gdb/testsuite/gdb.base/bp-permanent.exp

# Copyright (C) 2014-2024 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.

# Test stepping over permanent breakpoints.

standard_testfile

set options { debug }
if { ![target_info exists gdb,nosignals] } {
    lappend options "additional_flags=-DSIGNALS"
}

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

set line_bp [gdb_get_line_number "write permanent bp"]

# The test proper.  ALWAYS_INSERTED indicates whether testing in
# "breakpoint always-inserted" mode.  If SW_WATCHPOINT is true, set a
# software watchpoint, which forces constantly single-stepping, and
# exercises stepping the permanent breakpoint while delivering a
# signal at the same time.

proc test {always_inserted sw_watchpoint} {
    global line_bp
    global hex decimal
    global gdb_prompt
    global srcfile binfile

    clean_restart $binfile

    if {![runto_main]} {
	return -1
    }

    gdb_test "set breakpoint always-inserted $always_inserted"

    if {$sw_watchpoint} {
	# Watching a convenience variable forces a software
	# watchpoint.
	gdb_test "watch \$dummy_convenience" "Watchpoint .*"
    }

    set address_bp ""
    set address_after_bp ""

    with_test_prefix "setup" {

	# Set a breakpoint where we'll manually plant a permanent
	# breakpoint.
	set test "set probe breakpoint"
	gdb_test_multiple "break $line_bp" $test {
	    -re "Breakpoint .* at ($hex).*$gdb_prompt $" {
		set address_bp $expect_out(1,string)
		pass $test
	    }
	}
	if {$address_bp == ""} {
	    return
	}

	# Get the size of the instruction where the breakpoint will
	# manually inserted.
	set test "get size of instruction"
	gdb_test_multiple "x/2i $address_bp" $test {
	    -re ".*$hex <test\\+$decimal>:\[^\r\n\]+\r\n\[ \]+($hex).*\.\r\n$gdb_prompt $" {
		set address_after_bp $expect_out(1,string)
		pass $test
	    }
	}
	if {$address_after_bp == ""} {
	    return
	}

	# Write address range where the breakpoint is inserted to the
	# corresponding variables in the inferior.
	gdb_test "p /x addr_bp = $address_bp" " = $address_bp" \
	    "write addr_bp"
	gdb_test "p /x addr_after_bp = $address_after_bp" " = $address_after_bp" \
	    "write addr_after_bp"

	# Run the "setup" function in the inferior.  This memcpy's the
	# breakpoint instruction to a buffer in the inferior.
	gdb_test "next" "test_basics \\(\\).*" "next over setup"

	delete_breakpoints

	# We now have the breakpoint instruction stored in 'buffer'.  Poke it
	# to memory manually.
	set count [expr $address_after_bp - $address_bp]
	for {set i 0} {$i < $count} {incr i} {
	    set test "p /x addr_bp\[$i\] = buffer\[$i\]"
	    gdb_test_multiple $test $test {
		-re "Cannot access memory at address $hex.*$gdb_prompt $" {
		    # Some targets (QEMU for one) will disallow writes to the
		    # .text section under certain circumstances.  It is no use
		    # continuing with the test at this point.  Just return.
		    unsupported "cannot modify memory"
		    return
		}
		-re " = .*$gdb_prompt $" {
		    pass $test
		}
	    }
	}
    }

    with_test_prefix "basics" {
	# Run to the permanent breakpoint, just to make sure we've inserted it
	# correctly.
	# If the target fails to stop, the remainder of the test will not work
	# so just return.  This can happen on some simulator targets where
	# the running program doesn't see breakpoints that are visible to
	# the execution engine, or where writes to the .text section are
	# quietly ignored.
	set test "permanent breakpoint causes random signal"
	gdb_test_multiple "continue" $test {
	    -re "exited normally.*$gdb_prompt $" {
	        unsupported "failed to stop at permanent breakpoint"
		return
	    }
	    -re "Program received signal SIGTRAP.*$gdb_prompt $" {
	    	pass $test
	    }
	}

	# Now set a breakpoint on top, thus creating a permanent breakpoint.
	gdb_breakpoint "$line_bp"

	# Depending on whether this is a decr_pc_after_break arch, the PC will
	# be either pointing at the permanent breakpoint address, or just
	# after.  Set the GDB breakpoint on top, and continue, twice.  At
	# least once, GDB will need to step-over the permanent breakpoint.

	gdb_test "continue" "Breakpoint .*" "stop at permanent breakpoint"

	gdb_test "p \$prev_counter = counter" " = $decimal"

	gdb_test "continue" "Breakpoint .*" "stop at permanent breakpoint twice"

	# Check that indeed the continue made progress, instead of re-trapping
	# without advancing.
	gdb_test "p counter - \$prev_counter" " = 1"

	gdb_test "info breakpoints" \
	    "breakpoint.*keep.*y.*$hex.*in test at .*$srcfile:$line_bp.*already hit 2 times.*" \
	    "info breakpoints show enabled breakpoint"

	gdb_test "disable \$bpnum"

	gdb_test "commands\nset \$commands_ran = 1\nend" "" \
	    "set breakpoint commands"

	gdb_test "info breakpoints" \
	    "breakpoint.*keep.*n.*$hex.*in test at .*$srcfile:$line_bp.*already hit 2 times.*" \
	    "info breakpoints shows disabled breakpoint"

