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%{
#include <linux/tcp.h>
static struct tcphdr foo = {0};
%}
function get_ptr:long() %{ THIS->__retvalue = (long)&foo; /* pure */ %}
function get_ack:long() %{ THIS->__retvalue = foo.ack; /* pure */ %}
function get_urg:long() %{ THIS->__retvalue = foo.urg; /* pure */ %}
function check:long(ack:long, urg:long) {
ptr = get_ptr()
/* set the bits with cast */
@cast(ptr, "tcphdr")->ack = ack
@cast(ptr, "tcphdr")->urg = urg
/* check that reading with embedded-C is ok */
real_ack = get_ack()
real_urg = get_urg()
errors = (ack != real_ack) + (urg != real_urg)
/* check that reading with a cast is ok */
cast_ack = @cast(ptr, "tcphdr")->ack
cast_urg = @cast(ptr, "tcphdr")->urg
errors += (ack != cast_ack) + (urg != cast_urg)
if (errors)
printf("bitfield had %d errors; expect(%d%d), real(%d%d), cast(%d%d)\n",
errors, ack, urg, real_ack, real_urg, cast_ack, cast_urg)
return errors
}
probe begin {
println("systemtap starting probe")
errors = check(0, 0)
errors += check(0, 1)
errors += check(1, 0)
errors += check(1, 1)
println("systemtap ending probe")
if (errors == 0)
println("systemtap test success")
exit()
}
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