arm64: kill flush_cache_all()

The documented semantics of flush_cache_all are not possible to provide
for arm64 (short of flushing the entire physical address space by VA),
and there are currently no users; KVM uses VA maintenance exclusively,
cpu_reset is never called, and the only two users outside of arch code
cannot be built for arm64.

While cpu_soft_reset and related functions (which call flush_cache_all)
were thought to be useful for kexec, their current implementations only
serve to mask bugs. For correctness kexec will need to perform
maintenance by VA anyway to account for system caches, line migration,
and other subtleties of the cache architecture. As the extent of this
cache maintenance will be kexec-specific, it should probably live in the
kexec code.

This patch removes flush_cache_all, and related unused components,
preventing further abuse.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Geoff Levand <geoff@infradead.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/cache.S

@@ -26,79 +26,6 @@
 
 #include "proc-macros.S"
 
-/*
- *	__flush_dcache_all()
- *
- *	Flush the whole D-cache.
- *
- *	Corrupted registers: x0-x7, x9-x11
- */
-__flush_dcache_all:
-	dmb	sy				// ensure ordering with previous memory accesses
-	mrs	x0, clidr_el1			// read clidr
-	and	x3, x0, #0x7000000		// extract loc from clidr
-	lsr	x3, x3, #23			// left align loc bit field
-	cbz	x3, finished			// if loc is 0, then no need to clean
-	mov	x10, #0				// start clean at cache level 0
-loop1:
-	add	x2, x10, x10, lsr #1		// work out 3x current cache level
-	lsr	x1, x0, x2			// extract cache type bits from clidr
-	and	x1, x1, #7			// mask of the bits for current cache only
-	cmp	x1, #2				// see what cache we have at this level
-	b.lt	skip				// skip if no cache, or just i-cache
-	save_and_disable_irqs x9		// make CSSELR and CCSIDR access atomic
-	msr	csselr_el1, x10			// select current cache level in csselr
-	isb					// isb to sych the new cssr&csidr
-	mrs	x1, ccsidr_el1			// read the new ccsidr
-	restore_irqs x9
-	and	x2, x1, #7			// extract the length of the cache lines
-	add	x2, x2, #4			// add 4 (line length offset)
-	mov	x4, #0x3ff
-	and	x4, x4, x1, lsr #3		// find maximum number on the way size
-	clz	w5, w4				// find bit position of way size increment
-	mov	x7, #0x7fff
-	and	x7, x7, x1, lsr #13		// extract max number of the index size
-loop2:
-	mov	x9, x4				// create working copy of max way size
-loop3:
-	lsl	x6, x9, x5
-	orr	x11, x10, x6			// factor way and cache number into x11
-	lsl	x6, x7, x2
-	orr	x11, x11, x6			// factor index number into x11
-	dc	cisw, x11			// clean & invalidate by set/way
-	subs	x9, x9, #1			// decrement the way
-	b.ge	loop3
-	subs	x7, x7, #1			// decrement the index
-	b.ge	loop2
-skip:
-	add	x10, x10, #2			// increment cache number
-	cmp	x3, x10
-	b.gt	loop1
-finished:
-	mov	x10, #0				// swith back to cache level 0
-	msr	csselr_el1, x10			// select current cache level in csselr
-	dsb	sy
-	isb
-	ret
-ENDPROC(__flush_dcache_all)
-
-/*
- *	flush_cache_all()
- *
- *	Flush the entire cache system.  The data cache flush is now achieved
- *	using atomic clean / invalidates working outwards from L1 cache. This
- *	is done using Set/Way based cache maintainance instructions.  The
- *	instruction cache can still be invalidated back to the point of
- *	unification in a single instruction.
- */
-ENTRY(flush_cache_all)
-	mov	x12, lr
-	bl	__flush_dcache_all
-	mov	x0, #0
-	ic	ialluis				// I+BTB cache invalidate
-	ret	x12
-ENDPROC(flush_cache_all)
-
 /*
  *	flush_icache_range(start,end)
  *