Re: [GIT PULL] x86/topology changes for v5.3

[Xi Ruoyao]

On 2019-07-10 15:28 +0200, Jiri Kosina wrote:
> On Wed, 10 Jul 2019, Jiri Kosina wrote:

> > > > > BUG: unable to handle page fault for address: ffffffff9edc1598
> > > > > #PF: supervisor write access in kernel mode
> > > > > #PF: error_code(0x0003) - permissions violation

> > Hm, and it seems to explode on dereferencing the static_key* in %rsi
> 
> 								  ^^^ %rdi of
> course
> 
> >   21:   48 8b 37                mov    (%rdi),%rsi
> >   24:   83 e6 03                and    $0x3,%esi
> >   27:   48 09 c6                or     %rax,%rsi
> >   2a:*  48 89 37                mov    %rsi,(%rdi)              <-- trapping
> > instruction
> > 
> > which looks odd, as it derefenced it successfully just 3 instructions ago.

It seems the MMU (I guess ?) allows to read it, but disallows to write it:
"supervisor write access in kernel mode".
-- 
Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University