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Re: Fix ARM stepping over Thumb-mode "bx pc" or "blx pc"
On Sat, 11 Aug 2012, Yao Qi wrote:
> I don't have any preference on clearing either the last one bit in
> address or the last two bits. Looks like two ways coexist in arm-tdep.c
> nowadays. As 'pc_val' is set by MAKE_THUMB_ADDR at the beginning, it is
> better to revert its change by using UNMAKE_THUMB_ADDR (which only
> clears the last one bit of address).
This version uses UNMAKE_THUMB_ADDR as requested. Tested with no
regressions with cross to arm-none-linux-gnueabi.
2012-08-13 Joseph Myers <joseph@codesourcery.com>
* arm-tdep.c (thumb_get_next_pc_raw): Mask off low bits for bx pc
and blx pc.
testsuite:
2012-08-13 Joseph Myers <joseph@codesourcery.com>
* gdb.arch/thumb-bx-pc.S: New file.
* gdb.arch/thumb-bx-pc.exp: New file.
Index: gdb/arm-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.c,v
retrieving revision 1.365
diff -u -r1.365 arm-tdep.c
--- gdb/arm-tdep.c 25 Jun 2012 12:32:45 -0000 1.365
+++ gdb/arm-tdep.c 13 Aug 2012 13:56:04 -0000
@@ -4541,7 +4541,7 @@
else if ((inst1 & 0xff00) == 0x4700) /* bx REG, blx REG */
{
if (bits (inst1, 3, 6) == 0x0f)
- nextpc = pc_val;
+ nextpc = UNMAKE_THUMB_ADDR (pc_val);
else
nextpc = get_frame_register_unsigned (frame, bits (inst1, 3, 6));
}
Index: gdb/testsuite/gdb.arch/thumb-bx-pc.S
===================================================================
RCS file: gdb/testsuite/gdb.arch/thumb-bx-pc.S
diff -N gdb/testsuite/gdb.arch/thumb-bx-pc.S
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.arch/thumb-bx-pc.S 13 Aug 2012 13:56:05 -0000
@@ -0,0 +1,34 @@
+/* Test PC adjustment from Thumb-mode "bx pc" instruction.
+
+ Copyright 2012 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ 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/>. */
+
+ .syntax unified
+ .thumb
+ .text
+ .p2align 2
+ .global main
+ .thumb
+ .thumb_func
+ .type main, %function
+main:
+ bx pc
+ nop
+.code 32
+ mov r0, #0
+ bx lr
+ .size main, .-main
Index: gdb/testsuite/gdb.arch/thumb-bx-pc.exp
===================================================================
RCS file: gdb/testsuite/gdb.arch/thumb-bx-pc.exp
diff -N gdb/testsuite/gdb.arch/thumb-bx-pc.exp
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.arch/thumb-bx-pc.exp 13 Aug 2012 13:56:05 -0000
@@ -0,0 +1,41 @@
+# Copyright 2012 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/>.
+
+# Test PC adjustment from Thumb-mode "bx pc" instruction.
+
+if {![istarget arm*-*]} then {
+ verbose "Skipping ARM tests."
+ return
+}
+
+set testfile "thumb-bx-pc"
+set srcfile ${testfile}.S
+set opts {}
+
+if [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} $opts] {
+ untested ${testfile}.exp
+ return -1
+}
+
+if ![runto_main] then {
+ untested ${testfile}.exp
+ return -1
+}
+
+gdb_test "stepi" "0x\[0-9a-fA-F\]+ in main \\(\\)" "stepi for bx pc"
+
+gdb_test "x /i \$pc" \
+ "0x\[0-9a-fA-F\]+ <main\\+4>:\[ \t\]+mov\[ \t\]+r0,\[ \t\]+#0.*" \
+ "stepi reached correct instruction"
--
Joseph S. Myers
joseph@codesourcery.com