linux-compat semctl operation - bad address

[Joe Love]

> On Sep 9, 2016, at 4:34 PM, Joe Love <joe at getsomewhere.net> wrote:
> 
> Hi,
> 
> I have a linux binary I’m trying to run on a 12-CURRENT machine with the linux_base-c7 (64-bit) port.
> 
> When trying to run it, it starts up and then spits out this error:
> shm_semaphores_init: semctl init error: Bad address - trying again
> 
> I’m guessing that it’s reaching the end of the switch statement in sys/compat/linux/linux_ipc.c’s linux_semctl(…) function and getting an EINVAL result.  That’s a guess, however, as I don’t know enough about debugging at this level in order to tell what it’s actually doing.
> 
> Can anyone tell me how to get the results of the linux_msg() call at the end of the function to find out what ipc type it’s trying to utilize, and with a little luck maybe get a patch created to support whatever operation it’s trying?
> 
> Thanks,
> -Joe
> 

A little further explanation (since I failed to give it earlier): I have two linux game servers that do this, “7 Days to Die” (7dtd) and “Unturned.”  Based on the first dtrace probe I tried (entry), it seems that 7dtd might be easier to understand.  Obviously I don’t have access to game sources.

I did a little digging with dtrace, though my knowledge of dtrace is all new as of this experience.

/* my dtrace probe file, semprobe.d */
fbt:linux:linux_semctl:entry,
fbt:linux64:linux_semctl:entry
{
	/* args->cmd & ~LINUX_IPC_64 .. LINUX_IPC_64 = 0x0100 */
       	printf("%s (%d, %d, %d, %d)", probefunc, args[1]->cmd, args[1]->cmd & ~0x0100, args[1]->semid, args[1]->arg.val);
}
fbt:kernel:kern_semctl:entry
{
       	printf("%s  (%d, %d, %d, %d)", probefunc, args[3], args[3], args[1], args[4]->val);
}
fbt:kernel:kern_semctl:return
{
       	printf("%s  (%d, %d)", probefunc, args[1], errno);
}

fbt:linux:linux_semctl:return,
fbt:linux64:linux_semctl:return
{
       	printf("%s (%d, %d)\n", probefunc, args[1], errno);
}
I ran that with "dtrace -n semprobe.d”

When I ran the 7dtd server, dtrace proceeded to spit out this information (while 7dtd spat out it’s error in my first email):
dtrace: script 'semprobe.d' matched 6 probes
CPU     ID                    FUNCTION:NAME
 21  63000               linux_semctl:entry linux_semctl (0, 0, 952369158, 0)
 21  37620                kern_semctl:entry kern_semctl  (9, 9, 952369158, -11936)
 21  37621               kern_semctl:return kern_semctl  (14, 0)
 21  63001              linux_semctl:return linux_semctl (14, 0)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952369158, 0)
 21  37620                kern_semctl:entry kern_semctl  (0, 0, 952369158, 1876522240)
 21  37621               kern_semctl:return kern_semctl  (0, 14)
 21  63001              linux_semctl:return linux_semctl (0, 14)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952434694, 0)
 21  37620                kern_semctl:entry kern_semctl  (9, 9, 952434694, -11936)
 21  37621               kern_semctl:return kern_semctl  (14, 0)
 21  63001              linux_semctl:return linux_semctl (14, 0)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952434694, 0)
 21  37620                kern_semctl:entry kern_semctl  (0, 0, 952434694, 1876522240)
 21  37621               kern_semctl:return kern_semctl  (0, 14)
 21  63001              linux_semctl:return linux_semctl (0, 14)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952500230, 0)
 21  37620                kern_semctl:entry kern_semctl  (9, 9, 952500230, -11936)
 21  37621               kern_semctl:return kern_semctl  (14, 0)
 21  63001              linux_semctl:return linux_semctl (14, 0)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952500230, 0)
 21  37620                kern_semctl:entry kern_semctl  (0, 0, 952500230, 1876522240)
 21  37621               kern_semctl:return kern_semctl  (0, 14)
 21  63001              linux_semctl:return linux_semctl (0, 14)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952565766, 0)
 21  37620                kern_semctl:entry kern_semctl  (9, 9, 952565766, -11936)
 21  37621               kern_semctl:return kern_semctl  (14, 0)
 21  63001              linux_semctl:return linux_semctl (14, 0)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952565766, 0)
 21  37620                kern_semctl:entry kern_semctl  (0, 0, 952565766, 1876522240)
 21  37621               kern_semctl:return kern_semctl  (0, 0)
 21  63001              linux_semctl:return linux_semctl (0, 0)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952631302, 0)
 21  37620                kern_semctl:entry kern_semctl  (9, 9, 952631302, -11936)
 21  37621               kern_semctl:return kern_semctl  (14, 0)
 21  63001              linux_semctl:return linux_semctl (14, 0)

 21  63000               linux_semctl:entry linux_semctl (0, 0, 952631302, 0)
 21  37620                kern_semctl:entry kern_semctl  (0, 0, 952631302, 1876522240)
 21  37621               kern_semctl:return kern_semctl  (0, 0)
 21  63001              linux_semctl:return linux_semctl (0, 0)
(and repeated the last 2 ’sets', with other semaphore ID’s, always incrementing)


I’m hoping someone can find fault with my assessment, because I don't understand why args->cmd seems to go from LINUX_IPC_RMID (0) to bsd’s SETALL (9).

Anyone have thoughts on what to check, or maybe what is going on?

Thanks,
-Joe