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-rw-r--r--Documentation/bpf/standardization/instruction-set.rst6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst
index b44bdacd0195..997560abadab 100644
--- a/Documentation/bpf/standardization/instruction-set.rst
+++ b/Documentation/bpf/standardization/instruction-set.rst
@@ -469,6 +469,12 @@ JSLT 0xc any PC += offset if dst < src signed
JSLE 0xd any PC += offset if dst <= src signed
======== ===== ======= ================================= ===================================================
+where 'PC' denotes the program counter, and the offset to increment by
+is in units of 64-bit instructions relative to the instruction following
+the jump instruction. Thus 'PC += 1' skips execution of the next
+instruction if it's a basic instruction or results in undefined behavior
+if the next instruction is a 128-bit wide instruction.
+
The BPF program needs to store the return value into register R0 before doing an
``EXIT``.