Which events does simple C-program uses to fire USDT probe?

[ValchukDmitry]

No description provided.

[ValchukDmitry]

Here is strace of simple program, which fires USDT probe:

execve("./result", ["./result"], [/* 81 vars */]) = 0
brk(NULL)                               = 0x1946000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
...
open("tls/x86_64/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("tls/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("x86_64/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("libc.so.6", O_RDONLY|O_CLOEXEC)   = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=181605, ...}) = 0
mmap(NULL, 181605, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f70b2e86000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\t\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f70b2e85000
mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f70b28c4000
mprotect(0x7f70b2a84000, 2097152, PROT_NONE) = 0
mmap(0x7f70b2c84000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f70b2c84000
mmap(0x7f70b2c8a000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f70b2c8a000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f70b2e84000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f70b2e83000
arch_prctl(ARCH_SET_FS, 0x7f70b2e84700) = 0
mprotect(0x7f70b2c84000, 16384, PROT_READ) = 0
mprotect(0x600000, 4096, PROT_READ)     = 0
mprotect(0x7f70b2eb3000, 4096, PROT_READ) = 0
munmap(0x7f70b2e86000, 181605)          = 0
exit_group(0)                           = ?

[AntonKozlov]

Had anyone listened for the event?

https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
It seems that without a listener a tracepoint is just a sequence of nops and we need to attach something to turn the sequence into actual reporting code