The patchset fixes a tailcall hierarchy issue.
The issue is confirmed in the discussions of "bpf, x64: Fix tailcall infinite
loop"[0].
The issue is only resolved on x86.
Hopefully, the issue on arm64 and s390x will be resolved soon.
I provide a long commit message in the second patch to describe how the issue
happens and how this patchset resolves the issue in detail.
RFC v2 -> v1:
* address comments from Maciej:
* Replace all memcpy(prog, x86_nops[5], X86_PATCH_SIZE) with
emit_nops(&prog, X86_PATCH_SIZE)
RFC v1 -> RFC v2:
* address comments from Stanislav:
* Separate moving emit_nops() as first patch.
Links:
[0] https://lore.kernel.org/bpf/6203dd01-789d-f02c-5293-def4c1b18aef@xxxxxxxxx/
Leon Hwang (4):
bpf, x64: Use emit_nops() to replace memcpy()'ing x86_nops[5]
bpf, x64: Fix tailcall hierarchy
bpf, x64: Rename RESTORE_TAIL_CALL_CNT() to LOAD_TAIL_CALL_CNT_PTR()
selftests/bpf: Add testcases for tailcall hierarchy fixing
arch/x86/net/bpf_jit_comp.c | 108 ++---
.../selftests/bpf/prog_tests/tailcalls.c | 418 ++++++++++++++++++
.../bpf/progs/tailcall_bpf2bpf_hierarchy1.c | 34 ++
.../bpf/progs/tailcall_bpf2bpf_hierarchy2.c | 55 +++
.../bpf/progs/tailcall_bpf2bpf_hierarchy3.c | 46 ++
5 files changed, 609 insertions(+), 52 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy1.c
create mode 100644 tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c
create mode 100644 tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c
base-commit: 0c14840ae36f8170f06c2fa768203ef5a8e389e1
--
2.42.1
