[PATCH/RFC] remove frv usage of flush_tlb_pgtables()

[PATCH/RFC] remove frv usage of flush_tlb_pgtables()

[Benjamin Herrenschmidt]

frv is the last user in the tree of that dubious hook, and it's my
understanding that it's not even needed. It's only called by memory.c
free_pgd_range() which is always called within an mmu_gather, and
tlb_flush() on frv will do a flush_tlb_mm(), which from my reading
of the code, seems to do what flush_tlb_ptables() does, which is
to clear the cached PGE.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

Hi David ! I want to get rid of flush_tlb_pgtables() as part of my
work on the mmu_gather and frv seems to be the only one to still use it.
I don't think it needs it though, can you double check ?

Thanks !
Ben.

Index: linux-work/include/asm-frv/tlbflush.h
===================================================================
--- linux-work.orig/include/asm-frv/tlbflush.h	2007-07-27 09:40:38.000000000 +1000
+++ linux-work/include/asm-frv/tlbflush.h	2007-07-27 09:43:17.000000000 +1000
@@ -57,8 +57,7 @@ do {								\
 #define __flush_tlb_global()			flush_tlb_all()
 #define flush_tlb()				flush_tlb_all()
 #define flush_tlb_kernel_range(start, end)	flush_tlb_all()
-#define flush_tlb_pgtables(mm,start,end) \
-	asm volatile("movgs %0,scr0 ! movgs %0,scr1" :: "r"(ULONG_MAX) : "memory");
+#define flush_tlb_pgtables(mm,start,end)	do { } while(0)
 
 #else
 


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Re: [PATCH/RFC] remove frv usage of flush_tlb_pgtables()

[David Howells]

Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> frv is the last user in the tree of that dubious hook, and it's my
> understanding that it's not even needed. It's only called by memory.c
> free_pgd_range() which is always called within an mmu_gather, and
> tlb_flush() on frv will do a flush_tlb_mm(), which from my reading
> of the code, seems to do what flush_tlb_ptables() does, which is
> to clear the cached PGE.

Yeah...  I hadn't got around to killing myself yet.

Acked-By: David Howells <dhowells@redhat.com>

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Re: [PATCH/RFC] remove frv usage of flush_tlb_pgtables()

[Benjamin Herrenschmidt]

On Fri, 2007-07-27 at 10:43 +0100, David Howells wrote:
> > frv is the last user in the tree of that dubious hook, and it's my
> > understanding that it's not even needed. It's only called by
> memory.c
> > free_pgd_range() which is always called within an mmu_gather, and
> > tlb_flush() on frv will do a flush_tlb_mm(), which from my reading
> > of the code, seems to do what flush_tlb_ptables() does, which is
> > to clear the cached PGE.
> 
> Yeah...  I hadn't got around to killing myself yet.

Ahem... hopefully you won't get around to it any time soon :-)

Cheers,
Ben.


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