On Fri, Sep 09, 2016 at 12:47:20PM -0300, Arnaldo Carvalho de Melo wrote: > Em Fri, Sep 09, 2016 at 05:41:25PM +0200, Jiri Olsa escreveu: > > On Fri, Sep 09, 2016 at 12:36:26PM -0300, Arnaldo Carvalho de Melo wrote: > > > Hi Adrian, > > > > > > I noticed that 'perf test "object code reading"' is segfaulting > > > here: > > > > > > [root@jouet linux]# perf test -F "object code reading" > > > 21: Test object code reading :Segmentation fault > > > [root@jouet linux]# > > > > > > dmesg output below, trying to figure this out... > > > > heya, > > it's the new hardened user copy check.. I sent patches for that: > > > > http://marc.info/?l=linux-kernel&m=147332143929289&w=2 > > http://marc.info/?l=linux-kernel&m=147332145229291&w=2 > > Cool, but that is for the kernel, without thinking too much about it, is > there a way to change that 'perf test' entry to avoid doing what > triggers the segfault? > > My first thought was that it was reading 4K all the way to the end, > where it should instead read just what is remaining, but I haven't > checked this theory at all.
it's actually reading within the bounds of kernel text that triggers that, it's the new CONFIG_HARDENED_USERCOPY feature: f5509cc18daa mm: Hardened usercopy check the change log, there's list of conditions and one of them is: - object must not overlap with kernel text jirka
