binutils-gdb/gdb/testsuite/gdb.base/breakpoint-in-ro-region.exp

# Copyright 2014-2017 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/>.

# This file is part of the gdb testsuite

standard_testfile

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

if ![runto main] {
    return -1
}

delete_breakpoints

# Probe for hardware stepping.

proc probe_target_hardware_step {} {
    global gdb_prompt

    set hw_step 0

    gdb_test_no_output "set debug target 1"
    set test "probe target hardware step"
    gdb_test_multiple "si" $test {
	-re "to_resume \\(\[^\r\n\]+, step, .*$gdb_prompt $" {
	    set hw_step 1
	    pass $test
	}
	-re "$gdb_prompt $" {
	    pass $test
	}
    }
    gdb_test "set debug target 0" "->to_log_command.*\\).*"
    return $hw_step
}

# Get the bounds of a function, and write them to FUNC_LO (inclusive),
# FUNC_HI (exclusive).  Return true on success and false on failure.
proc get_function_bounds {function func_lo func_hi} {
    global gdb_prompt
    global hex decimal

    upvar $func_lo lo
    upvar $func_hi hi

    set lo ""
    set size ""

    set test "get lo address of $function"
    gdb_test_multiple "disassemble $function" $test {
	-re "($hex) .*$hex <\\+($decimal)>:\[^\r\n\]+\r\nEnd of assembler dump\.\r\n$gdb_prompt $" {
	    set lo $expect_out(1,string)
	    set size $expect_out(2,string)
	    pass $test
	}
    }

    if { $lo == "" || $size == "" } {
	return false
    }

    # Account for the size of the last instruction.
    set test "get hi address of $function"
    gdb_test_multiple "x/2i $function+$size" $test {
	-re ".*$hex <$function\\+$size>:\[^\r\n\]+\r\n\[ \]+($hex).*\.\r\n$gdb_prompt $" {
	    set hi $expect_out(1,string)
	    pass $test
	}
    }

    if { $hi == "" } {
	return false
    }

    # Remove unnecessary leading 0's (0x00000ADDR => 0xADDR) so we can
    # easily do matches.  Disassemble includes leading zeros, while
    # x/i doesn't.
    regsub -all "0x0\+" $lo "0x" lo
    regsub -all "0x0\+" $hi "0x" hi

    return true
}

# Get the address where the thread is currently stopped.
proc get_curr_insn {} {
    global gdb_prompt
    global hex

    set pc ""
    set test "get current insn"
    gdb_test_multiple "p /x \$pc" $test {
	-re " = ($hex)\r\n$gdb_prompt $" {
	    set pc $expect_out(1,string)
	    pass $test
	}
    }

    return $pc
}

# Get the address of where a single-step should land.
proc get_next_insn {} {
    global gdb_prompt
    global hex

    set next ""
    set test "get next insn"
    gdb_test_multiple "x/2i \$pc" $test {
	-re "$hex .*:\[^\r\n\]+\r\n\[ \]+($hex).*\.\r\n$gdb_prompt $" {
	    set next $expect_out(1,string)
	    pass $test
	}
    }

    return $next
}

set hw_step [probe_target_hardware_step]

if ![get_function_bounds "main" main_lo main_hi] {
    # Can't do the following tests if main's bounds are unknown.
    return -1
}

# Manually create a read-only memory region that covers 'main'.
gdb_test_no_output "mem $main_lo $main_hi ro" \
    "create read-only mem region covering main"

# So that we don't fail inserting breakpoints on addresses outside
# main, like the internal event breakpoints.
gdb_test_no_output "set mem inaccessible-by-default off"

# So we get an immediate warning/error without needing to resume the
# target.
gdb_test_no_output "set breakpoint always-inserted on"

# Disable the automatic fallback to HW breakpoints.  We want a
# software breakpoint to be attempted, and to fail.
gdb_test_no_output "set breakpoint auto-hw off"

# Confirm manual writes to the read-only memory region fail.
gdb_test "p /x *(char *) $main_lo = 1" \
    "Cannot access memory at address $main_lo" \
    "writing to read-only memory fails"

# Ensure that inserting a software breakpoint in a known-read-only
# region fails.
gdb_test "break *$main_lo" \
    "Cannot insert breakpoint .*Cannot set software breakpoint at read-only address $main_lo.*" \
    "inserting software breakpoint in read-only memory fails"

delete_breakpoints

set supports_hbreak 0
set test "probe hbreak support"
gdb_test_multiple "hbreak *$main_lo" $test {
    -re "You may have requested too many.*$gdb_prompt $" {
	pass "$test (no support)"
    }
    -re "No hardware breakpoint support.*$gdb_prompt $" {
	pass "$test (no support)"
    }
    -re "$gdb_prompt $" {
	pass "$test (support)"
	set supports_hbreak 1
    }
}

delete_breakpoints

# Check that the "auto-hw on/off" setting affects single-step
# breakpoints as expected, by stepping through the read-only region.
# If the target does hardware stepping, we won't exercise that aspect,
# but we should be able to step through the region without seeing the
# hardware breakpoint or read-only address errors.
proc test_single_step { always_inserted auto_hw } {
    global gdb_prompt
    global decimal
    global hex
    global supports_hbreak
    global hw_step

    gdb_test_no_output "set breakpoint always-inserted $always_inserted"
    gdb_test_no_output "set breakpoint auto-hw $auto_hw"

    # Get the address of the current instruction so we know where SI is
    # starting from.
    set curr_insn [get_curr_insn]

    # Get the address of the next instruction so we know where SI should
    # land.
    set next_insn [get_next_insn]

    set test "step in ro region"
    gdb_test_multiple "si" $test {
	-re "Could not insert hardware breakpoints.*$gdb_prompt $" {
	    gdb_assert {!$hw_step && $auto_hw == "on" && !$supports_hbreak} \
		"$test (cannot insert hw break)"
	}
	-re "Cannot set software breakpoint at read-only address $next_insn.*$gdb_prompt $" {
	    gdb_assert {!$hw_step && $auto_hw == "off"} \
		"$test (cannot insert sw break)"
	}
	-re "^si\r\nNote: automatically using hardware breakpoints for read-only addresses\.\r\n\(\?\:${hex}\[ \t\]\)\?${decimal}\[ \t\]+i = 0;\r\n$gdb_prompt $" {
	    gdb_assert {!$hw_step && $auto_hw == "on" && $supports_hbreak} \
		"$test (auto-hw)"
	}
	-re "^si\r\n\(\?\:${hex}\[ \t\]\)\?${decimal}\[ \t\]+i = 0;\r\n$gdb_prompt $" {
	    gdb_assert {$hw_step || ($auto_hw == "on" && $supports_hbreak)} \
		"$test (no error)"
	}
    }

    gdb_test "maint info breakpoints 0" \
	"No breakpoint or watchpoint matching '0'\." \
	"single-step breakpoint is not left behind"

    # Confirm the thread really advanced.
    if {$hw_step || ($auto_hw == "on" && $supports_hbreak)} {
	gdb_test "p /x \$pc" " = $next_insn" "thread advanced"
    } else {
	gdb_test "p /x \$pc" " = $curr_insn" "thread did not advance"
    }
}

foreach always_inserted {"off" "on"} {
    foreach auto_hw {"off" "on"} {
	with_test_prefix "always-inserted $always_inserted: auto-hw $auto_hw" {
	    test_single_step $always_inserted $auto_hw
	}
    }
}