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Martin Schwidefsky 2f569afd9c CONFIG_HIGHPTE vs. sub-page page tables. ... Background: I've implemented 1K/2K page tables for s390. These sub-page page tables are required to properly support the s390 virtualization instruction with KVM. The SIE instruction requires that the page tables have 256 page table entries (pte) followed by 256 page status table entries (pgste). The pgstes are only required if the process is using the SIE instruction. The pgstes are updated by the hardware and by the hypervisor for a number of reasons, one of them is dirty and reference bit tracking. To avoid wasting memory the standard pte table allocation should return 1K/2K (31/64 bit) and 2K/4K if the process is using SIE. Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means the s390 version for pte_alloc_one cannot return a pointer to a struct page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one cannot return a pointer to a pte either, since that would require more than 32 bit for the return value of pte_alloc_one (and the pte * would not be accessible since its not kmapped). Solution: The only solution I found to this dilemma is a new typedef: a pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a later patch. For everybody else it will be a (struct page *). The additional problem with the initialization of the ptl lock and the NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and a destructor pgtable_page_dtor. The page table allocation and free functions need to call these two whenever a page table page is allocated or freed. pmd_populate will get a pgtable_t instead of a struct page pointer. To get the pgtable_t back from a pmd entry that has been installed with pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page call in free_pte_range and apply_to_pte_range. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		17 years ago
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alpha	avoid overflows in kernel/time.c	17 years ago
arm	aout: remove unnecessary inclusions of {asm, linux}/a.out.h	17 years ago
avr32	Basic PWM driver for AVR32 and AT91	17 years ago
blackfin	procfs: constify function pointer tables	17 years ago
cris	avoid overflows in kernel/time.c	17 years ago
frv	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
h8300	avoid overflows in kernel/time.c	17 years ago
ia64	time: fix typo in comments	17 years ago
m32r	avoid overflows in kernel/time.c	17 years ago
m68k	avoid overflows in kernel/time.c	17 years ago
m68knommu	avoid overflows in kernel/time.c	17 years ago
mips	MIPS: Mark all but i8259 interrupts as no-probe.	17 years ago
mn10300	mn10300: add platform MTD support for the ASB2303 board	17 years ago
parisc	procfs: constify function pointer tables	17 years ago
powerpc	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
ppc	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
s390	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
sh	Fix container_of() usage	17 years ago
sparc	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
sparc64	misc: removal of final callers using fastcall	17 years ago
um	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
v850	avoid overflows in kernel/time.c	17 years ago
x86	CONFIG_HIGHPTE vs. sub-page page tables.	17 years ago
xtensa	avoid overflows in kernel/time.c	17 years ago
.gitignore	…
Kconfig	Move Kconfig.instrumentation to arch/Kconfig and init/Kconfig	17 years ago