path: root/gdb/testsuite/gdb.base/step-over-syscall.exp

# This testcase is part of GDB, the GNU debugger.

# Copyright 2011-2021 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
# (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/>.

set syscall_insn ""
set syscall_register ""
array set syscall_number {}

# Define the syscall instructions, registers and numbers for each target.

if { [istarget "i\[34567\]86-*-linux*"] || [istarget "x86_64-*-linux*"] } {
    set syscall_insn "\[ \t\](int|syscall|sysenter)\[ \t\]"
    set syscall_register "eax"
    array set syscall_number {fork "(56|120)" vfork "(58|190)" \
      clone "(56|120)"}
} elseif { [istarget "aarch64*-*-linux*"] || [istarget "arm*-*-linux*"] } {
    set syscall_insn "\[ \t\](swi|svc)\[ \t\]"

    if { [istarget "aarch64*-*-linux*"] } {
	set syscall_register "x8"
    } else {
	set syscall_register "r7"
    }

    array set syscall_number {fork "(120|220)" vfork "(190|220)" \
      clone "(120|220)"}
} else {
    return -1
}

proc_with_prefix check_pc_after_cross_syscall { displaced syscall syscall_insn_next_addr } {
    global gdb_prompt

    set syscall_insn_next_addr_found [get_hexadecimal_valueof "\$pc" "0"]

    # After the 'stepi' we expect thread 1 to still be selected.
    # However, when displaced stepping over a clone bug gdb/19675
    # means this might not be the case.
    #
    # Which thread we end up in depends on a race between the original
    # thread-1, and the new thread (created by the clone), so we can't
    # guarantee which thread we will be in at this point.
    #
    # For the fork/vfork syscalls, which are correctly handled by
    # displaced stepping we will always be in thread-1 or the original
    # process at this point.
    set curr_thread "unknown"
    gdb_test_multiple "info threads" "" {
	-re "Id\\s+Target Id\\s+Frame\\s*\r\n" {
	    exp_continue
	}
	-re "^\\* (\\d+)\\s+\[^\r\n\]+\r\n" {
	    set curr_thread $expect_out(1,string)
	    exp_continue
	}
	-re "^\\s+\\d+\\s+\[^\r\n\]+\r\n" {
	    exp_continue
	}
	-re "$gdb_prompt " {
	}
    }

    # If we are displaced stepping over a clone, and we ended up in
    # the wrong thread then the following check of the $pc value will
    # fail.
    if { $displaced == "on" && $syscall == "clone" && $curr_thread != 1 } {
	# GDB doesn't support stepping over clone syscall with
	# displaced stepping.
	setup_kfail "*-*-*" "gdb/19675"
    }

    gdb_assert {$syscall_insn_next_addr != 0 \
      && $syscall_insn_next_addr == $syscall_insn_next_addr_found \
      && $curr_thread == 1} \
	"single step over $syscall final pc"
}

# Verify the syscall number is the correct one.

proc syscall_number_matches { syscall } {
  global syscall_register syscall_number

  if {[gdb_test "p \$$syscall_register" ".*= $syscall_number($syscall)" \
    "syscall number matches"] != 0} {
      return 0
  }

  return 1
}

# Restart GDB and set up the test.  Return a list in which the first one
# is the address of syscall instruction and the second one is the address
# of the next instruction address of syscall instruction.  If anything
# wrong, the two elements of list are -1.

proc setup { syscall } {
    global gdb_prompt syscall_insn

    global hex
    set next_insn_addr -1
    set testfile "step-over-$syscall"

    clean_restart $testfile

    if { ![runto_main] } then {
	fail "run to main ($syscall)"
	return -1
    }

    # Delete the breakpoint on main.
    gdb_test_no_output "delete break 1"

    gdb_test_no_output "set displaced-stepping off" \
	"set displaced-stepping off during test setup"

    gdb_test "break \*$syscall" "Breakpoint \[0-9\]* at .*"

    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
	"continue to $syscall (1st time)"
    # Hit the breakpoint on $syscall for the first time.  In this time,
    # we will let PLT resolution done, and the number single steps we will
    # do later will be reduced.

    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
	"continue to $syscall (2nd time)"
    # Hit the breakpoint on $syscall for the second time.  In this time,
    # the address of syscall insn and next insn of syscall are recorded.

