From: [email protected]
> Sent: 27 May 2020 13:31
>
> From: Kan Liang <[email protected]>
>
> When counting IMC uncore events on some TGL machines, an oops will be
> triggered.
> [ 393.101262] BUG: unable to handle page fault for address:
> ffffb45200e15858
> [ 393.101269] #PF: supervisor read access in kernel mode
> [ 393.101271] #PF: error_code(0x0000) - not-present page
>
> Current perf uncore driver still use the IMC MAP SIZE inherited from
> SNB, which is 0x6000.
> However, the offset of IMC uncore counters for some TGL machines is
> larger than 0x6000, e.g. 0xd8a0.
>
> Enlarge the IMC MAP SIZE for TGL to 0xe000.
Replacing one 'random' constant with a different one
doesn't seem like a proper fix.
Surely the actual bounds of the 'memory' area are properly
defined somewhere.
Or at least should come from a table.
You also need to verify that the offsets are within the mapped area.
An unexpected offset shouldn't try to access an invalid address.
David
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