[DTrace-devel] [PATCH] test: Clean up stack_fbt test

[Kris Van Hees]

On Thu, Oct 16, 2025 at 04:56:41PM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> The idea behind the test is to check the stack() output for some fbt
> probe for specific expected frames.  An attempt was made to specify the
> exact stack that was expected, but there are too many variations among
> kernel versions and so maintaining the test was difficult.  Loosen the
> test to check for only a few expected frames.
> 
> The test was also checking that stack()'s first 3 frames matched
> stack(3), but such a test is already provided by, for example,
>     test/unittest/printf/tst.stack.d
>     test/unittest/stack/tst.stack.d
> So, drop the stack(3) stuff.
> 
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

... with caveat that we really ought to take a look at some of these tests
    that need more frequent updating due to kernel details changing underneath
    us.

> ---
>  test/unittest/stack/tst.stack_fbt.r  |  1 +
>  test/unittest/stack/tst.stack_fbt.sh | 89 +++++++---------------------
>  2 files changed, 23 insertions(+), 67 deletions(-)
>  create mode 100644 test/unittest/stack/tst.stack_fbt.r
> 
> diff --git a/test/unittest/stack/tst.stack_fbt.r b/test/unittest/stack/tst.stack_fbt.r
> new file mode 100644
> index 000000000..2e9ba477f
> --- /dev/null
> +++ b/test/unittest/stack/tst.stack_fbt.r
> @@ -0,0 +1 @@
> +success
> diff --git a/test/unittest/stack/tst.stack_fbt.sh b/test/unittest/stack/tst.stack_fbt.sh
> index 15b85be13..f3d321e7f 100755
> --- a/test/unittest/stack/tst.stack_fbt.sh
> +++ b/test/unittest/stack/tst.stack_fbt.sh
> @@ -5,7 +5,7 @@
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
>  #
> -# Test the stack action with default stack depth and depth 3.
> +# Check the stack action for expected frames.
>  
>  dtrace=$1
>  
> @@ -26,8 +26,6 @@ BEGIN
>  fbt::vfs_write:entry
>  {
>  	stack();
> -	printf("first 3 frames\n");
> -	stack(3);
>  	exit(0);
>  }' >& dtrace.out
>  
> @@ -37,17 +35,16 @@ if [ $? -ne 0 ]; then
>  	exit 1
>  fi
>  
> -# Strip out
> -# - blank lines
> -# - "constprop"
> -# - "isra"
> +# Ignore blank lines and strip out
> +# - ".constprop.[0-9]"
>  # - "_after_hwframe"    (x86 starting with UEK8)
> -# - pointer values
> +# - "+0x[0-9a-f]*$"
> +# - leading spaces
>  
>  awk 'NF != 0 { sub("\\.constprop\\.[0-9]", "");
> -               sub("\\.isra\\.[0-9]", "");
>                 sub("_after_hwframe\\+", "+");
> -               sub(/+0x[0-9a-f]*$/, "+{ptr}");
> +               sub(/+0x[0-9a-f]*$/, "");
> +               sub(/^ */, "");
>                 print }' dtrace.out > dtrace.post
>  if [ $? -ne 0 ]; then
>  	echo ERROR: awk failed
> @@ -55,77 +52,35 @@ if [ $? -ne 0 ]; then
>  	exit 1
>  fi
>  
> -# Figure out what stack to expect.
> +# Identify, in order, a few frames we expect to see.
>  
> -read MAJOR MINOR <<< `uname -r | grep -Eo '^[0-9]+\.[0-9]+' | tr '.' ' '`
> -
> -if [ $MAJOR -eq 5 -a $MINOR -lt 8 ]; then
> -	# up to 5.8
> -	KERVER="A"
> -else
> -	# starting at 5.8
> -	KERVER="B"
> -fi
> -
> -if [ $(uname -m) == "x86_64" -a $KERVER == "A" ]; then
> -cat << EOF > dtrace.cmp
> -              vmlinux\`vfs_write+{ptr}
> -              vmlinux\`__x64_sys_write+{ptr}
> -              vmlinux\`x64_sys_call+{ptr}
> -              vmlinux\`do_syscall_64+{ptr}
> -              vmlinux\`entry_SYSCALL_64+{ptr}
> -EOF
> -elif [ $(uname -m) == "aarch64" -a $KERVER == "A" ]; then
> -cat << EOF > dtrace.cmp
> -              vmlinux\`vfs_write
> -              vmlinux\`__arm64_sys_write+{ptr}
> -              vmlinux\`el0_svc_common+{ptr}
> -              vmlinux\`el0_svc_handler+{ptr}
> -              vmlinux\`el0_svc+{ptr}
> -EOF
> -elif [ $(uname -m) == "x86_64" -a $KERVER == "B" ]; then
> -cat << EOF > dtrace.cmp
> -              vmlinux\`vfs_write+{ptr}
> -              vmlinux\`ksys_write+{ptr}
> -              vmlinux\`do_syscall_64+{ptr}
> -              vmlinux\`entry_SYSCALL_64+{ptr}
> -EOF
> -elif [ $(uname -m) == "aarch64" -a $KERVER == "B" ]; then
> -cat << EOF > dtrace.cmp
> -              vmlinux\`vfs_write
> -              vmlinux\`__arm64_sys_write+{ptr}
> -              vmlinux\`invoke_syscall+{ptr}
> -              vmlinux\`el0_svc_common+{ptr}
> -              vmlinux\`do_el0_svc+{ptr}
> -              vmlinux\`el0_svc+{ptr}
> -              vmlinux\`el0t_64_sync_handler+{ptr}
> -              vmlinux\`el0t_64_sync+{ptr}
> -EOF
> +if [ $(uname -m) == "x86_64" ]; then
> +	frames="vfs_write do_syscall_64 entry_SYSCALL_64"
> +elif [ $(uname -m) == "aarch64" ]; then
> +	frames="vfs_write __arm64_sys_write el0_svc_common el0_svc"
>  else
>  	echo ERROR: unrecognized platform
>  	uname -r
>  	uname -m
>  	exit 1
>  fi
> -
> -# Add the first 3 frames a second time.
> -
> -head -3 dtrace.cmp > dtrace.tmp
> -echo first 3 frames >> dtrace.cmp
> -cat dtrace.tmp >> dtrace.cmp
> +for frame in $frames; do
> +	echo 'vmlinux`'$frame >> dtrace.cmp
> +done
>  
>  # Compare results.
>  
> -if ! diff -q dtrace.cmp dtrace.post; then
> -	echo ERROR: results do not match
> -	diff dtrace.cmp dtrace.post
> -	echo "==== expect"
> +diff dtrace.cmp dtrace.post | grep '^<' > missing.frames
> +if [ `cat missing.frames | wc -l` -ne 0 ]; then
> +	echo ERROR: missing some expected frames
> +	echo === expected frames include:
>  	cat dtrace.cmp
> -	echo "==== actual"
> +	echo === actual frames are:
>  	cat dtrace.out
> +	echo === missing expected frames:
> +	cat missing.frames
>  	exit 1
>  fi
>  
>  echo success
> -
>  exit 0
> -- 
> 2.47.3
>