Re: [patch/RFA] multiarch INSTRUCTION_NULLIFIED

Randolph Chung
2004-12-04T00:00:51Z

I've committed the following.

randolph

2004-12-03 Randolph Chung <tausq@debian.org>

* gdbarch.sh (instruction_nullified): Delete.
* gdbarch.c: Regenerate.
* gdbarch.h: Regenerate.
* hppa-tdep.c (hppa_target_read_pc): Adjust pc if instruction is
nullified.
(hppa_unwind_pc): Likewise.
(hppa_instruction_nullified): Delete.
(hppa_gdbarch_init): Don't set instruction_nullified method.
* infrun.c (infwait_states): Remove infwait_nullified_state.
(handle_inferior_event): Remove handling of infwait_nullified_state.
Remove handling of nullified instructions.

testsuite/

* gdb.arch/pa-nullify.exp: New file.
* gdb.arch/pa-nullify.s: New file.

Index: gdbarch.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.c,v
retrieving revision 1.315
diff -u -p -r1.315 gdbarch.c
--- gdbarch.c 23 Nov 2004 21:05:18 -0000 1.315
+++ gdbarch.c 3 Dec 2004 23:57:54 -0000
@@ -212,7 +212,6 @@ struct gdbarch
gdbarch_smash_text_address_ftype *smash_text_address;
gdbarch_software_single_step_ftype *software_single_step;
gdbarch_single_step_through_delay_ftype *single_step_through_delay;
- gdbarch_instruction_nullified_ftype *instruction_nullified;
gdbarch_print_insn_ftype *print_insn;
gdbarch_skip_trampoline_code_ftype *skip_trampoline_code;
gdbarch_skip_solib_resolver_ftype *skip_solib_resolver;
@@ -339,7 +338,6 @@ struct gdbarch startup_gdbarch =
0, /* smash_text_address */
0, /* software_single_step */
0, /* single_step_through_delay */
- generic_instruction_nullified, /* instruction_nullified */
0, /* print_insn */
0, /* skip_trampoline_code */
generic_skip_solib_resolver, /* skip_solib_resolver */
@@ -437,7 +435,6 @@ gdbarch_alloc (const struct gdbarch_info
current_gdbarch->convert_from_func_ptr_addr = convert_from_func_ptr_addr_identity;
current_gdbarch->addr_bits_remove = core_addr_identity;
current_gdbarch->smash_text_address = core_addr_identity;
- current_gdbarch->instruction_nullified = generic_instruction_nullified;
current_gdbarch->skip_trampoline_code = generic_skip_trampoline_code;
current_gdbarch->skip_solib_resolver = generic_skip_solib_resolver;
current_gdbarch->in_solib_return_trampoline = generic_in_solib_return_trampoline;
@@ -594,7 +591,6 @@ verify_gdbarch (struct gdbarch *current_
/* Skip verify of smash_text_address, invalid_p == 0 */
/* Skip verify of software_single_step, has predicate */
/* Skip verify of single_step_through_delay, has predicate */
- /* Skip verify of instruction_nullified, invalid_p == 0 */
if (current_gdbarch->print_insn == 0)
fprintf_unfiltered (log, "\n\tprint_insn");
/* Skip verify of skip_trampoline_code, invalid_p == 0 */
@@ -1199,9 +1195,6 @@ gdbarch_dump (struct gdbarch *current_gd
fprintf_unfiltered (file,
"gdbarch_dump: inner_than = <0x%lx>\n",
(long) current_gdbarch->inner_than);
- fprintf_unfiltered (file,
- "gdbarch_dump: instruction_nullified = <0x%lx>\n",
- (long) current_gdbarch->instruction_nullified);
#ifdef TARGET_INT_BIT
fprintf_unfiltered (file,
"gdbarch_dump: TARGET_INT_BIT # %s\n",
@@ -3373,23 +3366,6 @@ set_gdbarch_single_step_through_delay (s
}

