SUMMARY

adjtime system call is not supported on arm-linux. I was able to get it to work in my system by locally patching syswrap-arm-linux.c and uncommenting the line:

//zz    LINXY(__NR_adjtimex,          sys_adjtimex),       // 124

Looks like this has been commented out since at least 2010 for arm-linux. I could not find the reason.

STEPS TO REPRODUCE
1. Build an arm-linux (32bit) program and have it call adjtime()
2. Run it under valgrind

OBSERVED RESULT

--2040-- WARNING: unhandled arm-linux syscall: 124
--2040-- You may be able to write your own handler.
--2040-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--2040-- Nevertheless we consider this a bug.  Please report
--2040-- it at http://valgrind.org/support/bug_reports.html.

EXPECTED RESULT

adjtime should be supported

SOFTWARE/OS VERSIONS

Valgrind 3.15.0 
Embedded system running BusyBox linux distribution
Linux version: 3.4.91-WR5.0.1.40_standard+

ADDITIONAL INFORMATION