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Re: [Xen-devel] Xen GCC coverage ARM64 testing - Unexpected Trap: Data Abort

(+ Wei)

On 5/2/19 5:55 PM, Viktor Mitin wrote:
Hi Julien,


Please find trace log below:

root@h3ulcb:~# xencov reset
(XEN) Data Abort Trap. Syndrome=0x7
(XEN) Walking Hypervisor VA 0x361700 on CPU3 via TTBR 0x0000000078266000
So this is a data abort when trying to access VA 0x361700 (it is part of Xen itself). I misread the Arm Arm before, while ISV is 0 DFSC will still provide a correct value. So here we have a "Translation fault, level 3".

Which makes sense because ...

(XEN) 0TH[0x0] = 0x0000000078265f7f
(XEN) 1ST[0x0] = 0x0000000078262f7f
(XEN) 2ND[0x1] = 0x004000007825ff7f
(XEN) 3RD[0x161] = 0x00600000781e1f7e

the 3rd entry is not valid. I managed to reduce the error and it looks like gcov is trying to access a counter in the section init.data.

As all the .init.* sections are stripped after boot, it means that anything in .init.data cannot be accessed anymore.

Wei, how do you deal with counters in init.data on x86?


Julien Grall

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