int
-gdbarch_instruction_nullified (struct gdbarch *gdbarch, struct regcache *regcache)
-{
- gdb_assert (gdbarch != NULL);
- gdb_assert (gdbarch->instruction_nullified != NULL);
- if (gdbarch_debug >= 2)
- fprintf_unfiltered (gdb_stdlog, "gdbarch_instruction_nullified called\n");
- return gdbarch->instruction_nullified (gdbarch, regcache);
-}
-
-void
-set_gdbarch_instruction_nullified (struct gdbarch *gdbarch,
- gdbarch_instruction_nullified_ftype instruction_nullified)
-{
- gdbarch->instruction_nullified = instruction_nullified;
-}
-
-int
gdbarch_print_insn (struct gdbarch *gdbarch, bfd_vma vma, struct disassemble_info *info)
{
gdb_assert (gdbarch != NULL);
Index: gdbarch.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.h,v
retrieving revision 1.276
diff -u -p -r1.276 gdbarch.h
--- gdbarch.h 23 Nov 2004 21:05:19 -0000 1.276
+++ gdbarch.h 3 Dec 2004 23:57:55 -0000
@@ -1227,16 +1227,6 @@ typedef int (gdbarch_single_step_through
extern int gdbarch_single_step_through_delay (struct gdbarch *gdbarch, struct frame_info *frame);
extern void set_gdbarch_single_step_through_delay (struct gdbarch *gdbarch, gdbarch_single_step_through_delay_ftype *single_step_through_delay);

-/* On some systems, the PC may be left pointing at an instruction that won't
- actually be executed. This is usually indicated by a bit in the PSW. If
- we find ourselves in such a state, then we step the target beyond the
- nullified instruction before returning control to gdb.
- Return non-zero if the processor is about to execute a nullified instruction. */
-
-typedef int (gdbarch_instruction_nullified_ftype) (struct gdbarch *gdbarch, struct regcache *regcache);
-extern int gdbarch_instruction_nullified (struct gdbarch *gdbarch, struct regcache *regcache);
-extern void set_gdbarch_instruction_nullified (struct gdbarch *gdbarch, gdbarch_instruction_nullified_ftype *instruction_nullified);
-
/* FIXME: cagney/2003-08-28: Need to find a better way of selecting the
disassembler. Perhaps objdump can handle it? */

Index: gdbarch.sh
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.sh,v
retrieving revision 1.351
diff -u -p -r1.351 gdbarch.sh
--- gdbarch.sh 23 Nov 2004 21:05:20 -0000 1.351
+++ gdbarch.sh 3 Dec 2004 23:57:55 -0000
@@ -614,12 +614,6 @@ F:=:void:software_single_step:enum targe
# Return non-zero if the processor is executing a delay slot and a
# further single-step is needed before the instruction finishes.
M::int:single_step_through_delay:struct frame_info *frame:frame
-# On some systems, the PC may be left pointing at an instruction that won't
-# actually be executed. This is usually indicated by a bit in the PSW. If
-# we find ourselves in such a state, then we step the target beyond the
-# nullified instruction before returning control to gdb.
-# Return non-zero if the processor is about to execute a nullified instruction.
-m::int:instruction_nullified:struct regcache *regcache:regcache::generic_instruction_nullified::0
# FIXME: cagney/2003-08-28: Need to find a better way of selecting the
# disassembler. Perhaps objdump can handle it?
f:TARGET_PRINT_INSN:int:print_insn:bfd_vma vma, struct disassemble_info *info:vma, info::0:
Index: hppa-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/hppa-tdep.c,v
retrieving revision 1.183
diff -u -p -r1.183 hppa-tdep.c
--- hppa-tdep.c 1 Dec 2004 06:54:56 -0000 1.183
+++ hppa-tdep.c 3 Dec 2004 23:57:56 -0000
@@ -1042,6 +1042,8 @@ static CORE_ADDR
hppa_target_read_pc (ptid_t ptid)
{
int flags = read_register_pid (HPPA_FLAGS_REGNUM, ptid);
+ ULONGEST ipsw = read_register_pid (HPPA_IPSW_REGNUM, ptid);
+ CORE_ADDR pc;

/* The following test does not belong here. It is OS-specific, and belongs
in native code. */
@@ -1049,7 +1051,17 @@ hppa_target_read_pc (ptid_t ptid)
if (flags & 2)
return read_register_pid (31, ptid) & ~0x3;

