1# This testcase is part of GDB, the GNU debugger. 2 3# Copyright 2004, 2005, 2007 Free Software Foundation, Inc. 4 5# This program is free software; you can redistribute it and/or modify 6# it under the terms of the GNU General Public License as published by 7# the Free Software Foundation; either version 3 of the License, or 8# (at your option) any later version. 9# 10# This program is distributed in the hope that it will be useful, 11# but WITHOUT ANY WARRANTY; without even the implied warranty of 12# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13# GNU General Public License for more details. 14# 15# You should have received a copy of the GNU General Public License 16# along with this program. If not, see <http://www.gnu.org/licenses/>. 17 18# Check that GDB can and only executes single instructions when 19# stepping through a sequence of breakpoints interleaved by a signal 20# handler. 21 22# This test is known to tickle the following problems: kernel letting 23# the inferior execute both the system call, and the instruction 24# following, when single-stepping a system call; kernel failing to 25# propogate the single-step state when single-stepping the sigreturn 26# system call, instead resuming the inferior at full speed; GDB 27# doesn't know how to software single-step across a sigreturn 28# instruction. Since the kernel problems can be "fixed" using 29# software single-step this is KFAILed rather than XFAILed. 30 31if [target_info exists gdb,nosignals] { 32 verbose "Skipping sigbpt.exp because of nosignals." 33 continue 34} 35 36if $tracelevel { 37 strace $tracelevel 38} 39 40set prms_id 0 41set bug_id 0 42 43set testfile "sigbpt" 44set srcfile ${testfile}.c 45set binfile ${objdir}/${subdir}/${testfile} 46if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } { 47 untested sigbpt.exp 48 return -1 49} 50 51gdb_exit 52gdb_start 53gdb_reinitialize_dir $srcdir/$subdir 54gdb_load ${binfile} 55 56# 57# Run to `main' where we begin our tests. 58# 59 60if ![runto_main] then { 61 gdb_suppress_tests 62} 63 64# If we can examine what's at memory address 0, it is possible that we 65# could also execute it. This could probably make us run away, 66# executing random code, which could have all sorts of ill effects, 67# especially on targets without an MMU. Don't run the tests in that 68# case. 69 70send_gdb "x 0\n" 71gdb_expect { 72 -re "0x0:.*Cannot access memory at address 0x0.*$gdb_prompt $" { } 73 -re "0x0:.*Error accessing memory address 0x0.*$gdb_prompt $" { } 74 -re ".*$gdb_prompt $" { 75 untested "Memory at address 0 is possibly executable" 76 return 77 } 78} 79 80gdb_test "break keeper" 81 82# Run to bowler, and then single step until there's a SIGSEGV. Record 83# the address of each single-step instruction (up to and including the 84# instruction that causes the SIGSEGV) in bowler_addrs, and the address 85# of the actual SIGSEGV in segv_addr. 86 87set bowler_addrs bowler 88set segv_addr none 89gdb_test {display/i $pc} 90gdb_test "advance *bowler" "bowler.*" "advance to the bowler" 91set test "stepping to SIGSEGV" 92gdb_test_multiple "stepi" "$test" { 93 -re "Program received signal SIGSEGV.*pc(\r\n| *) *(0x\[0-9a-f\]*).*$gdb_prompt $" { 94 set segv_addr $expect_out(2,string) 95 pass "$test" 96 } 97 -re " .*pc(\r\n| *)(0x\[0-9a-f\]*).*bowler.*$gdb_prompt $" { 98 set bowler_addrs [concat $expect_out(2,string) $bowler_addrs] 99 send_gdb "stepi\n" 100 exp_continue 101 } 102} 103 104# Now record the address of the instruction following the faulting 105# instruction in bowler_addrs. 106 107set test "get insn after fault" 108gdb_test_multiple {x/2i $pc} "$test" { 109 -re "(0x\[0-9a-f\]*).*bowler.*(0x\[0-9a-f\]*).*bowler.*$gdb_prompt $" { 110 set bowler_addrs [concat $expect_out(2,string) $bowler_addrs] 111 pass "$test" 112 } 113} 114 115# Procedures for returning the address of the instruction before, at 116# and after, the faulting instruction. 117 118proc before_segv { } { 119 global bowler_addrs 120 return [lindex $bowler_addrs 2] 121} 122 123proc at_segv { } { 124 global bowler_addrs 125 return [lindex $bowler_addrs 1] 126} 127 128proc after_segv { } { 129 global bowler_addrs 130 return [lindex $bowler_addrs 0] 131} 132 133# Check that the address table and SIGSEGV correspond. 134 135set test "Verify that SIGSEGV occurs at the last STEPI insn" 136if {[string compare $segv_addr [at_segv]] == 0} { 137 pass "$test" 138} else { 139 fail "$test ($segv_addr [at_segv])" 140} 141 142# Check that the inferior is correctly single stepped all the way back 143# to a faulting instruction. 144 145proc stepi_out { name args } { 146 global gdb_prompt 147 148 # Set SIGSEGV to pass+nostop and then run the inferior all the way 149 # through to the signal handler. With the handler is reached, 150 # disable SIGSEGV, ensuring that further signals stop the 151 # inferior. Stops a SIGSEGV infinite loop when a broke system 152 # keeps re-executing the faulting instruction. 