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bc3905a71f
The tailcall_bpf2bpf_hierarchy_fentry test hangs on s390. Its call
graph is as follows:
entry()
subprog_tail()
trampoline()
fentry()
the rest of subprog_tail() # via BPF_TRAMP_F_CALL_ORIG
return to entry()
The problem is that the rest of subprog_tail() increments the tail call
counter, but the trampoline discards the incremented value. This
results in an astronomically large number of tail calls.
Fix by making the trampoline write the incremented tail call counter
back.
Fixes: 528eb2cb87 ("s390/bpf: Implement arch_prepare_bpf_trampoline()")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250813121016.163375-4-iii@linux.ibm.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.