- return read_register_pid (HPPA_PCOQ_HEAD_REGNUM, ptid) & ~0x3;
+ pc = read_register_pid (HPPA_PCOQ_HEAD_REGNUM, ptid) & ~0x3;
+
+ /* If the current instruction is nullified, then we are effectively
+ still executing the previous instruction. Pretend we are still
+ there. This is needed when single stepping; if the nullified instruction
+ is on a different line, we don't want gdb to think we've stepped onto
+ that line. */
+ if (ipsw & 0x00200000)
+ pc -= 4;
+
+ return pc;
}

/* Write out the PC. If currently in a syscall, then also write the new
@@ -2185,7 +2197,21 @@ hppa_unwind_dummy_id (struct gdbarch *gd
static CORE_ADDR
hppa_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
- return frame_unwind_register_signed (next_frame, HPPA_PCOQ_HEAD_REGNUM) & ~3;
+ ULONGEST ipsw;
+ CORE_ADDR pc;
+
+ ipsw = frame_unwind_register_signed (next_frame, HPPA_IPSW_REGNUM);
+ pc = frame_unwind_register_signed (next_frame, HPPA_PCOQ_HEAD_REGNUM) & ~3;
+
+ /* If the current instruction is nullified, then we are effectively
+ still executing the previous instruction. Pretend we are still
+ there. This is needed when single stepping; if the nullified instruction
+ is on a different line, we don't want gdb to think we've stepped onto
+ that line. */
+ if (ipsw & 0x00200000)
+ pc -= 4;
+
+ return pc;
}

/* Instead of this nasty cast, add a method pvoid() that prints out a
@@ -2291,22 +2317,6 @@ hppa_pc_requires_run_before_use (CORE_AD
return (!target_has_stack && (pc & 0xFF000000));
}

-static int
-hppa_instruction_nullified (struct gdbarch *gdbarch, struct regcache *regcache)
-{
- ULONGEST tmp, ipsw, flags;
-
- regcache_cooked_read (regcache, HPPA_IPSW_REGNUM, &tmp);
- ipsw = extract_unsigned_integer (&tmp,
- register_size (gdbarch, HPPA_IPSW_REGNUM));
-
- regcache_cooked_read (regcache, HPPA_FLAGS_REGNUM, &tmp);
- flags = extract_unsigned_integer (&tmp,
- register_size (gdbarch, HPPA_FLAGS_REGNUM));
-
- return ((ipsw & 0x00200000) && !(flags & 0x2));
-}
-
/* Return the GDB type object for the "standard" data type of data
in register N. */

@@ -2573,7 +2583,6 @@ hppa_gdbarch_init (struct gdbarch_info i

set_gdbarch_breakpoint_from_pc (gdbarch, hppa_breakpoint_from_pc);
set_gdbarch_pseudo_register_read (gdbarch, hppa_pseudo_register_read);
- set_gdbarch_instruction_nullified (gdbarch, hppa_instruction_nullified);

/* Frame unwind methods. */
set_gdbarch_unwind_dummy_id (gdbarch, hppa_unwind_dummy_id);
Index: infrun.c
===================================================================
RCS file: /cvs/src/src/gdb/infrun.c,v
retrieving revision 1.183
diff -u -p -r1.183 infrun.c
--- infrun.c 23 Nov 2004 21:05:23 -0000 1.183
+++ infrun.c 3 Dec 2004 23:57:58 -0000
@@ -870,7 +870,6 @@ enum infwait_states
{
infwait_normal_state,
infwait_thread_hop_state,
- infwait_nullified_state,
infwait_nonstep_watch_state
};

@@ -1263,12 +1262,6 @@ handle_inferior_event (struct execution_
stepped_after_stopped_by_watchpoint = 0;
break;

- case infwait_nullified_state:
- if (debug_infrun)
- printf_unfiltered ("infrun: infwait_nullified_state\n");
- stepped_after_stopped_by_watchpoint = 0;
- break;
-
case infwait_nonstep_watch_state:
if (debug_infrun)
printf_unfiltered ("infrun: infwait_nonstep_watch_state\n");
@@ -1730,30 +1723,6 @@ handle_inferior_event (struct execution_
singlestep_breakpoints_inserted_p = 0;
}

