Hello Everyone,

I was reviewing the systemtap testsuite results for ARM on Fedora 19 and I found that one of the tests (systemtap.base/deref.stp) failing on ARM for uint16_t reads and writes. The same tests work on x86_64. There appears to be ARM specific code in linux/arch/arm/include/asm/uaccess.h to read and write memory. I suspect that the 16-bit case for copies isn't being handled correctly.

The issue can be observed by

# yum install kernel-devel systemtap-testsuite -y # debuginfo-install kernel-`uname -r` -y

$ uname -a Linux dhcp129-3.rdu.redhat.com 3.11.1-300.fc19.armv7hl #1 SMP Thu Sep 19 16:31:05 EDT 2013 armv7l armv7l armv7l GNU/Linux $ rpm -q systemtap systemtap-2.3-1.fc19.armv7hl

$cd /usr/share/systemtap/testsuite $sudo make installcheck RUNTESTFLAGS="--debug systemtap.base/deref.exp"

On ARM Fedora 19 The tests reports some failures:

=== systemtap Summary ===

# of expected passes 2 # of unexpected failures 1

Looking at the systemtap.log shows the tests starting up, but the 16-bit read/write operations failing:

PASS: ./systemtap.base/deref.stp startup PASS: ./systemtap.base/deref.stp load generation systemtap ending probe systemtap test failure - kread u16 systemtap test failure - kread const u16 systemtap test failure - kwrite u16

On x86_64 the tests all passed:

=== systemtap Summary ===

# of expected passes 6

I modified the deref.stp script to see precisely what the arm machine was reasing and writing. It looked like it only got the lower 8-bits of the 16-bit quanity correct. The uper 8-bits are non-zero but it isn't clear where those values are coming from.

-Will