Re: [PATCH v3 4/5] gdb/testsuite: Add gdb.arch/aarch64-mops-single-step.exp

[Luis Machado <luis.machado@arm.com>]

Thanks. Just one nit.

On 5/10/24 06:24, Thiago Jung Bauermann wrote:
> The testcase verifies that MOPS sequences are correctly single-stepped.
> ---
>  .../gdb.arch/aarch64-mops-single-step.c       |  73 ++++++++++
>  .../gdb.arch/aarch64-mops-single-step.exp     | 132 ++++++++++++++++++
>  2 files changed, 205 insertions(+)
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-mops-single-step.c
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-mops-single-step.exp
> 
> Changes in v3:
> - Renamed gdb.arch/aarch64-mops-atomic-inst.exp to
>   gdb.arch/aarch64-mops-single-step.exp.
> - Adjusted test to expect the MOPS sequence to reset back to the prologue
>   instruction.
> - Set size variable before the cpyf and cpy sequences, because after each
>   sequence the variable is set to zero.  This bug didn't affect the
>   effectiveness of the test.
> 
> Changes in v2:
> - Add prfm instruction after each MOPS sequence and look for it in the
>   testcase to verify that the sequence was stepped through (Suggested by
>   Christophe).
> 
> diff --git a/gdb/testsuite/gdb.arch/aarch64-mops-single-step.c b/gdb/testsuite/gdb.arch/aarch64-mops-single-step.c
> new file mode 100644
> index 000000000000..4a27867d4b57
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-mops-single-step.c
> @@ -0,0 +1,73 @@
> +/* This file is part of GDB, the GNU debugger.
> +
> +   Copyright 2024 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/>.  */
> +
> +#define TEST_STRING "Just a test string."
> +#define BUF_SIZE sizeof(TEST_STRING)
> +
> +int
> +main (void)
> +{
> +  char source[BUF_SIZE] = TEST_STRING;
> +  char dest[BUF_SIZE];
> +  char *p, *q;
> +  long size, zero;
> +
> +  /* Note: The prfm instruction in the asm statements below is there just
> +     to allow the testcase to recognize when the PC is at the instruction
> +     right after the MOPS sequence.  */
> +
> +  p = dest;
> +  size = sizeof (dest);
> +  zero = 0;
> +  /* Break memset.  */
> +  /* memset implemented in MOPS instructions.  */
> +  __asm__ volatile ("setp [%0]!, %1!, %2\n\t"
> +		    "setm [%0]!, %1!, %2\n\t"
> +		    "sete [%0]!, %1!, %2\n\t"
> +		    "prfm pldl3keep, [%0, #0]\n\t"
> +		    : "+&r"(p), "+&r"(size)
> +		    : "r"(zero)
> +		    : "memory");
> +
> +  p = dest;
> +  q = source;
> +  size = sizeof (dest);
> +  /* Break memcpy.  */
> +  /* memcpy implemented in MOPS instructions.  */
> +  __asm__ volatile ("cpyfp [%0]!, [%1]!, %2!\n\t"
> +		    "cpyfm [%0]!, [%1]!, %2!\n\t"
> +		    "cpyfe [%0]!, [%1]!, %2!\n\t"
> +		    "prfm pldl3keep, [%0, #0]\n\t"
> +		    : "+&r" (p), "+&r" (q), "+&r" (size)
> +		    :
> +		    : "memory");
> +
> +  p = dest;
> +  q = source;
> +  size = sizeof (dest);
> +  /* Break memmove.  */
> +  /* memmove implemented in MOPS instructions.  */
> +  __asm__ volatile ("cpyp [%0]!, [%1]!, %2!\n\t"
> +		    "cpym [%0]!, [%1]!, %2!\n\t"
> +		    "cpye [%0]!, [%1]!, %2!\n\t"
> +		    "prfm pldl3keep, [%0, #0]\n\t"
> +		    : "+&r" (p), "+&r" (q), "+&r" (size)
> +		    :
> +		    : "memory");
> +
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/aarch64-mops-single-step.exp b/gdb/testsuite/gdb.arch/aarch64-mops-single-step.exp
> new file mode 100644
> index 000000000000..a6390d4bff7e
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-mops-single-step.exp
> @@ -0,0 +1,132 @@
> +# Copyright 2024 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 single stepping through MOPS (memory operations) instruction sequences.
> +
> +require allow_aarch64_mops_tests
> +
> +standard_testfile
> +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} \
> +	  [list debug additional_flags=-march=armv9.3-a]] } {
> +    return -1
> +}
> +
> +# INSTRUCTION should be just its mnemonic, without any arguments.
> +proc is_at_instruction { instruction } {
> +    global gdb_prompt hex
> +
> +    set test "pc points to $instruction"
> +    gdb_test_multiple {x/i $pc} $test {
> +	-re -wrap "=> $hex \[^\r\n\]+:\t$instruction\t\[^\r\n\]+" {
> +	    return 1
> +	}
> +	-re "\r\n$gdb_prompt $" {
> +	    return 0
> +	}
> +    }
> +
> +    return 0
> +}
> +
> +proc arrive_at_instruction { instruction } {
> +    set count 0
> +
> +    while { [is_at_instruction $instruction] != 1 } {
> +	gdb_test -nopass "stepi" ".*__asm__ volatile.*" \
> +	    "stepi #$count to reach $instruction"
> +	incr count
> +
> +	if { $count > 50 } {
> +	    fail "didn't reach $instruction"
> +	    return 0
> +	}
> +    }
> +
> +    return 1
> +}
> +
> +# If the inferior is reschedule to another CPU while a main or epilogue

