testsuite/gdb.base/watchpoint-reuse-slot.exp

# Copyright 2014-2020 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 alternating between watchpoint types, watching a sliding window
# of addresses (thus alternating between aligned and unaligned
# addresses).  Only a single watchpoint exists at any given time.  On
# targets that only update the debug registers on resume, this
# stresses the debug register setup code, both in GDB and in the
# target/kernel as one watchpoint replaces the other in a single
# operation.  (Note that we don't have any of these watchpoints
# trigger.)

standard_testfile

if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
    return -1
}

if ![runto_main] then {
    fail "can't run to main"
    return 0
}

# The line we'll be stepping.
set srcline [gdb_get_line_number "stepi line"]

# The address the program is stopped at currently.
set cur_addr ""

# Get the current PC.

proc get_pc {} {
    global hex gdb_prompt

    set addr ""
    set test "get PC"
    gdb_test_multiple "p /x \$pc" "$test" {
	-re " = ($hex).*$gdb_prompt $" {
	    set addr $expect_out(1,string)
	    pass "$test"
	}
    }

    return $addr
}


# Issue a stepi, and make sure the program advanced past the current
# instruction (stored in the CUR_ADDR global).

proc stepi {} {
    global hex gdb_prompt cur_addr

    set srcline "  for (i = 0; i < 100000; i++); /* stepi line */"
    set test "stepi advanced"
    gdb_test_multiple "stepi" $test {
	-re -wrap "[string_to_regexp $srcline]" {
	    set addr [get_valueof "/x" "\$pc" "0"]
	    if {$addr != $cur_addr} {
		pass $test
	    } else {
		fail $test
	    }
	    set cur_addr $addr
	}
    }
}

gdb_breakpoint $srcline
gdb_continue_to_breakpoint "stepi line"
set cur_addr [get_pc]

# The test tries various sequences of different types of watchpoints.
# Probe for support first.
proc build_cmds_list {} {
    global gdb_prompt

    # So we get an immediate warning/error if the target doesn't support a
    # given watchpoint type.
    gdb_test_no_output "set breakpoint always-inserted on" \
	"Set breakpoints always inserted while building cmds list"

    # The list of supported commands.  Below we'll probe for support and
    # add elements to this list.
    set cmds {}

    foreach cmd {"watch" "awatch" "rwatch"} {
	set test $cmd
	gdb_test_multiple "$cmd buf.byte\[0\]" $test {
	    -re "You may have requested too many.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "Target does not support.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "Can't set read/access watchpoint when hardware watchpoints are disabled.*$gdb_prompt $" {
		unsupported $test
	    }
	    -re "$gdb_prompt $" {
		pass $test
		lappend cmds $cmd
	    }
	}

	delete_breakpoints
    }

    set test "hbreak"
    gdb_test_multiple "hbreak main" $test {
	-re "You may have requested too many.*$gdb_prompt $" {
	    unsupported $test
	}
	-re "No hardware breakpoint support.*$gdb_prompt $" {
	    unsupported $test
	}
	-re "$gdb_prompt $" {
	    pass $test
	    lappend cmds "hbreak"
	}
    }

    delete_breakpoints

    return $cmds
}

# Return true if the memory range [buf.byte + OFFSET, +WIDTH] can be
# monitored by CMD, otherwise return false.

proc valid_addr_p {cmd offset width} {

    if { [istarget "aarch64*-*-linux*"] } {
	# The aarch64 Linux kernel port only accepts 4-byte aligned addresses
	# for hardware breakpoints and 8-byte aligned addresses for hardware
	# watchpoints.  However, both GDB and GDBserver support unaligned
	# watchpoints by using more than one properly aligned watchpoint
	# registers to represent the whole unaligned region.  Breakpoint
	# addresses must still be aligned though.
	if {$cmd == "hbreak" } {
	    if { [expr ($offset) % 4] != 0 } {
		return 0
	    }
	}
    } elseif { [istarget "arm*-*-linux*"] } {
	if { $cmd == "hbreak" } {
	    # Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
	    if { $width != 2 && $width != 4 } {
		return 0
	    }
	} else {
	    # Watchpoints can be of length 1, 2, 4 or 8 bytes.
	    if { [expr $width % 2] != 0 } {
		return 0
	    }
	}