- /* If PC is pointing at a nullified instruction, then step beyond
- it before deciding what to do. This is required when we are stepping
- through a function where the last instruction is a branch with a
- nullified instruction in the delay slot that belongs to the next
- line (which may be in a different function altogether). */
-
- if (gdbarch_instruction_nullified (current_gdbarch, current_regcache))
- {
- if (debug_infrun)
- printf_unfiltered ("infrun: instruction nullified\n");
- registers_changed ();
- target_resume (ecs->ptid, 1, TARGET_SIGNAL_0);
-
- /* We may have received a signal that we want to pass to
- the inferior; therefore, we must not clobber the waitstatus
- in WS. */
-
- ecs->infwait_state = infwait_nullified_state;
- ecs->waiton_ptid = ecs->ptid;
- ecs->wp = &(ecs->tmpstatus);
- prepare_to_wait (ecs);
- return;
- }
-
/* It may not be necessary to disable the watchpoint to stop over
it. For example, the PA can (with some kernel cooperation)
single step over a watchpoint without disabling the watchpoint. */
Index: testsuite/gdb.arch/pa-nullify.exp
===================================================================
RCS file: testsuite/gdb.arch/pa-nullify.exp
diff -N testsuite/gdb.arch/pa-nullify.exp
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.arch/pa-nullify.exp 3 Dec 2004 23:58:01 -0000
@@ -0,0 +1,152 @@
+# Copyright 2004 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 2 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, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+#
+# This file is part of the gdb testsuite.
+
+if $tracelevel {
+ strace $tracelevel
+}
+
+set prms_id 0
+set bug_id 0
+
+# Test handling of nullified instructions for the pa target.
+
+if ![istarget "hppa*-*-*"] then {
+ verbose "Skipping hppa nullification tests."
+ return
+}
+
+set testfile "pa-nullify"
+set srcfile ${testfile}.s
+set binfile ${objdir}/${subdir}/${testfile}
+set gcorefile ${objdir}/${subdir}/${testfile}.gcore
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {}] != "" } {
+ unsupported "Testcase compile failed."
+ return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# In the first test, we do a "step" on a function whose last instruction
+# contains a branch-with-nullify. The instruction in the delay slot belongs
+# to the next function. We verify that when we step off the first function
+# that we end up back at the caller and not at the second instruction.
+
+gdb_breakpoint foo
+gdb_test "run" "Breakpoint 1, .* in foo.*" "Breakpoint at foo"
+
+set test "stepi till main"
+gdb_test_multiple "stepi" "${test}" {
+ -re ".*in foo.*$gdb_prompt $" {
+ send_gdb "stepi\n"
+ exp_continue -continue_timer
+ }
+ -re ".*in bar.*$gdb_prompt $" {
+ fail $test
+ }
+ -re ".*in main.*$gdb_prompt $" {
+ pass $test
+ }
+}
+
+# In the second test, we verify that we can get a proper backtrace
+# even when we are in a nullified instruction that belongs to the next function.
+# We also verify that when stepping over a branch-with-nullify insn that we
+# stay on the same insn for two steps.
+
+proc get_addr_of_sym { sym } {
+ set addr 0
+ global gdb_prompt
+ global hex
+
+ set test "get address of $sym"
+ send_gdb "print $sym\n"
+ gdb_test_multiple "print $sym" $test {
