proot: termux-chroot does not work on Nexus 9

[vainikkaj]

Installing latest version of proot and running termux-chrootgives following error:

proot warning: can't set the syscall number: Invalid argument
proot warning: can't set the syscall number: Invalid argument
proot warning: can't set the syscall number: Invalid argument
proot warning: can't set the syscall number: Invalid argument
proot warning: can't set the syscall number: Invalid argument
proot warning: can't set the syscall number: Invalid argument
proot info: vpid 1: terminated with signal 11

Full strace available at https://gist.github.com/vainikkaj/122b795b286ad3849e1e9be74e450522

[fornwall]

Can you attach the output of running

uname -a

Perhaps it's something with the kernel version or configuration on the Nexus 9.

[vainikkaj]

$ uname -a
Linux localhost 3.10.40-gcc76e44 #1 SMP PREEMPT Fri Mar 25 15:18:18 UTC 2016 aarch64 Android

[fornwall]

Can you test if setting

export PROOT_NO_SECCOMP=1

before running termux-chroot makes a difference?

[vainikkaj]

Unfortunately, still broken even with exported variable. Output is exactly the same as before.

[michalbednarski]

This strace is for termux-chroot wrapper script which prepares arguments and launches proot, could You check if just simple proot ls works and provide strace for it if it's enough to cause error (otherwise we'll have to try adding other arguments that were provided by termux-chroot script)

[vainikkaj]

Running proot lsalso fails.

$ proot ls
proot warning: can't set the syscall number: Invalid argument
proot warning: can't set the syscall number: Invalid argument
proot info: vpid 1: terminated with signal 11

strace output

[michalbednarski]

I've noticed that ARM64 build of proot shouldn't have code path with this message, which suggests that ARM64 build of PRoot in Termux was compiled without ARCH_ARM64 defined.

https://github.com/proot-me/PRoot/blob/f393b4daf9bfd6d034cf2c8dd56d44f135b08e93/src/tracee/reg.c#L300-L321

[fornwall]

@michalbednarski We're building from the next branch, so there is can't set the syscall number path also for ARM64:

https://github.com/proot-me/PRoot/blob/next/src/tracee/reg.c#L302

[michalbednarski]

Ah, that way, I was a bit lost about different ptrace() in source and strace.

ptrace(PTRACE_SETREGSET, 19457, 0x404 /* NT_??? */, [{0x7fedb85df8, 8}]) = -1 EINVAL (Invalid argument)

It looks like kernel did't recognize NT_ARM_SYSTEM_CALL so not much we can do here

For reference
PRoot commit
Linux kernel commit (which apparently wasn't applied on this device)

[fornwall]

Closing this since there is not much to do if the kernel lacks support (the Nexus 9 kernel seems to rather odd in how it's configured compared to other devices).

[9990242854]

When i use that export PROOT_NO_SECCOMP=1 , it will work but when i update then its show BUS ERROR
Please fix that.

[ghost]

then its show BUS ERROR
Please fix that.

@9990242854 I suggest you to open issue at https://github.com/termux/proot/issues - more probability that it will be fixed.