Re: [PATCH v3 05/11] arc: mm: Convert to GENERIC_IOREMAP

[Baoquan He]

On 10/12/22 at 10:17am, Christophe Leroy wrote:
......
> > -/*
> > - * ioremap with access flags
> > - * Cache semantics wise it is same as ioremap - "forced" uncached.
> > - * However unlike vanilla ioremap which bypasses ARC MMU for addresses in
> > - * ARC hardware uncached region, this one still goes thru the MMU as caller
> > - * might need finer access control (R/W/X)
> > - */
> > -void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
> > -			   unsigned long flags)
> > +void __iomem *
> > +arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
> >   {
> > -	unsigned int off;
> > -	unsigned long vaddr;
> > -	struct vm_struct *area;
> > -	phys_addr_t end;
> > -	pgprot_t prot = __pgprot(flags);
> > -
> > -	/* Don't allow wraparound, zero size */
> > -	end = paddr + size - 1;
> > -	if ((!size) || (end < paddr))
> > -		return NULL;
> > -
> >   	/* An early platform driver might end up here */
> >   	if (!slab_is_available())
> > -		return NULL;
> > +		return IOMEM_ERR_PTR(-EINVAL);
> 
> I think the slab_is_available() check should be done in the generic 
> functions. On all architectures SLAB must be available before you can 
> use get_vm_area_caller() and vunmap()

Tend to agree.

W/o slab initialized, the get_vm_area_caller() calling definitely will
fail. The arch's early ioremap code could call into this.