MIPS: asm: uaccess: Add EVA support for str*_user operations

The str*_user functions are used to securely access NULL terminated
strings from userland. Therefore, it's necessary to use the appropriate
EVA function. However, if the string is in kernel space, then the normal
instructions are being used to access it. The __str*_kernel_asm and
__str*_user_asm symbols are the same for non-EVA mode so there is no
functional change for the non-EVA kernels.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: kernel: unaligned: Add EVA instruction wrappers

Use the load/store instruction wrappers from asm/asm.h to
perform such operations when operating in EVA mode.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: kernel: unaligned: Handle unaligned accesses for EVA

Handle unaligned accesses when we access userspace memory
EVA mode.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: checksum: Split the 'copy_user' symbol

The 'copy_user' symbol can be used to copy from or to
userland so we will use two different symbols for these
operations. This makes no difference in the existing code,
but when the core is operating in EVA mode, different instructions
need to be used to read and write to userland address space.
The old function has also been renamed to 'copy_kernel' to denote
that it is suitable for copy data to and from kernel space.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: lib: csum_partial: Merge EXC and load/store macros

Each load/store macro always adds an entry to the __ex_table
using the EXC macro. There are cases where a load instruction may
never fail such as when we are sure the load happens in the kernel
address space. Therefore, we merge these the EXC and LOADX/STOREX
macros into a single one. We also expand the argument list in the EXC
macro to make the macro more flexible. The extra 'type' argument is not
used by this commit, but it will be used when EVA support is added to
memcpy.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: lib: csum_partial: Add macro to build csum_partial symbols

In preparation for EVA support, we use a macro to build the
__csum_partial_copy_user main code so it can be shared across
multiple implementations. EVA uses the same code but it replaces
the load/store/prefetch instructions with the EVA specific ones
therefore using a macro avoids unnecessary code duplications.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: lib: csum_partial: Add EVA support

Use EVA specific functions to read and write data to
user address space.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: checksum: Split kernel and user copy operations

In EVA mode, different instructions need to be used to read/write
from kernel and userland. In non-EVA mode, there is no functional
difference. The current address limit is checked to decide the
type of operation that will be performed.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS: asm: checksum: Add MIPS specific csum_and_copy_from_user function

A MIPS specific csum_and_copy_from_user function is necessary because
the generic one from include/net/checksum.h will not work for EVA.
This is because the generic one will link to symbols from lib/checksum.c
which are not EVA aware.

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