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>
Add set_memory_ro/rw/x/nx architecture hooks to change the page
attribution.
Use own set_memory.h rather than generic set_memory.h (i.e.
include/asm-generic/set_memory.h), because we want to add other function
prototypes here.
Note: We can only set attributes for KVRANGE/XKVRANGE kernel addresses.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
1/8 of kernel addresses reserved for shadow memory. But for LoongArch,
There are a lot of holes between different segments and valid address
space (256T available) is insufficient to map all these segments to kasan
shadow memory with the common formula provided by kasan core, saying
(addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET
So LoongArch has a arch-specific mapping formula, different segments are
mapped individually, and only limited space lengths of these specific
segments are mapped to shadow.
At early boot stage the whole shadow region populated with just one
physical page (kasan_early_shadow_page). Later, this page is reused as
readonly zero shadow for some memory that kasan currently don't track.
After mapping the physical memory, pages for shadow memory are allocated
and mapped.
Functions like memset()/memcpy()/memmove() do a lot of memory accesses.
If bad pointer passed to one of these function it is important to be
caught. Compiler's instrumentation cannot do this since these functions
are written in assembly.
KASan replaces memory functions with manually instrumented variants.
Original functions declared as weak symbols so strong definitions in
mm/kasan/kasan.c could replace them. Original functions have aliases
with '__' prefix in names, so we could call non-instrumented variant
if needed.
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
