Building a Pixel kernel with KASAN+KCOV

[Dmitry Vyukov]

Just noticed this article on source.android.com:

https://source.android.com/devices/tech/debug/kasan-kcov

Don't know who wrote it, but it goes through configuring, building,
imaging kernel for a Pixel device.

[王赛]

Hi Dmitry,

I build a pixel xl kernel with KASAN+KCOV enabled, 

but the produced kernel image is too large to flash to pixel boot partition.

KASAN+KCOV config: 

CONFIG_KASAN=y

CONFIG_KASAN_INLINE=y

CONFIG_KCOV=y

prodeuced kernel image size: 29.8 MB

boot.img size: 37 MB

pixel xl boot partition size: 32 MB

Any idea how I can overcome this problem?

Thanks,

Sai

在 2017年10月10日星期二 UTC+8下午5:03:43，Dmitry Vyukov写道：

[dar...@gmail.com]

Hi Sai, make sure you are using the latest Android NDK, this shrank the generated kernel for me. Also, not mentioned in the article, make sure you have CONFIG_CC_OPTIMIZE_FOR_SIZE=y (this is not enabled by default).

[Dmitry Vyukov]

On Sat, Oct 14, 2017 at 3:29 PM, <dar...@gmail.com> wrote:
> Hi Sai, make sure you are using the latest Android NDK, this shrank the
> generated kernel for me. Also, not mentioned in the article, make sure you
> have CONFIG_CC_OPTIMIZE_FOR_SIZE=y (this is not enabled by default).

+Billy, is it something we should mention in the article?

> On Thursday, October 12, 2017 at 10:06:43 PM UTC-4, 王赛 wrote:
>>
>> Hi Dmitry,
>> I build a pixel xl kernel with KASAN+KCOV enabled,
>> but the produced kernel image is too large to flash to pixel boot
>> partition.
>>
>> KASAN+KCOV config:
>> CONFIG_KASAN=y
>> CONFIG_KASAN_INLINE=y
>> CONFIG_KCOV=y
>>
>> prodeuced kernel image size: 29.8 MB
>> boot.img size: 37 MB
>>
>> pixel xl boot partition size: 32 MB
>>
>> Any idea how I can overcome this problem?
>>
>> Thanks,
>>
>> Sai
>>
>> 在 2017年10月10日星期二 UTC+8下午5:03:43，Dmitry Vyukov写道：
>>>
>>> Just noticed this article on source.android.com:
>>>
>>> https://source.android.com/devices/tech/debug/kasan-kcov
>>>
>>> Don't know who wrote it, but it goes through configuring, building,
>>> imaging kernel for a Pixel device.
>

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[王赛]

Thanks, according to your instructions, with both KCOV and KASAN enabled, I build a smaller kernel and flash to pixel xl success, 

but I got a failed boot, any suggestions？

Some related infomation:

1. NDK version is r16 beta1

2. With only KCOV enabled, the boot is ok, and syzkaller can get cover info from kernel

3. With KASAN enabled, I got a messge: scripts/Makefile.kasan:25: CONFIG_KASAN: compiler does not support all options. Trying minimal configuration.

在 2017年10月14日星期六 UTC+8下午9:29:22，dar...@gmail.com写道：

[yuki]

Thanks for the tip, it works nicely on PixelXL.

[edward...@gmail.com]

seem doesn't work in Pixel(sailfish). :(

Dmitry Vyukov於 2017年10月10日星期二 UTC+8下午5時03分43秒寫道：

[Billy Lau]

Yes, CONFIG_CC_OPTIMIZE_FOR_SIZE=y is something that should have been included in the article. When I was writing and testing it, that flag was still in defconfig. I guess that flag was somehow turned off during one of the commits.

> email to syzkaller+unsubscribe@googlegroups.com.

[王赛]

It's OK now, after I switch android 7.1.2 to android 8.0.

在 2017年10月16日星期一 UTC+8上午11:37:04，王赛写道：

[User :D]

can you help me create boot.img for pixel 3 i can't find the ramdisk