How to get function param in kretprobe bpf program? #bcc #pragma


Forrest Chen
 

When using kprobe in bcc, I can get param directly like `int kprobe__tcp_set_state(struct pt_regs *ctx, struct sock *sk, int state)`
But it seems not to work in kretprobe, I've found that I can get first param by using `struct sock *sk = (void*)ctx->bx`
but I can't get the second param through `ctx->cx`.
Am I get the wrong register? I'm in x86-64

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