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Joel Brobecker e8af5d7a5c Always consider infcall breakpoints as non-permanent. 
A recent change...

    commit 1a853c5224
    Date:   Wed Nov 12 10:10:49 2014 +0000
    Subject: make "permanent breakpoints" per location and disableable

... broke function calls on sparc-elf when running over QEMU. Any
function call should demonstrate the problem.

For instance, seen from the debugger:

    (gdb) call pn(1234)
    [Inferior 1 (Remote target) exited normally]
    The program being debugged exited while in a function called from GDB.
    Evaluation of the expression containing the function

And seen from QEMU:

    qemu: fatal: Trap 0x02 while interrupts disabled, Error state
    [register dump removed]

What happens in this case is that GDB sets the inferior function call
by not only creating the dummy frame, but also writing a breakpoint
instruction at the return address for our function call. See infcall.c:

        /* Write a legitimate instruction at the point where the infcall
           breakpoint is going to be inserted.  While this instruction
           is never going to be executed, a user investigating the
           memory from GDB would see this instruction instead of random
           uninitialized bytes.  We chose the breakpoint instruction
           as it may look as the most logical one to the user and also
           valgrind 3.7.0 needs it for proper vgdb inferior calls.

           If software breakpoints are unsupported for this target we
           leave the user visible memory content uninitialized.  */

        bp_addr_as_address = bp_addr;
        bp_bytes = gdbarch_breakpoint_from_pc (gdbarch, &bp_addr_as_address,
                                               &bp_size);
        if (bp_bytes != NULL)
          write_memory (bp_addr_as_address, bp_bytes, bp_size);

This instruction triggers a change introduced by the commit above,
where we consider bp locations as being permanent breakpoints
if there is already a breakpoint instruction at that address:

        +  if (bp_loc_is_permanent (loc))
        +    {
        +      loc->inserted = 1;
        +      loc->permanent = 1;
        +    }

As a result, when resuming the program's execution for the inferior
function call, GDB decides that it does not need to insert a breakpoint
at this address, expecting the target to just report a SIGTRAP when
trying to execute that instruction.

But unfortunately for us, at least some versions of QEMU for SPARC
just terminate the execution entirely instead of reporting a breakpoint,
thus producing the behavior reported here.

Although it appears like QEMU might be misbehaving and should therefore
be fixed (to be verified) from the user's point of view, the recent
change does introduce a regression. So this patch tries to mitigate
a bit the damage by handling such infcall breakpoints as special and
making sure that they are never considered permanent, thus restoring
the previous behavior specifically for those breakpoints.

The option of not writing the breakpoint instructions in the first
place was considered, and would probably work also. But the comment
associated to it seems to indicate that there is still reason to
keep it.

gdb/ChangeLog:

        * breakpoint.c (bp_loc_is_permanent): Return 0 if LOC corresponds
        to a bp_call_dummy breakpoint type.

Tested on x86_64-linux. Also testing on sparc-elf/QEMU using
AdaCore's testsuite.
2014-11-23 14:34:52 +04:00
bfd Automatic date update in version.in 2014-11-23 00:00:09 +00:00
binutils Fixes for memory access violations exposed by fuzzinf various binaries. 2014-11-21 21:44:04 +00:00
config Fix --diable-shared --enable-plugins build breakage 2014-08-19 21:59:56 +09:30
cpu or1k: add missing l.msync, l.psync and l.psync instructions. 2014-07-20 20:26:09 +03:00
elfcpp Add tls support to gold aarch64 backend. 2014-09-17 14:24:10 -07:00
etc PR external/{16327,16328}: Remove etc/configure.texi and etc/standards.texi. 2014-06-27 11:33:25 +02:00
gas Calculate ARM arch attribute after relaxation 2014-11-21 11:54:39 +08:00
gdb Always consider infcall breakpoints as non-permanent. 2014-11-23 14:34:52 +04:00
gold Check PC-relative offset overflow in PLT entry 2014-11-21 11:26:56 -08:00
gprof Import updated translations supplied by the Translation Project. 2014-11-03 12:26:48 +00:00
include Merge include/* files from GCC commit 69a2f316d3. 2014-11-21 22:47:32 +00:00
intl
ld Add function and function pointer tests for i386 2014-11-21 08:45:02 -08:00
libdecnumber PR c/59871 c/ * c-typeck.c (build_compound_expr): Warn even for right-hand operand of a comma expression. (emit_side_effect_warnings): Likewise. libdecnumber/ * decNumberLocal.h (UBFROMUS, UBFROMUI): Remove last argument. testsuite/ * gcc.dg/20020220-2.c: Adjust dg-warning message. * gcc.dg/pr59871.c: New test. 2014-05-08 10:18:28 -06:00
libiberty Sync libiberty from GCC 2014-11-17 03:30:13 +01:00
opcodes Add AVX512VBMI instructions 2014-11-17 06:03:41 -08:00
readline readline/search.c: Remove useless parameter '0' for rl_message() 2014-09-22 09:52:06 -04:00
sim sim/ppc/*: Change immediatly to immediately 2014-11-23 07:11:39 +04:00
texinfo
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore
ChangeLog Update config.{guess,sub} from upstream config repo 2014-11-16 20:15:00 +01:00
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in
config.guess Update config.{guess,sub} from upstream config repo 2014-11-16 20:15:00 +01:00
config.rpath
config.sub Update config.{guess,sub} from upstream config repo 2014-11-16 20:15:00 +01:00
configure Add aarch64 to list of targets that support gold. 2014-10-03 14:48:14 -07:00
configure.ac Add aarch64 to list of targets that support gold. 2014-10-03 14:48:14 -07:00
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4
lt~obsolete.m4
ltgcc.m4
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def PR sanitizer/56781 * Makefile.def: Set bootstrap=true; for host fixincludes. * configure.ac: Don't bootstrap host fixincludes unless --with-build-config=bootstrap-{a,ub}san. * Makefile.in: Regenerated. * configure: Regenerated. 2014-05-08 10:18:30 -06:00
Makefile.in PR sanitizer/56781 * Makefile.def: Set bootstrap=true; for host fixincludes. * configure.ac: Don't bootstrap host fixincludes unless --with-build-config=bootstrap-{a,ub}san. * Makefile.in: Regenerated. * configure: Regenerated. 2014-05-08 10:18:30 -06:00
Makefile.tpl PR bootstrap/58572 * Makefile.tpl (POSTSTAGE1_CXX_EXPORT): Use -isystem instead of -I for libstdc++-v3 includes if $(LEAN). * Makefile.in: Regenerated. 2014-05-08 10:18:29 -06:00
makefile.vms
missing Update from upstream Automake 2014-11-16 13:43:48 +01:00
mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
README
README-maintainer-mode
setup.com
src-release.sh src-release.sh: configure using --target. 2014-10-15 09:50:53 +02:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

README 

		   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.