    # Check if the first instruction we stopped at is the syscall one.
    set syscall_insn_addr -1
    gdb_test_multiple "display/i \$pc" "fetch first stop pc" {
	-re "display/i .*: x/i .*=> ($hex) .*:.*$syscall_insn.*$gdb_prompt $" {
	    set insn_addr $expect_out(1,string)

	    # Is the syscall number the correct one?
	    if {[syscall_number_matches $syscall]} {
		set syscall_insn_addr $insn_addr
	    }
	    pass $gdb_test_name
	}
	-re ".*$gdb_prompt $" {
	    pass $gdb_test_name
	}
    }

    # If we are not at the syscall instruction yet, keep looking for it with
    # stepi commands.
    if {$syscall_insn_addr == -1} {
	# Single step until we see a syscall insn or we reach the
	# upper bound of loop iterations.
	set steps 0
	set max_steps 1000
	gdb_test_multiple "stepi" "find syscall insn in $syscall" {
	    -re ".*$syscall_insn.*$gdb_prompt $" {
		# Is the syscall number the correct one?
		if {[syscall_number_matches $syscall]} {
		    pass $gdb_test_name
		} else {
		    exp_continue
		}
	    }
	    -re "x/i .*=>.*\r\n$gdb_prompt $" {
		incr steps
		if {$steps == $max_steps} {
		    fail $gdb_test_name
		} else {
		    send_gdb "stepi\n"
		    exp_continue
		}
	    }
	}

	if {$steps == $max_steps} {
	    return { -1, -1 }
	}
    }

    # We have found the syscall instruction.  Now record the next instruction.
    # Use the X command instead of stepi since we can't guarantee
    # stepi is working properly.
    gdb_test_multiple "x/2i \$pc" "pc before/after syscall instruction" {
	-re "x/2i .*=> ($hex) .*:.*$syscall_insn.* ($hex) .*:.*$gdb_prompt $" {
	    set syscall_insn_addr $expect_out(1,string)
	    set actual_syscall_insn $expect_out(2,string)
	    set next_insn_addr $expect_out(3,string)
	    pass $gdb_test_name
	}
    }

    # If we encounter a sequence:
    #   0xf7fd5155 <__kernel_vsyscall+5>:    sysenter
    #   0xf7fd5157 <__kernel_vsyscall+7>:    int    $0x80
    #   0xf7fd5159 <__kernel_vsyscall+9>:    pop    %ebp
    # then a stepi at sysenter will step over the int insn, so make sure
    # next_insn_addr points after the int insn.
    if { $actual_syscall_insn == "sysenter" } {
	set test "pc after sysenter instruction"
	set re_int_insn "\[ \t\]*int\[ \t\]\[^\r\n\]*"
	set re [multi_line \
		    "x/2i $hex" \
		    "\[^\r\n\]* $hex \[^\r\n\]*:$re_int_insn" \
		    "\[^\r\n\]* ($hex) \[^\r\n\]*:\[^\r\n\]*"]
	gdb_test_multiple "x/2i $next_insn_addr" $test {
	    -re -wrap $re {
		set next_insn_addr $expect_out(1,string)
	    }
	    -re -wrap "" {
	    }
	}
    }

    if {[gdb_test "stepi" "x/i .*=>.*" "stepi $syscall insn"] != 0} {
	return { -1, -1 }
    }

    set pc_after_stepi [get_hexadecimal_valueof "\$pc" "0" \
			    "pc after stepi"]

    gdb_assert {$next_insn_addr == $pc_after_stepi} \
	"pc after stepi matches insn addr after syscall"

    return [list $syscall_insn_addr $pc_after_stepi]
}

proc step_over_syscall { syscall } {
    with_test_prefix "$syscall" {
	global syscall_insn
	global gdb_prompt

	set testfile "step-over-$syscall"

	set options [list debug]
	if { $syscall == "clone" } {
	    lappend options "pthreads"
	}

	if [build_executable ${testfile}.exp ${testfile} ${testfile}.c $options] {
	    untested "failed to compile"
	    return -1
	}

	foreach_with_prefix displaced {"off" "on"} {
	    if {$displaced == "on" && ![support_displaced_stepping]} {
		continue
	    }

	    set ret [setup $syscall]

	    set syscall_insn_addr [lindex $ret 0]
	    set syscall_insn_next_addr [lindex $ret 1]
	    if { $syscall_insn_addr == -1 } {
		return -1
	    }

	    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
		"continue to $syscall (3rd time)"

	    # Hit the breakpoint on $syscall for the third time.  In this time, we'll set
	    # breakpoint on the syscall insn we recorded previously, and single step over it.

	    set syscall_insn_bp 0
	    gdb_test_multiple "break \*$syscall_insn_addr"  "break on syscall insn" {
		-re "Breakpoint (\[0-9\]*) at .*$gdb_prompt $" {
		    set syscall_insn_bp $expect_out(1,string)
		    pass "break on syscall insns"
		}
	    }

