mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2025-01-12 12:16:04 +08:00
af48d08f97
The gdb.arch/i386-bp_permanent.exp test is currently failing an
assertion recently added:
(gdb) stepi
../../src/gdb/infrun.c:2237: internal-error: resume: Assertion `sig != GDB_SIGNAL_0' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
FAIL: gdb.arch/i386-bp_permanent.exp: Single stepping past permanent breakpoint. (GDB internal error)
The assertion expects that the only reason we currently need to step a
breakpoint instruction is when we have a signal to deliver. But when
stepping a permanent breakpoint (with or without a signal) we also
reach this code.
The assertion is correct and the permanent breakpoints skipping code
is wrong.
Consider the case of the user doing "step/stepi" when stopped at a
permanent breakpoint. GDB's `resume' calls the
gdbarch_skip_permanent_breakpoint hook and then happily continues
stepping:
/* Normally, by the time we reach `resume', the breakpoints are either
removed or inserted, as appropriate. The exception is if we're sitting
at a permanent breakpoint; we need to step over it, but permanent
breakpoints can't be removed. So we have to test for it here. */
if (breakpoint_here_p (aspace, pc) == permanent_breakpoint_here)
{
gdbarch_skip_permanent_breakpoint (gdbarch, regcache);
}
But since gdbarch_skip_permanent_breakpoint already advanced the PC
manually, this ends up executing the instruction that is _after_ the
breakpoint instruction. The user-visible result is that a single-step
steps two instructions.
The gdb.arch/i386-bp_permanent.exp test is actually ensuring that
that's indeed how things work. It runs to an int3 instruction, does
"stepi", and checks that "leave" was executed with that "stepi". Like
this:
(gdb) b *0x0804848c
Breakpoint 2 at 0x804848c
(gdb) c
Continuing.
Breakpoint 2, 0x0804848c in standard ()
(gdb) disassemble
Dump of assembler code for function standard:
0x08048488 <+0>: push %ebp
0x08048489 <+1>: mov %esp,%ebp
0x0804848b <+3>: push %edi
=> 0x0804848c <+4>: int3
0x0804848d <+5>: leave
0x0804848e <+6>: ret
0x0804848f <+7>: nop
(gdb) si
0x0804848e in standard ()
(gdb) disassemble
Dump of assembler code for function standard:
0x08048488 <+0>: push %ebp
0x08048489 <+1>: mov %esp,%ebp
0x0804848b <+3>: push %edi
0x0804848c <+4>: int3
0x0804848d <+5>: leave
=> 0x0804848e <+6>: ret
0x0804848f <+7>: nop
End of assembler dump.
(gdb)
One would instead expect that a stepi at 0x0804848c stops at
0x0804848d, _before_ the "leave" is executed. This commit changes GDB
this way. Care is taken to make stepping into a signal handler when
the step starts at a permanent breakpoint instruction work correctly.
The patch adjusts gdb.arch/i386-bp_permanent.exp in this direction,
and also makes it work on x86_64 (currently it only works on i*86).
The patch also adds a new gdb.base/bp-permanent.exp test that
exercises many different code paths related to stepping permanent
breakpoints, including the stepping with signals cases. The test uses
"hack/trick" to make it work on all (or most) platforms -- it doesn't
really hard code a breakpoint instruction.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2014-11-12 Pedro Alves <palves@redhat.com>
* infrun.c (resume): Clear the thread's 'stepped_breakpoint' flag.
Rewrite stepping over a permanent breakpoint.
(thread_still_needs_step_over, proceed): Don't set
stepping_over_breakpoint for permanent breakpoints.
(handle_signal_stop): Don't clear stepped_breakpoint. Also pull
single-step breakpoints out of the target on hardware step
targets.
(process_event_stop_test): If stepping a permanent breakpoint
doesn't hit the step-resume breakpoint, delete the step-resume
breakpoint.
(switch_back_to_stepped_thread): Also check if the stepped thread
has advanced already on hardware step targets.
(currently_stepping): Return true if the thread stepped a
breakpoint.
gdb/testsuite/
2014-11-12 Pedro Alves <palves@redhat.com>
* gdb.arch/i386-bp_permanent.c: New file.
* gdb.arch/i386-bp_permanent.exp: Don't skip on x86_64.
(srcfile): Set to i386-bp_permanent.c.
(top level): Adjust to work in both 32-bit and 64-bit modes. Test
that stepi does not execute the 'leave' instruction, instead of
testing it does execute.
* gdb.base/bp-permanent.c: New file.
* gdb.base/bp-permanent.exp: New file.
90 lines
2.7 KiB
Plaintext
90 lines
2.7 KiB
Plaintext
# Copyright (C) 2008-2014 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 on i386.
|
|
|
|
if { ![istarget "i?86-*-*"] && ![istarget "x86_64-*-*"] } then {
|
|
verbose "Skipping skip over permanent breakpoint on i386 tests."
|
|
return
|
|
}
|
|
|
|
set testfile "i386-bp_permanent"
|
|
set srcfile i386-bp_permanent.c
|
|
set binfile ${objdir}/${subdir}/${testfile}
|
|
|
|
# some targets have leading underscores on assembly symbols.
|
|
set additional_flags [gdb_target_symbol_prefix_flags]
|
|
|
|
# Don't use "debug", so that we don't have line information for the assembly
|
|
# fragments.
|
|
if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable [list $additional_flags]] != "" } {
|
|
untested ${testfile}.exp
|
|
return -1
|
|
}
|
|
|
|
|
|
gdb_exit
|
|
gdb_start
|
|
gdb_reinitialize_dir $srcdir/$subdir
|
|
gdb_load ${binfile}
|
|
|
|
#
|
|
# Run to `main' where we begin our tests.
|
|
#
|
|
|
|
if ![runto_main] then {
|
|
return -1
|
|
}
|
|
|
|
set function "standard"
|
|
|
|
set retcode [gdb_test_multiple "disassemble $function" "Disassemble function '$function'" {
|
|
-re "($hex) <\\+0>.*($hex) <\\+$decimal>.*int3.*($hex) <\\+$decimal>.*leave.*$gdb_prompt $" {
|
|
set address_bp $expect_out(2,string)
|
|
set address_after_bp $expect_out(3,string)
|
|
}
|
|
}]
|
|
|
|
if {$retcode != 0} {
|
|
fail "Disassemble failed, skipping entire test."
|
|
return -1
|
|
}
|
|
|
|
gdb_breakpoint "*$address_bp"
|
|
|
|
gdb_test "continue" "Breakpoint .*, $address_bp in $function.*" \
|
|
"stop at permanent breakpoint"
|
|
|
|
# We want to fetch the stack pointer at the start of '$function'
|
|
# function to make sure the skip_permanent_breakpoint implementation
|
|
# really skips only the permanent breakpoint. If, for whatever
|
|
# reason, the 'leave' instruction executes, the stack pointer will not
|
|
# have this value.
|
|
set start_sp 0
|
|
gdb_test_multiple "print \$sp" "fetch stack pointer value" {
|
|
-re "\\\$1.*($hex).*$gdb_prompt $" {
|
|
set start_sp $expect_out(1,string)
|
|
}
|
|
}
|
|
|
|
gdb_test "stepi" "$address_after_bp in $function.*" \
|
|
"single-step past permanent breakpoint"
|
|
|
|
gdb_test "print \$sp" ".*$start_sp.*" \
|
|
"stack pointer value matches"
|