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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>
This commit is contained in:
John David Anglin 2016-12-06 22:02:01 -05:00 committed by Helge Deller
parent c78e710c1c
commit febe42964f
1 changed files with 1 additions and 21 deletions
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22
arch/parisc/kernel/pacache.S
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@ -892,19 +892,10 @@ ENTRY_CFI(flush_dcache_page_asm)
fdc,m r31(%r28)
fdc,m r31(%r28)
fdc,m r31(%r28)
cmpb,COND(<<) %r28, %r25,1b
cmpb,COND(<<) %r28, %r25,1b
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