csky/tlb: Remove tlb_flush() define

The previous patch removed the tlb_flush_end() implementation which
used tlb_flush_range(). This means:

- csky did double invalidates, a range invalidate per vma and a full
invalidate at the end

- csky actually has range invalidates and as such the generic
tlb_flush implementation is more efficient for it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mmu_gather: Remove per arch tlb_{start,end}_vma()

Scattered across the archs are 3 basic forms of tlb_{start,end}_vma().
Provide two new MMU_GATHER_knobs to enumerate them and remove the per
arch tlb_{start,end}_vma() implementations.

- MMU_GATHER_NO_FLUSH_CACHE indicates the arch has flush_cache_range()
but does *NOT* want to call it for each VMA.

- MMU_GATHER_MERGE_VMAS indicates the arch wants to merge the
invalidate across multiple VMAs if possible.

With these it is possible to capture the three forms:

1) empty stubs;
select MMU_GATHER_NO_FLUSH_CACHE and MMU_GATHER_MERGE_VMAS

2) start: flush_cache_range(), end: empty;
select MMU_GATHER_MERGE_VMAS

3) start: flush_cache_range(), end: flush_tlb_range();
default

Obviously, if the architecture does not have flush_cache_range() then
it also doesn't need to select MMU_GATHER_NO_FLUSH_CACHE.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

csky: Fixup compile error

: error: C++ style comments are not allowed in ISO C90
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
^
error: (this will be reported only once per input file)

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: add missing brackets in a macro for tlb.h

As an earlier patch made the macro argument more complicated, compilation
now fails with:

In file included from mm/madvise.c:30:
mm/madvise.c: In function 'madvise_free_single_vma':
arch/csky/include/asm/tlb.h:11:11: error:
invalid type argument of '->' (have 'struct mmu_gather')

Link: https://lore.kernel.org/r/20190901193601.GB5208@mellanox.com
Fixes: 923bfc561e75 ("pagewalk: separate function pointers from iterator data")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

csky: Cache and TLB routines

This patch adds cache and tlb sync codes for abiv1 & abiv2.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>