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

[Jan Kratochvil <jan.kratochvil@redhat.com>]

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"