Re: [PATCH 2/2][AArch64] Test handling of additional brk instruction patterns

[Simon Marchi <simark at simark dot ca>]

On 2020-01-13 12:25 p.m., Luis Machado wrote:
> This test exercises the previous patch's code and makes sure GDB can
> properly get a SIGTRAP from various brk instruction patterns.
> 
> GDB needs to be able to see the program exiting normally. If GDB doesn't
> support the additional brk instructions, we will see timeouts.
> 
> We bail out with the first timeout since we won't be able to step through
> the program breakpoint anyway, so it is no use carrying on.
> 
> gdb/testsuite/ChangeLog:
> 
> 2020-01-13  Luis Machado  <luis.machado@linaro.org>
> 
> 	* gdb.arch/aarch64-brk-patterns.c: New source file.
> 	* gdb.arch/aarch64-brk-patterns.exp: New test.
> ---
>  gdb/testsuite/gdb.arch/aarch64-brk-patterns.c | 30 +++++++++
>  .../gdb.arch/aarch64-brk-patterns.exp         | 67 +++++++++++++++++++
>  2 files changed, 97 insertions(+)
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-brk-patterns.c
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-brk-patterns.exp
> 
> diff --git a/gdb/testsuite/gdb.arch/aarch64-brk-patterns.c b/gdb/testsuite/gdb.arch/aarch64-brk-patterns.c
> new file mode 100644
> index 0000000000..ccf9a35a94
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-brk-patterns.c
> @@ -0,0 +1,30 @@
> +/* This file is part of GDB, the GNU debugger.
> +
> +   Copyright 2020 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/>.  */
> +
> +int main(void)
> +{
> +  /* Dummy instruction just so GDB doesn't stop at the first breakpoint
> +     instruction.  */
> +  __asm __volatile ("nop\n\t");
> +
> +  /* Multiple BRK instruction patterns.  */
> +  __asm __volatile ("brk %0\n\t" ::"n"(0x0));
> +  __asm __volatile ("brk %0\n\t" ::"n"(0x900 + 0xf));
> +  __asm __volatile ("brk %0\n\t" ::"n"(0xf000));
> +
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/aarch64-brk-patterns.exp b/gdb/testsuite/gdb.arch/aarch64-brk-patterns.exp
> new file mode 100644
> index 0000000000..3532a0df95
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-brk-patterns.exp
> @@ -0,0 +1,67 @@
> +# Copyright 2020 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 if GDB stops at various BRK instruction patterns inserted into
> +# the code.
> +
> +if {![is_aarch64_target]} {
> +    verbose "Skipping ${gdb_test_file_name}."
> +    return
> +}
> +
> +standard_testfile
> +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
> +    return -1
> +}
> +
> +if ![runto_main] {
> +    untested "could not run to main"
> +    return -1
> +}
> +
> +set keep_going 1
> +set count 0
> +set old_timeout $timeout
> +set timeout 10
> +
> +while { $keep_going } {
> +
> +  set test "brk instruction $count causes SIGTRAP"
> +
> +  # Continue to next program breakpoint instruction.
> +  gdb_test_multiple "continue" $test {
> +      -re "Program received signal SIGTRAP, Trace/breakpoint trap.*$gdb_prompt $" {
> +	  pass $test
> +
> +	  # Insert a breakpoint at the program breakpoint instruction so GDB
> +	  # can step over it.
> +	  gdb_test "break" \
> +	    "Breakpoint $decimal at $hex: file .*$srcfile, line $decimal.*" \
> +	    "insert breakpoint at brk instruction $count"
> +      }
> +      -re "exited normally.*$gdb_prompt $" {
> +	  set keep_going 0
> +      }
> +      timeout {
> +	  fail $test
> +	  set keep_going 0
> +      }
> +  }
> +  set count [expr "$count + 1"]
> +}
> +
> +set timeout $old_timeout
> -- 
> 2.17.1
> 

I don't see anything wrong with the test, but I was wondering if we should
assert that $count is the right value in the end, to make sure that we did
hit the expected number of breakpoints.

Simon