bpf: mark tail calls using __declare_tail, remove iproute2 compat code #39510
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bimmlerd
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May 13, 2025
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smagnani96
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May 16, 2025
cilium_calls was the last map on the deprecated bpf_elf_map format. This patch converts the map definition to BTF and replaces the __section_tail macro with __declare_tail that implicitly uses cilium_calls, as it was only calls map left that was populated statically from the ELF. Drop reasons were moved out to drop_reasons.h to avoid including common.h from lib/tailcall.h, which would otherwise need a tc or xdp context defined. skb.h and xdp.h no longer declare __section_entry directly; instead, they now declare a common section name stem for other macros to use, like __declare_tail. Make sure a context header is included before tailcall.h to avoid ending up with the macro name in the section name like PROG_TYPE/tail. Signed-off-by: Timo Beckers <timo@isovalent.com>
common.h imports tailcall.h, which now requires a program type to be chosen before importing the header to avoid ending up with a section name like PROG_TYPE/entry. In many cases, the amount of explicit imports was slightly reduced and made more consistent. Signed-off-by: Timo Beckers <timo@isovalent.com>
…entry This was always meant as an off-ramp from the iproute2 loader, so now this code no longer needs to be there. Explicitly specify a type on every program. Remove the classifyProgramTypes helper in favor of a check with a helpful error message suggesting the right macros to use. Signed-off-by: Timo Beckers <timo@isovalent.com>
Since ebpf-go 1.17, the library automatically resizes the log buffer when needed. This test should've been removed during the upgrade. Signed-off-by: Timo Beckers <timo@isovalent.com>
…l tags
This commit removes the venerable ip2 compat code. The new conventions are:
- {tc,xdp}/entry section marks bpf entry points or mocked tail calls in bpf
tests
- {tc,xdp}/tail section marks tail calls to be inserted into cilium_calls
- The tail:cilium_calls/<slot> decl tag format is now used to specify which
slot the tail call is inserted to after loading
The prior commits got the bpf C code base in shape to conform to these
conventions.
Signed-off-by: Timo Beckers <timo@isovalent.com>
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Some highlights:
cilium_calls was the last map on the deprecated bpf_elf_map format. This patch converts the map definition to BTF and replaces the __section_tail macro with __declare_tail that implicitly uses cilium_calls, as it was only calls map left that was populated statically from the ELF.
The datapath now requires a program type to be chosen before importing the header to avoid ending up with a section name like PROG_TYPE/entry. The loader now rejects any programs of unspecified type. The loader used to pick one based on a 🪄 heuristic 🪄 (it was the object file name..).
Entrypoints now go into the
{tc,xdp}/entrysections, tail calls go into the{tc,xdp}/tailsections, and decl tags are used for specifying their slot in thecilium_callsmap. Use the__section_entryand__declare_tail()macros to mark programs as their respective types.