truss(1): add AIO syscalls

[tmunro]

Summary

Display the arguments of aio_read(2), aio_write(2), aio_suspend(2), aio_error(2), aio_return(2), aio_cancel(2), aio_fsync(2), aio_mlock(2), aio_waitcomplete(2) and lio_listio(2) in human-readable form.

Test Plan

Trace simple test programs. Example output:

aio_read({ 3,0,0x7fffffffc5f0,1,LIO_NOP,{ sigev_notify=SIGEV_NONE } }) = 0 (0x0)
aio_waitcomplete({ 3,0,0x7fffffffc5f0,1,LIO_NOP,{ sigev_notify=SIGEV_NONE } },{ 1.000000000 }) = 1 (0x1)
lio_listio(LIO_NOWAIT,[{ 3,0,0x7fffffffc5f0,1,LIO_READ,{ sigev_notify=SIGEV_NONE } },{ 3,0,0x7fffffffc5f0,1,LIO_WRITE,{ sigev_notify=SIGEV_NONE } }],2,0x0) = 0 (0x0)

[asomers]

This looks like a good change, but I'm not a truss user. I use ktrace instead. With this patch, how does the output of truss compare to ktrace? And could you also please add aio_mlock?

[tmunro]

Added aio_mlock(2).

[tmunro]

In D27518#615067, @asomers wrote:

This looks like a good change, but I'm not a truss user. I use ktrace instead. With this patch, how does the output of truss compare to ktrace?

I'm not too familiar with ktrace, but kdump doesn't seem to show the contents of the aiocb structs/arrays, just pointers; with -r it shows some other structs as STRU records but not these ones, perhaps some ktrstruct() calls might need to be sprinkled in vfs_aio.c?

96425 a.out    CALL  lio_listio(LIO_NOWAIT,0x7fffffffb0d0,0x2,0)
96425 a.out    RET   lio_listio 0

[asomers]

usr.bin/truss/syscalls.c

1384 ↗

(On Diff #80467)

Probably not very useful to print sigev_notify_function if it's just a pointer, don't you think?

2732 ↗

(On Diff #80467)

This limit is obsolete. I removed it in r324941 (but now I see that I neglected to update the man page accordingly). You should either malloc cbs so there won't be a limit, or else impose some reasonable limit based on the text format of the output, or something like that.

[tmunro]

Dropped the SIGEV_THREAD function pointer. Switched to a hardcoded limit on how many lio_listio array elements to display, following a coding pattern from nearby similar things.

[asomers]

Thanks for doing this. It looks like it could be pretty helpful. Helpful enough that I may need to learn to start using truss.

[tmunro]

In D27518#615127, @asomers wrote:

Thanks for doing this. It looks like it could be pretty helpful. Helpful enough that I may need to learn to start using truss.

Thanks for the review! I've found this useful for debugging a complicated AIO-based app.