+ -re ".*($hex) <$sym>.*$gdb_prompt $" {
+ set addr $expect_out(1,string)
+ pass $test
+ }
+ }
+
+ return $addr
+}
+
+if { ! [ runto_main ] } then { gdb_suppress_tests; }
+
+set foo [get_addr_of_sym "foo"]
+set bar [get_addr_of_sym "bar"]
+set foo_last [expr $bar - 4]
+
+gdb_breakpoint "*$foo_last"
+
+gdb_test "continue" "Breakpoint \[0-9\]*,.* in foo.*"
+gdb_test "backtrace" "in foo.*in main.*" "Backtrace from last insn in foo"
+gdb_test "stepi" "in foo.*" "stepi to nullified instruction stays in foo"
+gdb_test "backtrace" "in foo.*in main.*" "Backtrace from nullified insn"
+gdb_test "stepi" "in main.*" "stepi to main"
+
+# In the third test, we verify that backtraces from nullified instructions
+# work even in coredumps
+
+proc gen_core { test } {
+ global gcorefile
+ global gdb_prompt
+ set gcore_works 0
+ set escapedfilename [string_to_regexp $gcorefile]
+
+ gdb_test_multiple "gcore $gcorefile" "$test: gcore" {
+ -re "Saved corefile ${escapedfilename}\[\r\n\]+$gdb_prompt $" {
+ pass "$test: gcore"
+ set gcore_works 1
+ }
+ -re "Can't create a corefile\[\r\n\]+$gdb_prompt $" {
+ fail "$test: gcore"
+ }
+ }
+
+ return $gcore_works
+}
+
+proc test_core_bt { test } {
+ global gcorefile
+
+ gdb_test "core $gcorefile" "Core was generated by.*" \
+ "$test: load core file" "A program is being debugged already.*" "y"
+
+ gdb_test "backtrace" ".*in foo.*in main.*" "$test: backtrace in gcore"
+}
+
+set test "core at last insn in foo"
+if { ! [ runto_main ] } then { gdb_suppress_tests; }
+gdb_breakpoint "*$foo_last"
+gdb_test "continue" "Breakpoint \[0-9\]*,.* in foo.*" "$test: continue to breakpoint"
+if [gen_core $test] {
+ test_core_bt $test
+}
+
+set test "core at nullified insn"
+if { ! [ runto_main ] } then { gdb_suppress_tests; }
+gdb_breakpoint "*$foo_last"
+gdb_test "continue" "Breakpoint \[0-9\]*,.* in foo.*" "$test: continue to breakpoint"
+gdb_test "stepi" ".*in foo.*" "$test: step to nullified instruction"
+if [gen_core $test] {
+ test_core_bt $test
+}
Index: testsuite/gdb.arch/pa-nullify.s
===================================================================
RCS file: testsuite/gdb.arch/pa-nullify.s
diff -N testsuite/gdb.arch/pa-nullify.s
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.arch/pa-nullify.s 3 Dec 2004 23:58:01 -0000
@@ -0,0 +1,59 @@
+ .LEVEL 1.1
+ .text
+ .align 4
+.globl foo
+ .type foo, @function
+foo:
+ .PROC
+ .CALLINFO FRAME=64,NO_CALLS,SAVE_SP,ENTRY_GR=3
+ .ENTRY
+ copy %r3,%r1
+ copy %r30,%r3
+ stwm %r1,64(%r30)
+ stw %r26,-36(%r3)
+ ldw -36(%r3),%r19
+ copy %r19,%r28
+ ldo 64(%r3),%r30
+ ldwm -64(%r30),%r3
+ bv,n %r0(%r2)
+ .EXIT
+ .PROCEND
+
+.globl bar
+ .type bar, @function
+bar:
+ .PROC
+ .CALLINFO FRAME=64,NO_CALLS,SAVE_SP,ENTRY_GR=3
+ .ENTRY
+ copy %r3,%r1
+ copy %r30,%r3
+ stwm %r1,64(%r30)
+ ldo 64(%r3),%r30
+ ldwm -64(%r30),%r3
+ bv,n %r0(%r2)
+ .EXIT
+ .PROCEND
+
+.globl main
+ .type main, @function
+main:
+ .PROC
+ .CALLINFO FRAME=64,CALLS,SAVE_RP,SAVE_SP,ENTRY_GR=3
+ .ENTRY
+ stw %r2,-20(%r30)
+ copy %r3,%r1
+ copy %r30,%r3
+ stwm %r1,64(%r30)
+ stw %r26,-36(%r3)
+ stw %r25,-40(%r3)
+ ldw -36(%r3),%r26
+ bl foo,%r2
+ nop
+ copy %r28,%r19
+ copy %r19,%r28
+ ldw -20(%r3),%r2
+ ldo 64(%r3),%r30
+ ldwm -64(%r30),%r3
+ bv,n %r0(%r2)
+ .EXIT
+ .PROCEND