On Thu, Oct 26, 2023 at 11:24:39AM +0100, Will Deacon wrote:
> On Thu, Oct 26, 2023 at 11:58:00AM +0300, Mike Rapoport wrote:
> > On Mon, Oct 23, 2023 at 06:14:20PM +0100, Will Deacon wrote:
> > > On Mon, Sep 18, 2023 at 10:29:46AM +0300, Mike Rapoport wrote:
> > > > diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
> > > > index dd851297596e..cd6320de1c54 100644
> > > > --- a/arch/arm64/kernel/module.c
> > > > +++ b/arch/arm64/kernel/module.c
...
> > > > - if (module_direct_base) {
> > > > - p = __vmalloc_node_range(size, MODULE_ALIGN,
> > > > - module_direct_base,
> > > > - module_direct_base + SZ_128M,
> > > > - GFP_KERNEL | __GFP_NOWARN,
> > > > - PAGE_KERNEL, 0, NUMA_NO_NODE,
> > > > - __builtin_return_address(0));
> > > > - }
> > > > + module_init_limits();
> > >
> > > Hmm, this used to be run from subsys_initcall(), but now you're running
> > > it _really_ early, before random_init(), so randomization of the module
> > > space is no longer going to be very random if we don't have early entropy
> > > from the firmware or the CPU, which is likely to be the case on most SoCs.
> >
> > Well, it will be as random as KASLR. Won't that be enough?
>
> I don't think that's true -- we have the 'kaslr-seed' property for KASLR,
> but I'm not seeing anything like that for the module randomisation and I
> also don't see why we need to set these limits so early.
x86 needs execmem initialized before ftrace_init() so I thought it would be
best to setup execmem along with most of MM in mm_core_init().
I'll move execmem initialization for !x86 to a later point, say
core_initcall.
> Will
--
Sincerely yours,
Mike.
