129 lines
4.9 KiB
Plaintext
129 lines
4.9 KiB
Plaintext
From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
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From: Kevin Buettner <kevinb@redhat.com>
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Date: Tue, 1 Feb 2022 11:32:48 -0700
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Subject: gdb-rhbz2042664-fix-sect_index_data-internal-error
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;; Backport fix which fixes internal error due to libcc_s lacking a
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;; .data section.
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Fix GDB internal error by using text (instead of data) section offset
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Fedora Rawhide is now using gcc-12.0. As part of updating to the
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gcc-12.0 package set, Rawhide is also now using a version of libgcc_s
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which lacks a .data section. This causes gdb to fail in the following
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fashion while debugging a program (such as gdb) which uses libgcc_s:
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(top-gdb) run
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Starting program: rawhide-master/bld/gdb/gdb
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...
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objfiles.h:467: internal-error: sect_index_data not initialized
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A problem internal to GDB has been detected,
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further debugging may prove unreliable.
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...
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I snipped the backtrace from the above output. Instead, here's a
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portion of a backtrace obtained using GDB's backtrace command.
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(Obviously, in order to obtain it, I used a GDB which has been patched
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with this commit.)
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#0 internal_error (
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file=0xc6a508 "gdb/objfiles.h", line=467,
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fmt=0xc6a4e8 "sect_index_data not initialized")
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at gdbsupport/errors.cc:51
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#1 0x00000000005f9651 in objfile::data_section_offset (this=0x4fa48f0)
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at gdb/objfiles.h:467
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#2 0x000000000097c5f8 in relocate_address (address=0x17244, objfile=0x4fa48f0)
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at gdb/stap-probe.c:1333
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#3 0x000000000097c630 in stap_probe::get_relocated_address (this=0xa1a17a0,
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objfile=0x4fa48f0)
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at gdb/stap-probe.c:1341
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#4 0x00000000004d7025 in create_exception_master_breakpoint_probe (
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objfile=0x4fa48f0)
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at gdb/breakpoint.c:3505
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#5 0x00000000004d7426 in create_exception_master_breakpoint ()
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at gdb/breakpoint.c:3575
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#6 0x00000000004efcc1 in breakpoint_re_set ()
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at gdb/breakpoint.c:13407
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#7 0x0000000000956998 in solib_add (pattern=0x0, from_tty=0, readsyms=1)
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at gdb/solib.c:1001
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#8 0x00000000009576a8 in handle_solib_event ()
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at gdb/solib.c:1269
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...
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The function 'relocate_address' in gdb/stap-probe.c attempts to do
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its "relocation" by using objfile->data_section_offset(). That
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method, data_section_offset() is defined as follows in objfiles.h:
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CORE_ADDR data_section_offset () const
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{
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return section_offsets[SECT_OFF_DATA (this)];
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}
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The internal error occurs when the SECT_OFF_DATA macro finds that the
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'sect_index_data' field is -1:
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#define SECT_OFF_DATA(objfile) \
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((objfile->sect_index_data == -1) \
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? (internal_error (__FILE__, __LINE__, \
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_("sect_index_data not initialized")), -1) \
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: objfile->sect_index_data)
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relocate_address() is obtaining the section offset in order to compute
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a relocated address. For some ABIs, such as the System V ABI, the
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section offsets will all be the same. So for those ABIs, it doesn't
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matter which offset is used. However, other ABIs, such as the FDPIC
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ABI, will have different offsets for the various sections. Thus, for
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those ABIs, it is vital that this and other relocation code use the
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correct offset.
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In stap_probe::get_relocated_address, the address to which to add the
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offset (thus forming the relocated address) is obtained via
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this->get_address (); get_address is a getter for m_address in
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probe.h. It's documented/defined as follows (also in probe.h):
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/* The address where the probe is inserted, relative to
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SECT_OFF_TEXT. */
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CORE_ADDR m_address;
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(Thanks to Tom Tromey for this observation.)
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So, based on this, the current use of data_section_offset /
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SECT_OFF_DATA is wrong. This relocation code should have been using
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text_section_offset / SECT_OFF_TEXT all along. That being the
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case, I've adjusted the stap-probe.c relocation code accordingly.
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Searching the sources turned up one other use of data_section_offset,
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in gdb/dtrace-probe.c, so I've updated that code as well. The same
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reasoning presented above applies to this case too.
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Summary:
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* gdb/dtrace-probe.c (dtrace_probe::get_relocated_address):
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Use method text_section_offset instead of data_section_offset.
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* gdb/stap-probe.c (relocate_address): Likewise.
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diff --git a/gdb/dtrace-probe.c b/gdb/dtrace-probe.c
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--- a/gdb/dtrace-probe.c
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+++ b/gdb/dtrace-probe.c
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@@ -684,7 +684,7 @@ dtrace_probe::is_enabled () const
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CORE_ADDR
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dtrace_probe::get_relocated_address (struct objfile *objfile)
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{
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- return this->get_address () + objfile->data_section_offset ();
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+ return this->get_address () + objfile->text_section_offset ();
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}
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/* Implementation of the get_argument_count method. */
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diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
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--- a/gdb/stap-probe.c
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+++ b/gdb/stap-probe.c
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@@ -1330,7 +1330,7 @@ stap_probe::parse_arguments (struct gdbarch *gdbarch)
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static CORE_ADDR
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relocate_address (CORE_ADDR address, struct objfile *objfile)
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{
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- return address + objfile->data_section_offset ();
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+ return address + objfile->text_section_offset ();
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}
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/* Implementation of the get_relocated_address method. */
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