	# Run to the permanent breakpoint again.  This time, since it's
	# disabled, it should act as if we hadn't created it in the first
	# place.  IOW, we should get a random signal, and, the breakpoint's
	# command should not run.
	gdb_test "continue" "Program received signal SIGTRAP.*" \
	    "disabled permanent breakpoint doesn't explain stop"

	gdb_test "info breakpoints" \
	    "breakpoint.*keep.*n.*$hex.*in test at .*$srcfile:$line_bp.*already hit 2 times.*" \
	    "info breakpoints still shows same number of hits"

	gdb_test "print \$commands_ran" " = void" \
	    "breakpoint commands didn't run"

	# Reenable the breakpoint, and check that it gets hit and accounted
	# for this time.
	gdb_test "enable \$bpnum" "" "reenable breakpoint"

	gdb_test "continue" "Breakpoint .*" \
	    "stop at permanent breakpoint thrice"

	gdb_test "info breakpoints" \
	    "breakpoint.*keep.*y.*$hex.*in test at .*$srcfile:$line_bp.*already hit 3 times.*" \
	    "info breakpoints shows one more hit"

	gdb_test "print \$commands_ran" " = 1" "breakpoint commands ran"

	# Check that stepi advances only past the permanent breakpoint, and
	# not a single instruction more.
	gdb_test "stepi" "after permanent bp .*" \
	    "single-step past permanent breakpoint"
    }

    with_test_prefix "next trips on permanent bp" {
	delete_breakpoints

	gdb_breakpoint "test_next"
	gdb_continue_to_breakpoint "test_next"

	gdb_breakpoint "$line_bp"
	gdb_test "condition \$bpnum 0"

	gdb_test "next" "after next .*"
    }

    if ![target_info exists gdb,nosignals] {

	with_test_prefix "continue trips on nested permanent bp" {
	    delete_breakpoints

	    gdb_breakpoint "test_signal_nested"
	    gdb_continue_to_breakpoint "test_signal_nested"

	    gdb_breakpoint "$line_bp"
	    gdb_continue_to_breakpoint "permanent bp"
	    gdb_test "condition \$bpnum 0"

	    # Let SIGALRM trigger.
	    sleep 2

	    # We're now stopped at a permanent breakpoint, with a
	    # signal pending.
	    gdb_breakpoint "test_signal_nested_done"
	    gdb_continue_to_breakpoint "test_signal_nested_done"

	    # Ensure that the handler did run.  There's one call to
	    # test in the mainline code, and another in the signal
	    # handler.
	    gdb_test "p counter" " = 2"
	}

	if [can_single_step_to_signal_handler] {

	    with_test_prefix "stepi signal with handler" {
		delete_breakpoints

		gdb_breakpoint "test_signal_with_handler"
		gdb_continue_to_breakpoint "test_signal_with_handler"

		gdb_breakpoint "$line_bp"

		gdb_test "continue" "Breakpoint .*" "stop at permanent breakpoint"

		gdb_test "queue-signal SIGUSR1"

		set test "single-step to handler"
		gdb_test_multiple "stepi" $test {
		    -re "Program received signal SIGTRAP.*$gdb_prompt $" {
			fail $test
		    }
		    -re "signal handler called.*$gdb_prompt $" {
			# After PowerPC Linux kernel commit:
			#
			#   commit: 0138ba5783ae0dcc799ad401a1e8ac8333790df9
			#   powerpc/64/signal: Balance return predictor
			#   stack in signal trampoline.
			#
			# The kernel places an additional brctl instruction
			# in the vdso to call the user handler.
			#
			# And then this commit:
			#
			#   commit 24321ac668e452a4942598533d267805f291fdc9
			#   powerpc/64/signal: Fix regression in
			#   __kernel_sigtramp_rt64() semantics
			#
			# updates the semantics of __kernel_sigtramp_rt64().
			# It added a new symbol to serve as a jump target from
			# the kernel to the trampoline.
			#
			# The net result of these changes is that gdb stops
			# at  __kernel_start_sigtramp_rt64.  Need to do one
			# more stepi to reach the expected location in the user
			# signal handler.
			gdb_test "p \$pc" "__kernel_start_sigtramp_rt64.*" \
			    "in kernel code"
			gdb_test "stepi" "handler .*" $test
		    }
		    -re "handler .*$gdb_prompt $" {
			pass $test
		    }
		}

		# Check that the mainline PC points at the permanent
		# breakpoint.
		gdb_test "up 2" "test .*" "up to mainline code"

		gdb_test "p /x \$pc" " = $address_bp" \
		    "mainline pc points at permanent breakpoint"

		gdb_test "continue" "Breakpoint .*" \
		    "stop at permanent breakpoint, out of handler"
	    }

	    with_test_prefix "stepi signal with no handler" {
		gdb_breakpoint "test_signal_no_handler"
		gdb_continue_to_breakpoint "test_signal_no_handler"

		gdb_test "continue" "Breakpoint .*" "stop at permanent breakpoint"

		gdb_test "queue-signal SIGUSR1"

		gdb_test "stepi" "after permanent bp .*" \
		    "single-step past permanent breakpoint"
	    }
	}
    }
}

foreach always_inserted {off on} {
    foreach sw_watchpoint {0 1} {
	with_test_prefix "always_inserted=$always_inserted, sw_watchpoint=$sw_watchpoint" {
	    test $always_inserted $sw_watchpoint
	}
    }
}