Re: [PATCH bpf-next v2 2/5] bpf, x86: allow function arguments up to 14 for TRACING

On Fri, Jun 2, 2023 at 3:01 PM menglong8.dong@gmail.com wrote:

From: Menglong Dong imagedong@tencent.com @@ -2262,6 +2327,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i

    if (flags & BPF_TRAMP_F_CALL_ORIG) {
            restore_regs(m, &prog, nr_regs, regs_off);

•           prepare_origin_stack(m, &prog, nr_regs, arg_stack_off);
  
            if (flags & BPF_TRAMP_F_ORIG_STACK) {
                    emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8);
  

@@ -2321,14 +2387,14 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i if (save_ret) emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);

•   EMIT1(0x5B); /* pop rbx */
  

•   emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, -rbx_off);
    EMIT1(0xC9); /* leave */
    if (flags & BPF_TRAMP_F_SKIP_FRAME)
            /* skip our return address and return to parent */
            EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */
    emit_return(&prog, prog);
    /* Make sure the trampoline generation logic doesn't overflow */
  

•   if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) {
  

•   if (prog > (u8 *)image_end - BPF_INSN_SAFETY) {
  

Oops, this line is a mistake, and I should keep it still.

            ret = -EFAULT;
            goto cleanup;
    }

-- 2.40.1