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Commit 9a94c579 authored by David Gibson's avatar David Gibson Committed by Paul Mackerras
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[PATCH] powerpc: More hugepage boundary case fixes 



Blah.  The patch [0] I recently sent fixing errors with
in_hugepage_area() and prepare_hugepage_range() for powerpc itself has
an off-by-one bug.  Furthermore, the related functions
touches_hugepage_*_range() and within_hugepage_*_range() are also
buggy.  Some of the bugs, like those addressed in [0] originated with
commit 7d24f0b8 where we tweaked the
semantics of where hugepages are allowed.  Other bugs have been there
essentially forever, and are due to the undefined behaviour of '<<'
with shift counts greater than the type width (LOW_ESID_MASK could
return non-zero for high ranges with the right congruences).

The good news is that I now have a testsuite which should pick up
things like this if they creep in again.

[0] "powerpc-fix-for-hugepage-areas-straddling-4gb-boundary"

Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 26925c59

arch/powerpc/mm/hugetlbpage.c

+1 −1
Original line number Diff line number Diff line
@@ -295,7 +295,7 @@ int prepare_hugepage_range(unsigned long addr, unsigned long len) 
	if (addr < 0x100000000UL)

		err = open_low_hpage_areas(current->mm,

					  LOW_ESID_MASK(addr, len));

	if ((addr + len) >= 0x100000000UL)

	if ((addr + len) > 0x100000000UL)

		err = open_high_hpage_areas(current->mm,

					    HTLB_AREA_MASK(addr, len));

	if (err) {

include/asm-powerpc/page_64.h

+11 −6
Original line number Diff line number Diff line
@@ -103,8 +103,9 @@ extern unsigned int HPAGE_SHIFT; 
#define HTLB_AREA_SIZE		(1UL << HTLB_AREA_SHIFT)

#define GET_HTLB_AREA(x)	((x) >> HTLB_AREA_SHIFT)



#define LOW_ESID_MASK(addr, len)    (((1U << (GET_ESID(addr+len-1)+1)) \

		                      - (1U << GET_ESID(addr))) & 0xffff)

#define LOW_ESID_MASK(addr, len)    \

	(((1U << (GET_ESID(min((addr)+(len)-1, 0x100000000UL))+1)) \

	  - (1U << GET_ESID(min((addr), 0x100000000UL)))) & 0xffff)

#define HTLB_AREA_MASK(addr, len)   (((1U << (GET_HTLB_AREA(addr+len-1)+1)) \

		                      - (1U << GET_HTLB_AREA(addr))) & 0xffff)
@@ -113,17 +114,21 @@ extern unsigned int HPAGE_SHIFT; 
#define ARCH_HAS_SETCLEAR_HUGE_PTE



#define touches_hugepage_low_range(mm, addr, len) \

	(LOW_ESID_MASK((addr), (len)) & (mm)->context.low_htlb_areas)

	(((addr) < 0x100000000UL) \

	 && (LOW_ESID_MASK((addr), (len)) & (mm)->context.low_htlb_areas))

#define touches_hugepage_high_range(mm, addr, len) \

	(HTLB_AREA_MASK((addr), (len)) & (mm)->context.high_htlb_areas)

	((((addr) + (len)) > 0x100000000UL) \

	  && (HTLB_AREA_MASK((addr), (len)) & (mm)->context.high_htlb_areas))



#define __within_hugepage_low_range(addr, len, segmask) \

	((LOW_ESID_MASK((addr), (len)) | (segmask)) == (segmask))

	( (((addr)+(len)) <= 0x100000000UL) \

	  && ((LOW_ESID_MASK((addr), (len)) | (segmask)) == (segmask)))

#define within_hugepage_low_range(addr, len) \

	__within_hugepage_low_range((addr), (len), \

				    current->mm->context.low_htlb_areas)

#define __within_hugepage_high_range(addr, len, zonemask) \

	((HTLB_AREA_MASK((addr), (len)) | (zonemask)) == (zonemask))

	( ((addr) >= 0x100000000UL) \

	  && ((HTLB_AREA_MASK((addr), (len)) | (zonemask)) == (zonemask)))

#define within_hugepage_high_range(addr, len) \

	__within_hugepage_high_range((addr), (len), \

				    current->mm->context.high_htlb_areas)