arm64: unhandled level 0 translation fault

[Will Deacon]

Hi Geert,

On Tue, Dec 12, 2017 at 11:20:09AM +0100, Geert Uytterhoeven wrote:
> During userspace (Debian jessie NFS root) boot on arm64:
> 
> rpcbind[1083]: unhandled level 0 translation fault (11) at 0x00000008,
> esr 0x92000004, in dash[aaaaadf77000+1a000]
> CPU: 0 PID: 1083 Comm: rpcbind Not tainted
> 4.15.0-rc3-arm64-renesas-02176-g14f9a1826e48e355 #51
> Hardware name: Renesas Salvator-X 2nd version board based on r8a7795 ES2.0+ (DT)
> pstate: 80000000 (Nzcv daif -PAN -UAO)
> pc : 0xaaaaadf8a51c
> lr : 0xaaaaadf8ac08
> sp : 0000ffffcffeac00
> x29: 0000ffffcffeac00 x28: 0000aaaaadfa1000
> x27: 0000ffffcffebf7c x26: 0000ffffcffead20
> x25: 0000aaaacea1c5f0 x24: 0000000000000000
> x23: 0000aaaaadfa1000 x22: 0000aaaaadfa1000
> x21: 0000000000000000 x20: 0000000000000008
> x19: 0000000000000000 x18: 0000ffffcffeb500
> x17: 0000ffffa22babfc x16: 0000aaaaadfa1ae8
> x15: 0000ffffa2363588 x14: ffffffffffffffff
> x13: 0000000000000020 x12: 0000000000000010
> x11: 0101010101010101 x10: 0000aaaaadfa1000
> x9 : 00000000ffffff81 x8 : 0000aaaaadfa2000
> x7 : 0000000000000000 x6 : 0000000000000000
> x5 : 0000aaaaadfa2338 x4 : 0000aaaaadfa2000
> x3 : 0000aaaaadfa2338 x2 : 0000000000000000
> x1 : 0000aaaaadfa28b0 x0 : 0000aaaaadfa4c30
> 
> Sometimes it happens with other processes, but the main address, esr, and
> pstate values are always the same.
> 
> I regularly run arm64/for-next/core (through bi-weekly renesas-drivers
> releases, so the last time was two weeks ago), but never saw the issue
> before until today, so probably v4.15-rc1 is OK.
> Unfortunately it doesn't happen during every boot, which makes it
> cumbersome to bisect.
> 
> My first guess was UNMAP_KERNEL_AT_EL0, but even after disabling that,
> and even without today's arm64/for-next/core merged in, I still managed to
> reproduce the issue, so I believe it was introduced in v4.15-rc2 or
> v4.15-rc3.

Urgh, this looks nasty. Thanks for the report! A few questions:

 - Can you share your .config somewhere please?
 - What was your last known-good kernel?
 - Have you seen it on any other Soc?
 - What's the CPU in your SoC?

If I can reproduce the failure here, then I should be able to debug ASAP.

Cheers,

Will