Go to file
Tom de Vries 545e49f5ee [gdb/tdep] Fix inferior plt calls in PIE for i386
Consider test-case test.c:
...
int main (void) {
  void *p = malloc (10);
  return 0;
}
...

When compiled to a non-PIE exec:
...
$ gcc -m32 test.c
...
the call sequence looks like:
...
 8048447:       83 ec 0c                sub    $0xc,%esp
 804844a:       6a 0a                   push   $0xa
 804844c:       e8 bf fe ff ff          call   8048310 <malloc@plt>
...
which calls to:
...
08048310 <malloc@plt>:
 8048310:       ff 25 0c a0 04 08       jmp    *0x804a00c
 8048316:       68 00 00 00 00          push   $0x0
 804831b:       e9 e0 ff ff ff          jmp    8048300 <.plt>
...
where the first insn at 0x8048310 initially jumps to the following address
0x8048316, read from the .got.plt @ 0x804a00c:
...
 804a000 0c9f0408 00000000 00000000 16830408  ................
 804a010 26830408                             &...
...

Likewise, when compiled as a PIE:
...
$ gcc -m32 -fPIE -pie test.c
...
we have this call sequence (with %ebx setup to point to the .got.plt):
...
0000055d <main>:
 579:   83 ec 0c                sub    $0xc,%esp
 57c:   6a 0a                   push   $0xa
 57e:   89 c3                   mov    %eax,%ebx
 580:   e8 6b fe ff ff          call   3f0 <malloc@plt>
...
which calls to:
...
000003f0 <malloc@plt>:
 3f0:   ff a3 0c 00 00 00       jmp    *0xc(%ebx)
 3f6:   68 00 00 00 00          push   $0x0
 3fb:   e9 e0 ff ff ff          jmp    3e0 <.plt>
...
where the insn at 0x3f0 initially jumps to following address 0x3f6, read from
the .got.plt at offset 0xc:
...
 2000 f41e0000 00000000 00000000 f6030000  ................
 2010 06040000                             ....
...

When instead doing an inferior call to malloc (with nosharedlib to force
malloc to resolve to malloc@plt rather than the functions in ld.so or libc.so)
with the non-PIE exec, we have the expected:
...
$ gdb -q -batch a.out -ex start -ex nosharedlib -ex "p /x (void *)malloc (10)"
Temporary breakpoint 1 at 0x8048444

Temporary breakpoint 1, 0x08048444 in main ()
$1 = 0x804b160
...

But with the PIE exec, we run into:
...
$ gdb -q -batch a.out -ex start -ex nosharedlib -ex "p /x (void *)malloc (10)"
Temporary breakpoint 1 at 0x56c

Temporary breakpoint 1, 0x5655556c in main ()

Program received signal SIGSEGV, Segmentation fault.
0x565553f0 in malloc@plt ()
...

The segfault happens because:
- the inferior call mechanism doesn't setup %ebx
- %ebx instead is 0
- the jump to "*0xc(%ebx)" reads from memory at 0xc

Fix this by setting up %ebx properly in i386_thiscall_push_dummy_call.

Fixes this failure with target board unix/-m32/-pie/-fPIE reported in
PR28467:
...
FAIL: gdb.base/nodebug.exp: p/c (int) array_index("abcdef",2)
...

Tested on x86_64-linux, with target board unix/-m32 and unix/-m32/-fPIE/-pie.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28467
2021-12-07 08:07:18 +01:00
bfd Automatic date update in version.in 2021-12-07 00:00:10 +00:00
binutils Re: Add support for AArch64 EFI (efi-*-aarch64) 2021-12-07 16:10:27 +10:30
config Deprecate a.out support for NetBSD targets. 2021-08-11 13:17:54 +01:00
contrib
cpu Re: opcodes: constify & local meps macros 2021-07-05 21:40:49 +09:30
elfcpp arm: add armv9-a architecture to -march 2021-11-01 10:51:03 +00:00
etc etc: switch to automake 2021-09-09 23:30:12 -04:00
gas aarch64: Update gas/NEWS for recent changes 2021-12-02 15:00:57 +00:00
gdb [gdb/tdep] Fix inferior plt calls in PIE for i386 2021-12-07 08:07:18 +01:00
gdbserver [gdb/tdep] Fix avx512 -m32 support in gdbserver 2021-12-02 18:20:13 +01:00
gdbsupport gdbsupport: fix memory leak in create_file_handler when re-using file handler 2021-12-04 21:42:43 -05:00
gnulib gnulib: import various network functions 2021-09-08 17:48:09 -04:00
gold [GOLD] PowerPC64 inline plt sequences 2021-12-06 22:16:46 +10:30
gprof gprof: enable silent build rules 2021-11-29 20:28:29 -05:00
include sim: reorder header includes 2021-12-04 22:09:26 -05:00
intl Regenerate a couple of files 2021-11-15 12:20:12 +10:30
ld Error on ld output file name matching input file name 2021-12-07 16:10:22 +10:30
libbacktrace sync libbacktrace from gcc 2021-11-14 18:07:50 +10:30
libctf libctf: workaround automake bug with conditional info pages 2021-12-02 23:26:18 -05:00
libdecnumber
libiberty Deprecate a.out support for NetBSD targets. 2021-08-11 13:17:54 +01:00
opcodes aarch64: Fix uninitialised memory 2021-12-03 11:57:17 +00:00
readline Update config.sub and config.guess for MIPS R3 and R5 ISA support 2021-05-24 18:11:49 +02:00
sim sim: include ansidecl.h when needed 2021-12-04 22:10:04 -05:00
texinfo
zlib zlib: enable silent build rules 2021-11-29 20:28:29 -05:00
.cvsignore
.gitattributes
.gitignore
ar-lib
ChangeLog Document "memory-tag-violations". 2021-10-29 13:31:37 +03:00
compile
config-ml.in
config.guess Update config.sub and config.guess for MIPS R3 and R5 ISA support 2021-05-24 18:11:49 +02:00
config.rpath
config.sub Update config.sub and config.guess for MIPS R3 and R5 ISA support 2021-05-24 18:11:49 +02:00
configure top-level configure: setup target_configdirs based on repository 2021-09-28 12:21:21 +01:00
configure.ac top-level configure: setup target_configdirs based on repository 2021-09-28 12:21:21 +01:00
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
depcomp
djunpack.bat
install-sh
libtool.m4 libtool.m4: fix nm BSD flag detection 2021-09-27 20:31:23 +01:00
lt~obsolete.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS MAINTAINERS: Update path to readline config.{sub,guess} files 2021-05-24 18:11:49 +02:00
Makefile.def Import Makefile.def from gcc 2021-11-12 19:02:12 +10:30
Makefile.in Sync Makefile.tpl with GCC 2021-11-13 09:04:03 -08:00
Makefile.tpl Sync Makefile.tpl with GCC 2021-11-13 09:04:03 -08:00
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
multilib.am
README
README-maintainer-mode
setup.com
src-release.sh src-release.sh: add libbacktrace to GDB_SUPPORT_DIRS 2021-09-28 12:21:21 +01:00
symlink-tree
test-driver
ylwrap

		   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.