From FEDORA_PATCHES Mon Sep 17 00:00:00 2001

From: Kevin Buettner <kevinb@redhat.com>

Date: Tue, 1 Feb 2022 11:32:48 -0700

Subject: gdb-rhbz2042664-fix-sect_index_data-internal-error

;; Backport fix which fixes internal error due to libcc_s lacking a

;; .data section.

Fix GDB internal error by using text (instead of data) section offset

Fedora Rawhide is now using gcc-12.0.  As part of updating to the

gcc-12.0 package set, Rawhide is also now using a version of libgcc_s

which lacks a .data section.  This causes gdb to fail in the following

fashion while debugging a program (such as gdb) which uses libgcc_s:

    (top-gdb) run

    Starting program: rawhide-master/bld/gdb/gdb

    ...

    objfiles.h:467: internal-error: sect_index_data not initialized

    A problem internal to GDB has been detected,

    further debugging may prove unreliable.

    ...

I snipped the backtrace from the above output.  Instead, here's a

portion of a backtrace obtained using GDB's backtrace command.

(Obviously, in order to obtain it, I used a GDB which has been patched

with this commit.)

    #0  internal_error (

	file=0xc6a508 "gdb/objfiles.h", line=467,

	fmt=0xc6a4e8 "sect_index_data not initialized")

	at gdbsupport/errors.cc:51

    #1  0x00000000005f9651 in objfile::data_section_offset (this=0x4fa48f0)

	at gdb/objfiles.h:467

    #2  0x000000000097c5f8 in relocate_address (address=0x17244, objfile=0x4fa48f0)

	at gdb/stap-probe.c:1333

    #3  0x000000000097c630 in stap_probe::get_relocated_address (this=0xa1a17a0,

	objfile=0x4fa48f0)

	at gdb/stap-probe.c:1341

    #4  0x00000000004d7025 in create_exception_master_breakpoint_probe (

	objfile=0x4fa48f0)

	at gdb/breakpoint.c:3505

    #5  0x00000000004d7426 in create_exception_master_breakpoint ()

	at gdb/breakpoint.c:3575

    #6  0x00000000004efcc1 in breakpoint_re_set ()

	at gdb/breakpoint.c:13407

    #7  0x0000000000956998 in solib_add (pattern=0x0, from_tty=0, readsyms=1)

	at gdb/solib.c:1001

    #8  0x00000000009576a8 in handle_solib_event ()

	at gdb/solib.c:1269

    ...

The function 'relocate_address' in gdb/stap-probe.c attempts to do

its "relocation" by using objfile->data_section_offset().  That

method, data_section_offset() is defined as follows in objfiles.h:

  CORE_ADDR data_section_offset () const

  {

    return section_offsets[SECT_OFF_DATA (this)];

  }

The internal error occurs when the SECT_OFF_DATA macro finds that the

'sect_index_data' field is -1:

    #define SECT_OFF_DATA(objfile) \

	 ((objfile->sect_index_data == -1) \

	  ? (internal_error (__FILE__, __LINE__, \

			     _("sect_index_data not initialized")), -1)	\

	  : objfile->sect_index_data)

relocate_address() is obtaining the section offset in order to compute

a relocated address.  For some ABIs, such as the System V ABI, the

section offsets will all be the same.  So for those ABIs, it doesn't

matter which offset is used.  However, other ABIs, such as the FDPIC

ABI, will have different offsets for the various sections.  Thus, for

those ABIs, it is vital that this and other relocation code use the

correct offset.

In stap_probe::get_relocated_address, the address to which to add the

offset (thus forming the relocated address) is obtained via

this->get_address (); get_address is a getter for m_address in

probe.h.  It's documented/defined as follows (also in probe.h):

  /* The address where the probe is inserted, relative to

     SECT_OFF_TEXT.  */

  CORE_ADDR m_address;

(Thanks to Tom Tromey for this observation.)

So, based on this, the current use of data_section_offset /

SECT_OFF_DATA is wrong.  This relocation code should have been using

text_section_offset / SECT_OFF_TEXT all along.  That being the

case, I've adjusted the stap-probe.c relocation code accordingly.

Searching the sources turned up one other use of data_section_offset,

in gdb/dtrace-probe.c, so I've updated that code as well.  The same

reasoning presented above applies to this case too.

Summary:

	* gdb/dtrace-probe.c (dtrace_probe::get_relocated_address):

	Use method text_section_offset instead of data_section_offset.

	* gdb/stap-probe.c (relocate_address): Likewise.

diff --git a/gdb/dtrace-probe.c b/gdb/dtrace-probe.c

--- a/gdb/dtrace-probe.c

+++ b/gdb/dtrace-probe.c

@@ -684,7 +684,7 @@ dtrace_probe::is_enabled () const

 CORE_ADDR

 dtrace_probe::get_relocated_address (struct objfile *objfile)

 {

-  return this->get_address () + objfile->data_section_offset ();

+  return this->get_address () + objfile->text_section_offset ();

 }

 /* Implementation of the get_argument_count method.  */

diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c

--- a/gdb/stap-probe.c

+++ b/gdb/stap-probe.c

@@ -1330,7 +1330,7 @@ stap_probe::parse_arguments (struct gdbarch *gdbarch)

 static CORE_ADDR

 relocate_address (CORE_ADDR address, struct objfile *objfile)

 {

-  return address + objfile->data_section_offset ();

+  return address + objfile->text_section_offset ();

 }

 /* Implementation of the get_relocated_address method.  */