xtensa: use CONFIG_USE_OF instead of CONFIG_OF

CONFIG_OF can be set by a randconfig or by a user -- without setting the
early flattree option (OF_EARLY_FLATTREE). This causes build errors.
However, if randconfig or a user sets USE_OF in the Xtensa config,
the right kconfig symbols are set to fix the build.

Fixes these build errors:

../arch/xtensa/kernel/setup.c:67:19: error: ‘__dtb_start’ undeclared here (not in a function); did you mean ‘dtb_start’?
67 | void *dtb_start = __dtb_start;
| ^~~~~~~~~~~
../arch/xtensa/kernel/setup.c: In function 'xtensa_dt_io_area':
../arch/xtensa/kernel/setup.c:201:14: error: implicit declaration of function 'of_flat_dt_is_compatible'; did you mean 'of_machine_is_compatible'? [-Werror=implicit-function-declaration]
201 | if (!of_flat_dt_is_compatible(node, "simple-bus"))
../arch/xtensa/kernel/setup.c:204:18: error: implicit declaration of function 'of_get_flat_dt_prop' [-Werror=implicit-function-declaration]
204 | ranges = of_get_flat_dt_prop(node, "ranges", &len);
../arch/xtensa/kernel/setup.c:204:16: error: assignment to 'const __be32 *' {aka 'const unsigned int *'} from 'int' makes pointer from integer without a cast [-Werror=int-conversion]
204 | ranges = of_get_flat_dt_prop(node, "ranges", &len);
| ^
../arch/xtensa/kernel/setup.c: In function 'early_init_devtree':
../arch/xtensa/kernel/setup.c:228:9: error: implicit declaration of function 'early_init_dt_scan'; did you mean 'early_init_devtree'? [-Werror=implicit-function-declaration]
228 | early_init_dt_scan(params);
../arch/xtensa/kernel/setup.c:229:9: error: implicit declaration of function 'of_scan_flat_dt' [-Werror=implicit-function-declaration]
229 | of_scan_flat_dt(xtensa_dt_io_area, NULL);

xtensa-elf-ld: arch/xtensa/mm/mmu.o:(.text+0x0): undefined reference to `xtensa_kio_paddr'

Fixes: da844a81779e ("xtensa: add device trees support")
Fixes: 6cb971114f63 ("xtensa: remap io area defined in device tree")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: move XCHAL_KIO_* definitions to kmem_layout.h

These address and size definitions define xtensa kernel memory layout,
move them from vectors.h to the kmem_layout.h

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: platform-specific handling of coherent memory

Memory layout is not fixed for noMMU xtensa configurations. Platforms
that need to use coherent DMA should implement platform_vaddr_* helpers
that check address type (cached/uncached) and convert addresses between
these types.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: add support for KASAN

Cover kernel addresses above 0x90000000 by the shadow map. Enable
HAVE_ARCH_KASAN when MMU is enabled. Provide kasan_early_init that fills
shadow map with writable copies of kasan_zero_page. Call
kasan_early_init right after mmu initialization in the setup_arch.
Provide kasan_init that allocates proper shadow map pages from the
memblock and puts these pages into the shadow map for addresses from
VMALLOC area to the end of KSEG. Call kasan_init right after memblock
initialization. Don't use KASAN for the boot code, MMU and KASAN
initialization and page fault handler. Make kernel stack size 4 times
larger when KASAN is enabled to avoid stack overflows.
GCC 7.3, 8 or newer is required to build the xtensa kernel with KASAN.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: consolidate kernel stack size related definitions

Define kernel stack size in kmem_layout and use it in
current_thread_info, GET_THREAD_INFO, THREAD_SIZE and THERAD_SIZE_ORDER
definitions.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: cleanup MMU setup and kernel layout macros

Make kernel load address explicit, independent of the selected MMU
configuration and configurable from Kconfig. Do not restrict it to the
first 512MB of the physical address space.

Cleanup kernel memory layout macros:

- rename VECBASE_RESET_VADDR to VECBASE_VADDR, XC_VADDR to VECTOR_VADDR;
- drop VIRTUAL_MEMORY_ADDRESS and LOAD_MEMORY_ADDRESS;
- introduce PHYS_OFFSET and use it in __va and __pa definitions;
- synchronize MMU/noMMU vectors, drop unused NMI vector;
- replace hardcoded vectors offset of 0x3000 with Kconfig symbol.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: add alternative kernel memory layouts

MMUv3 is able to support low memory bigger than 128MB.
Implement 256MB and 512MB KSEG layouts:

- add Kconfig selector for KSEG layout;
- add KSEG base address, size and alignment definitions to
arch/xtensa/include/asm/kmem_layout.h;
- use new definitions in TLB initialization;
- add build time memory map consistency checks.

See Documentation/xtensa/mmu.txt for the details of new memory layouts.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: move kernel mapping addresses into kmem_layout.h

Create a header dedicated to memory layout definitions. Include it from
places where these definitions are needed.
Express vmalloc area address, VIRTUAL_MEMORY_ADDRESS and KERNELOFFSET
through KSEG address.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>