[v1.15] Replaced declare_tailcall_if with logic in the loader #31554
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[ upstream commit 46db413 ] Remove `declare_tailcall_if`, so we always emit the tailcall programs into the ELF. The followup commit will implement pruning logic based on the actual usage of the tail calls. This means that we will only need the `invoke_tailcall_if` without the need to keep both the declaration and invocation in sync. Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com> Signed-off-by: Timo Beckers <timo@isovalent.com>
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[ upstream commit c4cbb38 ] Before this change the tail_call_static function would emit the following instructions to perform a tailcall: ``` Mov R1, Rctx Mov R2, Rmap_ptr Mov R3, <slot> Call TailCall ``` Since the second instruction is always a Register to Register move, we would have to backtrack to find the actual map which is being used. These changes makes it so the following instructions are emitted: ``` Mov R1, Rctx Mov R2, 0 ll <calls_map> Mov R3, <slot> Call TailCall ``` By always using a double word immediate, with a relocation entry on the Mov R2 instruction it is much easier to find the actual map which is being used. As a side effect, we usually eliminate an extra instruction clang was otherwise forced to emit. Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com>
[ upstream commit 16033b9 ] This commit implements unreachable tail call pruning. When loading a collection we check if a tail call is reachable. If not, we remove the tail call from the collection. This saves us from having to load the tail call program into the kernel. Previously, we would conditionally not include tail calls in the collection with pre-processor directives. Now that we do it in the loader, we can remove the pre-processor directives. Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com>
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We might also want to include #31419 where the CI contrib script got fixed which included an issue in my initial PR |
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[ upstream commit 217426a ] [ backporter's notes: regenerated testdata ] This commit adds a test to verify the behavior of the dead tail call pruning. It consists of 5 tail calls, of which 2 are unreachable. The test asserts that only the unreachable tail calls are removed from the spec. Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com> Signed-off-by: Timo Beckers <timo@isovalent.com>
[ upstream commit e1afa06 ] The changes to the dead tail call elimination revealed 2 cases of missing tail calls. First is to do with NAT46x64 logic where there still existed a call path from the IPv4 logic which would attempt to tail call into IPv6 to recirculate the packet, even when the IPv6 tail call wasn't compiled in. The second was that when XDP offloaded, the IPv6 logic would tail call into a ICMP6 tail call which is only compiled in for TC programs. This commit fixes both possible missing tail calls. Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com> Signed-off-by: Timo Beckers <timo@isovalent.com>
[ upstream commit d6666ed ] Currently, check-go-testdata.sh doesn't work as expected on CI. It reports the following error and the GitHub action (Go Precheck) succeeds without error. ``` contrib/scripts/check-go-testdata.sh make[1]: Entering directory '/home/runner/work/cilium/cilium/src/github.com/cilium/cilium/pkg/bpf/testdata' docker run -it --rm -v /home/runner/work/cilium/cilium/src/github.com/cilium/cilium:/cilium quay.io/cilium/cilium-builder:819a4f1e57eaacb6aabfc6a1a39d11d4fd794a88@sha256:24781dc80f2be2d8fd66b0ce1405e1f117a3a0ef388758b1ede7831778e3a4f7 clang -target bpf -Wall -O2 -g -I -I/usr/include -I/cilium/bpf -I/cilium/bpf/include -c /cilium/pkg/bpf/testdata/unreachable-tailcall.c -o /cilium/pkg/bpf/testdata/unreachable-tailcall.o the input device is not a TTY make[1]: *** [Makefile:9: build] Error 1 make[1]: Leaving directory '/home/runner/work/cilium/cilium/src/github.com/cilium/cilium/pkg/bpf/testdata' ``` This commit fixes the following issues: - Don't execute docker interactive - Use 'set -e' in check script Signed-off-by: Marco Hofstetter <marco.hofstetter@isovalent.com>
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declare_tailcall_ifwith logic in the loader #30467 (@dylandreimerink)Once this PR is merged, a GitHub action will update the labels of these PRs: