macosdtrace

dtrace errors out with incorrect type for thread_t on macOS 12.2.1

The following dtrace invocation used to work on MacOS 11.6.2 but after upgrading to MacOS 12.2.1 it stopped working

sudo --non-interactive  dtrace -l -b 16m -x mangled -x disallow_dsym -x strip -x evaltime=preinit -x preallocate=256m  -n 'oneshot$target:a.out::entry { hdr_vm_addr = ((thread_t)curthread)->task->mach_header_vm_address; }' -w -p 4557 

dtrace: invalid probe specifier oneshot$target:a.out::entry { hdr_vm_addr = ((thread_t)curthread)->task->mach_header_vm_address; }: in action list: task is not a member of struct thread

How do I get task from thread_t now?

Solution

  • It looks like it may be t_task. Here's how you can view the type of a built-in variable such as curthread:

    $ sudo dtrace -n 'BEGIN { print(*curthread); exit(0); }'
dtrace: description 'BEGIN ' matched 1 probe
CPU     ID                    FUNCTION:NAME
  4      1                           :BEGIN struct thread {
    union  {
        queue_chain_t runq_links = {
            struct queue_entry *next = 0
            struct queue_entry *prev = 0
        }
...
    struct task *t_task = 0xffffff8bd07859f0
...
}