diff options
106 files changed, 4444 insertions, 619 deletions
diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst index 609b71f5747d..de27e1620821 100644 --- a/Documentation/bpf/bpf_devel_QA.rst +++ b/Documentation/bpf/bpf_devel_QA.rst @@ -635,12 +635,12 @@ test coverage. Q: clang flag for target bpf? ----------------------------- -Q: In some cases clang flag ``-target bpf`` is used but in other cases the +Q: In some cases clang flag ``--target=bpf`` is used but in other cases the default clang target, which matches the underlying architecture, is used. What is the difference and when I should use which? A: Although LLVM IR generation and optimization try to stay architecture -independent, ``-target <arch>`` still has some impact on generated code: +independent, ``--target=<arch>`` still has some impact on generated code: - BPF program may recursively include header file(s) with file scope inline assembly codes. The default target can handle this well, @@ -658,7 +658,7 @@ independent, ``-target <arch>`` still has some impact on generated code: The clang option ``-fno-jump-tables`` can be used to disable switch table generation. -- For clang ``-target bpf``, it is guaranteed that pointer or long / +- For clang ``--target=bpf``, it is guaranteed that pointer or long / unsigned long types will always have a width of 64 bit, no matter whether underlying clang binary or default target (or kernel) is 32 bit. However, when native clang target is used, then it will @@ -668,7 +668,7 @@ independent, ``-target <arch>`` still has some impact on generated code: while the BPF LLVM back end still operates in 64 bit. The native target is mostly needed in tracing for the case of walking ``pt_regs`` or other kernel structures where CPU's register width matters. - Otherwise, ``clang -target bpf`` is generally recommended. + Otherwise, ``clang --target=bpf`` is generally recommended. You should use default target when: @@ -685,7 +685,7 @@ when: into these structures is verified by the BPF verifier and may result in verification failures if the native architecture is not aligned with the BPF architecture, e.g. 64-bit. An example of this is - BPF_PROG_TYPE_SK_MSG require ``-target bpf`` + BPF_PROG_TYPE_SK_MSG require ``--target=bpf`` .. Links diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index 7cd7c5415a99..f32db1f44ae9 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -990,7 +990,7 @@ format.:: } g2; int main() { return 0; } int test() { return 0; } - -bash-4.4$ clang -c -g -O2 -target bpf t2.c + -bash-4.4$ clang -c -g -O2 --target=bpf t2.c -bash-4.4$ readelf -S t2.o ...... [ 8] .BTF PROGBITS 0000000000000000 00000247 @@ -1000,7 +1000,7 @@ format.:: [10] .rel.BTF.ext REL 0000000000000000 000007e0 0000000000000040 0000000000000010 16 9 8 ...... - -bash-4.4$ clang -S -g -O2 -target bpf t2.c + -bash-4.4$ clang -S -g -O2 --target=bpf t2.c -bash-4.4$ cat t2.s ...... .section .BTF,"",@progbits diff --git a/Documentation/bpf/index.rst b/Documentation/bpf/index.rst index dbb39e8f9889..1ff177b89d66 100644 --- a/Documentation/bpf/index.rst +++ b/Documentation/bpf/index.rst @@ -12,9 +12,9 @@ that goes into great technical depth about the BPF Architecture. .. toctree:: :maxdepth: 1 - instruction-set verifier libbpf/index + standardization/index btf faq syscall_api @@ -29,7 +29,6 @@ that goes into great technical depth about the BPF Architecture. bpf_licensing test_debug clang-notes - linux-notes other redirect diff --git a/Documentation/bpf/llvm_reloc.rst b/Documentation/bpf/llvm_reloc.rst index e4a777a6a3a2..450e6403fe3d 100644 --- a/Documentation/bpf/llvm_reloc.rst +++ b/Documentation/bpf/llvm_reloc.rst @@ -28,7 +28,7 @@ For example, for the following code:: return g1 + g2 + l1 + l2; } -Compiled with ``clang -target bpf -O2 -c test.c``, the following is +Compiled with ``clang --target=bpf -O2 -c test.c``, the following is the code with ``llvm-objdump -dr test.o``:: 0: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll @@ -157,7 +157,7 @@ and ``call`` instructions. For example:: return gfunc(a, b) + lfunc(a, b) + global; } -Compiled with ``clang -target bpf -O2 -c test.c``, we will have +Compiled with ``clang --target=bpf -O2 -c test.c``, we will have following code with `llvm-objdump -dr test.o``:: Disassembly of section .text: @@ -203,7 +203,7 @@ The following is an example to show how R_BPF_64_ABS64 could be generated:: int global() { return 0; } struct t { void *g; } gbl = { global }; -Compiled with ``clang -target bpf -O2 -g -c test.c``, we will see a +Compiled with ``clang --target=bpf -O2 -g -c test.c``, we will see a relocation below in ``.data`` section with command ``llvm-readelf -r test.o``:: diff --git a/Documentation/bpf/standardization/index.rst b/Documentation/bpf/standardization/index.rst new file mode 100644 index 000000000000..09c6ba055fd7 --- /dev/null +++ b/Documentation/bpf/standardization/index.rst @@ -0,0 +1,18 @@ +.. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) + +=================== +BPF Standardization +=================== + +This directory contains documents that are being iterated on as part of the BPF +standardization effort with the IETF. See the `IETF BPF Working Group`_ page +for the working group charter, documents, and more. + +.. toctree:: + :maxdepth: 1 + + instruction-set + linux-notes + +.. Links: +.. _IETF BPF Working Group: https://datatracker.ietf.org/wg/bpf/about/ diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst index 6644842cd3ea..751e657973f0 100644 --- a/Documentation/bpf/instruction-set.rst +++ b/Documentation/bpf/standardization/instruction-s |