powerpc: Fix demotion of segments to 4K pages
PATCH 1/1 powerpc: Fix demotion of segments to 4K pages
When demoting a process to use 4K HW pages (instead of 64K), which happens under various circumstances such as doing cache inhibited mappings on machines that do not support 64K CI pages, the assembly hash code calls back into the C function flush_hash_page(). This function prototype was recently changed to accomodate for 1T segments but the assembly call site was not updated, causing applications that do demotion to hang. In addition, when updating the per-CPU PACA for the new sizes, we didn't properly update the slice "map", thus causing the SLB miss code to re-insert segments for the wrong size.
This fixes both and adds a warning comment next to the C implementation to try to avoid it next time someone changes it.
---
Note that the PACA update bug is also present in 2.6.23, I'll do a patch for -stable separately, once this one is upstream.
arch/powerpc/mm/hash_low_64.S +3 -2
@@ -331,7 +331,7 @@ htab_pte_insert_failure: *****************************************************************************/ /* _hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid, - * pte_t *ptep, unsigned long trap, int local) + * pte_t *ptep, unsigned long trap, int local, int ssize) */ /*
@@ -557,7 +557,8 @@ htab_inval_old_hpte: mr r4,r31 /* PTE.pte */ li r5,0 /* PTE.hidx */ li r6,MMU_PAGE_64K /* psize */ - ld r7,STK_PARM(r8)(r1) /* local */ + ld r7,STK_PARM(r9)(r1) /* ssize */ + ld r8,STK_PARM(r8)(r1) /* local */ bl .flush_hash_page b htab_insert_pte
arch/powerpc/mm/hash_utils_64.c +4 -2
@@ -793,8 +793,7 @@ int hash_page(unsigned long ea, unsigned }if (user_region) {if (psize !=get_paca ()->context.user_psize) { -get_paca ()->context.user_psize = - mm->context.user_psize; +get_paca ()->context = mm->context;slb_flush_and_rebolt (); } } else if (get_paca()->vmalloc_sllp !=
@@ -887,6 +886,9 @@ void hash_preload(struct mm_struct *mm,local_irq_restore (flags); } +/* WARNING: This is called from hash_low_64.S, if you change this prototype, +* do not forget to update the assembly call site ! +*/ void flush_hash_page (unsigned long va,real_pte_t pte,int psize,int ssize,int local) {
Hi Ben,
arch/powerpc/mm/hash_utils_64.c void hash_preload(struct mm_struct *mm, · line 891
Quoted 7 lines · Benjamin Herrenschmidt
arch/powerpc/mm/hash_utils_64.c +3
-0@@ -887,6 +886,9 @@ void hash_preload(struct mm_struct *mm,local_irq_restore (flags); } +/* WARNING: This is called from hash_low_64.S, if you change this prototype, +* do not forget to update the assembly call site ! +*/
Since we're already policing whitespace on this list today: We're normally not using spaces before exclamation marks.
-Olof
Quoted 7 lines · Olof Johansson
Hi Ben,
Quoted 4 lines · Benjamin Herrenschmidt
arch/powerpc/mm/hash_utils_64.c +0
-0@@ -887,6 +886,9 @@ void hash_preload(struct mm_struct *mm,local_irq_restore (flags); }
Quoted 6 lines
arch/powerpc/mm/hash_utils_64.c void hash_preload(struct mm_struct *mm, · line 891
Quoted 3 lines
arch/powerpc/mm/hash_utils_64.c +3
-0+/* WARNING: This is called from hash_low_64.S, if you change this prototype, +* do not forget to update the assembly call site ! +*/ Since we're already policing whitespace on this list today: We're normally not using spaces before exclamation marks.
And I don't care, I will continue adding them because the opposite is fugly :-)
There is a limit to what I accept from the style police, it's not like Linux has to look like it's written by a single person either.
Ben.
Quoted 15 lines · Benjamin Herrenschmidt
Quoted 7 lines · Olof Johansson
Hi Ben,
Quoted 4 lines · Benjamin Herrenschmidt
arch/powerpc/mm/hash_utils_64.c +0
-0@@ -887,6 +886,9 @@ void hash_preload(struct mm_struct *mm,local_irq_restore (flags); }Quoted 6 lines
arch/powerpc/mm/hash_utils_64.c void hash_preload(struct mm_struct *mm, · line 891
Quoted 3 lines
arch/powerpc/mm/hash_utils_64.c +3
-0+/* WARNING: This is called from hash_low_64.S, if you change this prototype, +* do not forget to update the assembly call site ! +*/ Since we're already policing whitespace on this list today: We're normally not using spaces before exclamation marks.
Quoted 2 lines
And I don't care, I will continue adding them because the opposite is fugly :-)
Yeah , I know what you mean . This looks so much more natural .
Quoted 2 lines
There is a limit to what I accept from the style police, it's not like Linux has to look like it's written by a single person either.
Good one ! That one goes to the bookmark list . :-)
I agree though , whitespace policing tends to be counter-productive , together with (minor) grammar and spelling errors in comments . Still, people love to point them out so I figured I would do it too .
- Olof
Quoted 5 lines · Olof Johansson
Quoted 1 line
And I don't care, I will continue adding them because the opposite
is
Quoted 1 line
fugly :-)
Yeah , I know what you mean . This looks so much more natural .
Who said it has to be consistent ? :-)
I use spaces before ? and ! mostly. In fact, it might even be the rule in french, I'm not too sure :-)
Ben.
Quoted 11 lines · Benjamin Herrenschmidt
Quoted 5 lines · Olof Johansson
Quoted 1 line
And I don't care, I will continue adding them because the opposite
is
Quoted 1 line
fugly :-)
Yeah , I know what you mean . This looks so much more natural .
Who said it has to be consistent ? :-)
I use spaces before ? and ! mostly. In fact, it might even be the rule in french, I'm not too sure :-)
Yes it is http://en.wikipedia.org/wiki/Punctuation_in_French ;-)
C'est permis, mais seulement en Français ;-)
With kind regards,
Geert Uytterhoeven
Software Architect
Sony Network and Software Technology Center Europe
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On Mon, 29 Oct 2007 12:05:18 +1100 Benjamin Herrenschmidt <[email protected]> wrote:
Just to be fair to Olof, "diffstats are good" ...
Signature · 3 lines
Cheers, Stephen Rothwell [email protected] http://www.canb.auug.org.au/~sfr/