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authorWill Hawkins <whh8b@obs.cr>2023-04-28 04:30:15 +0200
committerAlexei Starovoitov <ast@kernel.org>2023-05-05 17:20:39 +0200
commit69535186297b37e6e0a16290766666f4e8a55793 (patch)
tree06d4dd2bf8e4a91165600b791b1ab7ef6dff7840 /Documentation/bpf
parentMerge branch 'Add precision propagation for subprogs and callbacks' (diff)
downloadlinux-69535186297b37e6e0a16290766666f4e8a55793.tar.xz
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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>
Diffstat (limited to 'Documentation/bpf')
-rw-r--r--Documentation/bpf/llvm_reloc.rst18
1 files changed, 10 insertions, 8 deletions
diff --git a/Documentation/bpf/llvm_reloc.rst b/Documentation/bpf/llvm_reloc.rst
index ca8957d5b671..e4a777a6a3a2 100644
--- a/Documentation/bpf/llvm_reloc.rst
+++ b/Documentation/bpf/llvm_reloc.rst
@@ -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.
-
-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
+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 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``.