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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>
This commit is contained in:
Will Hawkins 2023-04-27 22:30:15 -04:00 committed by Alexei Starovoitov
parent fbc0b02530
commit 6953518629
1 changed files with 9 additions and 7 deletions
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16
Documentation/bpf/llvm_reloc.rst
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@ -48,7 +48,7 @@ the code with ``llvm-objdump -dr test.o``::
14: 0f 10 00 00 00 00 00 00 r0 += r1
15: 95 00 00 00 00 00 00 00 exit
There are four relations in the above for four ``LD_imm64`` instructions.
There are four relocations in the above for four ``LD_imm64`` instructions.
The following ``llvm-readelf -r test.o`` shows the binary values of the four
relocations::
@ -79,14 +79,16 @@ The following is the symbol table with ``llvm-readelf -s test.o``::
The 6th entry is global variable ``g1`` with value 0.
Similarly, the second relocation is at ``.text`` offset ``0x18``, instruction 3,
for global variable ``g2`` which has a symbol value 4, the offset
from the start of ``.data`` section.
has a type of ``R_BPF_64_64`` and refers to entry 7 in the symbol table.
The second relocation resolves to global variable ``g2`` which has a symbol
value 4. The symbol value represents the offset from the start of ``.data``
section where the initial value of the global variable ``g2`` is stored.
The third and fourth relocations refers to static variables ``l1``
and ``l2``. From ``.rel.text`` section above, it is not clear
which symbols they really refers to as they both refers to
The third and fourth relocations refer to static variables ``l1``
and ``l2``. From the ``.rel.text`` section above, it is not clear
to which symbols they really refer as they both refer to
symbol table entry 4, symbol ``sec``, which has ``STT_SECTION`` type
and represents a section. So for static variable or function,
and represents a section. So for a static variable or function,
the section offset is written to the original insn
buffer, which is called ``A`` (addend). Looking at
above insn ``7`` and ``11``, they have section offset ``8`` and ``12``.