| Message ID | 20230912150442.2009-2-hffilwlqm@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 2bee9770f3c6be736a28725cb0f93775ed22e720 |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf, x64: Fix tailcall infinite loop | expand |
| Context | Check | Description |
|---|---|---|
| bpf/vmtest-bpf-next-PR | success | PR summary |
| bpf/vmtest-bpf-next-VM_Test-25 | success | Logs for test_verifier on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-15 | success | Logs for test_progs_no_alu32 on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-11 | success | Logs for test_progs on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-7 | success | Logs for test_maps on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-0 | success | Logs for ShellCheck |
| bpf/vmtest-bpf-next-VM_Test-5 | success | Logs for set-matrix |
| bpf/vmtest-bpf-next-VM_Test-1 | success | Logs for build for aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-4 | success | Logs for build for x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-3 | success | Logs for build for x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-2 | success | Logs for build for s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-6 | success | Logs for test_maps on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-10 | success | Logs for test_progs on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-14 | success | Logs for test_progs_no_alu32 on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-18 | success | Logs for test_progs_no_alu32_parallel on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-24 | success | Logs for test_verifier on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-21 | success | Logs for test_progs_parallel on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-8 | success | Logs for test_maps on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-9 | success | Logs for test_maps on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-19 | success | Logs for test_progs_no_alu32_parallel on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-20 | success | Logs for test_progs_no_alu32_parallel on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-26 | success | Logs for test_verifier on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-27 | success | Logs for test_verifier on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-28 | success | Logs for veristat |
| bpf/vmtest-bpf-next-VM_Test-22 | success | Logs for test_progs_parallel on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-13 | success | Logs for test_progs on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-12 | success | Logs for test_progs on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-23 | success | Logs for test_progs_parallel on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-17 | success | Logs for test_progs_no_alu32 on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-16 | success | Logs for test_progs_no_alu32 on x86_64 with gcc |
| netdev/tree_selection | success | Clearly marked for bpf-next, async |
| netdev/apply | success | Patch already applied to bpf-next |
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index a5930042139d3..bcca1c9b9a027 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -303,8 +303,12 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf, prog += X86_PATCH_SIZE; if (!ebpf_from_cbpf) { if (tail_call_reachable && !is_subprog) + /* When it's the entry of the whole tailcall context, + * zeroing rax means initialising tail_call_cnt. + */ EMIT2(0x31, 0xC0); /* xor eax, eax */ else + /* Keep the same instruction layout. */ EMIT2(0x66, 0x90); /* nop2 */ } EMIT1(0x55); /* push rbp */
Without understanding emit_prologue(), it is really hard to figure out where does tail_call_cnt come from, even though searching tail_call_cnt in the whole kernel repo. By adding these comments, it is a little bit easier to understand tail_call_cnt initialisation. Signed-off-by: Leon Hwang <hffilwlqm@gmail.com> --- arch/x86/net/bpf_jit_comp.c | 4 ++++ 1 file changed, 4 insertions(+)