153 rerun_to_main 154 gdb_test "handle SIGSEGV nostop print pass" "" "${name}; pass SIGSEGV" 155 gdb_test "continue" "keeper.*" "${name}; continue to keeper" 156 gdb_test "handle SIGSEGV stop print nopass" "" "${name}; nopass SIGSEGV" 157 158 # Insert all the breakpoints. To avoid the need to step over 159 # these instructions, this is delayed until after the keeper has 160 # been reached. 161 for {set i 0} {$i < [llength $args]} {incr i} { 162 gdb_test "break [lindex $args $i]" "Breakpoint.*" \ 163 "${name}; set breakpoint $i of [llength $args]" 164 } 165 166 # Single step our way out of the keeper, through the signal 167 # trampoline, and back to the instruction that faulted. 168 set test "${name}; stepi out of handler" 169 gdb_test_multiple "stepi" "$test" { 170 -re "Could not insert single-step breakpoint.*$gdb_prompt $" { 171 setup_kfail "sparc*-*-openbsd*" gdb/1736 172 fail "$test (could not insert single-step breakpoint)" 173 } 174 -re "keeper.*$gdb_prompt $" { 175 send_gdb "stepi\n" 176 exp_continue 177 } 178 -re "signal handler.*$gdb_prompt $" { 179 send_gdb "stepi\n" 180 exp_continue 181 } 182 -re "Program received signal SIGSEGV.*$gdb_prompt $" { 183 kfail gdb/1702 "$test (executed fault insn)" 184 } 185 -re "Breakpoint.*pc(\r\n| *)[at_segv] .*bowler.*$gdb_prompt $" { 186 pass "$test (at breakpoint)" 187 } 188 -re "Breakpoint.*pc(\r\n| *)[after_segv] .*bowler.*$gdb_prompt $" { 189 kfail gdb/1702 "$test (executed breakpoint)" 190 } 191 -re "pc(\r\n| *)[at_segv] .*bowler.*$gdb_prompt $" { 192 pass "$test" 193 } 194 -re "pc(\r\n| *)[after_segv] .*bowler.*$gdb_prompt $" { 195 kfail gdb/1702 "$test (skipped fault insn)" 196 } 197 -re "pc(\r\n| *)0x\[a-z0-9\]* .*bowler.*$gdb_prompt $" { 198 kfail gdb/1702 "$test (corrupt pc)" 199 } 200 } 201 202 # Clear any breakpoints 203 for {set i 0} {$i < [llength $args]} {incr i} { 204 gdb_test "clear [lindex $args $i]" "Deleted .*" \ 205 "${name}; clear breakpoint $i of [llength $args]" 206 } 207} 208 209# Let a signal handler exit, returning to a breakpoint instruction 210# inserted at the original fault instruction. Check that the 211# breakpoint is hit, and that single stepping off that breakpoint 212# executes the underlying fault instruction causing a SIGSEGV. 213 214proc cont_out { name args } { 215 global gdb_prompt 216 217 # Set SIGSEGV to pass+nostop and then run the inferior all the way 218 # through to the signal handler. With the handler is reached, 219 # disable SIGSEGV, ensuring that further signals stop the 220 # inferior. Stops a SIGSEGV infinite loop when a broke system 221 # keeps re-executing the faulting instruction. 222 rerun_to_main 223 gdb_test "handle SIGSEGV nostop print pass" "" "${name}; pass SIGSEGV" 224 gdb_test "continue" "keeper.*" "${name}; continue to keeper" 225 gdb_test "handle SIGSEGV stop print nopass" "" "${name}; nopass SIGSEGV" 226 227 # Insert all the breakpoints. To avoid the need to step over 228 # these instructions, this is delayed until after the keeper has 229 # been reached. Always set a breakpoint at the signal trampoline 230 # instruction. 231 set args [concat $args "*[at_segv]"] 232 for {set i 0} {$i < [llength $args]} {incr i} { 233 gdb_test "break [lindex $args $i]" "Breakpoint.*" \ 234 "${name}; set breakpoint $i of [llength $args]" 235 } 236 237 # Let the handler return, it should "appear to hit" the breakpoint 238 # inserted at the faulting instruction. Note that the breakpoint 239 # instruction wasn't executed, rather the inferior was SIGTRAPed 240 # with the PC at the breakpoint. 241 gdb_test "continue" "Breakpoint.*pc(\r\n| *)[at_segv] .*" \ 242 "${name}; continue to breakpoint at fault" 243 244 # Now single step the faulted instrction at that breakpoint. 245 gdb_test "stepi" \ 246 "Program received signal SIGSEGV.*pc(\r\n| *)[at_segv] .*" \ 247 "${name}; stepi fault" 248 249 # Clear any breakpoints 250 for {set i 0} {$i < [llength $args]} {incr i} { 251 gdb_test "clear [lindex $args $i]" "Deleted .*" \ 252 "${name}; clear breakpoint $i of [llength $args]" 253 } 254 255} 256 257 258 259# Try to confuse DECR_PC_AFTER_BREAK architectures by scattering 260# breakpoints around the faulting address. In all cases the inferior 261# should single-step out of the signal trampoline halting (but not 262# executing) the fault instruction. 263 264stepi_out "stepi" 265stepi_out "stepi bp before segv" "*[before_segv]" 266stepi_out "stepi bp at segv" "*[at_segv]" 267stepi_out "stepi bp before and at segv" "*[at_segv]" "*[before_segv]" 268 269 270# Try to confuse DECR_PC_AFTER_BREAK architectures by scattering 271# breakpoints around the faulting address. In all cases the inferior 272# should exit the signal trampoline halting at the breakpoint that 273# replaced the fault instruction. 274cont_out "cont" 275cont_out "cont bp after segv" "*[before_segv]" 276cont_out "cont bp before and after segv" "*[before_segv]" "*[after_segv]" 277