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bpf, docs: Update llvm_relocs.rst with typo fixes
Correct a few typographical errors and fix some mistakes in examples.
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230428023015.1698072-2-hawkinsw@obs.cr
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
authored by
Will Hawkins
and committed by
Alexei Starovoitov
69535186
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Documentation/bpf/llvm_reloc.rst
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Documentation/bpf/llvm_reloc.rst
···
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14: 0f 10 00 00 00 00 00 00 r0 += r1
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15: 95 00 00 00 00 00 00 00 exit
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There are four relations in the above for four ``LD_imm64`` instructions.
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There are four relocations in the above for four ``LD_imm64`` instructions.
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The following ``llvm-readelf -r test.o`` shows the binary values of the four
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relocations::
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···
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The 6th entry is global variable ``g1`` with value 0.
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Similarly, the second relocation is at ``.text`` offset ``0x18``, instruction 3,
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for global variable ``g2`` which has a symbol value 4, the offset
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from the start of ``.data`` section.
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has a type of ``R_BPF_64_64`` and refers to entry 7 in the symbol table.
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The second relocation resolves to global variable ``g2`` which has a symbol
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value 4. The symbol value represents the offset from the start of ``.data``
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section where the initial value of the global variable ``g2`` is stored.
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The third and fourth relocations refers to static variables ``l1``
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and ``l2``. From ``.rel.text`` section above, it is not clear
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which symbols they really refers to as they both refers to
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The third and fourth relocations refer to static variables ``l1``
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and ``l2``. From the ``.rel.text`` section above, it is not clear
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to which symbols they really refer as they both refer to
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symbol table entry 4, symbol ``sec``, which has ``STT_SECTION`` type
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and represents a section. So for static variable or function,
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and represents a section. So for a static variable or function,
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the section offset is written to the original insn
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buffer, which is called ``A`` (addend). Looking at
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above insn ``7`` and ``11``, they have section offset ``8`` and ``12``.