Commit febe4296 authored Dec 06, 2016 by John David Anglin Committed by Helge Deller Dec 07, 2016

parisc: Remove unnecessary TLB purges from flush_dcache_page_asm and flush_icache_page_asm



We have four routines in pacache.S that use temporary alias pages:
copy_user_page_asm(), clear_user_page_asm(), flush_dcache_page_asm() and
flush_icache_page_asm().  copy_user_page_asm() and clear_user_page_asm()
don't purge the TLB entry used for the operation.
flush_dcache_page_asm() and flush_icache_page_asm do purge the entry.

Presumably, this was thought to optimize TLB use.  However, the
operation is quite heavy weight on PA 1.X processors as we need to take
the TLB lock and a TLB broadcast is sent to all processors.

This patch removes the purges from flush_dcache_page_asm() and
flush_icache_page_asm.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Helge Deller <deller@gmx.de>

parent c78e710c

arch/parisc/kernel/pacache.S

+1 −21

Original line number	Diff line number	Diff line
		@@ -896,15 +896,6 @@ ENTRY_CFI(flush_dcache_page_asm)
		fdc,m r31(%r28)

		sync

		#ifdef CONFIG_PA20
		pdtlb,l %r0(%r25)
		#else
		tlb_lock %r20,%r21,%r22
		pdtlb %r0(%r25)
		tlb_unlock %r20,%r21,%r22
		#endif

		bv %r0(%r2)
		nop
		.exit
		@@ -979,17 +970,6 @@ ENTRY_CFI(flush_icache_page_asm)
		fic,m %r31(%sr4,%r28)

		sync

		#ifdef CONFIG_PA20
		pdtlb,l %r0(%r28)
		pitlb,l %r0(%sr4,%r25)
		#else
		tlb_lock %r20,%r21,%r22
		pdtlb %r0(%r28)
		pitlb %r0(%sr4,%r25)
		tlb_unlock %r20,%r21,%r22
		#endif

		bv %r0(%r2)
		nop
		.exit

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