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I have a fun exception to this! When writing BPF programs, sometimes it's tricky to get the compiler to generate code that passes the verifier. This can lead y
by bjackman 2y ago
I have a fun exception to this!
When writing BPF programs, sometimes it's tricky to get the compiler to generate code that passes the verifier. This can lead you down a path of writing bizarre C in order to try and produce the right order of checks and register allocations.
So, use inline asm!
It's not portable any more... But it's a BPF program! There's nothing to port it to.
It's less readable... Wait no, it's _more_ readable because BPF asm has good syntax and you can avoid the bizarre C backflips to satisfy the verifier.
It's unsafe... Wait no, it's checked for safety at load time!
- deleted 2y ago[deleted]
- ryandrake 2y agoFor the curious, BPF in this case might mean Berkeley Packet Filter[1]. Not sure. Kind of an obscure acronym but Google search seems to have a consensus. 1: https://en.wikipedia.org/wiki/Berkeley_Packet_Filter https://en.wikipedia.org/wiki/Berkeley_Packet_Filter
- wyldfire 2y agoIt does. These days, it's probably eBPF and a popular target is the linux kernel [1]. You can write C hooks for tracing and profiling, etc. - with inline asm! [1] https://docs.kernel.org/bpf/ https://docs.kernel.org/bpf/