systemtap fails to instrument kernel modules on ARM

[Da Zheng]

Hello,

I tried to instrument the some function in the kernel module, but failed.
I have a script called squashfs.stp:
probe module("squashfs").function("squashfs_read_data") {
         printf("%s, squashfs_read_data: length: %d, srclength: %d, 
blocksize: %d\n",
                 execname(), $length, $srclength, $sb->s_blocksize)
}

When I cross compile the script, I got the following error:

$ stap --vp 01 -a arm -r 
/build/tegra2_seaboard/tmp/portage/sys-kernel/chromeos-kernel-9999/work/chromeos-kernel-9999/build/tegra2_seaboard/ 
-p 4 -B CROSS_COMPILE=armv7a-cros-linux-gnueabi- -k squashfs.stp -m 
squashfs --all-modules
semantic error: no match while resolving probe point 
module("squashfs").function("squashfs_read_data")
Pass 2: analyzed script: 0 probe(s), 0 function(s), 0 embed(s), 0 
global(s) using 51668virt/21632res/2132shr kb, in 0usr/40sys/36real ms.
Pass 2: analysis failed.  Try again with another '--vp 01' option.

I see Cohen reported a bug of instrumenting a kernel module on ARM, but 
it seems the error message is a little bit different.
I wonder if the error was caused because stap can't find the module, as 
all kernel modules aren't in the standard path and aren't in 
/build/tegra2_seaboard/tmp/portage/sys-kernel/chromeos-kernel-9999/work/chromeos-kernel-9999/build/tegra2_seaboard/ 
either.

Thanks,
Da