Re: [RFC] [gdb/testsuite] Add xfail in gdb.base/hbreak.exp

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

On 7/17/24 16:10, Tom de Vries wrote:
> On an aarch64-linux system with 32-bit userland running in a chroot, and using
> target board unix/mthumb I get:
> ...
> (gdb) hbreak hbreak.c:27^M
> Hardware assisted breakpoint 2 at 0x4004e2: file hbreak.c, line 27.^M

That is a bit odd, but it goes through the compat layer, which is not exercised
as often as the 32-bit code.

Let me see if I can reproduce this one on my end.


> (gdb) PASS: gdb.base/hbreak.exp: hbreak
> continue^M
> Continuing.^M
> Unexpected error setting breakpoint: Invalid argument.^M
> (gdb) FAIL: gdb.base/hbreak.exp: continue to break-at-exit after hbreak
> ...
> due to this call in arm_linux_nat_target::low_prepare_to_resume:
> ...
>           if (ptrace (PTRACE_SETHBPREGS, pid,
>               (PTRACE_TYPE_ARG3) ((i << 1) + 1), &bpts[i].address) < 0)
>             perror_with_name (_("Unexpected error setting breakpoint"));
> ...
> 
> This problem does not happen if instead we use a 4-byte aligned address.
> 
> I'm not sure if this is simply unsupported or if there's a kernel bug of some
> sort, but I don't see what gdb can do about this.
> 
> Tentatively mark this as xfail.
> 
> Tested on aarch64-linux.
> ---
>  gdb/testsuite/gdb.base/hbreak.exp | 40 ++++++++++++++++++++++++++-----
>  1 file changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.base/hbreak.exp b/gdb/testsuite/gdb.base/hbreak.exp
> index 73a3e2afb67..b140257a23e 100644
> --- a/gdb/testsuite/gdb.base/hbreak.exp
> +++ b/gdb/testsuite/gdb.base/hbreak.exp
> @@ -27,10 +27,38 @@ if ![runto_main] {
>  
>  set breakline [gdb_get_line_number "break-at-exit"]
>  
> -gdb_test "hbreak ${srcfile}:${breakline}" \
> -	 "Hardware assisted breakpoint \[0-9\]+ at 0x\[0-9a-f\]+: file .*${srcfile}, line ${breakline}\\." \
> -	 "hbreak"
> +set re_loc "file \[^\r\n\]*$srcfile, line $breakline"
> +set re_dot [string_to_regexp .]
>  
> -gdb_test "continue" \
> -	 "Continuing\\.\[ \r\n\]+Breakpoint \[0-9\]+, .*break-at-exit.*" \
> -	 "continue to break-at-exit after hbreak"
> +set addr 0x0
> +gdb_test_multiple "hbreak ${srcfile}:${breakline}" "hbreak" {
> +    -re -wrap "Hardware assisted breakpoint $decimal at ($hex): $re_loc$re_dot" {
> +	set addr $expect_out(1,string)
> +	pass $gdb_test_name
> +    }
> +}
> +
> +set have_xfail 0
> +if { [istarget arm*-*-*] } {
> +    # When running 32-bit userland on aarch64 kernel, thumb instructions that
> +    # are not 4-byte aligned may not be supported for setting a hardware
> +    # breakpoint on.
> +    set have_xfail [expr ($addr & 0x2) == 2]
> +}
> +
> +set re_xfail \
> +    [string_to_regexp \
> +	 "Unexpected error setting breakpoint: Invalid argument."]
> +
> +gdb_test_multiple "continue" "continue to break-at-exit after hbreak" {
> +    -re -wrap "Continuing\\.\[ \r\n\]+Breakpoint \[0-9\]+, .*break-at-exit.*" {
> +	pass $gdb_test_name
> +    }
> +    -re -wrap $re_xfail {
> +	if { $have_xfail } {
> +	    xfail $gdb_test_name
> +	} else {
> +	    fail $gdb_test_name
> +	}
> +    }
> +}
> 
> base-commit: 0ed152c5c6b3c72fc505b331ed77e08b438d643a