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Andrew Burgess fb550a919a gdb: terminate upon receipt of SIGFPE
GDB's SIGFPE handling is broken, this is PR gdb/16505 and
PR gdb/17891.

We currently try to use an async event token to process SIGFPE.  So,
when a SIGFPE arrives the signal handler calls
mark_async_signal_handler then returns, effectively ignoring the
signal (for now).

The intention is that later the event loop will see that the async
token associated with SIGFPE has been marked and will call the async
handler, which just throws an error.

The problem is that SIGFPE is not safe to ignore.  Ignoring a
SIGFPE (unless it is generated artificially, e.g. by raise()) is
undefined behaviour, after ignoring the signal on many targets we
return to the instruction that caused the SIGFPE to be raised, which
immediately causes another SIGFPE to be raised, we get stuck in an
infinite loop.  The behaviour is certainly true on x86-64.

To view this behaviour I simply added some dummy code to GDB that
performed an integer divide by zero, compiled this on x86-64
GNU/Linux, ran GDB and saw GDB hang.

In this commit, I propose to remove all special handling of SIGFPE and
instead just let GDB make use of the default SIGFPE action, that is,
to terminate the process.

The only user visible change here should be:

  - If a user sends a SIGFPE to GDB using something like kill,
    previously GDB would just print an error and remain alive, now GDB
    will terminate.  This is inline with what happens if the user
    sends GDB a SIGSEGV from kill though, so I don't see this as an
    issue.

  - If a bug in GDB causes a real SIGFPE, previously the users GDB
    session would hang.  Now the GDB session will terminate.  Again,
    this is inline with what happens if GDB receives a SIGSEGV due to
    an internal bug.

In bug gdb/16505 there is mention that it would be nice if GDB did
more than just terminate when receiving a fatal signal.  I haven't
done that in this commit, but later commits will move in that
direction.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=16505
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17891
2021-08-11 12:35:14 +01:00
bfd PR28163, Segment fault in function rl78_special_reloc 2021-08-11 15:06:20 +09:30
binutils x86: have non-PE/COFF BEOS be recognized as ELF 2021-08-11 08:29:39 +02:00
config
contrib
cpu
elfcpp
etc texi2pod.pl: add no-op --no-split option support [PR28144] 2021-07-28 11:39:40 +01:00
gas Add a -mno-dollar-line-separator command line option to the AVR assembler. 2021-08-11 10:03:19 +01:00
gdb gdb: terminate upon receipt of SIGFPE 2021-08-11 12:35:14 +01:00
gdbserver Fix the Windows build 2021-07-26 07:34:37 -06:00
gdbsupport gdbsupport: add debug assertions in gdb::optional::get 2021-08-03 08:50:56 -04:00
gnulib
gold Updated Serbian and Russian translations for various sub-directories 2021-08-10 16:40:37 +01:00
gprof
include PATCH [6/10] arm: Add -march=armv8.1-m.main+pacbti flag 2021-07-26 14:18:24 +02:00
intl
ld PR28198, Support # as linker script comment marker 2021-08-11 19:46:43 +09:30
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libdecnumber
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opcodes Updated Serbian and Russian translations for various sub-directories 2021-08-10 16:40:37 +01:00
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		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.