From: kan.liang@xxxxxxxxxxxxxxx > Sent: 27 May 2020 13:31 > > From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx> > > 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 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
