[Bug tapsets/16956] New: nd_syscall.* tapset shouldn't rely on @cast() against kernel debuginfo

[Bug tapsets/16956] New: nd_syscall.* tapset shouldn't rely on @cast() against kernel debuginfo

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16956

            Bug ID: 16956
           Summary: nd_syscall.* tapset shouldn't rely on @cast() against
                    kernel debuginfo
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: tapsets
          Assignee: systemtap at sourceware dot org
          Reporter: fche at redhat dot com

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[Bug tapsets/16956] nd_syscall.* tapset shouldn't rely on @cast() against kernel debuginfo

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16956

--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> ---
The nd_syscall.* tapset conatins constructs such as:

probe __nd_syscall.socketcall.recv = kprobe.function("sys_socketcall").call ?
{
        asmlinkage()
        if (int_arg(1) != %{ SYS_RECV %}) next;
        __args = pointer_arg(2)
        s = __int32(user_ulong(&@cast(__args, "ulong")[0]))
        buf_uaddr = user_ulong(&@cast(__args, "ulong")[1])
        len = user_ulong(&@cast(__args, "ulong")[2])
        flags = __uint32(user_ulong(&@cast(__args, "ulong")[3]))
}

where all those @cast() expressions require kernel debuginfo
to resolve.  Build a CONFIG_DEBUG_INFO=n vmlinux, as available
on arch-linux e.g., then see

probe nd_syscall.* {}

cause

WARNING: cannot find module kernel debuginfo: No DWARF information found ...
semantic error: type definition 'ulong' not found in 'kernel' ...

The non-dwarf tapset shouldn't need dwarf that it can't fabricate
from e.g. headers like <linux/types.h>.

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[Bug tapsets/16956] nd_syscall.* tapset shouldn't rely on @cast() against kernel debuginfo

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16956

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #2 from Frank Ch. Eigler <fche at redhat dot com> ---
commit 11415bc59172

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[Bug tapsets/16956] nd_syscall.* tapset shouldn't rely on @cast() against kernel debuginfo

[dsmith at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16956

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dsmith at redhat dot com

--- Comment #3 from David Smith <dsmith at redhat dot com> ---
I improved things a bit more here in commit 27ce133. Now the nd_syscall tapset
testsuite sets SYSTEMTAP_DEBUGINFO_PATH to /dev/null, so that we can catch
errors like this on systems with debuginfo.

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