Dtrace shows "invalid addres" errors on 12.0-RELEASE on Thinkpad T480

B

Bojan Petrović

Hi,

I'm having issues using dtrace(1) on a Lenovo Thinkpad T480, even when using an official USB image of FreeBSD 12.0 RELEASE.

Here's a log demonstrating this issue on a FreeBSD-12.0-RELEASE-amd64-memstick.img. I'm tracing the openat(2) syscall. I run dtrace in one console, and then try to log in in another:

Code: 
root@:/tmp # uname -a
FreeBSD  12.0-RELEASE FreeBSD 12.0-RELEASE r341666 GENERIC  amd64
root@:/tmp # dtrace -n 'syscall::openat:entry {print(copyinstr(arg1));}'
dtrace: description 'syscall::openat:entry ' matched 2 probes
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x8002076a3) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x80020798d) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffe0a0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x800230000) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffe0a0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffe0a0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12
dtrace: error on enabled probe ID 1 (ID 64761: syscall:freebsd:openat:entry): invalid address (0x7fffffffdbd0) in action #1 at DIF offset 12

Below is the expected output which I can get when running
  • FreeBSD-11.2-RELEASE-amd64-memstick.img on the same laptop
  • FreeBSD-12.0-RELEASE-amd64-disc1.iso inside VirtualBox

Code: 
root@:/tmp # uname -a
FreeBSD  11.2-RELEASE FreeBSD 11.2-RELEASE #0 r335510: Fri Jun 22 04:32:14 UTC 2018     root@releng2.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64
root@:/tmp # dtrace -n 'syscall::openat:entry {print(copyinstr(arg1));}'
dtrace: description 'syscall::openat:entry ' matched 2 probes
CPU     ID                    FUNCTION:NAME
  2  63026                     openat:entry string "/etc/libmap.conf"

  2  63026                     openat:entry string "/var/run/ld-elf.so.hints"

  2  63026                     openat:entry string "/lib/libutil.so.9"

  2  63026                     openat:entry string "/usr/lib/libpam.so.6"

  2  63026                     openat:entry string "/usr/lib/libbsm.so.3"

  2  63026                     openat:entry string "/lib/libc.so.7"

  2  63026                     openat:entry string "/usr/lib/pam_self.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_opie.so.6"

  2  63026                     openat:entry string "/usr/lib/libopie.so.8"

  2  63026                     openat:entry string "/lib/libmd.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_opieaccess.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_unix.so.6"

  2  63026                     openat:entry string "/lib/libcrypt.so.5"

  2  63026                     openat:entry string "/usr/lib/libypclnt.so.4"

  2  63026                     openat:entry string "/usr/lib/pam_securetty.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_nologin.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_login_access.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_unix.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_lastlog.so.6"

  2  63026                     openat:entry string "/usr/lib/pam_unix.so.6"

Should I direct this question to freebsd-dtrace mailing list, or maybe file a bug report?

Regards,
Bojan
 
The suggestion from DTrace user guide to defer copyinstr to the return of the function does not solve the issue.

The following command also produces "invalid address" errors:

Code: 
dtrace -n 'syscall::openat:entry {self->file=arg1;}' \
       -n 'syscall::openat:return { print(copyinstr(self->file)); self->file=0;}'
 
After bisecting the kernel, I think the issue is related to commit r336876 ("Use SMAP on amd64") , mentioned in PR 230993 and PR 230460.

It seems to be resolved in the CURRENT and 12-STABLE, possibly in r342053 ("fix userspace access on boxes with SMAP") (didn't test).

If anyone is running a 12.0-RELEASE, the issue can be circumvented by disabling SMAP: add hw.cpu_stdext_disable=0x00100000 to /boot/loader.conf
 
Bojan Petrović said:
Hi,
Should I direct this question to freebsd-dtrace mailing list, or maybe file a bug report?

Regards,
Bojan
Click to expand...

Hi Bojan Petrović , since your question is very specific, and nobody still was able to tell you something, I guess it is better to go to the proper mailing list.

I don't know still dtrace so I can't say if that is a bug, If you are confident it could be a bug post on FreeBSD Bugzilla.

According to my past experiences you will get prompt answer either on mailing list or the bug platform.

bye
n.
 
Hi Nicola,

Thanks for your advice. I somehow went into investigation assuming that the issue is still present on CURRENT, but I was mistaken.

Regards,
Bojan
 
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