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4ce150b6a4
Now that binutils and gcc support for BPF is upstream, make use of it in
BPF selftests using alu32-like approach. Share as much as possible of
CFLAGS calculation with clang.
Fixes only obvious issues, leaving more complex ones for later:
- Use gcc-provided bpf-helpers.h instead of manually defining the
helpers, change bpf_helpers.h include guard to avoid conflict.
- Include <linux/stddef.h> for __always_inline.
- Add $(OUTPUT)/../usr/include to include path in order to use local
kernel headers instead of system kernel headers when building with O=.
In order to activate the bpf-gcc support, one needs to configure
binutils and gcc with --target=bpf and make them available in $PATH. In
particular, gcc must be installed as `bpf-gcc`, which is the default.
Right now with binutils 25a2915e8dba and gcc r275589 only a handful of
tests work:
# ./test_progs_bpf_gcc
# Summary: 7/39 PASSED, 1 SKIPPED, 98 FAILED
The reason for those failures are as follows:
- Build errors:
- `error: too many function arguments for eBPF` for __always_inline
functions read_str_var and read_map_var - must be inlining issue,
and for process_l3_headers_v6, which relies on optimizing away
function arguments.
- `error: indirect call in function, which are not supported by eBPF`
where there are no obvious indirect calls in the source calls, e.g.
in __encap_ipip_none.
- `error: field 'lock' has incomplete type` for fields of `struct
bpf_spin_lock` type - bpf_spin_lock is re#defined by bpf-helpers.h,
so its usage is sensitive to order of #includes.
- `error: eBPF stack limit exceeded` in sysctl_tcp_mem.
- Load errors:
- Missing object files due to above build errors.
- `libbpf: failed to create map (name: 'test_ver.bss')`.
- `libbpf: object file doesn't contain bpf program`.
- `libbpf: Program '.text' contains unrecognized relo data pointing to
section 0`.
- `libbpf: BTF is required, but is missing or corrupted` - no BTF
support in gcc yet.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Jose E. Marchesi <jose.marchesi@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text 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.