Re: [patch] Fix i386 memory-by-register access on amd64

Jan Kratochvil
2009-07-13T20:20:49Z

On Mon, 13 Jul 2009 19:08:09 +0200, Ulrich Weigand wrote:
> I've looked at a couple of ptrace implementations in the Linux kernel, and
> it seems this fix should be correct on all bi-arch Linux platforms.

Extended now the kernel ptrace testcase / tested besides x86_64 now also s390x
and ppc64:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/highmem-debugger.c?cvsroot=systemtap
http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/highmem-debuggee.c?cvsroot=systemtap

> > 2009-07-08 Jan Kratochvil <jan.kratochvil@redhat.com>
> >
> > Fix memory access from signed 32bit inferior registers on 64bit GDB.
> > * inf-ptrace.c (inf_ptrace_xfer_partial <TARGET_OBJECT_MEMORY>): New
> > variable addr_bit. Mask OFFSET by the ADDR_BIT width.
> > * linux-nat.c (linux_xfer_partial <TARGET_OBJECT_MEMORY>): Likewise.
> >
> > 2009-07-08 Jan Kratochvil <jan.kratochvil@redhat.com>
> >
> > * gdb.arch/amd64-i386-address.exp, gdb.arch/amd64-i386-address.S: New.
>
> The linux-nat.c change and the test case are OK.

Checked-in:
http://sourceware.org/ml/gdb-cvs/2009-07/msg00102.html

Thanks,
Jan

--- src/gdb/ChangeLog 2009/07/13 04:56:12 1.10713
+++ src/gdb/ChangeLog 2009/07/13 20:16:46 1.10714
@@ -1,3 +1,9 @@
+2009-07-13 Jan Kratochvil <jan.kratochvil@redhat.com>
+
+ Fix memory access from signed 32bit inferior registers on 64bit GDB.
+ * linux-nat.c (linux_xfer_partial <TARGET_OBJECT_MEMORY>): New variable
+ addr_bit. Mask OFFSET by the ADDR_BIT width.
+
2009-07-13 Anthony Green <green@moxielogic.com>

* moxie-tdep.c (moxie_gdbarch_init): Call
--- src/gdb/linux-nat.c 2009/07/02 21:57:27 1.144
+++ src/gdb/linux-nat.c 2009/07/13 20:16:47 1.145
@@ -4260,6 +4260,20 @@
return linux_nat_xfer_osdata (ops, object, annex, readbuf, writebuf,
offset, len);

+ /* GDB calculates all the addresses in possibly larget width of the address.
+ Address width needs to be masked before its final use - either by
+ linux_proc_xfer_partial or inf_ptrace_xfer_partial.
+
+ Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
+
+ if (object == TARGET_OBJECT_MEMORY)
+ {
+ int addr_bit = gdbarch_addr_bit (target_gdbarch);
+
+ if (addr_bit < (sizeof (ULONGEST) * HOST_CHAR_BIT))
+ offset &= ((ULONGEST) 1 << addr_bit) - 1;
+ }
+
xfer = linux_proc_xfer_partial (ops, object, annex, readbuf, writebuf,
offset, len);
if (xfer != 0)
--- src/gdb/testsuite/ChangeLog 2009/07/13 19:24:17 1.1925
+++ src/gdb/testsuite/ChangeLog 2009/07/13 20:16:47 1.1926
@@ -1,5 +1,9 @@
2009-07-13 Jan Kratochvil <jan.kratochvil@redhat.com>

+ * gdb.arch/amd64-i386-address.exp, gdb.arch/amd64-i386-address.S: New.
+
+2009-07-13 Jan Kratochvil <jan.kratochvil@redhat.com>
+
Fix gdb.base/macscp.exp when using custom inputrc.
* gdb.base/completion.exp: Remove env(INPUTRC) set and restore.
* gdb.base/readline.exp: Remove env(INPUTRC) set and restore. Remove
--- src/gdb/testsuite/gdb.arch/amd64-i386-address.S
+++ src/gdb/testsuite/gdb.arch/amd64-i386-address.S 2009-07-13 20:17:35.179465000 +0000
@@ -0,0 +1,24 @@
+/* Copyright 2009 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ This file is part of the gdb testsuite. */
+
+_start: .globl _start
+ movl $0xdeadf00d, %eax
+ pushl %eax
+ movl %esp, %ebx
+ int3
+ nop
+ nop
--- src/gdb/testsuite/gdb.arch/amd64-i386-address.exp
+++ src/gdb/testsuite/gdb.arch/amd64-i386-address.exp 2009-07-13 20:17:36.993238000 +0000
@@ -0,0 +1,43 @@
+# Copyright 2009 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite.
+
+# Test UNsigned extension of the 32-bit inferior address on a 64-bit host.
+# On native 32-bit host the test always PASSed.
+
+if {![istarget "x86_64-*-*"] && ![istarget "i?86-*-*"]} then {
+ verbose "Skipping amd64->i386 adress test."
+ return
+}
+
+if [prepare_for_testing amd64-i386-address.exp amd64-i386-address amd64-i386-address.S [list debug "additional_flags=-m32 -nostdlib"]] {
+ return -1
+}
+
+gdb_run_cmd
+
+set test "trap stop"
+gdb_test_multiple "" $test {
+ -re "Program received signal SIGTRAP,.*_start .*$gdb_prompt $" {
+ pass $test
+ }
+}
+
+gdb_test "x/wx \$esp" "0x\[0-9a-f\]*:\t0xdeadf00d"
+
+# Failure case would be:
+# 0xff8d7f00: Cannot access memory at address 0xff8d7f00
+gdb_test "x/wx \$ebx" "0x\[0-9a-f\]*:\t0xdeadf00d"