	if { [expr ($offset) % 8] == 0 && $width == 8 } {
	    # If WIDTH is 8 byte, the address should be 8-byte aligned.
	    return 1
	} elseif { [expr ($offset) % 4] == 0 } {
	    return 1
	} elseif { [expr ($offset) % 4] == 2 && $width == 2 } {
	    # Halfword watchpoints and breakpoints.
	    return 1
	} elseif { [expr ($offset) % 4] == 1 && $width == 1 && $cmd != "hbreak" } {
	    # Single byte watchpoints.
	    return 1
	} else {
	    return 0
	}
    }

    return 1
}

# Watch WIDTH bytes at BASE + OFFSET.  CMD specifices the specific
# type of watchpoint to use.  If CMD is "hbreak", WIDTH is ignored.
# The HW_WP_P flag tells us if hardware watchpoints are enabled or
# not.

proc watch_command {cmd base offset width hw_wp_p} {
    global srcfile srcline hex

    if {$cmd == "hbreak"} {
	set expr "*(buf.byte + $base + $offset)"
	gdb_test "hbreak $expr" "Hardware assisted breakpoint \[0-9\]+ at $hex"
    } elseif {$cmd == "watch"} {
	set expr "*(buf.byte + $base + $offset)@$width"

	if { ! $hw_wp_p } {
	    set wp_prefix "Watchpoint"
	} else {
	    set wp_prefix "Hardware watchpoint"
	}

	gdb_test "$cmd $expr" \
	    "${wp_prefix} \[0-9\]+: [string_to_regexp $expr]"
    } elseif {$cmd == "awatch"} {
	set expr "*(buf.byte + $base + $offset)@$width"
	gdb_test "$cmd $expr" \
	    "Hardware access \\(read/write\\) watchpoint \[0-9\]+: [string_to_regexp $expr]"
    } elseif {$cmd == "rwatch"} {
	set expr "*(buf.byte + $base + $offset)@$width"
	gdb_test "$cmd $expr" \
	    "Hardware read watchpoint \[0-9\]+: [string_to_regexp $expr]"
    }
}

# Run the watchpoint tests (see the description at the top for details), the
# HW_WP_P flag tells us if hardware watchpoints are enabled or not.
proc run_watchpoints_tests {hw_wp_p} {

    set cmds [build_cmds_list]

    foreach always_inserted {"off" "on" } {
	gdb_test_no_output "set breakpoint always-inserted $always_inserted"
	foreach cmd1 $cmds {
	    foreach cmd2 $cmds {
		for {set width 1} {$width < 4} {incr width} {

		    if {$cmd1 == "hbreak" && $cmd2 == "hbreak" \
			    && $width > 1} {
			# hbreak ignores WIDTH, no use testing more than
			# once.
			continue
		    }

		    for {set x 0} {$x < 4} {incr x} {

			if { ![valid_addr_p $cmd1 $x $width]
			     || ![valid_addr_p $cmd2 $x+1 $width] } {
			    # Skip tests if requested address or length
			    # of breakpoint or watchpoint don't meet
			    # target or kernel requirements.
			    continue
			}

			set prefix "always-inserted $always_inserted: "
			append prefix "$cmd1 x $cmd2: "
			with_test_prefix "$prefix: width $width, iter $x" {
			    with_test_prefix "base + 0" {
				watch_command $cmd1 $x 0 $width $hw_wp_p
				stepi
				gdb_test_no_output "delete \$bpnum"
			    }
			    with_test_prefix "base + 1" {
				watch_command $cmd2 $x 1 $width $hw_wp_p
				stepi
				gdb_test_no_output "delete \$bpnum"
			    }
			}
		    }
		}
	    }
	}
    }
}

# Based on HW_WP_P set whether hardware watchpoints can be used or
# not, then call RUN_WATCHPOINTS_TESTS.
proc setup_and_run_watchpoints_tests { hw_wp_p } {
    if {$hw_wp_p} {
	set prefix "hw-watch"
    } else {
	set prefix "sw-watch"
    }

    with_test_prefix $prefix {
	gdb_test_no_output "set can-use-hw-watchpoints ${hw_wp_p}"

	run_watchpoints_tests $hw_wp_p
    }
}

# Run tests with hardware watchpoints disabled, then again with them
# enabled (if this target supports hardware watchpoints).
if { ![target_info exists gdb,no_hardware_watchpoints]} {
    # Run test with H/W enabled.
    setup_and_run_watchpoints_tests 1
}

# Run test with H/W disabled
setup_and_run_watchpoints_tests 0