Re: [PATCH v7 10/25] arm64: compat: Add vDSO

Vincenzo Frascino
2019-07-10T09:48:59Z

On 10/07/2019 07:12, Thomas Gleixner wrote:
> On Tue, 9 Jul 2019, John Stultz wrote:
>> Though unfortunately, it seems the arm64 vdso code that just landed is
>> breaking AOSP for me.
>>
>> I see a lot of the following errors:
>> 01-01 01:22:14.097 755 755 F libc : Fatal signal 11 (SIGSEGV),
>> code 1 (SEGV_MAPERR), fault addr 0x3cf2c96c in tid 755 (cameraserver),
>> pid 755 (cameraserver)
>> 01-01 01:22:14.112 759 759 F libc : Fatal signal 11 (SIGSEGV),
>> code 1 (SEGV_MAPERR), fault addr 0x3cf2c96c in tid 759
>> (android.hardwar), pid 759 (android.hardwar)
>> 01-01 01:22:14.120 756 756 F libc : Fatal signal 11 (SIGSEGV),
>> code 1 (SEGV_MAPERR), fault addr 0x3cf2c96c in tid 756 (drmserver),
>> pid 756 (drmserver)
>>
>> Which go away if I revert the vdso merge that went in via tip/timers.
>>
>> I tried to bisect things down a bit, but as some later fixes are
>> required (at one point, date was returning the start epoch and never
>> increasing), this hasn't worked too well. But I'm guessing since I
>> see: "CROSS_COMPILE_COMPAT not defined or empty, the compat vDSO will
>> not be built", and the system is half working, I'm guessing this is an
>> issue with just the 32bit code failing. While I can try to sort out
>> the proper CROSS_COMPILE_COMPAT in my build environment, I assume
>> userland shouldn't be crashing if that value isn't set.
>
> The obvious question is whether the VDSO is mapped to the 32bit process in
> that case. It shouldn't...
>

Agreed. I am investing if/why this is happening and will post a fix accordingly.

> Thanks,
>
> tglx
>

--
Regards,
Vincenzo