a in gdb_get_datatype ...
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#18 0x00000000008f22c0 in gdb_command_funnel_1 ...
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#19 0x00000000008f2003 in gdb_command_funnel ...
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#20 0x00000000005b7f02 in gdb_interface ...
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#21 0x00000000005f8a9f in datatype_info ...
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#22 0x0000000000599947 in cpu_map_size ...
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#23 0x00000000005a975d in get_cpus_online ...
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#24 0x0000000000637a8b in diskdump_get_prstatus_percpu ...
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#25 0x000000000062f0e4 in get_netdump_regs_x86_64 ...
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#26 0x000000000059fe68 in back_trace ...
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#27 0x00000000005ab1cb in cmd_bt ...
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For the stacktrace of "dis -rl", it calls dw2_expand_all_symtabs() to expand
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all symtable of the objfile, or "*.ko.debug" in our case. However for
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the stacktrace of "bt", it doesn't expand all, but only a subset of symtable
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which is enough to find a symbol by dw2_lookup_symbol(). As a result, the
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objfile->compunit_symtabs, which is the head of a single linked list of
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struct compunit_symtab, is not NULL but didn't contain all symtables. It
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will not be reinitialized in gdb_get_line_number() by "dis -rl" because
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!objfile_has_full_symbols(objfile) check will fail, so it cannot display
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the proper code line number data.
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Since objfile_has_full_symbols(objfile) check cannot ensure all symbols
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been expanded, this patch add a new member as a flag for struct objfile
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to record if all symbols have been expanded. The flag will be set only ofter
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expand_all_symtabs been called.
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Signed-off-by: Tao Liu <ltao@redhat.com>
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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---
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gdb-10.2.patch | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 50 insertions(+)
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diff --git a/gdb-10.2.patch b/gdb-10.2.patch
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index d81030d946e8..2f7d585105aa 100644
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--- a/gdb-10.2.patch
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+++ b/gdb-10.2.patch
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@@ -3187,3 +3187,53 @@ exit 0
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result = stringtab + symbol_entry->_n._n_n._n_offset;
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}
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else
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+--- gdb-10.2/gdb/objfiles.h.orig
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++++ gdb-10.2/gdb/objfiles.h
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+@@ -712,6 +712,8 @@ struct objfile
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+ next time. If an objfile does not have the symbols, it will
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+ never have them. */
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+ bool skip_jit_symbol_lookup = false;
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++
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++ bool all_symtabs_expanded = false;
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+ };
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+
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+ /* A deleter for objfile. */
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+--- gdb-10.2/gdb/symfile.c.orig
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++++ gdb-10.2/gdb/symfile.c
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+@@ -1133,8 +1133,10 @@ symbol_file_add_with_addrs (bfd *abfd, const char *name,
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+ printf_filtered (_("Expanding full symbols from %ps...\n"),
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+ styled_string (file_name_style.style (), name));
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+
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+- if (objfile->sf)
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++ if (objfile->sf) {
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+ objfile->sf->qf->expand_all_symtabs (objfile);
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++ objfile->all_symtabs_expanded = true;
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++ }
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+ }
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+
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+ /* Note that we only print a message if we have no symbols and have
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+--- gdb-10.2/gdb/symtab.c.orig
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++++ gdb-10.2/gdb/symtab.c
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+@@ -7097,8 +7097,9 @@ gdb_get_line_number(struct gnu_request *req)
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+ */
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+ if (req->lm) {
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+ objfile = req->lm->loaded_objfile;
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+- if (!objfile_has_full_symbols(objfile) && objfile->sf) {
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++ if (!objfile->all_symtabs_expanded && objfile->sf) {
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+ objfile->sf->qf->expand_all_symtabs(objfile);
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++ objfile->all_symtabs_expanded = true;
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+ sal = find_pc_line(pc, 0);
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+ }
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+ }
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+@@ -7761,8 +7765,10 @@ iterate_datatypes (struct gnu_request *req)
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+ {
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+ for (objfile *objfile : current_program_space->objfiles ())
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+ {
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+- if (objfile->sf)
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++ if (objfile->sf) {
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+ objfile->sf->qf->expand_all_symtabs(objfile);
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++ objfile->all_symtabs_expanded = true;
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++ }
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+
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+ for (compunit_symtab *cust : objfile->compunits ())
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+ {
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--
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2.41.0
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