177 lines
5.3 KiB
Text
177 lines
5.3 KiB
Text
# This testcase is part of GDB, the GNU debugger.
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# Copyright 2014-2015 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# This file is part of the gdb testsuite.
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# Test that GDB presents a hardware watchpoint stop at the first
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# instruction right after the instruction that changes memory.
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#
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# Some targets trigger a hardware watchpoint after the instruction
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# that wrote memory executes, thus with the memory already changed and
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# the PC pointing to the instruction after the instruction that wrote
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# to memory. These targets are said to have "continuable"
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# watchpoints, referring to the fact that to make progress after the
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# watchpoint triggers, GDB just needs to continue the target.
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#
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# Other targets trigger a hardware watchpoint at the instruction which
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# has attempted to write to the piece of memory under control of the
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# watchpoint, with the instruction actually not executed yet. To be
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# able to check whether the watched value changed, GDB needs to
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# complete the memory write, single-stepping the target once. These
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# targets are said to have "non-continuable" watchpoints.
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#
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# This test makes sure that GDB knows which kind of watchpoint the
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# target has, using this sequence of steps:
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#
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# 1 - run to main
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#
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# 2 - set a software watchpoint
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#
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# 3 - continue until watchpoint triggers
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#
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# 4 - the PC now points to the instruction right after the instruction
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# that actually caused the memory write. So this is the address a
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# hardware watchpoint should present the stop to the user too.
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# Store the PC address.
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#
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# 5 - replace the software watchpoint by a hardware watchpoint
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#
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# 6 - continue until hardware watchpoint triggers
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#
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# 7 - the PC must point to the same address the software watchpoint
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# triggered at.
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#
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# If the target has continuable watchpoints, but GDB thinks it has
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# non-continuable watchpoints, GDB will stop the inferior two
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# instructions after the watched value change, rather than at the next
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# instruction.
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#
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# If the target has non-continuable watchpoints, while GDB thinks it
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# has continuable watchpoints, GDB will see a watchpoint trigger,
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# notice no value changed, and immediatly continue the target. Now,
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# either the target manages to step-over the watchpoint transparently,
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# and GDB thus fails to present to value change to the user, or, the
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# watchpoint will keep re-triggering, with the program never making
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# any progress.
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standard_testfile
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# No use testing this if we can't use hardware watchpoints.
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if {[target_info exists gdb,no_hardware_watchpoints]} {
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return -1
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}
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if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
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untested ${testfile}.exp
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return -1
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}
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if { ![runto main] } then {
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fail "run to main"
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return
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}
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# Get the current PC. TEST is used as test prefix.
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proc get_pc {test} {
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global hex gdb_prompt
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set addr ""
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gdb_test_multiple "p /x \$pc" "$test" {
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-re " = ($hex).*$gdb_prompt $" {
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set addr $expect_out(1,string)
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pass "$test"
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}
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}
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return $addr
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}
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# So we get an immediate warning/error if the target doesn't support a
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# given watchpoint type.
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gdb_test_no_output "set breakpoint always-inserted on"
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set hw_watchpoints_supported 0
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set test "set probe hw watchpoint"
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gdb_test_multiple "watch global" $test {
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-re "You may have requested too many.*$gdb_prompt $" {
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pass $test
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}
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-re "Target does not support.*$gdb_prompt $" {
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pass $test
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}
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-re "$gdb_prompt $" {
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pass $test
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set hw_watchpoints_supported 1
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}
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}
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if {!$hw_watchpoints_supported} {
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unsupported "no hw watchpoints support"
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return
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}
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delete_breakpoints
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proc test {always_inserted} {
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global srcfile binfile
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with_test_prefix "always-inserted $always_inserted" {
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clean_restart $binfile
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if { ![runto main] } then {
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fail "run to main"
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return
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}
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# Force use of software watchpoints.
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gdb_test_no_output "set can-use-hw-watchpoints 0"
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gdb_test "watch global" \
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"Watchpoint .*: global" \
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"set software watchpoint on global variable"
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gdb_test "continue" \
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"Watchpoint .*: global.*Old value = 0.*New value = 1.*set_global \\(val=1\\).*$srcfile.*" \
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"software watchpoint triggers"
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set sw_watch_pc [get_pc "get sw watchpoint PC"]
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delete_breakpoints
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# Allow hardware watchpoints again.
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gdb_test_no_output "set can-use-hw-watchpoints 1"
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gdb_test "watch global" \
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"Hardware watchpoint .*: global" \
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"set hardware watchpoint on global variable"
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gdb_test "continue" \
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"Hardware watchpoint .*: global.*Old value = 1.*New value = 2.*set_global \\(val=2\\).*$srcfile.*" \
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"hardware watchpoint triggers"
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set hw_watch_pc [get_pc "get hw watchpoint PC"]
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gdb_assert {$sw_watch_pc == $hw_watch_pc} "hw watchpoint stops at right instruction"
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}
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}
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foreach always_inserted {"off" "on" } {
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test $always_inserted
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}
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