	    # Check if the syscall breakpoint is at the syscall instruction
	    # address.  If so, no need to continue, otherwise we will run the
	    # inferior to completion.
	    if {$syscall_insn_addr != [get_hexadecimal_valueof "\$pc" "0"]} {
		gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, .*" \
		    "continue to syscall insn $syscall"
	    }

	    gdb_test_no_output "set displaced-stepping $displaced"

	    # Check the address of next instruction of syscall.
	    if {[gdb_test "stepi" "x/i .*=>.*" "single step over $syscall"] != 0} {
		return -1
	    }
	    check_pc_after_cross_syscall $displaced $syscall $syscall_insn_next_addr

	    # Delete breakpoint syscall insns to avoid interference to other syscalls.
	    delete_breakpoints

	    gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"

	    # If we are displaced stepping over a clone syscall then
	    # we expect the following check to fail.  See also the
	    # code in check_pc_after_cross_syscall.
	    if { $displaced == "on" && $syscall == "clone" } {
		# GDB doesn't support stepping over clone syscall with
		# displaced stepping.
		setup_kfail "*-*-*" "gdb/19675"
	    }

	    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
		"continue to marker ($syscall)"
	}
    }
}

# Set a breakpoint with a condition that evals false on syscall
# instruction.  In fact, it tests GDBserver steps over syscall
# instruction.  SYSCALL is the syscall the program calls.
# FOLLOW_FORK is either "parent" or "child".  DETACH_ON_FORK is
# "on" or "off".

proc break_cond_on_syscall { syscall follow_fork detach_on_fork } {
    with_test_prefix "break cond on target : $syscall" {
	set testfile "step-over-$syscall"

	set ret [setup $syscall]

	set syscall_insn_addr [lindex $ret 0]
	set syscall_insn_next_addr [lindex $ret 1]
	if { $syscall_insn_addr == -1 } {
	    return -1
	}

	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
	    "continue to $syscall"
	# Delete breakpoint syscall insns to avoid interference with other syscalls.
	delete_breakpoints

	gdb_test "set follow-fork-mode $follow_fork"
	gdb_test "set detach-on-fork $detach_on_fork"

	# Create a breakpoint with a condition that evals false.
	gdb_test "break \*$syscall_insn_addr if main == 0" \
	    "Breakpoint \[0-9\]* at .*"

	if { $syscall == "clone" } {
	    # Create a breakpoint in the child with the condition that
	    # evals false, so that GDBserver can get the event from the
	    # child but GDB doesn't see it.  In this way, we don't have
	    # to adjust the test flow for "clone".
	    # This is a regression test for PR server/19736.  In this way,
	    # we can test that GDBserver gets an event from the child and
	    # set suspend count correctly while the parent is stepping over
	    # the breakpoint.
	    gdb_test "break clone_fn if main == 0"
	}

	if { $syscall == "clone" } {
	    # follow-fork and detach-on-fork only make sense to
	    # fork and vfork.
	    gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
	    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
		"continue to marker"
	} else {
	    if { $follow_fork == "child" } {
		gdb_test "continue" "exited normally.*" "continue to end of inf 2"
		if { $detach_on_fork == "off" } {
		    gdb_test "inferior 1"
		    gdb_test "break marker" "Breakpoint.*at.*"
		    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
			"continue to marker"
		}
	    } else {
		gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
		gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
		    "continue to marker"
	    }
	}
    }
}

step_over_syscall "fork"
step_over_syscall "vfork"
step_over_syscall "clone"

set testfile "step-over-fork"
clean_restart $testfile
if { ![runto_main] } then {
    fail "run to main"
    return -1
}

set cond_bp_target 1

set test "set breakpoint condition-evaluation target"
gdb_test_multiple $test $test {
    -re "warning: Target does not support breakpoint condition evaluation.\r\nUsing host evaluation mode instead.\r\n$gdb_prompt $" {
	# Target doesn't support breakpoint condition
	# evaluation on its side.
	set cond_bp_target 0
    }
    -re "^$test\r\n$gdb_prompt $" {
    }
}

if { $cond_bp_target } {

    foreach_with_prefix detach-on-fork {"on" "off"} {
	foreach_with_prefix follow-fork {"parent" "child"} {
	    foreach syscall { "fork" "vfork" "clone" } {

		if { $syscall == "vfork"
		     && ${follow-fork} == "parent"
		     && ${detach-on-fork} == "off" } {
		    # Both vforked child process and parent process are
		    # under GDB's control, but GDB follows the parent
		    # process only, which can't be run until vforked child
		    # finishes.  Skip the test in this scenario.
		    continue
		}
		break_cond_on_syscall $syscall ${follow-fork} ${detach-on-fork}
	    }
	}
    }
}