s/reschedule/rescheduled

> +# instruction is executed, the OS resets the inferior back to the prologue
> +# instruction, so we need to allow for that possibility.
> +proc step_through_sequence { prefix } {
> +    set count 0
> +
> +    while { [is_at_instruction ${prefix}p] == 1 && $count < 50 } {
> +	incr count
> +
> +	# The stepi output isn't useful to detect whether we stepped over
> +	# the instruction.
> +	gdb_test "stepi" "\[^\r\n\]+" "step over ${prefix}p"
> +	if { [is_at_instruction ${prefix}m] == 1 } {
> +	    pass "stepped over ${prefix}p"
> +	} else {
> +	    fail "stepped over ${prefix}e"
> +	    return 0
> +	}
> +
> +	gdb_test "stepi" "\[^\r\n\]+" "step over ${prefix}m"
> +	if { [is_at_instruction ${prefix}e] == 1 } {
> +	    pass "stepped over ${prefix}m"
> +	} elseif { [is_at_instruction ${prefix}p] == 1 } {
> +	    # The inferior was rescheduled to another CPU.
> +	    pass "${prefix}m: reset back to prologue"
> +	    continue
> +	} else {
> +	    fail "stepped over ${prefix}m"
> +	    return 0
> +	}
> +
> +	gdb_test "stepi" "\[^\r\n\]+" "step over ${prefix}e"
> +	if { [is_at_instruction prfm] == 1 } {
> +	    pass "stepped over ${prefix}e"
> +	    return 1
> +	} elseif { [is_at_instruction ${prefix}p] == 1 } {
> +	    # The inferior was rescheduled to another CPU.
> +	    pass "${prefix}e: reset back to prologue"
> +	    continue
> +	}
> +    }
> +
> +    fail "step through $prefix sequence"
> +    return 0
> +}
> +
> +if ![runto_main] {
> +    return -1
> +}
> +
> +gdb_breakpoint ${srcfile}:[gdb_get_line_number "Break memset"]
> +gdb_breakpoint ${srcfile}:[gdb_get_line_number "Break memcpy"]
> +gdb_breakpoint ${srcfile}:[gdb_get_line_number "Break memmove"]
> +
> +gdb_continue_to_breakpoint "memset breakpoint"
> +
> +if { [arrive_at_instruction setp] } {
> +    step_through_sequence set
> +}
> +
> +gdb_continue_to_breakpoint "memcpy breakpoint"
> +
> +if { [arrive_at_instruction cpyfp] } {
> +    step_through_sequence cpyf
> +}
> +
> +gdb_continue_to_breakpoint "memmove breakpoint"
> +
> +if { [arrive_at_instruction cpyp] } {
> +    step_through_sequence cpy
> +}