[DTrace-devel] [PATCH] test: skip when /proc/kallmodsyms is not present

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>

On 2/9/26 14:04, Kris Van Hees wrote:
> On Mon, Feb 09, 2026 at 01:55:03PM -0500, Eugene Loh wrote:
>> I'm rusty on this stuff, but maybe you can help me out.  What happens with
>> the test if kallmodsyms is not there?  The test does not directly rely on
>> that file.  The test simply makes libdtrace calls, and dt_modsym_update()
>> can fail over to kallsyms if kallmodsyms is not present.
> The .x file depends on being able to read kallmodsyms to determine whether
> the kernel fix that the test depends on is in the running kernel, which
> cannot be when kallmodsyms isn't even in the kernel.
>
> Without kallmodsyms, this test becomes a verifier for the kallsyms data that
> the kernel provides, and then only in terms of loaded modules, which is pretty
> much guaranteed to be correct or the kernel modules would be conflicting and
> cause horrible crashes of the kernel.
>
> With modules.builtin.ranges, the association of an address with a builtin
> module is done by performing a lookup of the symbol address in the data that
> modules.builtin.ranges provides.  If that has overlapping ranges, then this
> is a kernel bug, and this test wouldn't be able to detect it anyway.
>
> So, if kallmodsyms is not present, the test is useless.
>
>> On 2/9/26 13:34, Kris Van Hees wrote:
>>> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
>>> ---
>>>    test/unittest/consumer/tst.merge_ranges_bug25767469.x | 6 +++++-
>>>    1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/test/unittest/consumer/tst.merge_ranges_bug25767469.x b/test/unittest/consumer/tst.merge_ranges_bug25767469.x
>>> index 7e265f2f..a92690ad 100755
>>> --- a/test/unittest/consumer/tst.merge_ranges_bug25767469.x
>>> +++ b/test/unittest/consumer/tst.merge_ranges_bug25767469.x
>>> @@ -1,10 +1,14 @@
>>>    #!/bin/bash
>>>    #
>>>    # Oracle Linux DTrace.
>>> -# Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
>>> +# Copyright (c) 2018, 2026, Oracle and/or its affiliates. All rights reserved.
>>>    # Licensed under the Universal Permissive License v 1.0 as shown at
>>>    # http://oss.oracle.com/licenses/upl.
>>> +# If /proc/kallmodsyms does not exist, there is nothing to test.
>>> +
>>> +[[ -r /proc/kallmodsyms ]] || exit 2
>>> +
>>>    # The test depends on a kernel fix to report kernel (and built-in-module)
>>>    # symbol sizes correctly in /proc/kallmodsyms.  An easy check is to count
>>>    # how many kernel and built-in-module symbols (that is, symbols that appear