MIPS: kernel: signal: Prevent save/restore FPU context in user memory

EVA does not have FPU specific instructions for reading or writing
FPU registers from userspace memory.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: r4kcache: Build flushing code for instruction cache

Build code to invalidate an address range in the  instruction cache
using the Hit Invalidate cache operation.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: r4kcache: Add protected cache operation for EVA

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: r4kcache: Add EVA cache flushing functions

Add EVA cache flushing functions similar to non-EVA configurations.
Because the cache may or may not contain user virtual addresses, we
need to use the 'cache' or 'cachee' instruction based on whether we
flush the cache on behalf of kernel or user respectively.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: kernel: {ftrace,kgdb}: Set correct address limit for cache flushes

When flushing the icache, make sure the address limit is correct
so the appropriate 'cache' instruction will be used. This has no
impact on cores operating in non-eva mode. However, when EVA is
enabled, we ensure that 'cache' will be used instead of 'cachee'.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: page: Allow __pa_symbol overrides

This will allow platforms to use an alternative way to get
the physical address of a symbol.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: cpu: Add cpu flag for Enhanced Virtual Addressing

The MIPS *Aptiv family uses bit 28 in Config5 CP0 register to
indicate whether the core supports EVA or not.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: kernel: cpu-probe: Enable EVA option on supported cores

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: kernel: proc: Add EVA to the list of CPU features

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: mm: init: Add free_init_pages() callback for EVA

A core in EVA mode can have any possible segment mapping, so the
default free_initmem_default() function may not always work as expected.
Therefore, add a callback that platforms can use to free up the init section.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: mm: c-r4k: Build EVA {d,i}cache flushing functions

Build EVA specific cache flushing functions (ie cachee).
They will be used by a subsequent patch.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: mm: c-r4k: Add support for flushing user pages from cache

Use the userspace cache flushing functions if the interrupted
process is a userspace one.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: mm: c-r4k: Flush scache to avoid cache aliases

There is a chance for the secondary cache to have memory
aliases. This can happen if the bootloader is in a non-EVA mode
(or even in EVA mode but with different mapping from the kernel)
and the kernel switching to EVA afterwards. It's best to flush
the icache to avoid having the secondary CPUs fetching stale
data from it.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: Configure Segment Control registers for EVA boot

The Malta board aliases 0x80000000 - 0xffffffff to 0x00000000
- 0x7fffffff ignoring the 256 MB IO hole in 0x10000000.
The physical memory is shifted to 0x80000000 so up to 2GB
can be used. Kuseg is expanded to 3GB (due to board limitations
only 2GB can be accessed) and lowmem (kernel space) is expanded to 2GB.

The Segment Control registers are programmed as follows:

Virtual memory           Physical memory           Mapping
0x00000000 - 0x7fffffff  0x80000000 - 0xfffffffff   MUSUK (kuseg)
0x80000000 - 0x9fffffff  0x00000000 - 0x1ffffffff   MUSUK (kseg0)
0xa0000000 - 0xbf000000  0x00000000 - 0x1ffffffff   MUSUK (kseg1)
0xc0000000 - 0xdfffffff             -                 MK  (kseg2)
0xe0000000 - 0xffffffff             -                 MK  (kseg3)

The location of exception vectors remain the same since 0xbfc00000
(traditional exception base) still maps to 0x1fc00000 physical.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: spaces.h: Add spaces.h file for Malta (EVA)

Add a spaces.h file for Malta to override certain memory macros
when operating in EVA mode.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: malta-memory: Add support for the 'ememsize' variable

The 'ememsize' variable is used to denote the real RAM which is
present on the Malta board. This is different compared to 'memsize'
which is capped to 256MB. The 'ememsize' is used to get the actual
physical memory when setting up the Malta memory layout. This only
makes sense in case the core operates in the EVA mode, and it's
ignored otherwise.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: malta-memory: Use the PHYS_OFFSET to build the memory map

PHYS_OFFSET is used to denote the physical start address of the
first bank of RAM. When the Malta board is in EVA mode, the physical
start address of RAM is shifted to 0x80000000 so it's necessary to use
this macro in order to make the code EVA agnostic.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: malta-memory: Add free_init_pages_eva() callback

Use a Malta specific function to free the init section once the
kernel has booted. When operating in EVA mode, the physical memory
is shifted to 0x80000000. Kernel is loaded into 0x80000000 (virtual)
so the offset between physical and virtual addresses is 0.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: malta-init: Fix System Controller memory mapping for EVA

Shift System Controller memory mapping to 0x80000000

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: malta: Add support for SMP EVA

Allow secondary cores to program their segment control registers
during smp bootstrap code. This enables EVA on Malta SMP
configurations

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>