Valgrind on ARM64, KVM

["Phil Endecott" <spam_from_debian_arm@chezphil.org>]

Hi everyone,

I'm getting mixed results trying to use valgrind on various ARM64 
devices.  Specifically, it works on my ODROID-C2 (Amlogic SoC with 
kernel 3.14.29), and on my APM Xgene system with kernel 4.9.1801, 
but not on a Scaleway virtual machine (Cavium ThunderX with kernel 
4.9.23, under KVM) [*].  They are all running stretch and valgrind 
3.12.0.SVN.

Google reports various issues using KVM/QEMU with valgrind but 
I think that's mostly related to running valgrind on the KVM 
host, not the guest.  Or something.

It would be useful to know whether this works for other people - 
especially if anyone is using KVM on ARM64 on another platform. 
If a few readers would be kind enough to:

# apt-get install valgrind
$ valgrind ls

and report what happens, that would be wonderful.

[*] The failure mode I see is that it runs forever at 100% CPU. 
If I strace the valgrind process - which may or may not be a 
sensible thing to do - I see this constantly repeated:

rt_sigprocmask(SIG_SETMASK, ~[], ~[ILL TRAP BUS FPE KILL SEGV STOP], 8) = 0
rt_sigtimedwait(~[], 0x802e9be28, {tv_sec=0, tv_nsec=0}, 8) = -1 EAGAIN (Resource temporarily unavailable)
rt_sigprocmask(SIG_SETMASK, ~[ILL TRAP BUS FPE KILL SEGV STOP], NULL, 8) = 0
gettid()                                = 20487
gettid()                                = 20487
write(1029, "P", 1)                     = 1
gettid()                                = 20487
read(1028, "P", 1)                      = 1
gettid()                                = 20487



Thanks, Phil.