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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.
|
||
|---|---|---|
| .. | ||
| aarch64-atomic-inst.c | ||
| aarch64-atomic-inst.exp | ||
| alpha-step.c | ||
| alpha-step.exp | ||
| altivec-abi.c | ||
| altivec-abi.exp | ||
| altivec-regs.c | ||
| altivec-regs.exp | ||
| amd64-byte.exp | ||
| amd64-disp-step.exp | ||
| amd64-disp-step.S | ||
| amd64-dword.exp | ||
| amd64-entry-value-inline.c | ||
| amd64-entry-value-inline.exp | ||
| amd64-entry-value-inline.S | ||
| amd64-entry-value-param.c | ||
| amd64-entry-value-param.exp | ||
| amd64-entry-value-param.S | ||
| amd64-entry-value-paramref.cc | ||
| amd64-entry-value-paramref.exp | ||
| amd64-entry-value-paramref.S | ||
| amd64-entry-value.cc | ||
| amd64-entry-value.exp | ||
| amd64-entry-value.s | ||
| amd64-i386-address.exp | ||
| amd64-i386-address.S | ||
| amd64-invalid-stack-middle.c | ||
| amd64-invalid-stack-middle.exp | ||
| amd64-invalid-stack-middle.S | ||
| amd64-invalid-stack-top.c | ||
| amd64-invalid-stack-top.exp | ||
| amd64-optimout-repeat.c | ||
| amd64-optimout-repeat.exp | ||
| amd64-optimout-repeat.S | ||
| amd64-prologue-xmm.c | ||
| amd64-prologue-xmm.exp | ||
| amd64-prologue-xmm.s | ||
| amd64-pseudo.c | ||
| amd64-stap-optional-prefix.exp | ||
| amd64-stap-optional-prefix.S | ||
| amd64-stap-special-operands.exp | ||
| amd64-stap-three-arg-disp.c | ||
| amd64-stap-three-arg-disp.S | ||
| amd64-stap-triplet.c | ||
| amd64-stap-triplet.S | ||
| amd64-stap-wrong-subexp.exp | ||
| amd64-stap-wrong-subexp.S | ||
| amd64-tailcall-cxx1.cc | ||
| amd64-tailcall-cxx1.S | ||
| amd64-tailcall-cxx2.cc | ||
| amd64-tailcall-cxx2.S | ||
| amd64-tailcall-cxx.exp | ||
| amd64-tailcall-noret.c | ||
| amd64-tailcall-noret.exp | ||
| amd64-tailcall-noret.S | ||
| amd64-tailcall-ret.c | ||
| amd64-tailcall-ret.exp | ||
| amd64-tailcall-ret.S | ||
| amd64-word.exp | ||
| arm-bl-branch-dest.c | ||
| arm-bl-branch-dest.exp | ||
| arm-disp-step.exp | ||
| arm-disp-step.S | ||
| avr-flash-qualifier.c | ||
| avr-flash-qualifier.exp | ||
| e500-abi.c | ||
| e500-abi.exp | ||
| e500-prologue.c | ||
| e500-prologue.exp | ||
| e500-regs.c | ||
| e500-regs.exp | ||
| gdb1291.exp | ||
| gdb1291.s | ||
| gdb1431.exp | ||
| gdb1431.s | ||
| gdb1558.c | ||
| gdb1558.exp | ||
| i386-avx512.c | ||
| i386-avx512.exp | ||
| i386-avx.c | ||
| i386-avx.exp | ||
| i386-bp_permanent.c | ||
| i386-bp_permanent.exp | ||
| i386-byte.exp | ||
| i386-cfi-notcurrent.exp | ||
| i386-cfi-notcurrent.S | ||
| i386-disp-step.exp | ||
| i386-disp-step.S | ||
| i386-dr3-watch.c | ||
| i386-dr3-watch.exp | ||
| i386-float.exp | ||
| i386-float.S | ||
| i386-gnu-cfi-asm.S | ||
| i386-gnu-cfi.c | ||
| i386-gnu-cfi.exp | ||
| i386-mpx.c | ||
| i386-mpx.exp | ||
| i386-permbkpt.exp | ||
| i386-permbkpt.S | ||
| i386-prologue.c | ||
| i386-prologue.exp | ||
| i386-pseudo.c | ||
| i386-signal.c | ||
| i386-signal.exp | ||
| i386-size-overlap.c | ||
| i386-size-overlap.exp | ||
| i386-size.c | ||
| i386-size.exp | ||
| i386-sse-stack-align.c | ||
| i386-sse-stack-align.exp | ||
| i386-sse-stack-align.S | ||
| i386-sse.c | ||
| i386-sse.exp | ||
| i386-stap-eval-lang-ada.c | ||
| i386-stap-eval-lang-ada.exp | ||
| i386-stap-eval-lang-ada.S | ||
| i386-unwind.c | ||
| i386-unwind.exp | ||
| i386-word.exp | ||
| ia64-breakpoint-shadow.exp | ||
| ia64-breakpoint-shadow.S | ||
| iwmmxt-regs.c | ||
| iwmmxt-regs.exp | ||
| Makefile.in | ||
| mips16-thunks-inmain.c | ||
| mips16-thunks-main.c | ||
| mips16-thunks-sin.c | ||
| mips16-thunks-sinfrob16.c | ||
| mips16-thunks-sinfrob.c | ||
| mips16-thunks-sinmain.c | ||
| mips16-thunks-sinmips16.c | ||
| mips16-thunks.exp | ||
| mips-octeon-bbit.c | ||
| mips-octeon-bbit.exp | ||
| pa64-nullify.s | ||
| pa-nullify.exp | ||
| pa-nullify.s | ||
| powerpc-aix-prologue.c | ||
| powerpc-aix-prologue.exp | ||
| powerpc-d128-regs.c | ||
| powerpc-d128-regs.exp | ||
| powerpc-power.exp | ||
| powerpc-power.s | ||
| powerpc-prologue.c | ||
| powerpc-prologue.exp | ||
| powerpc-stackless.exp | ||
| powerpc-stackless.S | ||
| ppc64-atomic-inst.exp | ||
| ppc64-atomic-inst.S | ||
| ppc-dfp.c | ||
| ppc-dfp.exp | ||
| ppc-fp.c | ||
| ppc-fp.exp | ||
| s390-multiarch.c | ||
| s390-multiarch.exp | ||
| s390-tdbregs.c | ||
| s390-tdbregs.exp | ||
| sparc-sysstep.c | ||
| sparc-sysstep.exp | ||
| spu-info.c | ||
| spu-info.exp | ||
| spu-ls.c | ||
| spu-ls.exp | ||
| thumb2-it.exp | ||
| thumb2-it.S | ||
| thumb-bx-pc.exp | ||
| thumb-bx-pc.S | ||
| thumb-prologue.c | ||
| thumb-prologue.exp | ||
| thumb-singlestep.exp | ||
| thumb-singlestep.S | ||
| vsx-regs.c | ||
| vsx-regs.exp | ||