gdb/testsuite/gdb.base/break-idempotent.exp

# Copyright 2014-2021 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
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#
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
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# along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

# Test that the Zx breakpoint/watchpoint packets are idempotent.

# GDBserver used to not treat Zx breakpoints other than Z0 as
# idempotent, although it must, to avoid problems with
# retransmissions.  Even without spurious transport problems, if the
# target supports target conditions or commands, GDB re-inserts Zx
# breakpoints even if they are already inserted, to update the
# target-side condition/commands.  E.g., simply when a duplicate
# breakpoint is created, or when a shared library load causes a
# re-set, which creates duplicate locations while breakpoints are
# inserted, or when the condition is really changed while breakpoints
# are inserted.  To make the test not depend on shared library support
# or on details of the breakpoint re-set implementation, or on GDB
# optimizing out re-sends if the condition hasn't actually changed, we
# force always-inserted on, and really change the breakpoint's
# condition.  For good measure, test with both always-inserted "on"
# and "off" modes.

# The test is written in black-box style, and doesn't actually use
# anything target remote specific, so let it run on all targets.

standard_testfile

# Force a breakpoint re-set in GDB.  Currently this is done by
# reloading symbols with the "file" command.

proc force_breakpoint_re_set {} {
    global binfile gdb_prompt

    set test "file \$binfile"
    gdb_test_multiple "file $binfile" $test {
	-re "Are you sure you want to change the file. .*y or n. $" {
	    send_gdb "y\n" optional
	    exp_continue
	}
	-re "Load new symbol table from \".*\".*y or n. $" {
	    send_gdb "y\n" optional
	    exp_continue
	}
	-re "Reading symbols from.*$gdb_prompt $" {
	    pass $test
	}
    }
}

# Set a break/hbreak/watch/rwatch/awatch.

proc set_breakpoint { break_command } {
    global gdb_prompt srcfile

    if { $break_command == "break" } {
	gdb_test "$break_command foo" "Breakpoint.*at.* file .*$srcfile, line.*"
    } elseif { $break_command == "hbreak" } {
	set test "$break_command foo"
	gdb_test_multiple $test $test {
	    -re "No hardware breakpoint support in the target.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "Hardware breakpoints used exceeds limit.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "Cannot insert hardware breakpoint.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "Hardware assisted breakpoint.*at.* file .*$srcfile, line.*$gdb_prompt $" {
		pass $test
	    }
	}
    } elseif { [string first "watch" $break_command] != -1 } {
	set test "$break_command global"
	gdb_test_multiple $test $test {
	    -re "Target does not support this type of hardware watchpoint\\.\r\n$gdb_prompt $" {
		unsupported $test
	    }
	    -re "Could not insert hardware watchpoint.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "atchpoint \[0-9\]+: global\r\n$gdb_prompt $" {
		pass $test
	    }
	}
    } else {
	error "unhandled command: $break_command"
    }
}

# Run the test proper.  ALWAYS_INSERT determines whether
# always-inserted mode is on/off, and BREAK_COMMAND is the
# break/watch/etc. command being tested.
#
proc test_break { always_inserted break_command } {
    set cmd [lindex [split "$break_command"] 0]

    with_test_prefix "$cmd" {
	delete_breakpoints

	if ![runto_main] then {
	    return
	}

	gdb_test_no_output "set breakpoint always-inserted $always_inserted"

	# Set breakpoints/watchpoints twice.  With always-inserted on,
	# GDB reinserts the exact same Z breakpoint twice...  Do this
	# to make sure the stub pays attention to idempotency even
	# when the condition doesn't change.  If GDB end up optimizing
	# out exact duplicate packets, we should come up with a way to
	# keep testing this case.
	foreach iter { "once" "twice" } {
	    with_test_prefix $iter {
		set_breakpoint $break_command
	    }
	}

	# Force a breakpoint re-set.  In always-inserted mode, this
	# makes GDB re-send Z packets too...
	force_breakpoint_re_set

	# Now really change the condition, which forces a reinsert by
	# design.
	gdb_test "condition \$bpnum cond_global == 0" ".*"

	# Now delete breakpoints, and let the program execute the
	# address where the breakpoint used to be set.  If the target
	# doesn't treat insertions an idempotent way, we'll get a
	# spurious SIGTRAP.
	delete_breakpoints
	gdb_test "b bar" "Breakpoint .* at .*"
	gdb_test "continue" "Breakpoint .*, bar .*"
    }
}

# The testcase uses the "file" command to force breakpoint re-set in
# GDB.  Test both with and without PIE, as GDB used to mishandle
# breakpoint re-set when reloading PIEs.
foreach_with_prefix pie { "nopie" "pie" } {

    set opts {debug}
    lappend opts $pie

    set binfile [standard_output_file $testfile-$pie]

    if {[prepare_for_testing "failed to prepare" $binfile $srcfile $opts]} {
	continue
    }

    if [is_remote host] {
	set arg [remote_download host $binfile]
	if { $arg == "" } {
	    untested "download failed"
	    continue
	}
    }

    foreach_with_prefix always_inserted { "off" "on" } {
	test_break $always_inserted "break"

	if {![skip_hw_breakpoint_tests]} {
	    test_break $always_inserted "hbreak"
	}

	if {![skip_hw_watchpoint_tests]} {
	    test_break $always_inserted "watch"
	}

	if {![skip_hw_watchpoint_access_tests]
	    && ![skip_hw_watchpoint_multi_tests]} {
	    test_break $always_inserted "rwatch"
	    test_break $always_inserted "awatch"
	}
    }
}