Add HIGHMEM (High Memory) support for LoongArch, mostly needed by 32BIT
kernel because the size of kernel virtual memory space is only 512MB and
the size of usable physical memory is only 256MB in this case.
HIGHMEM adds permanent kernel mapping (PKMAP) and fixed kernel mapping
(FIX_KMAP), which increase usable physical memory up to 2.25GB (2304MB).
We can just use the generic copy_user_highpage(), so remove the custom
version.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
We can support more cache attributes (e.g., CC, SUC and WUC) and page
protection when we use TLB for ioremap(). The implementation is based
on GENERIC_IOREMAP.
The existing simple ioremap() implementation has better performance so
we keep it and introduce ARCH_IOREMAP to control the selection.
We move pagetable_init() earlier to make early ioremap() works, and we
modify the PCI ecam mapping because the TLB-based version of ioremap()
will actually take the size into account.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Add memory management support for LoongArch, including: cache and tlb
management, page fault handling and ioremap/mmap support.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
