[PATCH v3 04/13] mm/execmem, arch: convert remaining overrides of module_alloc to execmem

[Will Deacon]

On Mon, Oct 30, 2023 at 09:00:53AM +0200, Mike Rapoport wrote:
> 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.

Thanks, Mike.

Will