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| author | Brendan Jackman <jackmanb@google.com> | 2021-01-20 13:39:45 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-01-20 17:02:49 -0800 |
| commit | 53fe5418fe3f286ddb28fc0f0862923a9c94d671 (patch) | |
| tree | 9739295731d9473ba31998db3afeb921082dff81 /Documentation/networking | |
| parent | 636d549f9133886663cba4e42c7a619d5e2e6e7f (diff) | |
| download | linux-53fe5418fe3f286ddb28fc0f0862923a9c94d671.tar.bz2 | |
docs: bpf: Fixup atomics markup
This fixes up the markup to fix a warning, be more consistent with
use of monospace, and use the correct .rst syntax for <em> (* instead
of _).
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/bpf/20210120133946.2107897-2-jackmanb@google.com
Diffstat (limited to 'Documentation/networking')
| -rw-r--r-- | Documentation/networking/filter.rst | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/Documentation/networking/filter.rst b/Documentation/networking/filter.rst index 45f6fde1776c..4c2bb4c6364d 100644 --- a/Documentation/networking/filter.rst +++ b/Documentation/networking/filter.rst @@ -1066,12 +1066,12 @@ memory location addresed by ``dst_reg + off`` is atomically modified, with immediate, then these operations also overwrite ``src_reg`` with the value that was in memory before it was modified. -The more special operations are: +The more special operations are:: BPF_XCHG This atomically exchanges ``src_reg`` with the value addressed by ``dst_reg + -off``. +off``. :: BPF_CMPXCHG @@ -1081,18 +1081,19 @@ before is loaded back to ``R0``. Note that 1 and 2 byte atomic operations are not supported. -Except ``BPF_ADD`` _without_ ``BPF_FETCH`` (for legacy reasons), all 4 byte +Except ``BPF_ADD`` *without* ``BPF_FETCH`` (for legacy reasons), all 4 byte atomic operations require alu32 mode. Clang enables this mode by default in architecture v3 (``-mcpu=v3``). For older versions it can be enabled with ``-Xclang -target-feature -Xclang +alu32``. -You may encounter BPF_XADD - this is a legacy name for BPF_ATOMIC, referring to -the exclusive-add operation encoded when the immediate field is zero. +You may encounter ``BPF_XADD`` - this is a legacy name for ``BPF_ATOMIC``, +referring to the exclusive-add operation encoded when the immediate field is +zero. -eBPF has one 16-byte instruction: BPF_LD | BPF_DW | BPF_IMM which consists +eBPF has one 16-byte instruction: ``BPF_LD | BPF_DW | BPF_IMM`` which consists of two consecutive ``struct bpf_insn`` 8-byte blocks and interpreted as single instruction that loads 64-bit immediate value into a dst_reg. -Classic BPF has similar instruction: BPF_LD | BPF_W | BPF_IMM which loads +Classic BPF has similar instruction: ``BPF_LD | BPF_W | BPF_IMM`` which loads 32-bit immediate value into a register. eBPF verifier |