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- .. contents::
- .. sectnum::
- ===================================================
- BPF ABI Recommended Conventions and Guidelines v1.0
- ===================================================
- This is version 1.0 of an informational document containing recommended
- conventions and guidelines for producing portable BPF program binaries.
- Registers and calling convention
- ================================
- BPF has 10 general purpose registers and a read-only frame pointer register,
- all of which are 64-bits wide.
- The BPF calling convention is defined as:
- * R0: return value from function calls, and exit value for BPF programs
- * R1 - R5: arguments for function calls
- * R6 - R9: callee saved registers that function calls will preserve
- * R10: read-only frame pointer to access stack
- R0 - R5 are scratch registers and BPF programs needs to spill/fill them if
- necessary across calls.
- The BPF program needs to store the return value into register R0 before doing an
- ``EXIT``.
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