how to get http whole request content from bpftrace - ebpf

Question

I Want to use bpftrace to get all the http request content of my program.
cat /etc/redhat-release
CentOS Linux release 8.0.1905 (Core)
uname -a
Linux infra-test4.18.0-305.12.1.el8_4.x86_64 #1 SMP Wed Aug 11
01:59:55 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
bpftrace bt :
BEGIN
{
printf("Welcome to Offensive BPF... Use Ctrl-C to exit.\n");
}
tracepoint:syscalls:sys_enter_accept*
{
#sk[tid] = args->upeer_sockaddr;
}
tracepoint:syscalls:sys_exit_accept*
/ #sk[tid] /
{
#sys_accepted[tid] = #sk[tid];
}
tracepoint:syscalls:sys_enter_read
/ #sys_accepted[tid] /
{
printf("->sys_enter_read for allowed thread (fd: %d)\n", args->fd);
#sys_read[tid] = args->buf;
}
tracepoint:syscalls:sys_exit_read
{
if (#sys_read[tid] != 0)
{
$len = args->ret;
$cmd = str(#sys_read[tid], $len);
printf("*** Command: %s\n", $cmd);
}
}
END
{
clear(#sk);
clear(#sys_read);
clear(#sys_accepted);
printf("Exiting. Bye.\n");
}
And I star my server on 8080 and then start bpftrace :
Attaching 8 probes...
Welcome to Offensive BPF... Use Ctrl-C to exit.
then I start to curl :
curl -H "traceparent: 00-123-456-01" 127.0.0.1:8080/misc/ping -lv
The bpftrace only output :
bpftrace --unsafe http.bt
Attaching 8 probes...
Welcome to Offensive BPF... Use Ctrl-C to exit.
->sys_enter_read for allowed thread (fd: 15)
*** Command: GET /misc/ping HTTP/1.1
Host: 127.0.0.1:8080
User-Agent: curl
->sys_enter_read for allowed thread (fd: 15)
*** Command: GET /misc/ping HTTP/1.1
Host: 127.0.0.1:8080
User-Agent: curl
output is not the whole curl content, I don`t know why, Can anyone help?