On Fri, Jul 10, 2020 at 08:55:42PM -0700, Palmer Dabbelt wrote:
> +ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
> + size_t csize, unsigned long offset,
> + int userbuf)
> +{
> + void *vaddr;
> +
> + if (!csize)
> + return 0;
> +
> + vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
> + if (!vaddr)
> + return -ENOMEM;
Doing a memremap for every page is very inefficient. Also I don't see
why you'd want to even do that. All memory is in the direct mapping
for RISC-V. For other architecture that support highmem kmap_atomic_pfn
would do the job, which is what I'd use in a generic version.
